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PSpice User's Guide

1. z CG Yee 10V e Ra Gout L ce Out qu Cin In B Qi ki Q2N2222 du Vin E T AC 1 v RAb2 7 Abmod 720 k Figure 84 Simple biased BJT amplifier Figure 85 is the circuit file used to run one of the following e a parametric analysis STEP shown enabled in the circuit file that sets the value of resistor Rb2 by stepping model parameter R through values spanning the specified DEV tolerance range or e aworst case analysis shown disabled in the circuit file that allows PSpice to determine the worst case value for parameter R based upon a sensitivity analysis 309 Chapter 12 Monte Carlo and sensitivity worst case analyses 310 Only one of these analyses can run in any given simulation Note The AC and worst case analysis specifications AC and WC statements are written so that the worst case analysis tries to minimize Vm OUT at 100 kHz The netlist and circuit file in Figure 85 are set up to run either a parametric STEP or worst case WC analysis of the specified AC analysis These simulations demonstrate the conditions under which worst case analysis works well and those that can produce misleading results when Worst case analysis comparing monotonic and non monotonic output with a variable parameter lib xxxx x Tnput signal and blocking capacitor Vin In 0 ac 1 Cin In B lu kkk k Amp1 ifi er KKKKK gain increases with small increase
2. Analysis type r Sweep variable 7 points per decade Time Domain Transient C Voltage source Hame or Current source a ree The analysis is run for each value of Rval 2 a ommpop Coe I z General Settings Modelnam Because the value of R1 is defined as went Carowost caso MA Rval the analysis is run for each value of EETA ne E i R1 as it logarithmically increases from Save Bias Point Sweep ype OLoad Bias Poin h tart 1002 to 10 ka in 20 steps resulting in a R Linear B total of 21 runs C Logarithmic Decade SEA Increment fi 0 C Value list Cancel Apply Help Figure 23 Parametric simulation settings 6 Click OK gt 7 From the PSpice menu choose Run to start the analysis 44 Parametric analysis Analyzing waveform families Continuing from the example above there are 21 analysis runs each with a different value of R1 After PSpice completes the simulation the Available Sections dialog box appears listing all 21 runs and the Rval parameter value for each You can select one or more runs to display To display all 21 traces 1 Inthe Available Sections dialog box click OK To select individual runs click each one separately All 21 traces the entire family of curves for VDB Out appear in the Probe window as shown in Figure 24 To see more information about the se
3. 4 REC filterexample soes ook hee we AER ee Ae Entering the design sc ku ween eos dk wed 4 oe de Running the simulation a4 64 22e 2020ne2 ease 9 Using performance analysis to plot overshoot and rise time Example frequency response vs arbitrary parameter Setting up the circuit 4 26 ako amp Foe SESH Bee bees Temperature analysis kala a 2k ed Oe BR BD Minimum requirements to run a temperature analysis Overview of temperature analysis 04 Monte Carlo and sensitivity worst case analyses 283 Chapleroverview souci ocs s os ehh ed a eb eee a aaa Se Statistical analyses 4 24 85 a4 Ge 4e Se dee Se hee ee eo Overview of statistical analyses 2 2 1 eee ee Output control for statistical analyses Model parameter values reports 0006 Waveform reports vec 6 he hee Dae eee Ree Dee Collating functions 244 064 bea e de eed DES ew ews Temperature considerations in statistical analyses Monte Carlo analysis 26t28 ceed 0 eee BY RA ORS oH ERS Reading the summary report 4 Example Monte Carlo analysis of a pressure sensor Drawing the schematic o 1 4 xs 5 Ped dae OR ee oS Defining part values lt 242o4 ee etete ctu s eke Setting up the parameters c s e gerne we oe ow EES Using resistors with models 04 Saving the design 45 64 6444 eae oe 6ae ee eS EO Defining tolerances for the resist
4. 250 Defining a time based stimulus 465 58404 55 POR we ERE 252 Overview of stimulus generation 004 252 The Stimulus Editor utility aoaaa aa hee me be RO 253 Stimulus fles aa re adti eaae aaa a 253 Configuring stimulus files 444 aaa 254 Starting the Stimulus Editor ee kee aa 254 Defining stimuli oe se escarpe dap sa Oe bee ee TE Kee ax 256 Example piecewise linear stimulus 256 Example sine wave sweep 6 6 ee ee 257 Creating new stimulus symbols 0 664460 eee ewe ee en 259 Editing a stimulus aaa BE EWS wwe Ow EO 260 To edit an existing stimulus aoao a a wes 260 To edit a PWL stimulus ooa a 000084 260 To select a time and value scale factor for PWL stimuli 260 Deleting and removing traces oaoa a 261 Chapter 11 Chapter 12 Manual stimulus configuration To manually configure a stimulus Transient time response 4 244 cee ee Bw Ra eS ORE Internal time steps in transient analyses Switching circuits in transient analyses Plotting hysteresis curves ose heb ee Re ee ee Ee POUREICOMPONENeS is gt s scs es sa aora s ee ee eR ae bk Parametric and temperature analysis 271 Chapter overview 424 4 pau4 05 424 ea PSS Eas 6 OE Ras Parametric analysis 4 4 4 444 bate Soke vey ob ZEB Minimum requirements to run a parametric analysis Overview of parametric analysis
5. Notation Examples Description Ctrl R Press Ctrl R A specific key or key stroke on the keyboard monospace Type VAC Commands text entered font from the keyborad XXV Before you begin Related documentation Documentation for OrCAD products is available in both printed and online forms To access an online manual instantly you can select it from the Help menu in its respective program for example access the Capture User s Guide from the Help menu in Capture Note The documentation you receive depends on the software configuration you have purchased The following table provides a brief description of those manuals available in both printed and online forms This manual Provides information about how to use OrCAD Capture OrCAD Capture which is a schematic capture front end program User s Guide with a direct interface to other OrCAD programs and options OrCAD Layout OrCAD Layout which is a PCB layout editor that lets you specify User s Guide printed circuit board sturcture as well as the components metal and graphics required for fabrication OrCAD PSpice amp Basics PSpice with Probe the Stimulus Editor and the Model Editor User s Guide which are circuit analysis programs that let you create simulate and test analog and digital circuit designs This manual provides examples on how to specify simulation parameters analyze simulation results edit input signals and create models
6. 3 To add additional data points either select Add from the Edit menu or click the Add Point button 4 Right click to end adding new points To select a time and value scale factor for PWL stimuli 1 Select the PWL trace by clicking on its name 2 Select Attributes from the Edit menu or click the corresponding toolbar button The Stimulus Editor utility Deleting and removing traces To delete a trace from the displayed screen select the trace name by clicking on its name then press Del This will only erase the display of the trace not delete it from your file The trace is still available by selecting Get from the Stimulus menu To remove a trace from a file select Remove from the Stimulus menu Note Once a trace is removed it is no longer retrievable Delete traces with caution Manual stimulus configuration Stimuli can be characterized by manually starting the Stimulus Editor and saving their specifications to a file These stimulus specifications can then be associated to stimulus instances in your schematic or to stimulus symbols in the symbol library To manually configure a stimulus 1 Start the Stimulus Editor by double clicking on the Stimulus Editor icon in the OrCAD program group 2 Open a stimulus file by selecting Open from the File menu If the file is not found in your current library search path you are prompted for a new file name 3 Create one or more stimuli to be used in your schematic
7. Chapter 14 Other output options describes the special symbols you can place on your schematic to generate additional information to the PSpice output file and PSpice window Analyzing waveforms 13 Chapter overview This chapter describes how to perform graphical waveform analysis of simulation results in PSpice This chapter includes the following e Overview of waveform analysis on page 13 320 e Setting up waveform analysis on page 13 324 e Viewing waveforms on page 13 327 e Analog example on page 13 341 e User interface features for waveform analysis on page 13 344 e User interface features for waveform analysis on page 13 344 e Tracking simulation messages on page 13 354 e Trace expressions on page 13 356 Chapter 13 Analyzing waveforms 320 Overview of waveform analysis You can use the waveform analysis features of PSpice to visually analyze and interactively manipulate the waveform data produced by circuit simulation PSpice uses high resolution graphics so you can view the results of a simulation both on the screen and in printed form On the screen waveforms appear as plots displayed in Probe windows within the PSpice workspace In effect waveform analysis is a software oscilloscope Performing a PSpice simulation corresponds to building or changing a breadboard and performing waveform analysis corresponds to looking at the breadboard with an oscilloscope With waveform analysis
8. lt c4 4445 6442 484 bi ee eed en 389 The dynamic range of TIME lt lt i202 2 4e8a a 389 Failure at the first time step bak x eee eee ae Ob oS Kan 390 Parasitic capacitances 4 c 900 2 ee ee Ke ee ee Re we ew 391 Inductors and transformers 0 00 000 eee eee ene 391 Bipolar transistors substrate junction 392 Diagnostics eka es et CR we ENG OE ED eS OS ew Rs 393 Index 395 Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Figure 19 Figure 20 Figure 21 Figure 22 Figure 23 Figure 24 Figure 25 Figure 26 Figure 27 Figure 28 Figure 29 Figure 30 Figure 31 Figure 32 Figure 33 User configurable data files that PSpice reads 11 Diode clipper circuit ee toe BRE See BASS ERK RS RE ES HS 16 C nnecti n POUNS lt s save ees tower ee bode e eh eee kee ewe 19 PSpice simulation output window 2 0 0 005000008 22 Simulation output file ceaous ss ee Ge bdo bw hed eew em om 24 DC sweep analysis settings db SW de ee RS RRO 27 Probe window 6 ows ekg Bek RS Rw RH ERE BR ORS oe Dee OHS 28 Clipper circuit with voltage marker on net Out 29 Voltage at In Mid and Out aaa 4h 42 Fae Seas Sd 29 Trace legend with cursors activated ooa aa eda weds 30 Trace legend with V Mid symbol outlined a
9. 176 EVALUE and GVALUE parts insted awn ee ees Oe es 176 EMULT GMULT ESUM and GSUM 6 ne 24 2 eae ee 178 Lookup tables ETABLE and GTABLE 179 Frequency domain device models 0004 181 Laplace transforms LAPLACE 24 lt 2 44 44 28444 26844 181 Frequency response tables EFREQ and GFREQ 183 Cautions and recommendations for simulation and analysis 186 Instantaneous device modeling 0 205 186 Frequency domiain parts sack cw Ree eGR RRS EER SS 187 Laplace transforms 2c 20 oes hed OMe ee eR OR BE Es 187 Non causality and Laplace transforms 188 Chebyshev filters s o 6t4 6442s hee ees ded HSS A 190 Prequency tables s 4 4 a oe 3 ded Raw amp RRR RE wo 190 Trading off computer resources for accuracy 191 Part three Chapter 7 Chapter 8 Chapter 9 Contents Basic controlled sources de ke oe ee Ee Ewe ee CHEE OA 192 Creating custom ABM parts 2 lt s lt ie 64 e5 eee OY Bee 4 192 Setting Up and Running Analyses Setting up analyses and starting simulation 195 Chapter overview 2 223 4 44 1ob 4 eee ht BESS BEERS SOE ES 195 Analysis ty Aes s y eg so sea pa Oa EAS OSE PRA Ee RO 196 Setting up analyses check tape ee hee Sek eee BES SEES 197 Execution order for standard analyses 198 Output variables 24 2405 eee Cee SR eee ed SESE S eres 199 Modifiers sores rers ses terto i erkat EVa 2
10. 5 Click OK twice to exit the dialog boxes Nested DC sweeps A second sweep variable can be selected after a primary sweep value has been specified in the DC Sweep dialog box When you specify a secondary sweep variable it forms the outer loop for the analysis That is for every increment of the second sweep variable the first sweep variable is stepped through its entire range of values Simulation Settings Example DC Nested Sweep ix General Analysis Include Files Libraries Stimulus Options Data Collection Probe Window Analysis type Sweep variable foc Sweep Voltage source Name RD C Current source Pere tne Set C Global parameter W Primary Sweep Pern Model name Monte Carlo Worst Case Temperature pall Parametric Sweep Temperature Sweep j Sweep type Save Bias Point nest Start value fio OLoad Bias Point Endivale fo Logarithmic Decade Increment fio Value list l To set up a nested sw eep 1 Under Options select the Secondary Sweep box for the DC Sweep Analysis type DC Sweep 219 Chapter 8 DC analyses 2 Enter the necessary parameter values and select the appropriate check boxes to complete the analysis specifications 220 Curve families for DC sweeps When a nested DC sweep is performed the entire curve family is displayed That is the nested DC sweep is treated as a single data section or you can think of
11. Caution Donotedit NOM LIB If you do PSpice will recreate the indexes for every model library referenced in NOM LIB This can take some time 124 Changing model library search order Two reasons why you might want to change the search order are to e reduce the search time e avoid using the wrong model when there are model names duplicated across libraries PSpice always uses the first instance To change the order of libraries 1 On the Libraries tab of the Simulation Settings dialog box a Select the library name you wish to move b Use either the Up Arrow or Down Arrow toolbar button to move the library name to a different place in the list 2 If you have listed multiple LIB commands within a single library like NOM LIB then edit the library using a text editor to change the order Example The model libraries DIODES LIB and EDIODES LIB European manufactured diodes shipped with your OrCAD programs have identically named device definitions If your design uses a device out of one of these libraries you need to position the model library containing the definition of choice earlier in the list If your system is configured as originally shipped this means you need to add the specific library to the list before NOM LIB Changing the library search path For model libraries that are configured without explicit path names PSpice first searches the directory where the current design resides then steps down
12. TRACE 2 specifies the second BRIGHTRED color used for trace display TRACE 3 specifies the third color BRIGHTBLUE used for trace display TRACE 4 specifies the fourth BRIGHTYELLOW color used for trace display TRACE _5 specifies the fifth color BRIGHTMAGENTA used for trace display TRACE 6 specifies the sixth color BRIGHTCYAN used for trace display 325 Chapter 13 Analyzing waveforms For information on what the default available colors and color order are and how to change them see Editing display and print colors in the PSPICE INI file on page 13 324 Probe Options x p Use Symbols p Trace Color Scheme Mark Data Points C Auto Normal s a Displ luati C Never C Match Axis isplay Evaluation G Always f Sequential Per Asse Display Statistics C Unique By File r Use ScrollBars gt Auto C Never C Always r Auto Update Interval Auto C Every fi sec I Highlight Error States C Eveyjo z 10 Number of Histogram Divisions 5 Number of Cursor Digits PSpice saves the selected color scheme for future waveform analyses 326 Configuring trace color schemes In the Probe Options dialog box you can set options for how the available colors and the color order specified in the PSPICE INI file are used to display the traces in a Probe window You can use e adifferent color for each trace e the same color for all the traces that belong to the same y axis e th
13. Temperature Sweep p Sweep type Save Bias Point linear Start value 0 125 Load Bias Point Leaeithme I Brigez jars ogarithmic Decade Increment fo 005 C Value list Cancel Apply Help 1 In Capture select New Simulation Profile or Edit Simulation Settings from the PSpice menu If this is a new simulation enter the name of the profile and click OK The Simulation Settings dialog box appears 2 Under Analysis type select DC Sweep 3 For the Primary Sweep option enter the necessary parameter values and select the appropriate check boxes to complete the analysis specifications 4 Click OK to save the simulation profile 5 Select Run under the PSpice menu to start the simulation Note Do not specify a DC sweep and a parametric analysis for the same variable 215 Chapter 8 DC analyses 216 Overview of DC sweep The DC sweep analysis causes a DC sweep to be performed on the circuit DC sweep allows you to sweep a source voltage or current a global parameter a model parameter or the temperature through a range of values The bias point of the circuit is calculated for each value of the sweep This is useful for finding the transfer function of an amplifier the high and low thresholds of a logic gate and so on For the DC sweep analysis specified in Figure 56 the voltage source V1 is swept from 0 125 volts to 0 125 volts by steps of 0 005 This means that the output has 0 125 0
14. To modify trace expressions 1 Click the trace name to select it selection is indicated by a color change 2 From the Edit menu choose Modify Object 3 In the Modify Trace dialog box edit the trace expression just as you would when adding a trace To modify text and ellipse labels 1 Click the text or ellipse to select it selection is indicated by a color change 2 From the Edit menu choose Modify Object 3 Edit the label by doing one of the following e Inthe Ellipse Label dialog box change the inclination angle e Inthe Text Label dialog box change the text label Moving and copying trace names and expressions Trace names and expressions can be selected and moved or copied either within the same Probe window or to another Probe window To copy or move trace names and expressions 1 Click one or more shift click trace names Selected trace names are highlighted 2 From the Edit menu choose Copy or Cut to save the trace names and expressions to the clipboard Cut removes trace names and traces from the Probe window 3 Inthe Probe window where traces are to be added do one of the following e To add trace names to the end of the currently displayed set choose Paste from the Edit menu User interface features for waveform analysis You can also double click the trace name to modify the trace expression For more information on adding traces see Adding traces from specific loaded waveform data
15. What is an instance model An instance model is a copy of the part s original model The copied model is limited to use in the current design You can customize the instance model without impacting any other design that uses the original part from the library When the schematic page editor creates the copy it assigns a unique name that is by default original_model_name Xn where nis lt blank 1 2 gt depending on the number of different instance models derived from the original model for the current design Starting the Model Editor To start editing an instance model 1 Inthe schematic page editor select the part on the schematic page 2 From the Edit menu choose PSpice Model The schematic page editor searches the configured libraries for the instance model e If found the schematic page editor starts the Model Editor which opens the library containing the instance model and displays the model for editing e If not found the schematic page editor assumes that this is a new instance model and starts the Model Editor which does the following makes a copy of the original model definition names it original_model_name Xn and displays the new model text for editing Saving design models When you save your edits the following is done for you to make sure the instance model is linked to the selected part instances in your design e The Model Editor saves the model definition to DESIGN_NAME LIB
16. because the symptom is that the Newton Raphson repeating series cannot converge onto a consistent set of voltages and currents The following discussion gives some background on the algorithms in PSpice and some guidelines for avoiding convergence problems The transient analysis has the additional possibility of being unable to continue because the time step required becomes too small from something in the circuit moving too fast This is also discussed below Newton Raphson requirements The Newton Raphson algorithm is guaranteed to converge to a solution However this guarantee has some conditions 1 The nonlinear equations must have a solution 2 The equations must be continuous 3 The algorithm needs the equations derivatives 4 The initial approximation must be close enough to the solution Each of these can be taken in order Remember that the PSpice algorithms are used in computer hardware that Introduction has finite precision and finite dynamic range that produce these limits e Voltages and currents in PSpice are limited to 1e10 volts and amps e Derivatives in PSpice are limited to 1e14 e The arithmetic used in PSpice is double precision and has 15 digits of accuracy Is there a solution Yes for any physically realistic circuit However it is not difficult to set up a circuit that has no solution within the limits of PSpice numerics Consider for example a voltage source of one megavolt con
17. Define tolerances on model parameters for statistical analyses Test behavior variations on a part Refine a model before making it available to all designs Derive subcircuit definitions from a hierarchical design Create or load the part first in the part editor then edit the model using the Model Editor Start the Model Editor and enable disable automatic part creation as needed then create or view the model Select the part instance on your schematic then edit the model using the Model Editor Select the part instance on your schematic page then edit the model using the Model Editor Use the Create Subcircuit command in the schematic page editor Running the Model Editor from the schematic page editor on page 4 101 Running the Model Editor alone on page 4 99 Starting the Model Editor from the schematic page editor in Capture on page 4 111 Running the Model Editor from the schematic page editor on page 4 101 Starting the Model Editor from the schematic page editor in Capture on page 4 111 Using the Create Subcircuit command on page 4 115 For a list of device types that the Model Editor supports see Model Editor supported device t es on page 4 95 If the Model Editor does not support the device type for the model definition that you want to create then you can edit the text using the Model Editor to create a model definition using the PSpice MODEL a
18. PSpice Basics is a limited version that does not include the Stimulus Editor OrCAD PSpice OrCAD PSpice with Probe is a circuit analysis program that lets User s Guide you create simulate and test analog only circuit designs OrCAD PSpice Optimizer OrCAD PSpice Optimizer which is an analog performance User s Guide optimization program that lets you fine tune your analog circuit designs xxvi The following table provides a brief description of those manuals available online only Related documentation This online manual Provides this OrCAD PSpice Online Reference Manual OrCAD Application Notes Online Manual OrCAD PSpice Library List Reference material for PSpice Also included detailed descriptions of the simulation controls and analysis specifications start up option definitions and a list of device types in the analog and digital model libraries User interface commands are provided to instruct you on each of the screen commands A variety of articles that show you how a particular task can be accomplished using OrCAD s products and examples that demonstrate a new or different approach to solving an engineering problem A complete list of the analog and digital parts in the model and part libraries Online Help Choosing Search for Help On from the Help menu displays an extensive online help system The online help includes e step by step instructions on how to set up PSpi
19. Using IC symbols sets the initial conditions for the bias point only It does not affect the DC sweep If your circuit design contains both an IC symbol and a NODESET symbol for the same net the NODESET symbol is ignored To specify the initial condition edit the value of the VALUE property to the desired initial condition PSpice attaches a voltage source with a 0 0002 ohm series resistance to each net to which an IC symbol is connected The voltages are clamped this way for the entire bias point calculation NODESET1 is a one pin symbol which helps calculate the bias point by providing a initial guess for some net NODESET2 is a two pin symbol which helps calculate the bias point between two nets Some or all of the circuit s nets may be given an initial guess NODESET symbols are effective for the bias point both small signal and transient bias points and for the first step of the DC sweep It has no effect during the rest of the DC sweep or during the transient analysis itself Setpoints Unlike the IC pseudocomponents NODESET provides only an initial guess for some net voltages It does not clamp those nodes to the specified voltages However by providing an initial guess NODESET symbols may be used to break the tie in a flip flop for instance and make it come up ina desired state To guess at the bias point enter the initial guess in the Value text box for the VALUE property PSpice attaches a voltage source with a 0 000
20. You can repeat this process and when you are satisfied with the results save them the Model Editor creates model libraries containing appropriate model and subcircuit definitions Analyzing the effect of model parameters on device characteristics You can also edit model parameters directly and see how changing their values affects a device characteristic As you change model parameters the Model Editor recalculates the behavior of the device characteristics and displays a new curve for each of the affected ones How to fit models For a given model the Model Editor displays a list of the device characteristics and a list of all model parameters and performance curves see Figure 29 24 bipolar lib Q2N2222 OrCAD Model Editor Ybe sat Voltage BEE EH Eie Edt View Model Plot Tools Window Help Cee ea S mme ale ModelName Type Creation Date Q Q2N2369 BIT Q2N2369 55C BJT Q2N2369 125C BJT yen ae E S amp a m e fr Vbe sat Voltage To include this spec in the model extraction please enter two or more data points in the following table Ie Vbe a 6 5U 466uA Ube 27 C 1 0mA 18mA al Collector Current E Vbelsat Vol fb Output Adm i Forward DC JE je Veeteat vat CB Capacit EEE Cepacit EE Storage Time E Gain Band Param Value Minimum Maximum Defau
21. 95 voltage source controlled 174 192 VPLOTn write voltage plot part 369 VPRINTn write voltage table part 370 VPULSE stimulus part 5 VPWL stimulus part 75 VPWL_F_N_TIMES stimulus part 76 VPWL_F_RE_FOREVER stimulus part 75 VPWL_N_TIMES stimulus part 76 VPWL_RE_FOREVER stimulus part 75 VSFFM stimulus part 76 VSIN stimulus part 76 VSRC stimulus part 74 75 78 218 233 VSTIM stimulus part 33 75 76 W WATCH view output variable part 368 waveform analysis 320 about 8 adding traces 28 cursors 350 displaying simulation results 28 39 expressions 364 functions 364 hysteresis curves 266 limiting waveform data file size 334 multiple y axes 276 output variables 356 for noise 245 363 performance analysis 49 274 placing a cursor on a trace 30 plot 321 printing Probe windows 323 setting colors 324 trace data tables 349 traces 334 traces displaying 344 traces using output variables 356 using markers 331 waveform data file DAT 14 waveform data file formats 339 waveform families 45 221 waveform data file formats 339 waveform families displaying 45 wavform analysis arithmetic expressions 364 worst case analysis 196 306 collating functions 287 example 309 hints 313 introduction 7 model parameter values reports 285 output control 285 overview 306 waveform reports 286 with temperature analysis 288 Z zoom regions Probe win
22. FTABLE frequency lookup ROW1 ROW5 table Control system parts 153 Chapter 6 Analog behavioral modeling 154 Table Control system parts continued Category Part Description Properties Laplace LAPLACE Laplace NUM DENOM transform expression Math functions ABS Ixl o x is the SORT 1 2 PWR x EXP EXP PWRS xee EXP LOG In x LOG10 log x EXP ex SIN sin x COS cos x TAN tan x ATAN tan x ARCTAN tan x Expression ABM no inputs Vout EXP1 EXP4 neice ABM1 linput Vout EXP1 EXP4 ABM2 2 inputs V out EXP1 EXP4 ABM3 3 inputs V out EXP1 EXP4 ABM I no input I out EXP1 EXP4 ABM1 I 1 input I out EXP1 EXP4 ABM2 I 2 inputs I out EXP1 EXP4 ABM3 I 3 inputs I out EXP1 EXP4 Control system parts Basic components The basic components provide fundamental functions and in many cases do not require specifying property values These parts are described below CONST VALUE constant value The CONST part outputs the voltage specified by the VALUE property This part provides no inputs and one output SUM The SUM part evaluates the voltages of the two input sources adds the two inputs together then outputs the sum This part provides two inputs and one output MULT The MULT part evaluates the voltages of the two input sources multiplies the two together then outputs the product This part provides two inputs and one output GAIN GAIN constant gain value The GAIN pa
23. For each stimulus a Name it whatever you want This name will be used to associate the stimulus specification to the stimulus instance in your schematic or to the symbol in the symbol library b Provide the transient specification From the File menu choose Save 261 Chapter 10 Transient analysis 262 In the schematic page editor configure the Stimulus Editor s output file into your schematic a From the Pspice menu choose Edit Simulation Settings a Inthe Simulation Settings dialog box select the Include Files tab bD Enter the file name specified in step 2 Ifthe stimulus specifications are for local use in the current design click the Add to design button For global use by any design use Add as global instead d Click OK Modify either the stimulus instances in the schematic or symbols in the symbol library to reference the new stimulus specification Associate the transient stimulus specification to a stimulus instance a Place a stimulus part in your schematic from the part set VSTIM ISTIM and DIGSTIMn b Click the VSTIM ISTIM or DIGSTIMn instance From the Edit menu choose Properties d Click the Implementation cell type in the name of the stimulus and click Apply e Complete specification of any VSTIM or ISTIM instances by selecting Properties from the Edit menu and editing their DC and AC attributes Click the DC cell and type its value Click the AC cell type its
24. PSpice computes the RMS sum of the noise propagated to the net by all noise generating devices in the circuit To calculate the equivalent input noise PSpice then divides total output noise by the gain from the input source to the output net This results in the amount of noise which if injected at the input source into a noiseless circuit would produce the total noise originally calculated for the output net Setting up a noise analysis To set up the noise analysis 1 From the PSpice menu choose New Simulation Profile or Edit Simulation Settings If this is a new simulation enter the name of the profile and click OK The Simulation Settings dialog box appears Simulation Settings AC Sweep General Analysis Include Files Libraries Stimulus Options Data Collection Probe window Analysis type fac Sweep Noise gt Options General Settings Monte Carlo worst Case Parametric Sweep Temperature Sweep Choose AC Sweep Noise in the Analysis type list box Under Options select General Settings if it is not already enabled AC Sweep Type Linear Start Frequency fi 00K Logarithmic End Frequency fi 0G Decade z Points Decade fi 0 r Noise Analysis V Enabled Dutput Voltage vOut IZY Source ir Interval fo x Cancel Apply Help Specify the AC sweep analysis parameters as described on page 9 235 Enable the Noise Analysis check b
25. S substrate A near side B far side C collector G gate E emitter Table 11 Noise types by device type Trace expressions Device type Noise types Meaning B GaAsFET FID flicker noise RD thermal noise associated with RD RG thermal noise associated with RG RS thermal noise associated with RS SID shot noise TOT total noise D diode FID flicker noise RS thermal noise associated with RS SID shot noise TOT total noise J JFET FID flicker noise RD thermal noise associated with RD RG thermal noise associated with RG RS thermal noise associated with RS SID shot noise TOT total noise M MOSFET FID flicker noise RB thermal noise associated with RB RD thermal noise associated with RD RG thermal noise associated with RG RS thermal noise associated with RS SID shot noise TOT total noise Q BJT FIB flicker noise RB thermal noise associated with RB RC thermal noise associated with RC RE thermal noise associated with RE SIB shot noise associated with base current SIC shot noise associated with collector current TOT total noise R resistor TOT total noise Iswitch TOT total noise Vswitch TOT total noise These variables report the contribution of the specified device s noise to the total output noise in units of V Hz This means that the sum of all device noise contributions is equal to the total output noise in V Hz NTOT ONOISE 363 Chapter 13 Analyzing waveforms 364 Analog trace exp
26. The Libraries and Include Files tabs The Libraries and Include Files tabs of the Simulation Settings dialog box are where you can add change and remove model libraries and include files from the configuration or resequence the search order Note Removing a library in this dialog box means that you are removing the model library from the configured list The library still exists on your computer and you can add it back to the configuration later To display the Libraries tab 1 In PSpice from the Simulation menu choose Edit Simulation Settings 2 Click the Libraries tab The Library Files list shows the model libraries that PSpice searches for definitions matching the parts in your design Files showing an asterisk after their name have global scope files with names left unmarked have design scope The buttons for adding model libraries to the configuration follow the same local global syntax convention Click one of the following e Add to Design for design models e Add as Global for global models How PSpice uses model libraries PSpice searches libraries for any information it needs to complete the definition of a part or to run a simulation If an up to date index does not already exist PSpice automatically generates an index file and uses the index to access only the model definitions relevant to the simulation This means Disk space is not used up with definitions that your design does not use There
27. This placeholder Means this lt output gt type of output quantity V for voltage I for current or N for noise terminal one or more terminals for devices with more than two terminals for a list of terminal IDs see Table 10 on age 13 362 AC suffix quantity to be reported for an AC analysis for a list of valid AC suffixes see Table 8 on page 13 361 lt name gt lt name gt net net pair or fully qualified device name for a list of device types see Table 9 on page 13 361 and Table 10 on page 13 362 Table 6 on page 13 358 summarizes the valid output formats Table 7 on page 13 360 provides examples of equivalent output variables Note that some of the output variable formats are unique to trace expressions Table6 Output variable formats Format Meaning Voltage variables V ac lt analog net gt lt analog net Voltage between gt and analog net ids V lt pin name gt ac lt device gt Voltage at pin name of a device Trace expressions Table6 Output variable formats continued Format Meaning V lt x gt ac lt 3 or 4 terminal device gt V lt z gt ac lt transmission line device gt Current variables I ac lt device gt I lt x gt ac lt 3 or 4 terminal device gt I lt z gt ac lt transmission line device gt Sweep variables lt DC sweep variable gt FREQUENCY TIME Noise variables V db ONOIS
28. amp 2 63 8 86 eae aE ee ee PR 88 Model library configuration 24246 4 4 e 8 RYSGR EEK DEES 89 Global vs design models and libraries 89 Nested model libraries 6242 5 naaa eee RY Be MRE ORES 4S 90 OrCAD provided models 64 4244 544 644 2644 woh od 4 90 Tools to create and edit models oa 6b Oho ee ee Oe RRS 91 Ways to create and edit models 6c cc ee bw ee eee Ew ees 92 Using the Model Editor to edit modelo s lt 6 ae 2st Re ERG RMS RAE HERR itetit hra 93 Ways to use the Model Editor s 224 4 5 45 05 bh 46 Sw ERAS 94 Model Editor supported device types 04 4 95 Ways To Characterize Models aaau 96 Creating models from data sheet information 96 Analyzing the effect of model parameters on device characteristics o oo 97 How to fit models os sis ioe s eosa BE aat Oh ee oe 97 Running the Model Editor alone aoaaa 99 Starting the Model Editor 2 4 26 2 214444 a 99 Enabling and disabling automatic part creation 100 Saving global models and parts 0 100 Running the Model Editor from the schematic page editor 101 What is an instance model 4 546 420408 258 e8 eo4 101 Starting the Model Editor ae ed amp we 4 ba ee oes A 102 Saving design models 222 ee ee eee Reed ee we Pe Peas 102 What happens if you don t save the instance model 103 The Model Editor tutorial 24421 sdn 20t e 454 48444 104 Creating the half
29. choose Part to display the Place Part dialog box Add the library for the parts you need to place a Click the Add Library button b Select SOURCE OLB from the PSpice library and click Open In the Part text box type VDC Click OK Move the pointer to the correct position on the schematic page see Figure 2 and click to place the first part Move the cursor and click again to place the second part Right click and choose End Mode to stop placing parts To place the diodes 1 From the Place menu choose Part to display the Place Part dialog box Add the library for the parts you need to place a Click the Add Library button 0 Select DIODE OLB from the PSpice library and click Open In the Part text box type D1N39 to display a list of diodes Select DIN3940 and click OK Press R to rotate the diode to the correct orientation Click to place the first diode D1 then click to place the second diode D2 Right click and choose End Mode to stop placing parts Example circuit creation ES eS Note There are two sets of library files supplied with Capture and PSpice The standard schematic part libraries are found in the directory Capture Library The part libraries that are designed for simulation with PSpice are found in the sub directory Capture Library PSpice In order to have access to specific parts you must first configure the library in Capture using the Add Library function pE o
30. lt net id gt or lt pin id gt lt fully qualified device name gt lt pin name gt out device specifies the lt fully qualified device name gt These building blocks can be used for specifying output variables as shown in Table 4 which summarizes the accepted output variable formats and Tables 5 through 8 which list valid elements for two terminal three or four terminal devices transmission line devices and AC specifications Table4 PSpice output variable formats Format Meaning V ac lt out id gt V ac lt out id gt lt out id gt V ac lt 2 terminal device out id gt V ac lt 3 or 4 terminal device out id gt or V lt x gt ac lt 3 or 4 terminal out device gt V lt x gt lt y gt ac lt 3 or 4 terminal out device gt V ac lt transmission line out id gt or V lt z gt ac lt transmission line out device gt voltage at out id voltage across and out id s voltage at a 2 terminal device out id voltage at non grounded terminal x of a3 or 4 terminal device voltage across terminals x and y ofa 3 or 4 terminal device voltage at one end Z of a transmission line device Setting up analyses 201 Chapter 7 Setting up analyses and starting simulation 202 Table4 PSpice output variable formats continued Format Meaning I ac lt 3 or 4 terminal out device gt lt X gt or I lt x gt ac lt 3 or 4 terminal
31. o Y ho 0 Aoi 4 0GHz 106Hz J A o 1661 requency Figure 62 Device and total noise traces for EXAMPLE DSN Frequency is swept from 100 kHz to 10 GHz by decades with 10 points per decade The V1 independent voltage source is the only input to an amplifier so it is the only AC stimulus to this circuit Magnitude equals 1 V and relative phase is left at zero degrees the default All other voltage sources have zero AC value Noise analysis To find out more about PSpice macros refer to PSpice A D online Help Note The source V1 is a VSIN source that is normally used for setting up sine wave signals for a transient analysis It also has an AC property so that you can use it for an AC analysis To find out more about VSIN and other source symbols that you can use for AC analysis see Using time based stimulus parts with AC and DC properties on page 3 77 247 Chapter9 AC analyses 248 Transient analysis 10 Chapter overview This chapter describes how to set up a transient analysis and includes the following sections Overview of transient analysis on page 10 250 Defining a time based stimulus on page 10 252 Transient time response on page 10 263 Internal time steps in transient analyses on page 10 265 Switching circuits in transient analyses on page 10 266 Plotting hysteresis curves on page 10 266 Fourier components on page 10 268 Chapter 10 Transient analysis
32. o oo 2 eee 320 Elements Of a plot s soss cheb cad aae aTe e eS RSS 321 Elements of a Probe window 0 a ee eens 322 Managing multiple Probe windows 323 Printing multiple windows 04 644 lt 4 4428048 G49 4 323 Setting up waveform analysis a6 o 44 4 age eM ba be eg 324 Setting up colors 246254 c8 Ss COS SAE Ee Pee GBS eG 324 Editing display and print colors in the PSPICE INI file 324 Configuring trace color schemes a aoaaa a 326 Viewing waveforms oaaao EEE SS ee we eo 327 Setting up waveform display from Capture 327 Viewing waveforms while simulating 328 Configuring update intervals 000 329 xii Contents Interacting with waveform analysis during simulation 329 Pausing a simulation and viewing waveforms 330 Using schematic page markers to add traces 331 Limiting waveform data filesize 0 4 334 Limiting file size using markers oie DG ER wR OSs 334 Limiting file size by excluding internal subcircuit data 336 Limiting file size by suppressing the first part of simulation output cease ween eet ee Raw eS 336 Using simulation data from multiple files 337 Appending waveform data files 0 4 337 Adding traces from specific loaded waveform data files 338 Saving simulation results in ASCII format 339 Analog example Gs oF
33. oe SGNF 1k PARAMETERS Peoeff 0 06 F a Pron 1 0 Rd R3 Hk 1 P Peget Prigen y Rbreak Por edk Figure 78 Pressure sensor circuit Here are a few things to know when placing and connecting the part e To get the part you want to place from the Place menu choose Part e To rotate a part before placing it press R e For V1and Meter place a generic voltage source using the VSRC part When you place the source for the meter change its name by double clicking the part and typing Meter in the Reference cell in the Parts Spreadsheet e For R1 R7 place a resistor using the R part e Place the analog ground using the 0 ground symbol 293 Chapter 12 Monte Carlo and sensitivity worst case analyses lt gt Shift w Note Because the Meter source is used to measure current it has no DC value and can be left unchanged Note The value for R3 1k 1 P Pcoeff Pnom is an expression that represents linear dependence of resistance on pressure To complete the definition for R3 you will create and define global parameters for Pcoeff P and Pnom later on in this example 294 e To connect the parts from the Place menu choose Wire e To move values or reference designators click the value or reference designator to select it then drag it to the new location Defining part values Define the part values as shown in Figure 78 For the pressure sensor you need to do the follo
34. radians SINH x sinh x where x is in radians COS x cos x where x is in radians ACOS x cos x where the result is in radians COSH x cosh x where x is in radians TAN x tan x where x is in radians ATAN x tan x where the result is in ARCTAN x radians ATAN2 y x tan y x where the result is in radians TANH x tanh x where x is in radians M x magnitude of x which is the same as ABS x P x phase of x in degrees returns 0 0 for real numbers R x real part of x IMG x imaginary part which is applicable to of x AC analysis only Using global parameters and expressions for values 71 Chapter 3 Preparing a design for simulation Note In waveform analysis this function is D x Note In waveform analysis this function is s x Example v 1 STP TIME 10ns gives a value of 0 0 until 10 nsec has elapsed then gives v 1 72 Table 10 Functions in arithmetic expressions continued This function Means this DDT x time derivative which is applicable to of x transient analysis only SDT x time integral of x which is applicable to TABLE x x1 y1 y value as a function of x MIN x y minimum of x and y MAX x y maximum of x and y LIMIT x min max min if x lt min max if x gt max else x SGN x 1ifx gt 0 Oifx 0 lifx lt 0 STP x lifx gt 0 0 otherwise IF t x y x if tis true y otherwise transient analysis only where X Yp point pairs are plott
35. s Plot menu choose Axis Settings 2 Select the X Axis tab For information about performance 3 Inthe Processing Options frame select the analysis see RLC filter example on Performance Analysis check box age llars 4 Click OK The histogram display appears The Y axis is the percent of samples You can also display this histogram by 5 From the Trace menu choose Goal Functions using the performance analysis wizard to h B ih display Bandwidth VDB OUT 1 P Choose Banavath 7 Click Eval 8 Enter VDB OUT in the Name of trace to search text box 9 Enter 1 in the db level down for bandwidth calc text box 10 Click OK then click Close to view the histogram To change the number of histogram divisions 1 From the Tools menu choose Options 2 Inthe Number of Histogram Divisions text box replace 10 with 20 3 Click OK The histogram for 1 dB bandwidth is shown in Figure 82 304 rata te m neran ne B 8 5K 1 8K i ea eee SK 2 8K 2 5K 1 Bandwidth UDBCOUT 1 n samples 100 sigma 404 553 median 1557 04 n divisions 26 minimum 44 042 98th ile 1937 74 mean 1440 71 1th Zile 766 895 maxinum 2049 8 Figure 82 1 dB bandwidth histogram The statistics for the histogram are shown along the bottom of the display The statistics show the number of Monte Carlo runs the number of divisions or ve
36. the desired name 150 Placing and specifying ABM parts Place and connect ABM parts the same way you place other parts After you place an ABM part you can edit the instance properties to customize the operational behavior of the part This is equivalent to defining an ABM expression describing how inputs are transformed into outputs The following sections describe the rules for specifying ABM expressions Net names and device names in ABM expressions In ABM expressions refer to signals by name This is also considerably more convenient than having to connect a wire froma pin on an ABM component to a point carrying the voltage of interest If you used an expression such as V 2 then the referenced net 2 in this case is interpreted as the name of a local or global net A local net is a labeled wire or bus segment in a hierarchical schematic or a labeled offpage connector A global net is a labeled wire or bus segment at the top level or a global connector OrCAD Capture recognizes these constructs in ABM expressions V lt net name gt V lt net name gt lt net name gt I lt vdevice gt When one of these is recognized Capture searches for lt net name gt or lt vdevice gt in the net name space or the device name space respectively Names are searched for first at the hierarchical level of the part being netlisted If not found there then the set of global names is searched If the fragment is not found t
37. then add a very large for example 1 Gohm resistor either e in parallel with the capacitor or open circuit or e from the isolated net to ground Example The circuit shown below connects capacitors DC open circuits such that both ends of inductor L2 are isolated from ground L1 Ci L2 c3 owyvya 2 3 4 j 10uH in 10uH in G 7 ane 1k When simulated PSpice flags nets 2 and 3 as floating The following topology solves this problem L1 C1 gt L2 c3 1 3 4 H 10UH in 10uH in c2 R3 R1 OG ER i in 1G ik Creating and editing models Chapter overview This chapter provides information about creating and editing models for parts that you want to simulate Topics are grouped into four areas introduced later in this overview If you want to find out quickly which tools to use to complete a given task and how to start then 1 Go to the roadmap in Ways to create and edit models on page 4 92 2 Find the task you want to complete 3 Go to the sections referenced for that task for more information about how to proceed Background information These sections present model library concepts and an overview of the tools that you can use to create and edit models e What are models on page 4 87 e How are models organized on page 4 88 Chapter 4 Creating and editing models 86 e Tools to create and edit models on page 4 91 Task roadmap This section helps you find other s
38. to the minimum value Output is non monotonic within the tolerance range thus producing incorrect worst case results 312 The second MODEL statement scales the nominal value of Rb2 by 1 1 to approximately 800 ohms The gain still increases with a small increase in R but a larger increase in R increases the base voltage so much that it drives the BJT into saturation and nearly eliminates the gain The worst case analysis is fooled by the sensitivity analysis into assuming that Rb2 must be minimized to degrade the gain but maximizing Rb2 is much worse see Figure 88 Note that even an optimizer which checks the local gradients to determine how the parameters should be varied is fooled by this circuit QOD oS se ae Se Sn ee 1 q 1504 max 5 i 1 0500 84 829 1 q 1 g q 1085 i Nominal 725 Ohm i 1 0000 40 246 i q 5g HC analysis result i min 5 f 950 000m 15 169 1 q 1 i a E E PPaSe Resa SS asSesse PoSSS RP sSSs seers POSR Rr SsS sSRncsse 4 8 4 9 1 6 1 1 1 2 o atx UCOut 188k Rbmod R Figure 87 Correct worst case results Nominal 800 Ohm 1 1000 140 772 1504 1 i WC analysis result woot LOS TT True worst case hae 24 3532 8 B 9 1 8 1 1 1 2 o atX U Out 180k Rbmod R Figure 88 Incorrect worst case results Worst case analysis Tips and other useful information VARY BOTH VARY DEV and VARY LOT W
39. 0000 AREER REE 13 Includ fle orra etree RMS wD ee ew ew we wee A 13 Configuring model library stimulus and include files 0 0 0 0 0000000 eee eee 13 Piles that PSpice generates o6 4 4 4 08 eps bee ee ew ee 14 Waveform datafile 0 0 0 0 0000000000004 14 PSpice output file 2 4 s s ove re ys Med be hee ee 14 Chapter 2 Simulation examples 15 Chapter overview 22468 0 h 00 kaadaa ee eee ee 15 Example circuit creation oaoa oc ee aw bee eG ee ea 16 Finding out more about setting up your design 21 hunning Popes s kei eens steria DEN Sha See d RoE 22 Performing a bias point analysis 22 amp cak 4 eee eR ee ey 22 Using the simulation output file 20 cv Gaae cae reeds 24 Finding out more about bias point calculations 25 DC sweep analysis eae 8e BES e eee REE Desh Dees 26 Setting up and running a DC sweep analysis 26 Displaying DC analysis results 244 244 54 5 aa eee deo 28 Finding out more about DC sweep analysis 31 Tra sienta alysis oos o sR RGR Oe Se RATE ae ee ee 32 Finding out more about transient analysis 36 AC sweep analysis 4 s se csa saue Aad REM Oe hee ew Rees 37 Setting up and running an AC sweep analysis 37 AC sweep analysis results ouaaa 39 Finding out more about AC sweep and noise analysis 41 FParam tric analysis oos aus Go ee ae FO Se e bw a eae 2 42 Setting up and running the param
40. 2 Place one Vdb marker on the Out net then place another on the Mid net 3 From the File menu choose Save to save the design AC sweep analysis results PSpice displays the dB magnitude 20log10 of the voltage at the marked nets Out and Mid in a Probe window as shown in Figure 20 below VDB Mid has a lowpass response due to the diode capacitances to ground The output capacitance and load resistor act as a highpass filter so the overall response illustrated by VDB out is a bandpass response Because AC is a linear analysis and the input voltage was set to 1V the output voltage is the same as the gain or attenuation of the circuit AC sweep analysis gt Note You must tirst detine a simulation profile for the AC Sweep Noise analysis in order to use advanced markers 39 Chapter 2 Simulation examples Note Depending upon where the Vphase marker was placed the trace name may be different such as VP Cout 2 VP R4 1 or VP R4 2 For more information on Probe windows and trace expressions see Chapter 13 Analyzing waveforms 40 press Ctrl x EA press Ctri V 1 OKHZ 16KHZ 100KHZ 1 6MHZ 10MHz 100HHz Frequency E pper CHE fi gure 20 dB magnitude curves for gain at Mid and Out To display a Bode plot of the output voltage including phase 1 oO Yt DD Ww From Capture s PSpice menu point to Markers point to
41. 233 ISTIM transient stimulus 76 JBREAK JFET 65 K_LINEAR transformer 64 KBREAK inductor coupling 65 KCOUPLEn coupled transmission line 64 LBREAK inductor 65 MBREAK MOSFET 65 MODEL property 138 NODESETn 376 PARAM global parameter 67 passive 64 QBREAK bipolar transistor 65 R resistor 64 RBREAK resistor 65 RVAR resistor 64 SBREAK voltage controlled switch 65 T ideal transmission line 64 TBREAK transmission line 65 TEMPLATE property 140 TnCOUPLEDx coupled transmission line 64 unmodeled 79 VAC AC stimulus 75 233 VDC DC stimulus 74 75 vendor supplied 61 VEXP transient stimulus 75 VPULSE transient stimulus 75 VPWL transient stimulus 75 VPWL_F_N_TIMES transient stimulus 76 VPWL_F_RE_FOREVER transient stimulus 75 VPWL_N_TIMES transient stimulus 76 VPWL_RE_FOREVER transient stimulus 75 VSFFM transient stimulus 76 VSIN transient stimulus 76 VSRC analog stimulus 74 75 233 VSTIM analog stimulus 75 VSTIM transient stimulus 76 WBREAK current controlled switch 65 XFRM_LINEAR transformer 64 XFRM_NONLINEAR transformer 65 ZBREAK IGBT 65 ABMn and ABMn I ABM 154 168 ABS ABM 154 167 ARCTAN ABM 154 167 ATAN ABM 154 167 BANDPASS ABM 153 158 BANDREJ ABM 153 159 CONST ABM 153 155 COS ABM 154 167 DIFF ABM 153 155 DIFFER ABM 153 160 E ABM controlled analog source 192 EFREQ ABM 17
42. ANASIM EXAMPLE EXAMPLE OPJ 3 From the PSpice menu choose Run to start the simulation PSpice generates a binary waveform data file containing the results of the simulation A new Probe window appears with the waveform data file EXAMPLE DAT already loaded Figure 96 1 Example TRAN OrCAD PSpice A D Example dat active Bi Fie Edt View Simulation Trace Plot Tools Window Help lal x a sseH8 reje sh 4 Een it QAAE KREA AV FWA AE 6 5U 7 Temperature 35 0 Time step 2 8796 03 Time 1 000E 06 End 1 000 06 AE Analysis A Watch A Devices For Help press F1 _ Time 1 000E 06 100 MNO ZAS 2 Figure 96 Waveform display for EXAMPLE DAT Because this sample project was set up as a transient analysis type the data currently loaded are the results of the transient analysis Note In this sample the voltage markers for OUTI and OUT2 are already placed in the design If the markers are not placed prior to simulating you can display the waveforms later as explained below in Displaying voltages on nets Analog example Displaying voltages on nets After selected an analysis voltages on nets and currents into device pins can be displayed in the Probe windows using either schematic markers or output variables as will be demonstrated in this example To display the voltages at the OUT1 and OUT2 nets using output vari
43. Basing new parts on a custom set of parts on page 5 133 Example If the model library is MYPARTS LIB then the Model Editor creates the part library MYPARTS OLB If you want to save the open model library to a new library then 1 From the File menu choose Save As 2 Enter the name of the new model library If you want to save only the model definition that you are currently editing to a different library then 1 From the Part menu select Export 2 Enter the name of the new file 3 If you want PSpice to search this file automatically configure it in Capture using the Libraries tab on the Simulation Settings dialog box 100 Enabling and disabling automatic part ceation Part creation in the Model Editor is optional By default automatic part creation is enabled However if you previously disabled part creation you will need to enable it before creating a new model and part To automatically create parts for new models 1 2 Note From the Tools menu choose Options If not already checked select Always Create Part to enable automatic part creation Under Save Part To enter the name of the part library for the new part Choose either e Part Library Path Same As Model Library to create or open the OLB file that has the same name prefix as the currently open model library LIB e User Defined Part Library and then enter a file name in the Part Library Name text box If you select a user d
44. DESO RE eee he E 69 Specifying expressions a2 a kek ce Zea Ree RE Re 69 Defining power supplies 242424422 ee4GR ee ee F4e 22S Ea a 74 For the analog portion of your circuit ooa a 74 Denning stimuli sa 4444 84S pe ee Se PRS Kee E AE E e e x Z5 Analog SUMO s 4 05 ee ae eH OL Oe RE PE ee ee Da 75 Using VSTIM and ISTIM 646 dee eee R EEE ROHS 76 If you want to specify multiple stimulus types 77 Things t watch fof ks ee sacom aoka ee RE eee Bee E 79 Unmodeled parts naaa hd he eweh d sae dO Ss 79 Do this if the part in question is from the OrCAD libraries 79 Check for this if the part in question is custom built 81 Unconfigured model stimulus or include files 81 Check for this 2 0 0 0 kka E Era OE 82 Unmodeled pins lt 4 2 Soe Ne 4 we Be ee eS Ee 82 Check for this arrevirat bh Be eA Bw BR we REO EES 83 Missing ground s es ge mopa ee ee ak Oe ee Be eS 83 Check for this se 2 6 4 fea SR we ee ee RS 83 Missing DC path te ground 4 44 s see eee eae bea eS 84 Check for this 2 0 0 0 AN APEAREN EENEG 84 Contents Chapter 4 vi Creating and editing models 85 Chapter overview lt 4 2364244649 64h bee eee eA EEE EH 85 What are models oie kkk Re ARO ME ESS OR Re Rw 87 Models defined as model parameter sets 87 Models defined as subcircuit netlists 0 87 How are models organized 225 64 4 4 44 es dee hen eee ee 88 Model libraries 4 Sam
45. Find the numeric value that you want to replace a component value model parameter value or other property value Replace the value with the name of the global parameter using the following syntax global_parameter_name The curly braces tell PSpice to evaluate the parameter and use its value Expressions An expression is a mathematical relationship that you can use to define a numeric or boolean TRUE FALSE value PSpice evaluates the expression to a single value every time e itreads in anew circuit and e a parameter value used within an expression changes during an analysis Spedfying expressions To use an expression in your circuit 1 Find the numeric or boolean value you want to replace a component value model parameter value other property value or logic in an IF function test see page 3 72 for a description of the IF function 2 Replace the value with an expression using the following syntax expression where expression can contain any of the following e standard operators listed in Table 9 e built in functions listed in Table 10 e user defined functions e system variables listed in Table 11 e user defined global parameters e literal operands The curly braces tell PSpice to evaluate the expression and use its value Using global parameters and expressions for values Example A parameter that changes with each step of a DC sweep or parametric analysis Example Suppose you
46. Gt ee eRe eS 341 Waveform display for EXAMPLE DAT 342 Cursors positioned on a trough and peak of V 1 352 Waveform display for a persistent hazard o aoaaa aaa 355 SEPON e eneg kan oe Gk oe a Enp EG Boe OE Se SEs 376 xvii Figures xviii Tables Table 1 Table 2 Table 3 Table 4 Table 5 Table 2 1 Table 10 Table 2 1 Table 2 1 Table 2 2 Table 2 3 Table 2 4 Table 5 Table 6 Table 7 Table 8 Table 9 Table 10 Table 11 Table 12 Table 13 Table 14 Table 15 Table 16 Table 17 Table 1 Table 2 Table 3 Table 4 Table 5 Table 6 Table 7 DC analysis types 4 eae pe ee Go RS eR Ome eee ee ye 3 PCC analysis types e iae Pa She GG FEM Bead Se KS RAPS ES EES 4 Time based analysis types 1 eee ee ee 5 Parametric and temperature analysis types 4 6 Statistical analysis types d44 24 he Oe eR Koe RETRO RS eH EE 7 25 Association of cursors with mouse buttons a oaoa aaa 30 31 36 41 48 51 58 59 Passive pafis 6 65 ai Aa n eee RRA G G aa BORE ERS S RES 64 Breakout parts oos se soa so sse ten ee aeee REDE e a x 65 Operators in expressions cca hee eRe he Ree oe RR AD 70 Functions in arithmetic expressions 2 2 ee ee ee 71 Syste yariabl s s so eaan e kaa aa ORR n A a aa wee ow Ee E A 73 74 75 77 78 80 Models supported in the Model Editor naaa aaa aa 95 Sample diode data sheet values n oaoa aa a 106 Part names for custom pa
47. Monte Carlo and sensitivity worst case analyses 12 Chapter overview This chapter describes how to set up Monte Carlo and sensitivity worst case analyses and includes the following sections e Statistical analyses on page 12 284 e Monte Carlo analysis on page 12 289 e Worst case analysis on page 12 306 Chapter 12 Monte Carlo and sensitivity worst case analyses Generating statistical results Asthe number of Monte Carlo or worst case runs increases simulation takes longer and the data file gets larger Large data files may be slow to open and slow to draw traces One way to work around thisis to set up an overnight batch job to run the simulation and execute commands You can even set up the batch job to produce a series of plots on paper to be ready for you in the morning 284 Statistical analyses Monte Carlo and sensitivity worst case are statistical analyses This section describes information common to both types of analyses See Monte Carlo analysis on page 12 289 for information specific to Monte Carlo analyses and see Worst case analysis on page 12 306 for information specific to sensitivity worst case analyses Overview of statistical analyses The Monte Carlo and worst case analyses vary the lot or device tolerances of devices between multiple runs of an analysis DC AC or transient Before running the analysis you must set up the model and or lot tolerances of the model paramete
48. OK The Simulation Settings dialog box appears R4 RAMonte ak Meter 2 Zak R RMonte1 R5 vt k R RTherm Zz ial Pressure Sensor PARAMETERS Pepet 0 06 Fnom 1 0 3 1k 14 P Pooeff Pnom f Figure 80 Pressure sensor circuit with RMontel and RTherm model definitions 2 Select DC Sweep in the Analysis type list box 3 In the Sweep Variable frame select Global Parameter 4 Enter the following values Monte Carlo analysis See Setting up analyses on page 7 197 for a description of the Simulation Settings dialog box 299 Chapter 12 Monte Carlo and sensitivity worst case analyses 300 Table 3 In this text box Type this Parameter name P Start value 0 End value 53 0 Increment Oel To set up the Monte Carlo analysis Sno wo A WS N FF Select the Monte Carlo Worst Case option Check Monte Carlo if it is not already selected In the Number of runs text box type 10 In the Save data from list box select All Type I Meter in the Output variable text box Click OK to save the simulation profile Running the analysis and viewing the results To complete setup simulate and view results 1 From Capture s PSpice menu choose Run to start the simulation When the simulation is complete PSpice automatically displays the selected waveform Because PSpice ran a Monte Carlo analysis it saved multiple runs or sections o
49. PARAMS IO_LEVEL IO_LEVEL MNTYMXDLY MNTYMXDLY Note For clarity the PSPICETEMPLATE property value is shown here in multiple lines in a part definition it is specified in one line no line breaks Table 3 To find out more about this property See this PSPICETEMPLATE page 5 140 Defining part properties needed for simulation Here are the things to check when editing part properties f Does the PSPICETEMPLATE specify the correct number of pins nodes V Are the pins nodes in the PSPICETEMPLATE specified in the proper order f Do the pin node names in the PSPICETEMPLATE match the pin names on the part To edit a property needed for simulation 1 Inthe schematic page editor select the part to edit 2 From the Edit menu choose Properties to display the Parts spreadsheet of the Property Editor 3 Click in the cell of the column you want to change for example PSPICETEMPLATE or click the New button to add a property and type the property name in the Name text box 4 f needed type a value in the Value text box 5 Click Apply to update the design then close the spreadsheet 139 Chapter 5 Creating parts for models Caution Creating parts not intended for simulation Some part libraries contain parts designed only for board layout PSpice cannot simulate these parts This means they do not have PSPICETEMPLATE properties or that the PSPICETEMPLATE property value is blank
50. PSpice window Capture provides a special WATCH 1 part that lets you monitor voltage values for up to three nets in your schematic as a DC sweep AC sweep or transient analysis proceeds Results are displayed in PSpice To display voltage values in the PSpice window 1 6 Place and connect a WATCH1 part from the PSpice library SPECIAL OLB on an analog net Double click the WATCH1 part instance to display the Parts spreadsheet In the ANALYSIS property column type DC AC or TRAN transient for the type of analysis results you want to see Enter values in the LO and HI properties columns to define the lower and upper bounds respectively on the values you expect to see on this net Repeat steps 1 through 4 for up to two more WATCH1 instances Start the simulation For example in the schematic fragment shown below WATCH1 parts are connected to the Mid and Vcc nets After starting the simulation PSpice displays voltages on the Mid and Vcc nets yec oO eH gt e R2 Z ie D1 3 3k DiIN3940 Le 4 Mid 4 Writing additional results to the PSpice output file Capture provides special parts that let you save additional simulation results to the PSpice output file as either line printer plots or tables Generating plots of voltage and current values You can generate voltage and current line printer plots for any DC sweep AC sweep or transient analysis To generate plots of volta
51. See Setting up analyses on page 7 197 for a description of the Analysis Setup dialog box 250 Overview of transient analysis Minimum requirements to run a transient analysis Minimum cdrait design requirements Circuit should contain one of the following An independent source with a transient specification see Table 10 An initial condition on a reactive element A controlled source that is a function of time Minimum program setup requirements 1 From the PSpice menu choose New Simulation Profile or Edit Simulation Settings If this is a new simulation enter the name of the profile and click OK The Simulation Settings dialog box appears From the Analysis type list box select Time Domain Transient Specify the required parameters for the transient analysis you want to run Click OK to save the simulation profile From the PSpice menu choose Run to start the simulation Overview of transient analysis Simulation Settings Transient Analysis General Setting Load Bias Point 251 Chapter 10 Transient analysis 252 Defining a time based stimulus Overview of stimulus generation Symbols that generate input signals for your circuit can be divided into two categories e those whose transient behavior is characterized graphically using the Stimulus Editor e those whose transient behavior is characterized by manually defining their properties within Capture Their symbols are s
52. Settings to modify any of the analysis setup parameters From the Simulation menu choose Run or click the Run toolbar button to begin the simulation Setting up batch simulations Multiple simulations can be run in batch mode when starting PSpice directly with circuit file input You can use batch mode for example to run a number of simulations overnight There are two ways to do this as described below Multiple simulation setups within one circuit file Multiple circuit simulation descriptions can be concatenated into a single circuit file and simulated all at once with PSpice Each circuit simulation description in the file must begin with a title line and end with a END statement The simulator reads all the circuits in the circuit file and then processes each one in sequence The data file and simulation output file contain the outputs from each circuit in the same order as they appeared in the circuit 207 Chapter 7 Setting up analyses and starting simulation 208 file The effect is the same as if you had run each circuit separately and then concatenated all of the outputs Running simulations with multiple circuit files You can direct PSpice to simulate multiple circuit files using either of the following methods Method 1 1 From the Start menu point to the OrCAD program group then choose PSpice Select Open Simulation from the File menu from the PSpice window Do one of the following e Ty
53. The Simulation Settings dialog box appears 3 Choose AC Sweep Noise in the Analysis type list box 4 Specify the required parameters for the AC sweep or noise analysis you want to run 3 Click OK to save the simulation profile 6 From the PSpice menu select Run to start the simulation What is AC sweep AC sweep is a frequency response analysis PSpice calculates the small signal response of the circuit to a combination of inputs by transforming it around the bias point and treating it as a linear circuit Here are a few things to note e Nonlinear devices such as voltage or current controlled switches are transformed to linear circuits about their bias point value before PSpice runs the linear small signal analysis e Because AC sweep analysis is a linear analysis it only considers the gain and phase response of the circuit it does not limit voltages or currents The best way to use AC sweep analysis is to set the source magnitude to one This way the measured output equals the gain relative to the input source at that output Setting up an AC stimulus To run an AC sweep analysis you need to place and connect one or more independent sources and then set the AC magnitude and phase for each source To set up an AC stimulus 1 Place and connect one of these symbols in your schematic Table 2 For voltage input Use this When you are running VAC An AC sweep analysis only VSRC Multiple analys
54. The output is a current applied between nets 5 and 0 The Laplace transform describes a Control system parts 1 1 001 3 Figure 40 LAPLACE part example one XP SORT C s RL 1 Figure 42 LAPLACE part example two 165 Chapter 6 Analog behavioral modeling 166 lossy transmission line R L and C are the resistance inductance and capacitance of the line per unit length If Ris small the characteristic impedance of such a line is Z R j a L j a C the delay per unit length is L C and the loss in dB per unit length is 23 R Z This could be represented by the device in Figure 42 The parameters R L and C can be defined in a PARAM statement contained in a model file Refer to the online OrCA D PSpice A D Reference Manual for more information about using PARAM statements More useful however is for R L and C to be arguments passed into a subcircuit This part has the following characteristics NUM EXP SQRT C s R L s DENOM 1 This produces a PSpice netlist declaration like this GLOSSY 5 O LAPLACE V 10 exp sqrt C s R L s The Laplace transform parts are however an inefficient way in both computer time and memory to implement a delay For ideal delays we recommend using the transmission line part instead Control system parts Math functions The ABM math function parts are shown in Table 1 For each device the corresponding temp
55. This part type definition form name prefix diode MODEL D bipolar transistor MODEL Q bipolar transistor SUBCKT X Darlington model IGBT MODEL Z JFET MODEL J power MOSFET MODEL M operational amplifier SSUBCKT X voltage comparator SUBCKT X nonlinear magnetic core MODEL K voltage regulator SUBCKT X voltage reference SUBCKT X This is the standard PSpice device letter notation Refer to the online OrCA D PSpice A D Reference Manual The Model Editor only supports SUBCKT models that were generated by the Model Editor However you can edit the text of a SUBCKT model created manually or by another tool using the Model Editor When you load a SSUBCKT model that the Model Editor did not create the Model Editor displays the text of the model for editing Using the Model Editor to edit models Device types that the Model Editor models using the MODEL statement are based on the models built into PSpice Note The model parameter defaults used by the Model Editor are different from those used by the models built into PSpice 95 Chapter 4 Creating and editing models Testing and verifying models created with the Model Editor Each curve in the Model Editor is defined only by the parameters being adjusted For the diode the forward current curve only shows the part of the current equation that is associated with the forward characteristic parameters such as IS N Rs However PSpice uses the full eq
56. Vdb OUT 21 Click OK 5 Use the search commands to find the value of the difference trace at its maximum and at a specific frequency a C d The search command tells PSpice to search for the point on the trace where the x axis value is 100 46 From the Tools menu point to Cursor and choose Display Right click then left click the trace part triangle for Vdb Out 1 Vdb Out 21 Make sure that you left click last to make cursor 1 the active cursor From the Trace menu point to Cursor and choose Max From the Trace menu point to Cursor and choose Search Commands In the Search Command text box type the following search forward x value 100 Select 2 as the Cursor to Move option Parametric analysis g Click OK Figure 25 shows the Probe window with cursors aa aaa aaa ea fen J da A F A Probe Curse i A1 100 000 35 776 i A2 100 0909 17 874 N i dif 180 090H 17 902 EE EE EEEE a 18Hz 168KHZ 1 OMHZ 1OMHZ 168MHZ 100Hz 1 OKHZ 1OKHZ a udb out 1 vdb out 21 vjudb out 1 vdb out 21 Frequency Figure 25 Small signal frequency response at 100 and 10 kQ input resistance Note that the Y value for cursor 2 in the cursor box is about 17 87 This indicates that when R1 is set to 10 kQ the small signal attenuation of the circuit at 100Hz is 17 87dB greater than when R1 is 100 From the Trace menu point to Cursor and choose Display to turn off the dis
57. W V So if you add this trace V 5 1D M13 the axis values are labeled with W For a demonstration of analog trace presentation see Analog example on page 13 341 366 e MIL and mil are not supported e With the exception of the m and M scale suffixes PSpice is not case sensitive therefore upper and lower case characters are equivalent Unit suffixes are only used to label the axis they never affect the numerical results Therefore it is always safe to leave off a unit suffix The units to use for trace expressions are shown in Table 13 Table13 Output units for trace expressions Symbol Unit V volt A amps W watt d degree of phase S second Hz hertz Other output options 14 Chapter overview This chapter describes how to output results in addition to those normally written to the data file or output file e Viewing analog results in the PSpice window on page 14 368 explains how to monitor the numerical values for voltages or currents on up to three nets in your circuit as the simulation proceeds e Writing additional results to the PSpice output file on page 14 369 explains how to generate additional line plots and tables of voltage and current values to the PSpice output file Chapter 14 Other output options If the results move outside of the specified bounds PSpice pauses the simulation so that you can investigate the behavior 368 View ing analog results in the
58. When placing parts e Leave space to connect the parts with wires e You will change part names and values that do not match those shown in Figure 2 later in this section 17 Chapter 2 Simulation examples To move the text associated with the diodes or any other object 1 Click the text to select it then drag the text to a new location To place the other parts o 1 From the Place menu choose Part to display the Place Part dialog box 2 Add the library for the parts you need to place a Click the Add Library button 0 Select ANALOG OLB from the PSpice library and click Open 3 Follow similar steps as described for the diodes to place the parts listed below according to Figure 2 The part names you need to type in the Part name text box of the Place Part dialog box are shown in parentheses e resistors R e capacitor C lt t 4 To place the off page connector parts OFFPAGELEFT R click the Place Off Page Connector button on the tool palette 5 Add the library for the parts you need to place a Click the Add Library button b Select CAPSYM OLB from the Capture library and click Open 6 Place the off page connector parts according to Figure 2 GNO 7 To place the ground parts 0 click the GND button on the tool palette 8 Add the library for the parts you need to place a Click the Add Library button b Select SOURCE OLB from the PSpice library and click Open 9 Place the ground parts acc
59. analyses Running transient analysis on switching circuits can lead to long run times PSpice must keep the internal time step short compared to the switching period but the circuit s response extends over many switching cycles One method of avoiding this problem is to transform the switching circuit into an equivalent circuit without switching The equivalent circuit represents a sort of quasi steady state of the actual circuit and can correctly model the actual circuit s response as long as the inputs do not change too fast Plotting hysteresis curves Transient analysis can be used to look at a circuit s hysteresis Consider for instance the circuit shown in Figure 65 netlist in Figure 66 Figure 65 ECL compatible Schmitt trigger Plotting hysteresis curves Capture Netlist ae 2 50 3 50 5 185 8 760 6 100 8 260 0 85 7 SPF 0 0 M 7 2 5 6 6 D D D D AA DD le ee a Im OP N m np gt re gt N RI dc 5 lt lt lt ODWDDWDDDADDD mF 4 go oO N b OUUU Om pei r ji S 1 0V 2MS 1 8V ja a DOOO D gt WP Fr 1 Figure 66 Netlist for Schmitt trigger circuit The QSTD model is defined as MODEL QSTD NPN is 1e 16 bf 50 br 0 1 rb 50 rc 10 tf 12ns tr 5ns cje 4pF pe 8 me 4 cjc 5pF pc 8 mc 333 ccs 1pF va 50 Instead of using the DC sweep to look at the hysteresis use the tra
60. append and click OK 337 Chapter 13 Analyzing waveforms or press The Simulation Output Variables list in the Add Traces dialog box contains the output variables for all loaded waveform data files Example To plot the V 1 output for data section 1 from the second data file loaded type the following trace expression V 1 1 f2 You can also use the name of the loaded data file to specify it For example to plot the V 1 output for all data sections of a loaded data file MYFILE DAT type the following trace expression V 1 MYFILE DAT jo w a o UCOuC trace symbols Figure 93 Trace legend symbols 338 If the file has multiple sections of data for the selected analysis type the Available Sections dialog box appears Do one of the following e Click the sections you want to use e Click the All button to use all sections Click OK Adding traces from spedfic loaded waveform data files If two or more waveform data files have identical simulation output variables trace expressions that include those variables generate traces for each file However you can specify which waveform data file to use in the trace expression You can also determine which waveform data file was used to generate a specific trace To add a trace from a specific loaded waveform data file 1 3 In PSpice from the Trace menu choose Add Trace to display the Add Traces dialog box In the Trace Expression text box type
61. are ordered so your definition precedes any other definitions Starting the Model Editor from the schematic page editor in Capture Start the model editor from the schematic page editor in Capture when you want to e define tolerances on model parameters for statistical analyses e test behavior variations on a part or e refine a model before making it available to all designs This means editing models for part instances in your design When you select a part instance and edit its model the schematic page editor automatically creates an instance model that you can then change Editing model text To find out more about instance model naming conventions see What is an instance model on page 4 112 To find out more about search order in the model library see Changing model library search order on page 4 124 You can also use the model editor to view the syntax for a model definition When you are finished viewing be sure to quit the Model Editor without saving the library so the schematic page editor does not create an instance model 111 Chapter 4 Creating and editing models For more information on instance models see Reusing instance models on page 4 118 After you start the Model Editor you can proceed to change the text as described in To display the model text on page 4 110 To find out how Capture searches the library see Changing model library search order on page 4 124 112
62. board layout The unmodeled pins map into packages but have no electrical significance PSpice ignores unmodeled pins during simulation Check for this Are there connections to unmodeled pins If so do one of the following e Remove wires connected to unmodeled pins e If you expect the connection to affect simulation To find out more about searching for parts results find an equivalent part that models the pinsin see Finding the part that you want question and draw the connections on page 3 62 Missing ground If for every net in your circuit you see this message in the PSpice output file ERROR Node node_name is floating then your circuit may not be tied to ground Check for this Are there ground parts named 0 zero connected appropriately in your design If not place and connect one or more as needed in your design You can use the 0 zero ground part in SOURCE OLB or any other ground part as long as you change its name to 0 83 Chapter 3 Preparing a design for simulation Note When calculating the bias point solution PSpice treats capadtors as open circuits and inductors as short circuits 84 Missing DC path to ground If for selected nets in your circuit you see this message in the PSpice output file ERROR Node node_name is floating then you may be missing a DC path to ground Check for this Are there any nets that are isolated from ground by either open circuits or capacitors If so
63. box In the Value text box type 5v Click OK Continue changing the Part Value properties of the parts until all the parts are defined as in Figure 2 on page 2 16 Your schematic page should now have the same parts wiring labels and properties as Figure 2 on page 2 16 To save your design 1 From the File menu choose Save Finding out more about setting up your design About setting up a design for simulation For a checklist of all of the things you need to do to set up your design for simulation and how to avoid common problems see Chapter 3 Preparing a design for simulation Example circuit creation 21 Chapter 2 Simulation examples You can set up a simulation profile to run one analysis at a time To run multiple analyses for example both DC sweep and transient analyses set up a batch simulation For more information see Chapter 7 Setting up analyses and starting simulation The root schematic listed is the schematic page associated with the simulation profile you are creating 22 Running PSpice When you perform a simulation PSpice generates an output file OUT While PSpice is running the progress of the simulation appears and is updated in the PSpice simulation output window see Figure 4 vm Simulation Profle SCHEMATIC Bias AN Simulation running circuit file for profil Bias Reading and checking circuit Circuit read in and checked no errors Calculating bias
64. design To create a part for the subcircuit 1 In the schematic page editor move to the level of hierarchy for which you want to create a subcircuit SUBCKT definition From the Place menu choose Hierarchical Port From the File menu choose Save In the Project Manager from the Tools menu choose Create Netlist Select the PSpice tab In the Options frame select Create SubCircuit Format Netlist Click OK to generate the subcircuit definition and save it to DESIGN_NAME SUB To configure the subcircuit file 1 In the schematic page editor from the PSpice menu choose Edit Simulation Settings to display the Simulation Settings dialog box Click either the Libraries tab or the Include Files tab then configure DESIGN_NAME SUB as either a model library or an include file see Configuring model libraries on page 4 120 If necessary refine the subcircuit definition for the new part or for a part instance on your schematic page using the Model Editor see Editing model text on page 4 110 From Capture s Edit menu choose Part to start the part editor Create a new part for the subcircuit definition One way to do this is to use the part wizard See Chapter 5 Creating parts for models for a complete discussion Changing the model reference to an existing model definition Changing the model reference to an existing model definition Parts are linked to models by the model name assigned to t
65. e Ifthe library is new the Model Editor configures DESIGN_NAME LIB for local use e The schematic page editor assigns the new model name to the Implementation property for each of the selected part instances To save instance models 1 Inthe Model Editor from the File menu choose Save 2 From the File menu choose Exit to quit the Model Editor Editing model text Actions that automatically configure the instance model library for global use instead Instance model libraries are normally configured for design use However if you perform the following action the model editor configures the library for global use instead e Save the model to a different library by typing a new file name in the Library text box in the Save To frame 113 Chapter 4 Creating and editing models To find out more about PSpice command and netlist syntax refer to the online OrCA D PSpice A D Reference Manual 114 Example editing a Q2N2222 instance model Suppose you have a design named MY OP J that contains several instances of a Q2N2222 bipolar transistor Suppose also that you are interested in the effect of base resistance variation on one specific device Q6 To do this you need to do the following e Define a tolerance in this example 5 on the Rb model parameter e Set up and run a Monte Carlo analysis The following example demonstrates how to set up the instance model for Q6 Starting the Model Editor To start t
66. ee Bu 1 00 2 00 3 00 4 o 5 Buu o ID HM1 5U U_UD 50K u uD Figure 59 Operating point determination for each member of the curve family 222 Bias point Bias point Minimum requirements to run a bias point analysis Minimum circuit design requirements None Minimum program setup requirements 1 Under Analysis type in the Simulation Settings dialog box select Bias Point 2 For the General Settings option enter the necessary parameter values and select the appropriate check boxes to complete the analysis specifications 3 Click OK to save the simulation profile 4 In Capture from the PSpice menu select Run to start the simulation Overview of bias point The bias point is calculated for any analysis whether or Also see Save and load bias point not the Bias Point analysis is enabled in the Simulation on page A 374 Settings dialog box However additional information is reported when the Bias Point analysis is enabled When Bias Point analysis is not enabled only analog node voltages and states are reported to the output file 223 Chapter 8 DC analyses 224 When the Bias Point analysis is enabled the following information is reported to the output file e alist of all analog node voltages e the currents of all voltage sources and their total power e alist of the small signal parameters for all devices If Bias Point is enabled you can suppress the reporting of the bias po
67. have declared a parameter named FACTOR with a value of 1 2 and want to scale a 10 V independent voltage source VEE by the value of FACTOR To do this set the DC property of VEE to 10 FACTOR PSpice evaluates this expression to 10 1 2 or 12 volts For more information on user defined functions see the FUNC command in the Commands chapter in the online OrCA D PSpice A D Reference Manual For more information on user defined parameters see Using global parameters and expressions for values on page 3 67 69 Chapter 3 Preparing a design for simulation Table9 Operators in expressions This operator Includes this dass operator Which means arithmetic addition or string concatenation 7 subtraction 7 multiplication division s exponentiation logical unary NOT boolean OR A boolean XOR amp boolean AND relational equality test l non equality test gt greater than test gt greater than or equal to test lt less than test lt less than or equal to test Logical and relational operators are used within the IF function 70 Table 10 Functions in arithmetic expressions This function Means this ABS x Ixl SQRT x x1 2 EXP x ex LOG x In x which is log base e LOG10 x log x which is log base 10 PWR x y Ixly PWRS x y 1xI if x gt 0 Ixl Gfx lt 0 SIN x sin x where x is in radians ASIN x sin x where the result is in
68. introduced later in this overview If you want to find out quickly which tools to use to complete a given task and how to start then 1 Go to the roadmap in Ways to create parts for models on age 5 129 2 Find the task you want to complete 3 Go to the sections referenced for that task for more information about how to proceed Chapter 5 Creating parts for models 128 Background information These sections provide background on the things you need to know and do to prepare for creating parts e What s different about parts used for simulation on page 5 129 e Preparing your models for part creation on page 5 130 Task roadmap This section helps you find the sections in this chapter that are relevant to the part creation task that you want to complete e Ways to create parts for models on page 5 129 How to use the tools These sections explain how to use different tools to create parts for model definitions e Using the Model Editor to create parts on page 5 131 e Using the Model Editor to create parts on page 5 131 e Basing new parts on a custom set of parts on page 5 133 Other useful information These sections explain how to refine part graphics and properties e Editing part graphics on page 5 135 e Defining part properties needed for simulation on page 5 139 What s different about parts used for simulation What s different about parts used for simulation A part used for simulation has these s
69. or e editing model parameters directly You can update individual model parameters by editing them in the Parameters frame of the Model Editor workspace When you save the model library the Model Editor automatically updates the device curves For this tutorial leave the model parameters at their current settings To save the model definition with the current parameter values and to make the model available to your design 1 From the File menu select Save to update RECTFR LIB and save the library to disk Your design is ready to simulate with the model definition you just created 109 Chapter 4 Creating and editing models Caution If you edit the text of a model that was created by entering data sheet values you may not be able to edit the model in Normal view again To find out more about PSpice command and netlist syntax refer to the online OrCA D PSpice A D Reference Manual 110 Editing model text For any model you can edit model text in the Model Editor instead of using the Spec Entry and Parameter frames However there are two cases where you must edit the model text e When you want to edit models of device types not supported by the Model Editor The model text is displayed automatically when you load one of these models e When you want to add DEV and LOT tolerances to a model for Monte Carlo or sensitivity worst case analysis By typing PSpice commands and netlist entries you can do th
70. otk Be Ny eS PAE OMS RE Dee RS 341 Running the simulation 2s 24 2 e6 need oe BER ES os 341 Displaying voltages on nets sees Oe oe CR ee ES 343 User interface features for waveform analysis 344 ZOOM TEg O 20 0645 2s Hepes Rd eee Che Eee Dee d 344 Scrolling MACS ste we wos be ee eee Ae ee Oe eae 346 Modifying trace expressions and labels 346 Moving and copying trace names and expressions 347 Copying and moving labels 0000 348 Tabulating trace data values 4s cee hh Sek ea ee ek oa eH 349 USING Cursors i eae hh Re KE RS eR Ew RSS YS EES 350 Displaying CURSOIS s s soe ee Kae eee Sack eA Be 350 MOVINE C FSOTS 2202442 had eerste itedsena eases 351 Example using cursors oe 4a Hee Pee EG BOE 352 Tracking simulation messages 2 2 eee ee ee 354 Message tracking from the message Summary 354 The Simulation Message Summary dialog box 354 Persistenthazards 0 00 0 cee arasus 355 Message tracking from the waveform 5 356 TRACE CRPIESSIONS s ece eae ew be he ed eo Ew ee Oa ee Re 356 Basic output variable form 4 4 4 aes See a ee bk ee 357 Output variable form for device terminals 358 Analog trace expressions 4 24 6 cha KERR a 364 Trace expression aliases o an 364 Arithmetic functions aoaaa ee 364 Rules for numeric values suffixes a aoaaa a aa 365 Chapter 14 Other output options
71. out device gt I ac lt transmission line out device gt lt Z gt or I lt z gt ac lt 3 or 4 terminal out device gt lt DC sweep variable gt current through non grounded terminal x of a3 or 4 terminal out device current through one end z of a transmission line out device voltage or current source name Table5 Element definitions for 2 terminal devices lt out id gt or Device type lt out device gt sna area device indicator P capacitor C V CAP 1 I CAP diode D V D23 1 I D23 voltage controlled E V E14 1 voltage source I E14 current controlled F V F1 1 current source I F1 voltage controlled G V G2 1 current source 1 G2 current controlled H V HSOURCE 1 voltage source I HSOURCE independent current I V IDRIV source I IDRIV inductor L V L1 1 I L1 Table5 Element definitions for 2 terminal devices saur idani Output variable Device type lt out device gt p mete examples device indicator resistor R V RC1 1 I RC1 voltage controlled S V SWITCH switch I SWITCH independent voltage V V VSRC source I VSRC current controlled W V W22 switch I W22 Table6 Element definitions for 3 or 4 terminal devices lt out id gt or lt out device gt device indicator Device type lt pin id gt pin id examples Output variable GaAs MESFET B Junction FET J D Drain terminal V B11 D G Gate terminal ID B11 S Source termina
72. parts How Capture places parts When placing parts on the schematic page the schematic page editor uses the grid as a point of reference for different editing activities The part s pin ends are positioned on the grid points Q S grid point S part body border 1 From Capture s File menu point to Open then choose Library To edit a part in a library 2 Select the library that has the part you want to edit The library opens and displays all its parts 3 Double click the part you want to edit The part appears in the part editor 4 Edit the part You can resize it add or delete graphics and add or delete pins Editing part graphics When changing part graphics check to see that all pins are on the grid For more information about specific part editing tasks refer to the OrCA D Capture User s Guide 135 Chapter 5 Creating parts for models Note Pin changes that alter the part template can occur if you either e change pin names or e delete pins In these cases you must adjust the value of the part s PSPICETEMPLATE property to reflect these changes To find out how see Pin callout in subcircuit templates on page 5 144 136 5 After you have finished editing the part from the File menu choose Save to save the part to its library Defining grid spacing Grid spacing for graphics The grid denoted by evenly spaced grid points regulates the sizing and positioning of gr
73. performed on the same example circuit to clearly illustrate analysis setup simulation and result analysis procedures for each analysis type This chapter includes the following sections e Example circuit creation on page 2 16 e Performing a bias point analysis on page 2 22 e DC sweep analysis on page 2 26 e Transient analysis on page 2 32 e AC sweep analysis on page 2 37 e Parametric analysis on page 2 42 e Performance analysis on page 2 49 Chapter 2 Simulation examples Example circuit creation This section describes how to use OrCAD Capture to create the simple diode clipper circuit shown in Figure 2 Vcc R2 ZA D 3 3k D1N3940 R1 c1 A n AAA Mid 4 JH sout 1k 0 47u R3 Z D2 R4 3 3k D1N3940 5 6k a lt salt HR Figure 2 Diode clipper circuit To create a new PSpice project 1 From the Windows Start menu choose the OrCAD Release 9 program folder and then the Capture shortcut to start Capture 2 Inthe Project Manager from the File menu point to New and choose Project 3 Select Analog Circuit Wizard 4 Inthe Name text box enter the name of the project CLIPPER 5 Click OK then click Finish No special libraries need to be configured at this time A new page will be displayed in Capture and the new project will be configured in the Project Manager To place the voltage sources 1 In Capture switch to the schematic page editor 16 From the Place menu
74. point Bias point calculated Simulation complete Figure 4 PSpice simulation output window Performing a bias point analysis To set up a bias point analysis in Capture 1 In Capture switch to CLIPPER OP in the schematic page editor 2 From the PSpice menu choose New Simulation Profile to display the New Simulation dialog box 3 Inthe Name text box type Bias gt From the Inherit From list select None then click Create The Simulation Settings dialog box appears 5 From the Analysis type list select Bias Point 6 Click OK to close the Simulation Settings dialog box Running PSpice To simulate the circuit from within Capture 1 From the PSpice menu choose Run gt PSpice simulates the circuit and calculates the bias point information Note Because waveform data is not calculated during a bias point analysis you will not see any plots displayed in the Probe window for this simulation To find out how to view the results of this simulation see Using the simulation output file below 23 Chapter 2 Simulation examples 24 Using the simulation output file The simulation output file acts as an audit trail of the simulation This file optionally echoes the contents of the circuit file as well as the results of the bias point calculation If there are any syntax errors in the netlist declarations or simulation commands or anomalies while performing the calculation PSpice writes error or warnin
75. provides an overview of setting up analyses and starting simulation that applies to any analysis type The other chapters in Part three Setting Up and Running Analyses provide specific analysis setup information for each analysis type This chapter includes the following sections e Analysis types on page 7 196 e Setting up analyses on page 7 197 e Starting a simulation on page 7 206 Chapter 7 Setting up analyses and starting simulation 196 Analysis types PSpice supports analyses that can simulate analog only circuits Table 2 provides a summary of the available PSpice analyses and the corresponding Analysis type options where the analysis parameters are specified In Capture switch to the PSpice view then from the PSpice menu choose New Simulation Profile Table2 Classes of PSpice analyses Analysis Analysis type or Option Swept variable Standard analyses DC sweep DC Sweep source parameter temperature Bias point Bias Point Small signal DC transfer Bias Point DC sensitivity Bias Point Frequency response AC Sweep Noise frequency Noise requires a frequency AC Sweep Noise frequency response analysis Transient response Time Domain time Transient Fourier requires transient Time Domain time response analysis Transient Simple multi run analyses Parametric Parametric Sweep Temperature Temperature Sweep Statistical analyses Monte Carlo Monte Carlo Worst Case Sensitivity worst case Mo
76. test circuit containing only the frequency domain device and then after proper validation proceed to incorporate it in your larger design The PSpice defaults will be appropriate most of the time if accuracy is your main concern but it is still worth checking Note Do not set RELTOL to a value above 0 01 This can seriously compromise the accuracy of your simulation 191 Chapter 6 Analog behavioral modeling Refer to your OrCA D Capture User s Guide for a description of how to create a custom part Refer to the online OrCA D PSpice A D Reference Manual for more information about E and G devices 192 Basic controlled sources As with basic SPICE PSpice has basic controlled sources derived from the standard SPICE E F G and H devices Table 1 summarizes the linear controlled source types provided in the standard part library Table1 Basic controlled sources in ANALOG OLB Device type Part name Controlled Voltage Source E PSpice E device Current Controlled Current Source F PSpice F device Controlled Current Source G PSpice G device Current Controlled Voltage Source H PSpice H device Creating custom ABM parts Create a custom part when you need a controlled source that is not provided in the special purpose set or that is more elaborate than you can build with the general purpose parts with multiple controlling inputs for example The transfer function can be built into the part two diff
77. that you can customize for specific expressions and lookup tables You can also create your own ABM parts Using global parameters and expressions for values Using global parameters and expressions for values In addition to literal values you can use global parameters and expressions to represent numeric values in your circuit design Global parameters A global parameter is like a programming variable that When multiple parts are set to the same represents a numeric value by name value global parameters provide a convenient way to change all of their Once you have defined a parameter declared its name f a values for what if analyses and given it a value you can use it to represent circuit values anywhere in the design this applies to any Example If two independent sources have hierarchical level a value defined by the parameter VSUPPLY then you can change both sources to 10 volts by assigning the value e Apply the same value to multiple part instances once to VSUPPLY Some ways that you can use parameters are as follows e Set up an analysis that sweeps a variable through a range of values for example DC sweep or parametric analysis Dedaring and using a global parameter To use a global parameter in your design you need to e define the parameter using a PARAM part and e use the parameter in place of a literal value somewhere in your design 67 Chapter 3 Preparing a design for simulation Note
78. the AC voltage source on the schematic page as shown in Figure 17 Double click the VAC part OV to display the Parts spreadsheet Change the Reference cell to Vin and change the ACMAG cell to 1V Click Apply to update the changes and then close the spreadsheet To set up and run the AC sweep simulation 1 From Capture s PSpice menu choose New Simulation Profile In the Name text box enter AC Sweep then click create The Simulation Settings dialog box appears Click the Analysis tab From the Analysis type list select AC Sweep Noise and enter the settings shown in Figure 19 Simulation Settings Example x General Analysis Include Files Libraries Stimulus Options Data Collection Probe Windows Analysis type AC Sweep Type AC Sweep Noise i C Linear Start Frequency fo Options Logarithmic End Frequency ficoMes General Settings E Mania Carnot Css Decade Point Decade T Parametric Sweep Temperature Sweep m Noise Analysis I Enabled Gutsut yolteoe lV Source a Interval al Cancel Apply Help Figure 19 AC sweep and noise analysis simulation settings 5 Click OK to close the Simulation Settings dialog box 6 From the PSpice menu choose Run to start the simulation PSpice performs the AC analysis To add markers for waveform analysis 1 From Capture s PSpice menu point to Markers point to Advanced then choose db Magnitude of Voltage
79. the OrCAD Library List 2 From the Tools menu choose Find 3 Inthe Find What text box type the generic part name 4 Enter any other search criteria and then click Find The Acrobat Reader displays the first page where it finds a match Each page maps the generic part name to the parts and corresponding vendor and part library name in the OrCAD libraries 5 Ifyou want to repeat the search from the Tools menu choose Find Again Note Ifyou are unsure of the device type you can scan all of the device type lists using the Acrobat search capability The first time you do this you need to set up the across list index To find out more refer to the online Adobe Acrobat manuals Using parts that you can simulate Note This method finds only parts that OrCAD supplies that have models If you want to include user defined parts in the search use the parts browser in Capture see page 3 62 or press Ctrl F Instead of the generic part name you can enter other kinds of search information such as device type or manufacturer press Ctrl G 63 Chapter 3 Preparing a design for simulation To find out more about how to use these parts and define their properties look up the corresponding PSpice device letter in the A nalog Devices chapter in the online OrCA D PSpice A D Reference Manual and then see the Capture Parts sections 64 Passive parts The OrCAD libraries supply several basic parts based on
80. the default configuration see How are models organized on page 4 88 To find out more about the library search path see Changing the library search path on page 4 125 82 Check for this e Does the relevant model library stimulus file or include file appear in the configuration list e Ifthe file is configured does the default library search path include the directory path where the file resides or explicitly define the directory path in the configuration list If the file is not configured add it to the list and make sure that it appears before any other library or file that has an identically named definition To view the configuration list 1 Inthe Simulation Settings dialog box click the Include Files tab If the directory path is not specified update the default library search path or change the file entry in the configuration list to include the full path specification To view the default library search path 1 Inthe Simulation Settings dialog box click the Libraries tab Unmodeled pins If you see messages like these in the PSpice Simulation Output window Warning Part part_name pin pin_name is unmodeled Warning Less than 2 connections at node node_name or messages like this in the PSpice output file Floating unmodeled pin fixups then you may have drawn a wire to an unmodeled pin Things to watch for The OrCAD libraries include parts that are suitable for both simulation and
81. the list of directories specified in the Library Path text box on the Libraries tab of the Simulation Settings dialog box Simulation Settings TRAN Eg General Analysis Include Files Libraries Stimulus Options Data Collection Probe Window Filename Browse Library files x 4 Add as Global nom lib Add to Design Edit Library Path C Program Files OrCAD Capture LibrarySPS pice Browse To change the library search path 1 From the Simulation menu choose Edit Simulation Settings to display the Simulation Settings dialog box Click the Libraries tab In the Library Path text box position the pointer after the directory path that PSpice should search before the new path Type in the new path name following these rules e Use a semi colon character to separate two path names e Donot follow the last path name with a semi colon Configuring model libraries Example To search first C ORCAD LIB then C MYLIBS for model libraries type Cr ORCAD LIB Cs MYLIBS in the Library Path text box 125 Chapter 4 Creating and editing models 126 Creating parts for models Chapter overview This chapter provides information about creating parts for For general information about creating model definitions so you can simulate the model from parts refer to the OrCA D Capture your design using OrCAD Capture User s Guide Topics are grouped into four areas
82. the trace listed first in the trace legend The corresponding trace symbol is outlined with a dashed line Moving cursors To move cursors along a trace using menu commands 1 From the Trace menu point to Cursor then choose Peak Trough Slope Min Max Point or Search To move cursors along a trace using the mouse 1 Use the right and left mouse buttons as described in Table 2 below Table2 Mouse actions for cursor control Click this To do this with the cursors cursor assignment Left click the analog trace Associate the first cursor with symbol the selected trace Right click the analog trace Associate the second cursor symbol with the selected trace cursor movement Left click in the display area Move the first cursor to the closest trace segment at the X position Right click in the display Move the second cursor to area the closest trace segment at the X position To move cursors along a trace using the keyboard 1 Use key combinations as described in Table 3 below Table3 Key combinations for cursor control Us this key combination To do this with the cursors CtrlJ lt and Cirl Change the trace associated with the first cursor Shift Ctrl and Change the trace associated with the Shift Ctrl second cursor and Move the first cursor along the trace Shift and Shitt gt Move the second cursor along the trace User
83. to tolerances and multiple analyses DC AC or transient predict yields on production runs of a are run using these tolerances drcuit For EXAMPLE DSN in Figure 74 on page 12 288 you can analyze the effects of variances in the values of resistors RC1 and RC2 by assigning a model description to these resistors that includes a 5 device tolerance on the multiplier parameter R Then you can perform a Monte Carlo analysis First the simulator performs a DC analysis with the nominal R multiplier value for RC1 and RC2 Then it performs a set number of additional runs with the R multiplier varied independently for RC1 and RC2 within a 5 tolerance To modify example dsn and set up simulation 1 Replace RC1 and RC2 with RBREAK parts setting property values to match the resistors that are being replaced VALUE 10k and reference designators to match previous names 2 Select PSpice Model from the Edit menu Create the model CRES as follows MODEL CRES RES R 1 DEV 5 TC1 0 02 TC1 is the linear temperature coefficient TC2 0 0045 TC2 is the quadratic temperature From the File menu choose Save By default Capture coefficient saves the definition to the model library EXAMPLE LIB and automatically configures the file for local use with the current schematic 3 In Capture set up a new Monte Carlo analysis as shown in Figure 75 The analysis specification tells PSpice to do one nominal run and four Monte Carlo Chapter 12 Monte
84. transient simulations create large waveform data files because PSpice stores many data points You can suppress a part of the data from a transient run by setting the simulation analysis to start the output at a time later than 0 This does not affect the transient calculations Viewing waveforms themselves these always start at time 0 This delay only suppresses the output for the first part of the simulation To limit file size by suppressing the first part of transient simulation output 1 From Capture s PSpice menu choose Edit Simulation Settings to display the Simulation Settings dialog box 2 Click the Analysis tab 3 From the Analysis type list select the Time Domain Transient option 4 In the Start saving data after text box type a delay time 5 Click OK to close the Simulation Settings dialog box 6 From the PSpice menu choose Run to start the simulation The simulation begins but no data is stored until after the delay has elapsed Using simulation data from multiple files You can load simulation data from multiple files into the same Probe window by appending waveform data files When more than one waveform data file is loaded you can add traces using all loaded data data from only one file or individual data sections from one or more files Appending waveform data files To append a waveform data file 1 In PSpice from the File menu choose Append Waveform DAT 2 Select a DAT file to
85. transistor Q2 voltage at port A of transmission line T32 current through drain of MOSFET device M1 voltage source named VIN AC analysis sweep variable flicker noise from MOSFET M1 360 Table8 Output variable AC suffixes Suffix Meaning of output variables none magnitude DB magnitude in decibels G group delay dPHASE dFREQUENCY I imaginary part M magnitude P phase in degrees R real part Table9 Device names for two terminal device types Two terminal device type Device type letter capacitor C diode D voltage controlled voltage source E current controlled current source F voltage controlled current source G current controlled voltage source H independent current source I inductor L resistor R voltage controlled switch S independent voltage source V current controlled switch WwW The pin name for two terminal devices is either 1 or 2 The controlling inputs for these devices are not considered terminals Trace expressions 361 Chapter 13 Analyzing waveforms 362 Table10 Terminal IDs by three amp four terminal device type Three amp four terminal device type Device type letter Terminal IDs GaAs MOSFET Junction FET MOSFET Bipolar transistor transmission line IGBT B D drain G gate S source D drain G gate S source D drain G gate S source B bulk substrate C collector B base E emitter
86. wave rectifier design 104 Using the Model Editor to edit the D1 diode model 105 Entering data sheet information 0 105 Extracting model parameters nia 2 ak a tobe ee eee 107 Adding curves for more than one temperature 108 Completing the model definition 109 Editing model text os hice eee ee oes Ok ow ER ewe ee 110 Editing MODEL definitions lt 6 as 4 Gace aed 110 Editing SUBCKT definitions 4 7 lt lt 442 42444444 os 111 Chapter 5 Contents Changing the model name a sb eee wae bbe ww es 111 Starting the Model Editor from the schematic page editor in Capture 111 What is an instance model osc e458 6 ee eee Ole 112 Starting the Model Editor 244222429444 24 2428244 112 Saving design models aaou be eee EEE we Ee RS 113 Example editing a Q2N2222 instance model 114 Starting the Model Editor 1 4 4444444 etes 4a ew ous 114 Editing the Q2N2222 X model instance 114 Saving the edits and updating the schematic 115 Using the Create Subcircuitcommand 115 Changing the model reference to an existing model definition 117 Reusing instance models 4 4 4 one eee etd eee a 118 Reusing instance models in the same schematic 118 Making instance models available to all designs 119 Configuring model libraries 24 4424 44 23244 oe ie oes 1
87. wee e Ra PRE ERE EE 177 EMULT partexample gt sq sosca eh ke Ree wR SEARS Re hGH 178 CMULT part example lt s o0s sev edan ee ede Se eee gee oe 179 BPREO partexample 4 sacs sa w ak eed eee eee eee wes 185 Voltage multiplier circuit mixer 624 6 644 d4 44245045 wees 186 Popice simulation window 4 24 44 68S ee ee eR ES RR 210 Example schematic EXAMPLE OPJ 2 2 020000005 217 Curve family example schematic 4 2 50 6 osedie ee eR ee eA 221 Device curve family o ioe BARR RS Ae eee Be Ee EA 222 Operating point determination for each member of the curve family 222 Circuit diagram for EXAMPLE OPJ 24 6 h 4 Se oe Boe SOR He RS 237 AC analysis setup for EXAMPLE OPJ 0 004 238 Device and total noise traces for EXAMPLE DSN 247 Transient analysis setup for EXAMPLE OPJ 263 Example schematic EXAMPLE OPJ 20 eo 8 GG oH eG Re 264 ECL compatible Schmitt trigger aoaaa 266 Netlist for Schmitt trigger circuit a aa ba amp od 267 Hysteresis curve example Schmitt trigger aaa 268 Passive filter schematic 1 a 274 Current of Ll when R1 is 1 5 ohms aoaaa 0000048 276 Rise time and overshoot vs damping resistance 277 RLC filter example circuit 68 aoa RR ES CER 278 Plot of capacitance versus bias voltage oono aaa 280 Example schematic EXAMPLE OPJ ouaaa aa 282 Example schematic EXAMPLE DSN oaan aaa 288 Monte Carlo anal
88. you can e View simulation results in multiple Probe windows e Compare simulation results from multiple circuit designs in a single Probe window e Display simple voltages currents and noise data e Display complex arithmetic expressions that use the basic measurements e Display Fourier transforms of voltages and currents or of arithmetic expressions involving voltages and currents e Add text labels and other annotation symbols for clarification PSpice generates two forms of output the simulation output file and the waveform data file The calculations and results reported in the simulation output file act as an audit trail of the simulation However the graphical analysis of information in the waveform data file is the most informative and flexible method for evaluating simulation results Overview of waveform analysis Elements of a plot A single plot consists of the analog lower area and the digital upper area neser fi digital area B OU panne nme EE analog area 2us a U U1 Y o U U2 Figure 91 Analog and digital areas of a plot You can display multiple plots at a time If you display only analog waveforms the entire plot will be an analog area Likewise if you display only digital waveforms the entire plot will be a digital area 321 Chapter 13 Analyzing waveforms From the View menu choose Toolbar to display orhide the toolbar 322 Elements of a Prob
89. 0 RELTOL times the frequency resolution or 10 RELTOL TSTOP For example consider the transform e79 001 s This is an ideal delay of 1 millisecond and has no frequency cutoff If TSTOP 10 milliseconds and RELTOL 001 then PSpice imposes a frequency cutoff of 10 MHz Since the time resolution is the inverse of the maximum frequency this is equivalent to saying that the delay cannot resolve changes in the input at a rate faster than 1 microseconds In general the time resolution will be limited to RELTOL TSTOP 10 A final computational consideration for Laplace parts is that the impulse response is determined by means of an FFT on the Laplace expression The FFT is limited to 8192 points to keep it tractable and this places an additional limit on the maximum frequency which may not be greater than 8192 times the frequency resolution If your circuit contains many Laplace parts which can be combined into a more complex single device it is generally preferable to do this This saves computation and memory since there are fewer impulse responses It also reduces the number of opportunities for numerical artifacts that might reduce the accuracy of your transient analyses Laplace transforms can contain poles in the left half plane Such poles will cause an impulse response that increases with time instead of decaying Since the transient analysis is always for a finite time span PSpice does not have a problem calculating the tran
90. 00 Starting a simulation aoaaa Bee Ree ESR 206 Starting a simulation from Capture 2 ee ee ee ees 206 Starting a simulation outside of Capture 207 Setting up batch simulations 0 04 207 Multiple simulation setups within one circuit file 207 Running simulations with multiple circuit files 208 The PSpice simulation window 25 4 65 46 es Meee ew es 208 DC analyses 213 Chapter OVERVICW s oosa sos oe kon i k Ce ee RS Oe we eee 213 DO SWeeD Ss oa eae eal cite Bs oh bw re OG ERED SY Yee 214 Minimum requirements to run a DC sweep analysis 214 Overview of DC sweep i sa oooh See Lee ee es eee 216 Setting up a DC stimulus 5 aso We oe ee Saree eee Eee 4 218 Nested DC sweeps 26 5 Ooo e hehe e ee ES EE Oe ee 219 Curve families for DC sweeps 6 2 cae ee dk eee ee 221 Bids POON 2 4 it eee bees CASES SY ee Eee ees Ee See RS 223 Minimum requirements to run a bias point analysis 223 Overview of bias point 5 a0 boa eas ok AE OS RT RR a 223 Small signal DC transfer 1c a eee CR ee eR ERD ee wR ES 225 Minimum requirements to run a small signal DC transfer analysis 225 Overview of small signal DC transfer 226 DE SENSI 8 4 6 e he Sh Re PRE ER AE SE oe ROSE HS 228 Minimum requirements to run a DC sensitivity analysis 228 Overview of DC sensitivity deck Ge A KR EE BR Ore 229 AC analyses 231 Chapter Overview so s aom oeioe b Eoae
91. 1 2 and 3 The small signal equivalent therefore has 0 gain the derivative of V 1 V 2 with respect to both V 1 and V 2 is 0 when V 1 V 2 0 So the output of the mixer during AC analysis will be 0 regardless of the AC values of V 1 and V 2 Another way of looking at this is that a mixer is a nonlinear device and AC analysis is a linear analysis The output of the mixer has 0 amplitude at the fundamental Output is nonzero at DC and twice the input frequency but these are not included in a linear analysis If you need to analyze nonlinear functions such as a mixer use transient analysis Transient analysis solves the full nonlinear circuit equations It also allows you to use input waveforms with different frequencies for example VIN1 could be 90 MHz and VIN2 could be 89 8 MHz AC analysis does not have this flexibility but in return it uses much less computer time Cautions and recommendations for simulation and analysis Frequency domain parts Some caution is in order when moving between frequency and time domains This section discusses several points that are involved in the implementation of frequency domain parts These discussions all involve the transient analysis since both the DC and AC analyses are straightforward The first point is that there are limits on the maximum values and on the resolution of both time and frequency These are related the frequency resolution is the inverse of the maximum time a
92. 124 MODEL property 87 138 models built in 2 changing associations to parts 117 creating parts for custom 133 using the Model Editor 100 131 creating with the Model Editor 110 defined as parameter sets 87 subcircuits 87 115 global vs design 89 instance 101 112 117 118 organization 88 preparing for part creation 130 saving as design using the Model Editor 101 saving as local using the Model Editor 111 testing verifying Model Editor created 96 tools to create 91 ways to create edit 92 Monte Carlo analysis 196 289 collating functions 287 histograms 301 introduction 7 model parameter values reports 285 output control 285 tutorial 293 using the Model Editor 114 waveform reports 286 with temperature analysis 288 MOSFET 95 204 362 363 multiple y axes waveform analysis 276 N netlist failure to netlist 58 file NET 10 Newton Raphson requirements 380 NODESETnh initial conditions parts 376 noise analysis 196 241 about 4 242 device noise 242 flicker noise 245 noise equations 245 setup 241 243 shot noise 245 thermal noise 245 total output and input noise 242 units of measure 246 viewing results 246 viewing simulation results 245 363 waveform analysis output variables 245 363 noise units 246 non causality 188 Index nonlinear magnetic core 95 nonlinear devices in AC sweep analysis 239 0 opamp 95 operators in expressions 70 op
93. 125 0 005 1 51 steps or simulation points A source with a DC specification such as VDC or IDC must be used if the swept variable is to be a voltage type or current source To set the DC value select Properties from the Edit menu then click on the cell under the DC column and type in its value The default DC value of V1 is overridden during the DC sweep analysis and is made to be the swept value All of the other sources retain their values After running the analysis the simulation output file EXAMPLE OUT for the EXAMPLE OPJ circuit in Figure 56 contains a table of voltages relating V1 node OUT1 and node OUT2 z a 3 q212222 readme example rdm RS2 k WOU eaaa RAINS RCI a a cloan OUTI t 4 0T2 RSI es N wt eae qd I oi at q212222 J F q212222 VEE Figure 56 Example schematic EXAMPLE OP To calculate the DC response of an analog circuit PSpice removes time from the circuit This is done by treating all capacitors as open circuits all inductors as shorts and using only the DC values of voltage and current sources In order to solve the circuit equations PSpice uses an iterative algorithm For analog devices the equations are continuous DC Sweep The example circuit EXAMPLE OP is provided with the OrCAD program installation 217 Chapter 8 DC analyses If you are planning to
94. 140 PSPICETEMPLATE The PSPICETEMPLATE property defines the PSpice syntax for the part s netlist entry When creating a netlist Capture substitutes actual values from the circuit into the appropriate places in the PSPICETEMPLATE syntax then saves the translated statement to the netlist file Any part that you want to simulate must have a defined PSPICETEMPLATE property These rules apply e The pin names specified in the PSPICETEMPLATE property must match the pin names on the part e The number and order of the pins listed in the PSPICETEMPLATE property must match those for the associated MODEL or SUBCKT definition referenced for simulation e The first character in a PSPICETEMPLATE must be a PSpice device letter appropriate for the part such as Q for a bipolar transistor PSPICETEMPLATE syntax The PSPICETEMPLATE contains e regular characters that the schematic page editor interprets verbatim e property names and control characters that the schematic page editor translates Regular characters in templates Regular characters include the following e alphanumerics e any keyboard part except the special syntactical parts used with properties amp e white space An identifier is a collection of regular characters of the form alphabetic character any other regular character Property names in templates Property names are preceded by a special character as follows 1 1 1 1 1 amp lt id
95. 2 ee eee ee cee eee xxviii OrCAD demo CD ROM 0 00 00 00084 xxviii What s New reren ee ee a ee a XxXix Simulation primer Things you need to know 1 Chapter overview dae 4 SEG OEE EU HS SE OER Ed EEE OOH 1 Whatisi Popice sueste oa uy ek ae eee ee eee eee eed 2 Analyses you can run with PSpice 244 80 Peeve do Pere ee OY S 3 Basic analyses 23 2 yank eb Oe Ae he Cee fh AA ee OA 3 DC sweep amp other DC calculations 0 3 AC sweep and noise 6 4 42 eh 4 bee eae MOE Ook 6 eA 4 Transient and Fourier 2 0 0 00 000 ce eee eee eee 5 Advanced multi run analyses 2 2 2 ee eee 6 Parametric and temperature 444 lt 2 2 40 04 2a eee ee ows 6 Monte Carlo and sensitivity worst case 7 Analyzing waveforms with PSpice naaa ES ee OD 8 What is waveform analysis uaaa aaa bbe pas 8 Using PSpice with other OrCAD programs oaoa aa 9 Using Capture to prepare for simulation 9 What is the Stimulus Editor aoaaa a 9 What is the Model Editor aooaa a a 10 Contents Files needed for simulation 0 0 00 00 e eee eee 10 Files that Capture generates 4 a0 eae 2 oe eA ewe Se Ke 10 Netlist file ae 202 4 4 Bos oO Se Se bw a sk A Se AS GS A 11 Circuit file eseas a coed eee aoe oe a dg BORO BA a ee SE 11 Other files that you can configure for simulation 11 Model library ss s s es eh bee kee Pee eee he maai 12 Stimulus file 0 0
96. 2 ohm series resistance to each net to which an IC symbol is connected These pseudocomponents are netlisted as PSpice IC and NODESET commands Refer to these commands in the online OrCAD PSpice A D Reference Manual for more information Setpoints can be created for inductor currents and capacitor voltages using the IC property described in Setting initial conditions on page A 378 377 Chapter A Setting initial state See Setpoints on page A 376 for more information about IC1 and IC2 378 Setting initial conditions The IC property allows initial conditions to be set on capacitors and inductors These conditions are applied during all bias point calculations However if you select the Skip Initial Transient Solution check box in the Transient Analysis Setup dialog box the bias point calculation is skipped and the simulation proceeds directly with transient analysis at TIME 0 Devices with the IC property defined start with the specified voltage or current value however all other such devices have an initial voltage or current of 0 Note Skipping the bias point calculation can make the transient analysis subject to convergence problems Applying an IC property for a capacitor has the same effect as applying one of the pseudocomponents IC1 or IC2 across its nodes PSpice attaches a voltage source with a 0 002 ohm series resistance in parallel with the capacitor The IC property allows the user to associate the initial cond
97. 20 The Libraries and Include Filestabs 0 0 0 120 How PSpice uses model libraries 0 121 Search ordet s i e soc ec sasat eee Eee oe ae e 121 Handling duplicate model names oaaao 122 Adding model libraries to the configuration 122 Changing design and global scope 0 4 123 Changing model library search order 124 Changing the library search path lt 4 6 4 eae amp ae ea as 125 Creating parts for models 127 Chapter overview sa sa tec eas See Ee a EA RDR a m ewe eS 127 What s different about parts used for simulation 129 Ways to create parts for models bee ae oS HE Ro eee a eo 4 129 Preparing your models for part creation 130 Using the Model Editor to create parts 0 0 4 131 Starting the Model Editor o 4 sae 4 Re oe eK Oe eRe 131 Setting up automatic part creation 004 132 Basing new parts on a custom set of parts 133 Editing part graphics 24 4 wae dvd dow ee aS ew Rw Rees 135 How Capture places parts 2 ooo eee OCG wees ON eR 135 Defining grid spacing ois cb we he Ree Ke ee a ee 136 Grid spacing for graphics i 0854 4480 06008 ee ea ees 136 Grid spacing for pins 446 Bee ee Se Se Se RR RG 136 Attaching models to parts lt a pea a fed oe eee eR eee eH RS A 138 Vii Contents Chapter 6 viii MODES re Go w Be eo ee os oe A ie bo ee es BS 138 Defin
98. 3 custom parts 192 frequency domain device models 181 frequency domain parts 181 187 instantaneous models 176 186 overview 148 placing and specifying ABM parts 150 PSpice A D equivalent parts 174 175 signal names 147 simulation accuracy 191 syntax 175 triode modeling example 171 AC stimulus property 234 AC sweep analysis 196 231 232 about 232 displaying simulation results 39 example 37 237 introduction 4 noise analysis 196 241 setup 37 232 235 stimulus 233 treatment of nonlinear devices 239 ACMAG stimulus property 234 ACPHASE stimulus property 234 adding a stimulus 33 AGND ground part 83 analog behavioral modeling see ABM analog parts basic components ABM 153 155 basic controlled sources ABM 192 behavioral 66 bipolar transistors 95 204 362 363 breakout 65 capacitors 202 Chebyshev filters 153 157 190 301 Darlington model transistors 95 diodes 95 202 363 expression parts ABM 154 168 frequency table parts ABM 174 183 190 GaAsFET 203 362 363 IGBT 95 204 362 inductors 202 integrators and differentiators ABM 153 160 JFET 95 203 362 363 Index Laplace transform ABM 154 164 174 181 187 limiters ABM 153 156 math functions ABM 154 167 mathematical expressions ABM 174 MOSFET 95 204 362 363 nonlinear magnetic core 95 opamp 95 passive 64 PSpice A D equivalent parts ABM 174 resistors 203 363 switch 363 t
99. 367 Chapter overview 4 24 06 6 aa a 367 Contents Appendix A Appendix B Xiv Viewing analog results in the PSpice window 368 Writing additional results to the PSpice output file 369 Generating plots of voltage and current values 369 Generating tables of voltage and current values 370 Setting initial state 373 AP Penix OVERVIEW a ss soeg a de wia a wd ee ae es 373 Save and load bias POI 24 244 eo ee CS ee eERESE EES SS eS 374 Dave i s DOME e ssi gt eee n gpn m de B eee eee ee On 374 Load bias point eta es oP a eRe oe PS BE REE HEL a RR 375 SEIPOINS n 2 6025 ka Ree en E See ee ed eS eS ee eee OE 376 Setting initial conditions os ee cae ee ke A ee ERG G e 378 Convergence and time step too small errors 379 Appendix overview 24 624 2 tees Re eR EG Keke Ee Rede Es 379 Introduction 2 wma deea a ea a A aE E 380 Newton Raphson requirements o oo a 380 Is there a solution 0 0 0 00 00 a 381 Are the Equations Continuous aosa a eee he eR 382 Are the derivatives correct aoaaa a a a 382 Is the initial approximation close enough 383 Bias point and DC sweep cco Geen te eee Lee Pe Pee oe ee 385 Semiconductors oa ea e a e a 385 OWCNES e Soc ae e ea e ee ed eae Oe ee Bee Dee ee 386 Behavioral modeling expressions 006 4 387 Transient analysis face eae hee ede ROS SESS ERR ERS ES 388 Skipping the bias point
100. 3940 c1 Rval 3 Vin 1 Qs ite ae Iili m V3 SINE I 60 m 0 47u D2 D1 N3940 PARAMETERS Rval 1k l Figure 22 Clipper circuit with global parameter Rval This example produces multiple analysis runs each with a different value of R1 After the analysis is complete you can analyze curve families for the analysis runs using PSpice Setting up and running the parametric analysis To change the value of R1 to the expression Rval 1 2 3 4 In Capture open CLIPPER OPJ Double click the value 1k of part R1 to display the Display Properties dialog box In the Value text box replace 1k with Rva1 Click OK To add a PARAM part to declare the parameter Rval 1 2 10 11 12 From Capture s Place menu choose Part In the Part text box type PARAM from the PSpice library SPECIAL OLB then click OK Place one PARAM part in any open area on the schematic page Double click the PARAM part to display the Parts spreadsheet then click New In the Property Name text box enter Rval no curly braces then click OK This creates a new property for the PARAM part as shown by the new column labeled Rval in the spreadsheet Click in the cell below the Rval column and enter 1k as the initial value of the parametric sweep While this cell is still selected click Display In the Display Format frame select Name and Value then click OK Click
101. 4 183 ELAPLACE ABM 174 181 EMULT ABM 174 178 ESUM ABM 174 178 ETABLE ABM 174 179 EVALUE ABM 174 176 177 EXP ABM 154 167 F ABM controlled analog source 192 FTABLE ABM 153 161 G ABM controlled analog source 192 GAIN ABM 153 155 GFREQ ABM 174 183 GLAPLACE ABM 174 181 GLIMIT ABM 153 156 GMULT ABM 174 178 GSUM ABM 174 178 GTABLE ABM 174 179 GVALUE ABM 174 176 177 H ABM controlled analog source 192 HIPASS ABM 153 158 ICn initial condition 376 INTEG ABM 153 160 LAPLACE ABM 154 164 LIMIT ABM 153 156 LOG ABM 154 167 LOG10 ABM 154 167 LOPASS ABM 153 157 MULT ABM 153 155 NODESETn initial bias point 376 PWR ABM 154 167 PWRS ABM 154 167 SIN ABM 154 167 SOFTLIM ABM 153 156 SQRT ABM 154 167 SUM ABM 153 155 TABLE ABM 153 160 TAN ABM 154 167 performance analysis 274 example 49 goal functions 275 phase 361 plots in waveform analysis 321 power supplies analog 74 Probe windows plot update methods 346 plots 321 322 printing Probe windows 323 scrolling 346 setting colors 324 trace data tables 349 traces displaying 28 zoom regions 344 properties part for simulation 139 PSpice default shortcut keys 344 waveform analysis 320 multiple y axes 276 PSpice A D about 2 expressions 69 functions 71 output file OUT 24 369 output variables 199 PSpice A D equ
102. 6E 04 28 5 718E 04 30 013E 04 32 4 464E 04 34 4 053E 04 36 3 781E 04 38 744E 04 40 4 127E 04 42 5 053E 04 44 6 380E 04 46 935E 04 48 1 139E 03 50 2 605E 03 52 8 259E 03 54 2 609E 02 56 7 418E 02 58 1 895E 01 60 4 426E 01 jo a K a fi Ga kog iP ot ieee IP oot Hot wa AR oa NA E a ja Frequency domain device models Frequency domain models ELAPLACE GLAPLACE EFREQ and GFREQ are characterized by output that depends on the current input as well as the input history The relationship is therefore non instantaneous For example the output may be equal to the integral of the input over time In other words the response depends upon frequency During AC analysis the frequency response determines the complex gain at each frequency During DC analysis and bias point calculation the gain is the zero frequency response During transient analysis the output of the device is the convolution of the input and the impulse response of the device Laplace transforms LAPLACE The ELAPLACE and GLAPLACE parts allow a transfer function to be described by a Laplace transform function The ELAPLACE and GLAPLACE parts are defined in part by the following properties default values are shown ELAPLACE EXPR V IN IN XFORM 1 s GLAPLACE EXPR V IN IN XFORM 1 s The LAPLACE parts use a Laplace transform description The input to t
103. 87 X2 30 25 0780 X2 31 26 2810 0 0 X3 34 1 771E 0 X3 35 1 0881 X3 36 4279 X2 XU1 6 1 2636 6 The message always includes the banner ERROR convergence problem and the trailer Last node voltages tried were Itcannot include all three of the middle blocks 393 Chapter B Convergence and time step too small errors 394 The Last node voltages tried trailer shows the voltages tried at the last Newton Raphson iteration If any of the nodes have unreasonable large values this is a clue that these nodes are related to the problem These voltages failed to converge lists the specific nodes which did not settle onto consistent values It also shows their values for the last two iterations These supply currents failed converge does the same for currents through voltage sources and inductors If any of the listed numbers are 1e10 then that is an indication that the value is being clipped from an unreasonable value Finally These devices failed to converge shows devices whose terminal currents or core fluxes did not settle onto consistent values The message gives a clue as to the part of the circuit which is causing the problem Looking at those devices and or nodes for the problems discussed above is recommended Index ABM ABM part templates 152 ABM OLB 149 basic controlled sources 192 cautions and recommendations for simulation 186 control system parts 15
104. AA E JE E FE IE JE FE JE FE JE FEIE FE Hean Deviation 2477 Sigma 3035 RUN MAS DEVIATION FROM NOMINAL Pass 3 5729 1 89 sigma lower at UW 82 94 885 of Nominal Pass 4 3549 1 17 sigma lower at U_U 82 i 96 832 of Nominal Pass 2 3122 1 63 sigma lower at UW 82 i 97 212 of Nominal Pass 5 2493 82 sigma higher at U_U 02 i 102 23 of Nominal Figure 76 Summary of Monte Carlo runs for EXAMPLE OP With the List option enabled a report is also generated showing the parameter value used for each device in each run In this case see Figure 77 run three shows the highest deviation 291 Chapter 12 Monte Carlo and sensitivity worst case analyses C ORCADXEXS EXAMPLE SCH HERE UPDATED MODEL PARAMETERS TEMPERATURE 35 000 DEG C MONTE CARLO PASS 3 HEEL JE E JE KEELE LK JE JE KEE KEE EEL EEE EE EEE JE ME AE JE JE JE JE JE EE EEE ELE JE JE E JE JE EE REL EEEERELEREREER xxx CURRENT MODEL PARAMETERS FOR DEVICES REFERENCING cres R_RC1 R_RC2 R 1 03004E 00 9 5053F 0 Figure 77 Parameter values for Monte Carlo pass three 292 Monte Carlo analysis Example Monte Carlo analysis of a pressure sensor This example shows how the performance of a pressure sensor circuit with a pressure dependent resistor bridge is affected by manufacturing tolerances using Monte Carlo analysis to explore these effects Drawing the schematic To begin construct the bridge as shown in Figure 78
105. Advanced and choose Phase of Voltage Place a Vphase marker on the output next to the Vdb marker Delete the Vdb marker on Mid Switch to PSpice In the Probe window the gain and phase plots both appear on the same graph with the same scale Click the trace name VP Out to select the trace From the Edit menu choose Cut From the Plot menu choose Add Y Axis From the Edit menu choose Paste The Bode plot appears as shown in Figure 21 154 GHz 166Hz 41 OKHZ 16KHZ 1 o VDB OUT 2 a UP OUT E ciooer SCHE 1G6KHZ 1 6NHZ 10HHz 100HHz Frequency Figure 21 Bode plot of clipper s frequency response Finding out more about AC sweep and noise analysis Table 2 2 To find out more about this AC sweep analysis noise analysis based on an AC sweep analysis See this AC sweep analysis on page 9 232 Noise analysis on_ page 9 241 AC sweep analysis 41 Chapter 2 Simulation examples i 42 Note Parametric Analysis is not supported in PSpice Basics Parametric analysis This example shows the effect of varying input resistance on the bandwidth and gain of the clipper circuit by e Changing the value of R1 to the expression Rval e Placing a PARAM part to declare the parameter Rval e Setting up and running a parametric analysis to step the value of R1 using Rval R1 lt WAY oO D1N
106. Apply to update all the changes to the PARAM part Close the Parts spreadsheet Select the VP marker and press to remove the marker from the schematic page From the File menu choose Save to save the design Parametric analysis PSpice interprets text in curly braces as an expression that evaluates to a numerical value This example uses the simplest form of an expression a constant The value of R1 will take on the value of the Rval parameter whatever it may be Note For more information about using the Parts spreadsheet see the OrCAD Capture User s Guide This example is only interested in the magnitude of the response 43 Chapter 2 Simulation examples To set up and run a parametric analysis to step the value of R1 using Rval 1 From Capture s PSpice menu choose New Simulation Profile The New Simulation dialog box appears 2 Inthe Name text box type Parametric The root schematic listed is the schematic 3 From the Inherit From list select AC Sweep then click page associated with the simulation profile Create JO areen The Simulation Settings dialog box appears 4 Click the Analysis tab 5 Under Options select Parametric Sweep and enter the settings as shown below This profile specifies that the parameter Rval is to be stepped from 100 to 10k logarithmically with a resolution of 10 General Analysis Include Files Libraries Stimulus Options Data Collection Probe Window
107. C age 9 233 for more details See Defining a time based VEXP or VSTIM stimulus on page 10 252 for more details VPULSE or VSTIM VPWL or VSTIM VPWL_RE_FOREVER or VPWL_F_RE_FOREVER 75 Chapter 3 Preparing a design for simulation Example The current source equivalent to VDC is IDC to VAC is IAC to VEXP is IEXP and so on 76 Table 13 If you want this kind of input Use this part for voltage piecewise linear that repeats n VPWL_N_TIMES or times VPWL_F_N_TIMES frequency modulated sine wave VSFFM or VSTIM sine wave VSIN or VSTIM VSTIM and ISTIM parts require the Stimulus Editor to define the input signal VPWL_F_RE_ FOREVER and VPWL_F_N_TIMES are file based parts the stimulus specification is saved in a file and adheres to PSpice netlist syntax To determine the part name for an equivalent current source 1 In the table of voltage source parts replace the first V in the part name with I Using VSTIM and ISTIM You can use VSTIM and ISTIM parts to define any kind of time based input signal To specify the input signal itself you need to use the Stimulus Editor See The Stimulus Editor utility on page 10 253 Defining stimuli If you want to spedfy multiple stimulus types If you want to run more than one analysis type including a transient analysis then you need to use either of the following e time based stimulus parts with AC and DC properties e VSRC or ISRC parts
108. Carlo and sensitivity worst case analyses PSpice offers a facility to generate histograms of data derived from Monte Carlo waveform families through the performance analysis feature For information about performance analysis see RLC filter example on age 11 274 For information about histograms see Creating histograms on page 12 303 290 runs saving the DC analysis output from those five runs General Analysis Include Files Libraries Stimulus Options Data Collection Probe Window Analysis lype Monte Carlo Joc Sweep a Worst case Sensitivity Output variable ft Options m Monte Carlo options fs 1 400 gt Distributions Random number seed 1 32767 lt none gt gt runs Senstviyoptians that have fboth DEY and LOT Limit devices to ypes ja Gave dete from each sensitivity ran More Settings Number of runs M Primary Sweep Secondary Sweep Monte Carlo Worst Case Parametric Sweep Temperature Sweep Save Bias Point OLoad Bias Point Use distribution Save data from ioerances Figure 75 Monte Carlo analysis setup for EXAMPLE DSN PSpice starts by running all of the analyses enabled in the Simulation Settings dialog box with all parameters set to their nominal values However with Monte Carlo enabled PSpice saves the DC sweep analysis results for later reference and comparison After the n
109. DES IN IN OUT OUT MODEL The rules of agreement are outlined in Figure 34 145 Chapter 5 Creating parts for models Number of nodes in first line of subcircuit definition must equal Number of pins called out must equal Number of modeled pins in template shown in part Sequence of nodes in first line of subcircuit definition must match Sequence of pins called out in template Names of pins called out in template ust match james of modeled pins shown in part Unmodeled pins may appear on a part like the two voltage offset pins on a 741 opamp part These pins are not netlisted and do not appear on the template Figure 34 Rules for pin callout in subcircuit templates 146 Analog behavioral modeling Chapter overview This chapter describes how to use the Analog Behavioral Modeling ABM feature of PSpice This chapter includes the following sections e Overview of analog behavioral modeling on page 6 148 e The ABM OLB part library file on page 6 149 e Placing and specifying ABM parts on page 6 150 e ABM part templates on page 6 152 e Control system parts on page 6 153 e PSpice equivalent parts on page 6 174 e Cautions and recommendations for simulation and analysis on page 6 186 e Basic controlled sources on page 6 192 Chapter 6 Analog behavioral modeling 148 Overview of analog behavioral modeling You can use the Analog Behav
110. E Voltage at non grounded terminal x of a 3 or 4 terminal device Voltage at end z of a transmission line device z is either A orB Current into a device Current into terminal x of a3 or 4 terminal device Current into end z of a transmission line device z is either A orB name of any variable used in the DC sweep analysis AC analysis sweep variable transient analysis sweep variable total RMS summed noise at output net 359 Chapter 13 Analyzing waveforms Table6 Output variable formats continued Format Meaning V db INOISE total equivalent noise at input source NTOT ONOISE sum of all noise N lt noise type gt lt device name gt contributors in the circuit contribution from noise type of device name to the total output noise See Table 11 on page 13 363 for a complete list of noise types by device type For information about noise output variable equations the units used to represent noise quantities in trace expressions and a noise analysis example see Analyzing Noise in the Probe window on page 9 245 Table 7 Examples of output variable formats Meaning A basic form An alias equivalent V NET3 NET2 same V C1 1 V1 C1 VP Q2 B VBP Q2 V T32 A VA T32 I M1 D ID M1 VIN same FREQUENCY same NFID M1 same voltage between analog nets labeled NET3 and NET2 voltage at pin1 of capacitor C1 phase of voltage at base of bipolar
111. E GAIN I V REFDES The fragments C REFDES V REFDES and E REFDES create a uniquely named capacitor current sensing V device and E device respectively The fragment U REFDES creates a name suitable for use as a local node The E device generates an output proportional to the current through the local V device Control system parts Control system parts have single pin inputs and outputs The reference for input and output voltages is analog ground 0 An enhancement to PSpice means these components can be connected together with no need for dummy load or input resistors Table 7 lists the control system parts grouped by function Also listed are characteristic properties that may be set In the sections that follow each part and its properties are described in more detail Table7 Control system parts Category Part Description Properties Basic CONST constant VALUE components SUM adder MULT multiplier GAIN gain block GAIN DIFF subtracter Limiters LIMIT hard limiter LO HI GLIMIT limiter with gain LO HI GAIN SOFTLIM soft tanh limiter LO HI GAIN Chebyshev LOPASS lowpass filter FP FS RIPPLE filters STOP HIPASS highpass filter FP FS RIPPLE STOP BANDPASS bandpass filter FO F1 F2 F3 RIPPLE STOP BANDREJ band reject FO F1 F2 F3 notch filter RIPPLE STOP Integrator and INTEG integrator GAIN IC differentiator DeFER differentiator GAIN Table look ups TABLE lookup table ROW1 ROW5
112. ES TAN x tan x YES ATAN x tan x YES ARCTAN x d x derivative of x with respect to the YES x axis variable s x integral of x over the range of the YES x axis variable AVG x running average of x over the range of NO the x axis variable AVGX x d running average of x from NO X_axis_value x d to X_axis_value x RMS x running RMS average of x over the NO range of the x axis variable DB x magnitude in decibels of x NO MIN x minimum of the real part of x NO MAX x maximum of the real part of x NO In PSpice this function is called DDT x In PSpice this function is called SDT x Note For AC analysis PSpice uses complex arithmetic to evaluate trace expressions If the result of the expression is complex then its magnitude is displayed Rules for numeric values suffixes Explicit numeric values are entered in trace expressions in the same form as in simulation analyses by means of part properties in Capture with the following exceptions e Suffixes M and MEG are replaced with m milli 1E 3 and M mega 1E 6 respectively Trace expressions 365 Chapter 13 Analyzing waveforms Example V 5 and v 5 are equivalent in trace expressions Example The quantities 2e 3 2mV and 002v all have the same numerical value For axis labeling purposes PSpice recognizes that the second and third forms are in volts whereas the first is dimensionless PSpice also knows that W V A V W A and A
113. Example If you select WARNING as the minimum severity level the Simulation Message Summary dialog box will display WARNING SERIOUS and FATAL messages 354 Tracking simulation messages PSpice provides explanatory messages for errors that occur during simulation with their corresponding waveforms You can view messages from e the Simulation Message Summary dialog box or e the waveform display Message tracking from the message summary A message summary is available for simulations where diagnostics have been logged to the waveform data file You can display the message summary e When loading a waveform data file click OK when the Simulation Errors dialog box appears e Anytime by choosing Simulation Messages from the View menu The Simulation Message Summary dialog box The Simulation Message Summary dialog box lists message header information You can filter the messages displayed in the list by selecting a severity level from the Minimum Severity Level drop down menu Messages are categorized in decreasing order of severity as FATAL SERIOUS WARNING or INFO informational When you select a severity level the Message Summary displays only those messages with the chosen severity or higher By default the minimum severity level displayed is SERIOUS Tracking simulation messages To display waveforms associated with messages 1 Inthe Simulation Message Summary dialog box double click a message For
114. For DC the output is simply equal to the input since the gain at s O is 1 For AC analysis the gain is found by substituting j for s This gives a flat response out to a corner frequency of 1000 27 159 Hz and a roll off of 6 dB per octave after 159 Hz There is also a phase shift centered around 159 Hz In other words the gain has both a real and an imaginary component The gain and phase characteristic is the same as that shown for the equivalent control system part example using the LAPLACE part see Figure 41 on page 6 165 For transient analysis the output is the convolution of the input waveform with the impulse response of 1 1 001 s The impulse response is a decaying exponential with a time constant of 1 millisecond This means that the output is the lossy integral of the input where the loss has a time constant of 1 millisecond This will produce a PSpice netlist declaration similar to ERC 5 0 LAPLACE V 10 1 1 001 s Frequency response tables EFREQ and GFREQ The EFREQ and GFREQ parts are described by a table of frequency responses in either the magnitude phase domain or complex number domain The entire table is read in and converted to magnitude in dB and phase in degrees Interpolation is performed between entries Phase is interpolated linearly magnitude is interpolated logarithmically For frequencies outside the table s range 0 zero magnitude is used EFREQ and GFREQ properties are d
115. For more information about using the Parts spreadsheet see the OrCAD Capture User s Guide Example To declare the global parameter VSUPPLY that will set the value of an independent voltage source to 14 volts place the PARAM part and then create a new property named VSUPPLY with a value of 14v Example To set the independent voltage source VCC to the value of the VSUPPLY parameter set its DC property to VSUPPLY PARAMETERS Al VSUPPLY 14V ik F a i vee in DO VSUPPLY 7 w a 68 To declare a global parameter 1 2 Note 4 5 Place a PARAM part in your design Double click the PARAM part to display the Parts spreadsheet then click New Declare up to three global parameters by doing the following for each global parameter a Click New 0 Inthe Property Name text box enter NAMEN then click OK This creates a new property for the PARAM part NAME in the spreadsheet Click in the cell below the NAMEn column and enter a default value for the parameter d While this cell is still selected click Display e Inthe Display Format frame select Name and Value then click OK The system variables in Table 11 on page 3 73 have reserved parameter names Do not use these parameter names when defining your own parameters Click Apply to update all the changes to the PARAM part Close the Parts spreadsheet To use the global parameter in your circuit 1
116. Inthe Part Creation Setup frame select Create Parts for Models if it is not already enabled 3 In the Save Part To frame define the name of the part library for the new part Choose one of the following e Part library path same as model library to create or open the OLB file that has the same filename as the open model library LIB e User defined part library and then enter a library name in the part Library Name text box Basing new parts on a custom set of parts Basing new parts ona custom set of parts If you are using the the Model Editor to automatically generate parts for model definitions and you want to base the new parts on a custom graphic standard rather than the OrCAD default parts then you can change which underlying parts either application uses by setting up your own set of parts To create a custom set of parts for automatic part generation 1 Create a part library with the custom parts Be sure to name these parts by their device type as shown in Table 2 this is how the Model Editor Guide determines which part to use for a model definition Table2 Part names for custom part generation Note If you use a custom part set the Model Editor always checks the custom part library first for a part that matches the model definition If none can be found they use the OrCAD default part instead For more information on creating parts refer to the OrCA D Capture User s For this device t
117. Next the parametric analysis is commented out and the worst case analysis is enabled Two runs are made using the two versions of the Rbmod MODEL statement shown in the circuit file The model parameter R is a multiplier which is used to scale the nominal value of any resistor referencing the Rbmod model Rb2 in this case The first MODEL statement leaves the nominal value of Rb2 at 720 ohms The sensitivity analysis increments R by a small amount and checks its effect on Vm OUT This slight increase in R causes an increase in the base bias voltage of the BJT and increases the amplifier s gain Vm OUT The worst case analysis correctly sets R to its minimum value for the lowest possible Vm OUT see Figure 87 Worst case analysis Note The YatX goal function is used on the simulation results for the parametric sweep STEP defined in Figure 85 The resulting curves are shown in Figure 87 and Figure 88 311 Chapter 12 Monte Carlo and sensitivity worst case analyses Consider a slightly different scenario Rb2 is set to 720 ohms so that maximizing it is not enough to saturate the BJT but Rb1 is variable also The true worst case occurs when Rb2 is maximized and Rb1 is minimized Checking their individual effects is not sufficent even if the circuit were simulated four times with each resistor in turn set to its extreme values Output is monotonic within the tolerance range Sensitivity analysis correctly points
118. Operational Amplifier Analog OP 27 AD ANLG_DEVSLB amp Davices Inc Operational Amplifier OP 27 Analog OP 27VAD ANLG_DEV SL8S Devices Inc Operational Amplifier OP 27 Analog OP 27B AD ANLG_DEV SL8 Devices Inc Operational Amplifier OP 27 Analog OP 27C AD ANLG_DEV SLB Devices Inc Operational Amplifiers OP 27 Analog OP 27E AD ANLG_DEV SL8 Devices Inc Operational Amplifier OP 27 Analog OP 27F AD ANLG_DEVSL amp Devices Ing Operational Amplifier OP 27 Analog OP 27G AD ANLG_DEV SLE Devices Inc Operational Amplifiers OP 27 Linear OP 27 LT LIN_TECH SLB Technology Corp Operational Amplifier OP 27 OP 27 OPAMP SLB Operational Amplifier OP 275 Analog OP 275 AD ANLG_DEV SLB Davices Inc Operational Amplifier OP 275 Analog OP 275G AD ANLG_DEV SL8S Devices Ing Operational Amplifier OP 27A Linear OP 27AAT LIN_TECH SLB Technology Corp Operational Amplifier OP 27C Linear OP 27C LT UN_TECH SLB Technology Corp Using parts that you can simulate For a listing of vendor supplied parts contained in the OrCAD libraries refer to the online Library List To find out more about each model library read the comments in the LIB file header New for Package 8 0 61 Chapter 3 Preparing a design for simulation Note This method finds any part contained in the current part libraries configuration including parts for user defined models If you want to find out more about a part supplied in the OrCAD libraries such
119. OrCAD PSpice User s Guide Copyright 1998 OrCAD Inc All rights reserved Trademarks OrCAD OrCAD Layout OrCAD Express OrCAD Capture OrCAD PSpice and OrCAD PSpice A D are registered trademarks of OrCAD Inc OrCAD Capture CIS and OrCAD Express CIS are trademarks of OrCAD Inc Microsoft Visual Basic Windows Windows NT and other names of Microsoft products referenced herein are trademarks or registered trademarks of Microsoft Corporation All other brand and product names mentioned herein are used for identification purposes only and are trademarks or registered trademarks of their respective holders Part Number 60 30 636 First edition 30 November 1998 Technical Support 503 671 9400 Corporate offices 503 671 9500 OrCAD Japan K K 81 45 621 1911 OrCAD UK Ltd 44 1256 381 400 Fax 503 671 9501 General email info orcad com Technical Support email techsupport orcad com World Wide Web http www orcad com OrCAD Design Network ODN http www orcad com odn 9300 SW Nimbus Ave Beaverton OR 97008 USA Contents Part one Chapter 1 Before you begin xxiii Welcome to OrCAD 0 0 0 0000 00 00 ee ee xxiii OrCAD PSpice overview Ge ee aaa a XxiV How to use this guide 4 2 2k oe RA A SERA Bk BRR BA XXV Typographical conventions aooo ee ee es XXV Related documentation 0 000 eee a xxvi Online Help 24 encd ccaue riven edu oauan Eie a lt xxvii If you have the demo CD ROM
120. PR For AC analysis EXPR is linearized around the bias point similar to EVALUE and GVALUE parts The output for each frequency is then the input times the gain of EXPR times the value of the table at that frequency For transient analysis the value of EXPR is evaluated at each time point The output is then the convolution of the past values of EXPR with the impulse response of the frequency response These rules follow the standard method of using Fourier transforms We recommend looking at one or more of the references cited in Frequency domain device models on page 6 181 for more information Note The table s frequencies must be in order from lowest to highest Figure 53 shows an EFREQ device used as a low pass filter The input to the frequency response is the voltage across the input pins The table describes a low pass filter with a response of 1 0 dB for frequencies below 5 kilohertz and a response of 001 60 dB for frequencies above 6 kilohertz The output is a voltage across the output pins This part is defined by the following properties TABLE 0 0 0 5kHz 0 5760 6kHz 60 6912 DELAY RI MAGUNITS PHASEUNITS Since R_I MAGUNITS and PHASEUNITS are undefined each table entry is interpreted as containing frequency magnitude value in dB and phase values in degrees Delay defaults to 0 The phase lags linearly with frequency meaning that this table exhibits a constant time group delay Th
121. PSpice starts the simulation As simulation progresses PSpice saves results to two files the data file and the PSpice output file Waveform data file The data file contains simulation results that that can be displayed graphically PSpice reads this file automatically and displays waveforms reflecting circuit response at nets pins and parts that you marked in your schematic cross probing You can set up your design so PSpice displays the results as the simulation progresses or after the simulation completes After PSpice has read the data file and displays the initial set of results you can add more waveforms and to perform post simulation analysis of the data PSpice output file The PSpice output file is an ASCII text file that contains e the netlist representation of the circuit e the PSpice command syntax for simulation commands and options like the enabled analyses e simulation results and e warning and error messages for problems encountered during read in or simulation Its content is determined by e the types of analyses you run e the options you select for running PSpice and e the simulation control symbols like VPRINT1 and VPLOT1 that you place and connect to nets in your design Simulation examples Chapter overview The examples in this chapter provide an introduction to the methods and tools for creating circuit designs running simulations and analyzing simulation results All analyses are
122. Part of Current imaginary Advanced Imaginary Part of Voltage Imaginary Part of Current You can use these markers instead of the built in functions provided in output variable expressions see Table 12 on page 13 364 However these markers are only available after defining a simulation profile for an AC Sweep Noise analysis 2 Point to the wires or pins you wish to mark and click to place the chosen markers 3 Right click and select End Mode to stop placing markers 4 If you have not simulated the circuit yet from the PSpice menu choose Run To hide or delete marked results 1 From Capture s PSpice menu point to Markers then choose one of the following Table 6 Viewing waveforms Choose this option To do this Hide All Delete All Hide traces in the waveform analysis display for all markers placed on any page or level of the schematic Remove all markers from the schematic and all corresponding traces from the waveform analysis display 333 Chapter 13 Analyzing waveforms 334 Limiting waveform data file size When PSpice performs a simulation it creates a waveform data file The size of this file for a transient analysis is roughly equal to transistors simulation time points 24 bytes The size for other analysis types is about 2 5 times smaller For long runs especially transient runs this can generate waveform data files that are several megabytes in size E
123. RI MAGUNITS PHASEUNITS This produces a PSpice netlist declaration like this ELOFILT 5 0 FREQ V 10 0 0 0 5kHz 0 0 6kHz 60 0 DELAY 3 2ms 163 Chapter 6 Analog behavioral modeling 164 Laplace transform part The LAPLACE part specifies a Laplace transform which is used to determine an output for each input value LAPLACE NUM numerator of the Laplace expression DENOM denominator of the Laplace expression The LAPLACE part uses a Laplace transform description The input to the transform is a voltage The numerator and denominator of the Laplace transform function are specified as properties for the part Note Voltages currents and TIME may not appear in a Laplace transform specification The output of the part depends on the type of analysis being done For DC and bias point the output is the zero frequency gain times the value of the input The zero frequency gain is the value of the Laplace transform with s 0 For AC analysis the output is then the input times the gain times the value of the Laplace transform The value of the Laplace transform at a frequency is calculated by substituting j o for s where o is 2x frequency For transient analysis the output is the convolution of the input waveform with the impulse response of the transform These rules follow the standard method of using Laplace transforms Example one The input to the Laplace transform is the voltage at net 10 The output is a volt
124. Transient Analysis type Fourier analysis calculates the DC and Fourier components of the result of a transient analysis By default the first through ninth components are computed however more can be specified When selecting Fourier to run a harmonic decomposition analysis on a transient waveform only a portion of the waveform is used Using the Probe window in PSpice a Fast Fourier Transform FFT of the complete waveform can be calculated and its spectrum displayed In the example shown in Figure 63 on page 10 263 the voltage waveform at node OUT2 from the transient analysis is to be used and the fundamental frequency is to be one megahertz for the harmonic decomposition The period of fundamental frequency is one microsecond inverse of the fundamental frequency Only the last one microsecond of the transient analysis is used and that portion is assumed to repeat indefinitely Since V1 s sine wave does indeed repeat every one microsecond this is sufficient In general however you must make sure that the fundamental Fourier period fits the waveform in the transient analysis Fourier components 269 Chapter 10 Transient analysis 270 Parametric and temperature analysis 11 Chapter overview This chapter describes how to set up parametric and temperature analyses Parametric and temperature are both simple multi run analysis types This chapter includes the following sections e Parametric analysis on p
125. Using time based stimulus parts with AC and DC properties The time based stimulus parts that you can use to define a transient DC and or AC input signal are listed below VEXP TEXP VPULSE IPULSE VPWL IPWL VPWL_F_RE_FOREVER IPWL_F_RE_FOREVER VPWL_F_N_TIMES IPWL_F_N_TIMES VPWL_RE_FOREVER IPWL_RE_FOREVER VPWL_RE_N_TIMES IPWL_RE_N_TIMES VSFFM ISFFM VSIN ISIN In addition to the transient properties each of these parts also has a DC and AC property When you use one of For the meaning of transient source these parts you must define all of the transient properties properties refer to the I V independent However it is common to leave DC and or AC undefined current and voltage source device type blank When you give them a value the syntax youneed syntax in the Analog Devices chapter to use is as follows in the online OrCA D PSpice A D Reference Manual Table 14 This property Has this syntax DC DC_value units AC magnitude_value units phase_value 77 Chapter 3 Preparing a design for simulation For the syntax and meaning of transient source specifications refer to the V independent current and voltage source device type in the A nalog Devices chapter in the online OrCA D PS pice A D Reference Manual 78 Using VSRC or ISRC parts The VSRC and ISRC parts have one property for each analysis type DC AC and TRAN You can set any or all of them using PSpice netlist syntax When you give them a
126. a nonlinear device is first linearized around the bias point and then the linear equivalent is used EVALUE and GVALUE parts The EVALUE and GVALUE parts allow an instantaneous transfer function to be written as a mathematical expression in standard notation These parts take the input signal perform the function specified by the EXPR property on the signal and output the result on the output pins In controlled sources EXPR may contain constants and parameters as well as voltages currents or time Voltages may be either the voltage at a net such as V 5 or the voltage across two nets such as V 4 5 Currents must be the current through a voltage source V device for example I VSENSE Voltage sources with a value of 0 are handy for sensing current for use in these expressions Functions may be used in expressions along with arithmetic operators and and parentheses Available built in functions are summarized in Table 10 on page 3 71 The EVALUE and GVALUE parts are defined in part by the following properties default values are shown EVALUE EXPR V IN IN GVALUE EXPR V IN IN Sources are controlled by expressions which may contain voltages currents or both The following examples illustrate customized EVALUE and GVALUE parts Example 1 In the example of an EVALUE device shown in Figure 49 the output voltage is set to 5 volts times the square root of the voltage between pins IN an
127. a simulation 2 Place a VSTIM part on your schematic 3 To name the stimulus double click the implementation property and type Vsin 4 Click the VSTIM part to select it 5 From the PSpice menu choose Edit Stimulus to start the Stimulus Editor 6 Define the stimulus parameter for amplitude a From the New Stimulus dialog box choose Cancel b From the Tools menu choose Parameters c Enter amp 1 in the Definition text box and click OK d From the Stimulus menu choose New or click the New Stimulus button in the toolbar 257 Chapter 10 Transient analysis 258 10 11 e f Give the stimulus the name of Vsin Select SIN as the type of stimulus to be created and click OK Define the other stimulus properties a b c d Enter 0 for Offset Value Enter AMP for Amplitude The curly braces are required They indicate that the expression needs to be evaluated at simulation time Enter 10k for Frequency and click OK From the File menu choose Save Within Capture place and define the PARAM symbol a b f From the Place menu choose Part Either browse SPECIAL OLB for the PARAM part or type in the name Place the part on your schematic and double click it Click New to add a new user property Set the value property name to AMP no curly braces Set the value of the VALUE property to 1 Set up the parametric sweep and other analyses a C From the PSpice menu choose S
128. a topoa AORO a a m AA 231 Contents AC sweep analysis 4 10 ce Peso bee eee EERE Re ee Bes 232 Setting up and running an AC sweep aaou 232 What is AC sweep 6444244455 404 6 ee She be Tees 232 Setting up an AC stimulus 4 04404 oe en ana eae n tae a ee o 233 Setting up an AC analysis 246 326 2484 26 P2eh 2442 45 235 AC sweep setup in example opj ooo a 237 How PSpice treats nonlinear devices o aaa aa yews s 239 What s required to transform a device into a linear circuit 239 What Popice does acs oh cued aoi a d a REARS a o aa Ge aG 239 Example nonlinear behavioral modeling block 239 NOISE ANALYSIS sc a 4 oh eee Codd ob eae Eee eee os 241 Setting up and running a noise analysis 241 What is noise analysis 2 163204 th04 wea eed Mee Shue 6 242 How PSpice calculates total output and INPULNOISe s 4 24 Bx aa anpe ee eee KS A 242 Setting up a noise analysis 44 64 404 2244694 244404494 4 243 Analyzing Noise in the Probe window 04 245 About noise units 5 he SG RE a eR Re Oe 246 Examples e da be oe eve ee ee Howes owe OE poe eb i E es 246 Chapter 10 Transient analysis 249 Chapter overview 24 eis amp baw oe ee eda eee a ee eee oe 249 Overview of transient analysis 4 15635 lt 4 84 84 eos De ee 250 Minimum requirements to run a transient analysis 250 Minimum circuit design requirements 250 Minimum program setup requirements
129. able an analysis type PSpice reports the transient results Generating tables of voltage and current values You can generate tables of voltage and current values on nets for any DC sweep AC sweep or transient analysis To generate tables of voltage or current to the output file 1 Place and connect any of the following parts from the PSpice library SPECIAL OLB Table 15 Use this part To tabulate this E VPRINT1 Voltage on the net that the part os terminal is connected to VPRINT2 Voltage differential between the two nets that the part terminals are connected to iPHNT IPRINT Current through a cut in the net Insert this part in series like a current meter 2 Double click the part instance to display the Parts spreadsheet 370 Writing additional results to the PSpice output file 3 Click the property name for the analysis type that you want tabulated DC AC or TRAN 4 In the columns for the analysis type that you want plotted DC AC or TRAN type any non blank value such as Y YES or 1 5 Ifyou selected the AC analysis type enable an output If you do not enable a format PSpice format defaults to MAG a Click the property name for one of the following output formats MAG magnitude PHASE REAL IMAG imaginary or DB b Type any non blank value such as Y YES or 1 C Repeat the previous steps a and b for as many AC output formats as
130. able look up ABM 153 160 174 179 transmission lines 204 362 vendor supplied 61 voltage comparator 95 voltage reference 95 voltage regulator 95 analyses AC sweep 37 196 231 232 bias point detail 22 196 DC sensitivity 196 228 DC sweep 26 196 214 execution order 198 Fourier 196 frequency response 196 Monte Carlo 196 289 noise 196 241 overview 3 parametric 42 196 272 performance analysis 49 sensitivity worst case 196 306 setup 197 small signal DC transfer 196 225 temperature 196 281 transient 32 196 types 196 approximation problems 383 basic components ABM 153 155 basic controlled sources ABM 192 behavioral modeling expressions 387 behavorial parts 66 bias point convergence analysis 389 save restore 374 skipping 389 bias point detail analysis 196 396 example 22 introduction 3 bipolar transistors 95 204 362 363 problems 392 Bode plot 4 40 C capacitors 202 Chebyshev filters 153 157 190 301 circuit file CIR 10 simulating multiple circuits 207 color settings for waveform analysis 324 comparator 95 continuous equations problems 382 control system parts ABM 153 controlled sources 174 192 convergence analysis bias point 389 convergence problems 379 approximations 383 behavioral modeling expressions 387 bias point 385 bipolar transistors 392 continuous equations 382 DC sweep 385 derivatives 382 diagnostics 393 dyna
131. ables 1 From the Trace menu choose Add Trace to display the press Add Traces dialog box The Simulation Output Variables frame displays a list of valid output variables 2 Click V OUT1 and V OUT2 then click OK The Probe window should look similar to Figure 96 343 Chapter 13 Analyzing waveforms Shortcut keys Many of the menu commands in PSpice have equivalent keyboard shortcuts For instance after placing a selection rectangle in the analog portion of the plot you can type Ctrl A instead of choosing Area from the View menu For a list of shortcut keys search on Keyboard Shortcuts in PSpice Help p p N Click anywhere on the plot to remove the selection rectangle without zooming 344 User interface features for waveform analysis PSpice provides direct manipulation techniques and shortcuts for analyzing waveform data These techniques are described below Zoom regions PSpice provides a direct manipulation method for marking the zoom region in the analog area of the plot To zoom in or out 1 Doone of the following on the toolbar e Click the View In toolbar button to zoom in by a factor of 2 around the point you specify e Click the View Out toolbar button to zoom out by a factor of 2 around the point you specify To zoom in the analog area using the mouse 1 Drag the mouse pointer to make a selection rectangle as shown below o UGS UCS v UCcomp_out User interface featur
132. ace page is the same as its corresponding waveform analysis trace If you change the color of the trace the color of the marker changes accordingly 5 Point to the wires or pins you wish to mark and click to place the chosen markers 6 Right click and select End Mode to stop placing markers 7 From the PSpice menu choose Run to start the simulation 335 Chapter 13 Analyzing waveforms Suppressing part of the data run also limits the size of the PSpice output file 336 Limiting file size by exduding internal subdrauit data By default PSpice saves data for all internal nodes and devices in subcircuit models in a design You can exclude data for internal subcircuit nodes and devices To limit file size by excluding data for internal subcircuits 1 From PSpice s Simulation menu choose Edit Simulation Settings to display the Simulation Settings dialog box General Analysis Include Files Libraries Stimulus Options Data Collection Probe Window gt Schematic Circuit Data C All voltages currents and digital states C At Markers only C None I Save data in the CSDF format CSD Cancel Apply Help 2 Click the Data Collection tab 3 Inthe Schematic Circuit Data frame choose All but internal subcircuit data then click OK 4 From the PSpice menu choose Run to start the simulation Limiting file size by suppressing the first part of simulation output Long
133. age 11 272 e Temperature analysis on page 11 281 Chapter 11 Parametric and temperature analysis See Setting up analyses on page 7 197 for a description of the Simulation Settings dialog box 272 Parametric analysis Minimum requirements to run a parametric analysis Minimum circuit design requirements e Set up the circuit according to the swept variable type as listed in Table 1 e Setup a DC sweep AC sweep or transient analysis Tablel1 Parametric analysis circuit design requirements Sw ept variable type Requirement voltage source voltage source with a DC specification VDC for example temperature none current source current source with a DC specification IDC for example model parameter PSpice model global parameter global parameter defined with a parameter block PARAM Minimum program setup requirements 1 Inthe Simulation Settings dialog box from the Analysis type list box select Time Domain Transient 2 Under Options select Parametric Sweep if it is not already enabled 3 Specify the required parameters for the sweep Simulation Settings Parametric Analysis x General Analysis Include Files Libraries Stimulus Options Data Collection Probe Window Analysis type r Sweep variable Time Domain Transient z Voltage source Nene C Current source ere EEE Jodel type p Options Global parameter z General Settings c Modellname Model et Monte Ca
134. age 8 218 Using VSRC or ISRC parts on page 3 78 Defining power supplies For the analog portion of your circuit If the analog portion of your circuit requires DC power then you need to include a DC source in your design To specify a DC source use one of the following parts Table 12 For this source type Use this part voltage VDC or VSRC current IDC or ISRC Defining stimuli Defining stimuli To simulate your circuit you need to connect one or more source parts that describe the input signal that the circuit must respond to The OrCAD libraries supply several source parts that are described in the tables that follow These parts depend on e the kind of analysis you are running e whether you are connecting to the analog portion of your circuit and e how you want to define the stimulus using the Stimulus Editor using a file specification or by defining part property values Analog stimuli Analog stimuli include both voltage and current sources The following table shows the part names for voltage sources Table 13 If you want this kind of input Use this part for voltage For DC analyses DC bias For AC analyses AC magnitude and phase For transient analyses exponential periodic pulse piecewise linear piecewise linear that repeats forever See Setting up a DC stimulus on VDC or VSRC age 8 218 for more details See Setting up an AC stimulus on VAC or VSR
135. age and is applied between nets 5 and 0 For DC the output is simply equal to the input since the gain at s 0 is 1 The transform 1 1 001 s describes a simple lossy integrator with a time constant of 1 millisecond This can be implemented with an RC pair that has a time constant of 1 millisecond For AC analysis the gain is found by substituting j for s This gives a flat response out to a corner frequency of 1000 27 159 hertz and a roll off of 6 dB per octave after 159 Hz There is also a phase shift centered around 159 Hz In other words the gain has both a real and an imaginary component For transient analysis the output is the convolution of the input waveform with the impulse response of 1 1 001 s The impulse response is a decaying exponential with a time constant of 1 millisecond This means that the output is the lossy integral of the input where the loss has a time constant of 1 millisecond The LAPLACE part shown in Figure 40 could be used for this purpose The transfer function is the Laplace transform 1 1 001 s This LAPLACE part is characterized by the following properties NUM 1 DENOM 1 001 s The gain and phase characteristics are shown in Figure 41 o UMi Frequency Figure 41 Viewing gain and phase characteristics of a lossy integrator This produces a PSpice netlist declaration like this ERC 5 O LAPLACE V 10 1 1 001 s Example two The input is V 10
136. alculated Waveforms are displayed for those nets that have markers attached in the schematic Waveforms are displayed according to the last display configuration that was used in the Probe window Viewing waveforms while simulating While a simulation is in progress you can monitor the results for the data section being written by PSpice This function is only available when the Display Probe window during simulation option is enabled in the Probe Window tab of the Simulation Settings dialog box To monitor results during a simulation 1 From Capture s PSpice menu choose Edit Simulation Settings to display the Simulation Settings dialog box 2 Click the Probe Window tab Select Display Probe window and then click during simulation 4 Click OK to close the Simulation Settings dialog box 5 From the PSpice menu choose Run to start the simulation One Probe window is displayed in monitor mode 6 Doone of the following to select the waveforms to be monitored e From PSpice s Trace menu choose Add and enter one or more trace expressions e From Capture s PSpice menu point to Markers then choose and place one or more markers The Probe window monitors the waveforms for as long as the most recent data section is being written After that data section is finished the window changes to manual mode To see the full set of runs you must update the display by using the Add Trace command under the Trace men
137. ameter name and corresponding value as follows Table 2 Property Value Pcoeff 0 06 0 Pnom 1 0 4 Click Apply to save the changes you have made then close the Parts Spreadsheet 295 Chapter 12 Monte Carlo and sensitivity worst case analyses When PSpice runs a Monte Carlo analysis it uses tolerance values to determine how to vary model parameters during the simulation 296 Using resistors with models To explore the effects of manufacturing tolerances on the behavior of this circuit you set device DEV and LOT tolerances on the model parameters for resistors R1 R2 R3 and R4 in a later step see page 12 297 This means you need to use resistor parts that have model associations Because R parts do not have associated models and therefore no model parameters change the resistor parts to Rbreak parts that do have models To replace R1 R2 R3 and R4 with the RBREAK part 1 Click R1 to select it 2 Hold down the key and click R2 R3 and R4 to add them to the selection set 3 Press to delete the selection set 4 From the Place menu choose Part 5 Type RBREAK in the Part text box If RBREAK is not available click the Add Library button and select BREAKOUT OLB to configure it for use in Capture 6 Click OK 7 Manually place the RBREAK part in the circuit diagram where R1 R2 R3 and R4 were located 8 Double click on each RBREAK part and change the reference designators as desir
138. an expression using the following syntax trace_expression fn where n is the numerical order from left to right of the waveform data file as it appears in the PSpice title bar or trace_expression s fn where s is a specific data section of a specific waveform data file Click OK To identify the source file for an individual trace 1 In the trace legend double click the symbol for the trace you want to identify Figure 93 The Section Information dialog box appears containing the trace name and if there is more than Viewing waveforms one waveform data file loaded in the plot the full path for the file from which the trace was generated Also listed is information about the simulation that generated the waveform data file and the number of data points used Figure 94 Section Information G V C1 1 This trace came from one simulation run from the data file one C OrCAD Projects Copy of clipper SCHEMATIC1 Pa dat Step param Aval 100 Temperature 27 0 Deg Simulation at 10 08 13 on 10 27 98 The simulator created 14 data points This trace is being displayed using 73 data points Figure 94 Section information message box Saving simulation results in ASCII format The default waveform data file format is binary However you can save the waveform data file in the Common Simulation Data Format CSDF instead Warning Data files saved in the CSDF format are two or more times the size of b
139. anew self documenting analysis setup dialog for creating simulation profiles see below PSpice now provides an editable simulation queue which shows you how many files are currently in line to be simulated You can edit or re order the list as needed And the plotting features have been improved by providing user controlled grid settings grid and trace properties style and color and metafile format copy and paste functions Simulation profiles PSpice Release 9 introduces the concept of simulation profiles Each simulation profile refers to one schematic in a design and includes one analysis type AC DC or Transient with any options sensitivity temperature parametric Monte Carlo etc You can define as many profiles as you need for your design and you can set up multiple analyses of the same type Simulation profiles help you keep your analysis results separate so you can delete one without losing the rest New OrCAD Capture front end Release 9 integrates OrCAD Capture as the front end schematic entry tool for PSpice Capture provides a professional design entry environment with many advanced capabilities that now work hand in hand with PSpice These include a project manager a new property editor spreadsheet right mouse button support and many other time saving features Xxix Before you begin To find out more see Creating and editing models on page 85 To find out more refer to MOSFET devices in the A nalo
140. aphic objects and the positioning of pins The default grid spacing with snap to grid enabled is 0 10 and the grid spacing is 0 01 You can turn off the grid spacing when you need to draw graphics in a tighter space To edit the part graphics 1 In Capture s part editor display the part you want to edit 2 Select the line arc circle or other graphic object you want to change and do any of the following e To stretch or shrink the graphic object click and drag one of the size handles e Tomove the entire part graphic click and drag the edge of the part The part body border automatically changes to fit the size of the part graphic 3 After you have finished editing the part from the File menu choose Save to save the part to its library Grid spacing for pins The part editor always places pins on the grid even when the snap to grid option is turned off The size of the part is relative to the pin to pin spacing for that part That means that pins placed one grid space apart in the part editor are displayed as one grid space apart in the schematic page editor Editing part graphics Pins must be placed on the grid at integer multiples of the grid spacing Because the default grid spacing for the Schematic Page Grid is set at 0 10 OrCAD recommends setting pin spacing in the Part and Symbol Grid at 0 10 intervals from the origin of the part and at least 0 10 from any adjacent pins For more information ab
141. ar button Add the following trace expression IMG I Vin V 1 0 2 3 1416 Frequency Or add the expression CvF I Vin V 1 0 Where CvF is a macro which measures the effective capacitance in a complex conductance Macros are defined using the Macros command on the Trace menu The CvF macro should be defined as Note CvF G IMG G 2 3 1416 Frequency I Vin V 1 is the complex admittance of the R C branch the minus sign is required for correct polarity To use performance analysis to plot capacitance vs bias voltage 1 2 3 4 From the Trace menu choose Performance Analysis Click Wizard Click Next gt Click YatX in the Choose a Goal Function list and then click Next gt In the Name of Trace text box type the following CvF I Vin V 1 In the X value to get Y value at text box type 10K Click Next gt The wizard displays the gain trace for the first run to text the goal function YatX Click Finish 279 Chapter 11 Parametric and temperature analysis The resultant plot is shown in Figure 72 SCHEMATICT P OrCAD PSpice A D_ rlc SCHEMATIC1 Parameti Edt Vi E jew Trace Plt Tools Window Help zF OF ja steage I M 22 4 an ll SCHEMATICT Parametric pn 8 amp a m foe E P E Si E a a a 30u 8 5 o YatX CuF I Uin U 1 16K BB tic SCHEMA For Help press F1 ME Figure 72 Plot of capacitance ver
142. aries shipped with your programs The model library names have a LIB extension If needed however you can create your own models and libraries either e manually using the Model Text view in the Model Editor or another text editor like Notepad or e automatically using the Model Editor Stimulus file A stimulus file contains time based definitions for analog input waveforms You can create a stimulus file either e manually using the Model Text View of the Model Editor or a standard text editor to create the definition a typical file extension is STM or e automatically using the Stimulus Editor which generates a STL file extension Indude file An include file is a user defined file that contains e PSpice commands or e supplemental text comments that you want to appear in the PSpice output file see page 1 14 You can create an include file using any text editor such as Notepad Typically include file names have a INC extension Configuring model library stimulus and indude files PSpice searches model libraries stimulus files and include files for any information it needs to complete the definition of a part or to run a simulation The files that PSpice searches depend on how you configure your model libraries and other files Much of the configuration is set up for you automatically however you can do the following yourself e Add and delete files from the configuration e Change the sco
143. arity the template is shown on three lines although the actual template is a single line 152 ABM part templates For most ABM parts a single PSpice E or G device declaration is output to the netlist per part instance The PSPICETEMPLATE property in these cases is straightforward For example the LOG part defines an expression variant of the E device with its output being the natural logarithm of the voltage between the input pin and ground E REFDES out 0 VALUE LOG V in The fragment EX REFDES is standard The E specifies a PSpice controlled voltage source E device in and out are the input and output pins respectively VALUE is the keyword specifying the type of ABM device and the expression inside the curly braces defines the logarithm of the input voltage Several ABM parts produce more than one primitive PSpice device per part instance In this case the PSPICETEMPLATE property may be quite complicated An example is the DIFFER differentiator part This is implemented as a capacitor in series with a current sensor together with an E device which outputs a voltage proportional to the current through the capacitor The template has several unusual features it gives rise to three primitives in the PSpice netlist and it creates a local node for the connection of the capacitor and its current sensing V device C REFDES in S U REFDES 1 n V REFDES S U REFDES 0 Ov n E REFDES Sout 0 VALU
144. as a box see Figure 3 R1 BVA 1k Figure 3 Connection points If you make a mistake when placing or connecting components 1 From the Edit menu choose Undo or dick ho 19 Chapter 2 Simulation examples A more efficient way to change the names values and other properties of several parts in your design is to use the Property Editor as follows 1 Select all of the parts to be modified by pressing and clicking each part 2 From the Edit menu choose Properties The Parts Spreadsheet appears Change the entries in as many of the cells as needed and then click Apply to update all of the changes at once 20 To assign names labels to the off page connectors Label the off page connectors as shown in Figure 2 on page 2 16 Double click the name of an off page connector to display the Display Properties dialog box In the Name text box type the new name Click OK Select and relocate the new name as desired To assign names to the parts 1 Double click the second VDC part to display the Parts spreadsheet Click in the first cell under the Reference column Type in the new name Vin Click Apply to update the changes to the part then close the spreadsheet Continue naming the remaining parts until your schematic looks like Figure 2 on page 2 16 To change the values of the parts 1 Double click the voltage label 0V on V1 to display the Display Properties dialog
145. as manufacturer or whether you can simulate it then search the online Library List see page 3 63 62 Notice the following There is a generic OP 27 part provided by OrCAD the OP 27 AD from Analog Devices Inc and the OP 27 LT from Linear Technology Corporation The Model column for all of these parts contains an asterisk This indicates that this part is modeled and that you can simulate it Finding the part that you want If you are having trouble finding a part you can search the libraries for parts with similar names by using either the parts browser in Capture and restricting the parts list to those names that match a specified wildcard text string or the online Library List and searching for the generic part name using capabilities of the Adobe Acrobat Reader To find parts using the parts brow ser 1 2 In Capture from the Place menu choose Part In the Part Name text box type a text string with wildcards that approximates the part name that you want to find Use this syntax lt wildcard gt lt part_name_fragment gt lt wildcard gt where lt wildcard gt is one of the following to match zero or more characters to match exactly one character The parts browser displays only the matching part names To find parts using the online OrCAD Library List 1 In Windows Explorer double click LIBLIST PDF located in the directory where PSpice is installed Acrobat Reader starts and displays
146. ays to create edit 92 see also models switch 363 problems 386 system variables in expressions 73 T table look up parts ABM 153 160 174 179 temperature analysis 196 281 introduction 6 with statistical analyses 288 TEMPLATE property 140 and non simulation parts 140 examples 143 naming conventions 141 regular characters 140 special characters 142 thermal noise 245 TIME Probe output variable 359 total noise 242 circuit 245 per device 245 traces adding 28 direct manipulation 344 displaying 28 35 markers 334 output variables 356 placing a cursor on 30 transformer problems 391 transient analysis 196 example 32 Fourier analysis 196 hysteresis curves 266 internal time steps 265 introduction 5 402 overview 250 problems 388 setting up 34 Stimulus Editor 253 stimulus generation 252 switching circuits 266 transient response 263 transistors Darlington model 95 transmission lines 362 triode 171 troubleshooting checklist 58 missing DC path to ground 84 missing ground 83 unconfigured libraries and files 81 unmodeled parts 79 unmodeled pins 82 tutorials see examples and tutorials U unmodeled parts 79 pins 82 updating plots 346 V VAC stimulus part 75 233 variables in expressions 73 VDC DC stimulus 218 VDC stimulus part 74 75 vendor supplied parts 61 VEXP stimulus part 75 voltage comparator 95 voltage reference 95 voltage regulator
147. band ripple in dB STOP stop band attenuation in dB The HIPASS part is characterized by two cutoff frequencies that delineate the boundaries of the filter pass band and stop band The attenuation values RIPPLE and STOP define the maximum allowable attenuation in the pass band and the minimum required attenuation in the stop band respectively The HIPASS part provides one input and one output one Figure 36 shows an example of a HIPASS filter device 2S so This is a high pass filter with the pass band above 1 2 kHz PAGE SEE and the stop band below 800 Hz Again the pass band Figure 36 HIPASS filter part example ripple is 0 1 dB and the minimum stop band attenuation is 50 dB This will produce a PSpice netlist declaration like this EHIGHPASS 5 0 CHEBYSHEV V 10 HP 1 2K 800 1dB 50dB BANDPASS RIPPLE pass band ripple in dB STOP stop band attenuation in dB FO F1 cutoff frequencies F2 F3 The BANDPASS part is characterized by four cutoff frequencies The attenuation values RIPPLE and STOP define the maximum allowable attenuation in the pass band and the minimum required attenuation in the stop 158 band respectively The BANDPASS part provides one input and one output Figure 37 shows an example of a BANDPASS filter device This is a band pass filter with the pass band between 1 2 kHz and 2 kHz and stop bands below 800 Hz and above 3 kHz The pass band ripple is 0 1 dB and the minimum stop band attenuatio
148. by setting all or any of the corresponding model parameters to new values using the PSpice MODEL syntax For example The MODEL syntax applies to the analog MODEL MLOAD NMOS models built in to PSpice LEVEL 1 VTO 0 7 CJ 0 02pF Models defined as subdrauit netlists For some devices there are no PSpice built in models that To find out more about PSpice command can describe their behavior fully These types of devices and netlist syntax refer to the online are defined using the PSpice SUBCKT ENDS or OrCA D PSpice A D Reference subcircuit syntax instead Manual Subcircuit syntax includes e Netlists to describe the structure and function of the part e Variable input parameters to fine tune the model For example 87 Chapter 4 Creating and editing models You can use the OrCAD Model Editor or any standard text editor to view model definitions in the libraries For example MOTOR_ RF LIB contains models for Motorola made RF bipolar transistors 88 FIRST ORDER RC STAGE SUBCKT LIN STG IN OUT AGND PARAMS CIVAL 1 C2VAL 1 RIVAL 1 R2VAL 1 GAIN 10000 C1 I N1 CIVAL C2 N1 OUT C2VAL R1 I N1 RIVAL R2 N1 OUT R2VAL EAMP1 OUT AGND VALUE V AGND N1 GAIN ENDS Sa aS How are models organized The key concepts behind model organization are as follows e Model definitions are saved in files called model libraries e Model libraries must be configured so that PSpice searches them
149. c Entry frame To start the Model Editor from within Capture 1 Inthe schematic page editor select the part whose model you want to edit 2 From the Edit menu choose PSpice Model The Model Editor starts with the model loaded for editing Using the Model Editor to create parts To find out how to use the Model Editor to create models see Using the Model Editor to edit models on page 4 93 To find out which device types the Model Editor supports see Model Editor supported device types on page 4 95 If you have already started the Model Editor from Capture and want to continue working on new models and parts then 1 Close the opened model library 2 Open a new model library 3 Load a device model or create a new one 131 Chapter 5 Creating parts for models Instead of using the OrCAD default part set you can use your own set of standard parts To find out more see Basing new parts on a custom set of parts on page 5 133 For example if the model library is named MYPARTS LIB then the Model Editor creates the part library named MYPARTS OLB 132 Setting up automatic part creation Part creation from the Model Editor is optional By default automatic part creation is enabled However if you previously disabled part creation you need to enable it before creating a new model and part To automatically create parts for new models 1 Inthe Model Editor from the Tools menu choose Options 2
150. can run with PSpice Basic analyses DC sweep amp other DC calculations These DC analyses evaluate circuit performance in response to a direct current source Table 1 summarizes what PSpice calculates for each DC analysis type Tablel DC analysis types For this DC analysis PSpice computes this DC sweep Steady state voltages and currents when sweeping a source a model parameter or temperature over a range of values Bias point detail Bias point data in addition to what is automatically computed in any simulation DC sensitivity Sensitivity of a net or part voltage as a function of bias point Small signal Small signal DC gain input resistance DC transfer and output resistance as a function of bias point Analyses you can run with PSpice See Chapter 2 Simulation examples for introductory examples showing how to run each type of analysis See Part three Setting Up and Running Analyses for a more detailed discussion of each type of analysis and how to set it up Chapter 1 Things you need to know AC sweep and noise These AC analyses evaluate circuit performance in response to a small signal alternating current source Table 2 summarizes what PSpice calculates for each AC analysis type Table2 AC analysis types For this AC analysis PSpice computes this AC sweep Small signal response of the circuit linearized around the bias point when sweeping one or more source
151. ce simulations and analyze simulation results e reference information about PSpice e Technical Support information If you are not familiar with Windows NT or 95 Help system choose How to Use Help from the Help menu xxvii Before you begin xxviii If you have the demo CD ROM OrCAD demo CD ROM The OrCAD demo CD ROM has the following limitations for PSpice circuit simulation limited to circuits with up to 64 nodes 10 transistors two operational amplifiers or 65 digital primitive devices and 10 transmission lines ideal or non ideal with not more than 4 pairwise coupled lines device characterization using the Model Editor limited to diodes stimulus generation limited to sine waves analog and clocks digital sample library of approximately 39 analog and 134 digital parts displays only simulation data created using the demo version of the simulator PSpice Optimizer limited to one goal one parameter and one constraint designs created in Capture can be saved if they have no more than 30 part instances What s New What s New New PSpice interface with integrated waveform To find out more see Analyzing analysis functionality Release 9 of PSpiceincludesall waveforms on page 319 of Probe s features and adds to them Included in one screen are tabbed windows for viewing plots text windows for viewing output files or other text files and a simulation status and message window Also included is
152. ce resets the X axis variable for the graph to be the parameter that changed between PSpice runs In the example this is the R parameter To see the rise time for the current through the inductor E L1 click the Add Trace toolbar button and then enter genrise I L1 The genrise and overshoot goal functions Figure 70 shows how the rise time decreases as the are contained in the file PSPICE PRB in the damping resistance increases for the filter ew EAI Another Y axis can be added to the plot for the overshoot of the current through L1 by selecting Add Y Axis from the Plot menu The Y axis is immediately added Now click the Add Trace toolbar button and enter overshoot I L1 Figure 70 shows how the overshoot increases with increasing resistance 276 Parametric analysis SCHEMATIC1 Parametric OrCAD PSpice A D_ ricfilt SCHEMATIC1 Test dat Fie Edt View Simulation Trace Plot Tools Window Help zlajxi Desaignes 8 a amp 9 m e E Smet A a a y a a e e 0 4 0 6 6 8 GD o GenRise 1 L1 Z v Overshoot 1 L1 Is 1 L1 9 E ricfit SCHEM For Help press F1 J I m Figure 70 Rise time and overshoot vs damping resistance 277 Chapter 11 Parametric and temperature analysis This technique for measuring branch capacitances works well in both simple and complex circuits PARAMETERS Vbias 10 1 c
153. ce symbols that you can use for AC analysis see Using time based stimulus parts with AC and DC properties on page 3 77 237 Chapter9 AC analyses Note The source V1 is a VSIN source that iS normally used for setting up sine wave signals for a transient analysis It also has an AC property so that you can use it for an AC analysis To find out more about VSIN and other source symbols that you can use for AC analysis see Using time based stimulus parts with AC and DC properties on page 3 77 238 Simulation Settings AC Sweep ix General Analysis include Files Libraries Stimulus Options Data Collection Probe Window Analysis type r AC Sweep Type Jac Sweep Noise zl Linear Start Frequency 100K Options Logarithmic End Frequency fi 0G Bl General Settings Decade z PAren mp CMonte Carlo Worst Case z i Parametric Sweep Temperature Sweep r Noise Analysis M Enabled Output Voltage fv 0ut2 lA Source fui Interval fo Figure 61 AC analysis setup for EXAMPLE OP Frequency is swept from 100 kHz to 10 GHz by decades with 10 points per decade The V1 independent voltage source is the only input to an amplifier so it is the only AC stimulus to this circuit Magnitude equals 1 V and relative phase is left at zero degrees the default All other voltage sources have zero AC value AC sweep analysis How PSpice treats nonlinear devices An AC Sweep analysis is a lin
154. cl DC Sweep then click Create The Simulation Settings dialog box appears 4 Click the Analysis tab 5 From the Analysis list select Time Domain Transient and enter the settings shown in Figure 16 TSTOP 2ms Start saving data after 20ns 6 Click OK to close the Simulation Settings dialog box 7 From the PSpice menu choose Run to perform the analysis PSpice uses its own internal time steps for computation The internal time step is adjusted according to the requirements of the transient analysis as it proceeds PSpice saves data to the waveform data file for each internal time step To display the input sine wave and clipped wave at V Out 1 From PSpice s Trace menu choose Add Trace 2 In the trace list select V In and V Out by clicking them 3 Click OK to display the traces 4 From the Tools menu choose Options to display the Probe Options dialog box 5 Inthe Use Symbols frame click Always if it is not already enabled 6 Click OK 6 5ms 1 6ns 1 5ms 2 8ns Os o UCIN UCOUT B lt lt Figure 17 Sinusoidal input and clipped output waveforms Transient analysis gt Note The internal time step is different from the Print Step value Print Step controls how often optional text format data is written to the simulation output file 0UT or press Insert These waveforms illustrate the clipping of the input signal 35 Chapter 2 Sim
155. create parts for them you should organize the definitions into libraries containing similar device types To set up a model library for part creation 1 If all of your models are in one file and you wish to keep them that way rename the file to e Reflect the kinds of models contained in the file e Have the LIB extension If each model is in its own file and you want to concatenate them into one file use the DOS copy command Example You can append a set of files with MMOD extensions into a single LIB file using the DOS command copy MOD MYLIB LIB Make sure the model names in your new library do not conflict with model names in any other model library Using the Model Editor to create parts If you want to run the Model Editor and enable automatic creation of parts for any model that you create or change then run the Model Editor alone This means any models you create are not tied to the current design or to a part editing session Note If you open an existing model library the Model Editor creates parts for only the models that you change or add to it Starting the Model Editor To start the Model Editor alone 1 From the Windows Start menu point to the OrCAD Release 9 program folder then choose PSpice Model Editor 2 From the File menu choose Open or New and enter an existing or new model library name 3 Inthe Models List frame select the name of a model to display it for editing in the Spe
156. ction that produced a specific trace double click the corresponding symbol in the legend below the x axis PBB 4 522 sos e ta sae poe cate c scat age tee e ee Ses esdape sen ces S acc ce pe cceescs asset gene sss eS ceet glee sec eset ees specs ecesssesse i 10Hz 109Hz 1 0KHZ 1OKHZ 180KHZ 1 0MHz 10MHz 100MHz 1 0GHz novAo xAY REDO vVAOHXAY 8 UDB Out Fi Figure 24 Small signal response as R1 is varied from 100Q to 10 kQ 2 Click the trace name to select it then press to You can also remove the traces by remove the traces shown removing the VDB marker from your schematic page in Capture 45 Chapter 2 Simulation examples To compare the last run to the first run press 1 From the Trace menu choose Add Trace to display the Add Traces dialog box 2 Inthe Trace Expression text box type the following You can avoid some of the typing for the Vdb Out 1 Vdb Out 21 Trace Expression text box by selecting lick OK V OUT twice in the trace list and inserting CCK OK B text where appropriate in the resulting Note The difference in gain is apparent You can also plot the difference Trace Expression of the waveforms for runs 21 and 1 then use the search commands to find certain characteristics of the difference 4 Plot the new trace by specifying a waveform expression press Insert 5 b C From the Trace menu choose Add Trace In the Trace Expression text box type the following waveform expression Vdb Out 1
157. cy filter The input to the frequency response is the voltage at net 10 The output is a voltage across nets 5 and 0 The table describes a low pass filter with a response of 1 0 dB for frequencies below 5 kilohertz and a response of 0 001 60 dB for frequencies above 6 kilohertz The phase lags linearly with frequency This is the same as a constant time delay The delay is necessary so that the impulse response is causal That is so that the impulse response does not have any significant components before time zero The FTABLE part in Figure 39 could be used Control system parts This part is characterized by the following properties ROW1 OHz 0 0 ROW2 5kHz 0 5760 ROW3 6kHz 60 6912 DELAY R_I MAGUNITS PHASEUNITS Since R_I MAGUNITS and PHASEUNITS are undefined each table entry is interpreted as containing frequency magnitude value in dB and phase values in degrees Delay defaults to 0 This produces a PSpice netlist declaration like this ELOFILT 5 0 FREQ V 10 0 0 0 5kHz 0 5760 6kHz 60 6912 Since constant group delay is calculated from the values for a given table entry as group delay phase 360 frequency An equivalent FTABLE instance could be defined using the DELAY property For this example the group delay is 3 2 msec 6912 360 6k 5760 360 6k 3 2m Equivalent property assignments are ROW OHz 0 0 ROW2 5kHz 0 0 ROW3 6kHz 60 0 DELAY 3 2ms
158. d IN The property settings for this device are as follows EXPR 5v SQRT V IN IN Example 2 Consider the device in Figure 50 This device could be used as an oscillator for a PSK Phase Shift Keyed modulator A current through a source is a sine wave with an amplitude of 15 mA and a frequency of 10 kHz The voltage at the input pin can shift the phase by 1 radian volt Note the use of the TIME parameter in this PSpice equivalent parts Esqroot H OJT H OJT 5y SO Figure 49 EVA Evalue AT VES6ING S6IN 3 LUE part example Gpsk H OUT N OUT Gvalue 15ma SIN 6 28 1 0KHzZ TIME 96 IN 9 IN Figure 50 GVALUE part example 177 Chapter 6 Analog behavioral modeling expression This is the PSpice internal sweep variable used in transient analyses For any analysis other than transient TIME 0 The relevant property settings for this device are shown below EXPR 15ma SIN 6 28 10kHz T IME V ZIN ZIN EMULT GMULT ESUM and GSUM The EMULT and GMULT parts provide output which is based on the product of two input sources The ESUM and GSUM parts provide output which is based on the sum of two input sources The complete transfer function may also include other mathematical expressions Example 1 i Epwr Consider the device in Figure 51 This device computes ECON um the instantaneous power by multiplying the voltage across pins IN a
159. d in the circuit file then the results of the nominal and worst case runs are saved for viewing in the Probe window Caution An important condition for correct worst case analysis Worst case analysis is not an optimization process it does not search for the set of parameter values that result in the worst result It assumes that the worst case occurs when each parameter has been either pushed to one of its limits or left at its nominal value as indicated by the sensitivity analysis It shows the true worst case results when the collating function is monotonic within all tolerance combinations Otherwise there is no guarantee Usually you cannot be certain whether this condition is true but insight into the operation of the circuit may alert you to possible anomalies Worst case analysis Worst case analysis example The schematic shown in Figure 84 is for an amplifier circuit that is a biased BJT This circuit is used to demonstrate how a simple worst case analysis works It also shows how non monotonic dependence of the output on a single parameter can adversely affect the worst case analysis Because an AC small signal analysis is being performed setting the input to unity means that the output Vm OUT is the magnitude of the gain of the amplifier The only variable declared in this circuit is the resistance of Rb2 Because the value of Rb2 determines the bias on the BJT it also affects the amplifier s gain
160. d set these properties appropriately One way to approach this is to edit the part that appears in your design To edit the properties for the part in question 1 Inthe schematic page editor select the part 2 From the Edit menu choose Part The part editor window appears with the part already loaded 3 From the Edit menu choose Properties and proceed to change the property values Unconfigured model stimulus or include files If you see messages like these in the PSpice Simulation Output window design_name Floating pin refdes pin pin_name Floating pin pin_id File not found Can t open stimulus file or messages like these in the PSpice output file Model model_name used by device_name is undefined Subcircuit subckt_name used by device_name is undefined Can t find STIMULUS refdes definition then you may be missing a model library stimulus file or include file from the configuration list or the configured file is not on the library path Things to watch for To find out more about setting the simulation properties for parts see Defining part properties needed for simulation on page 5 139 To find out more about using the part editor refer to your OrCA D Capture User s Guide 81 Chapter 3 Preparing a design for simulation To find out more about how to configure these files and about search order see Configuring model libraries on page 4 120 To find out more about
161. data 2 Inthe Vz text box type 7 5 3 Press Tab to move to the Iz text box and then type 20m 4 Press Tab to move to the Zz text box and then type 5 Extracting model parameters To generate new model parameter values 1 From the Tools menu choose Extract Parameters A check mark appears in the Active column of the Parameters frame for each extracted model parameter To display the curves for the five diode characteristics 1 From the Window menu choose Tile Some of the plots are shown in Figure 32 below Using the Model Editor to edit models The Model Editor accepts the same scale factors normally accepted by PSpice You can also do the following with an active plot window e Pan and zoom within the plot using commands on the View menu e Rescale axes using the Axis Settings command on the Plot menu 107 Chapter 4 Creating and editing models 108 BF rect ib Dbreak x O CAD Model Editor Eie Edt View Model Plot Tools Window Help Ofer Ba e Ree Mf elie Modeinane Type T Cieaion Date Craenen RAE Dbreak Diode 07 31 98 at ee Q2N22224 Z Forward Current f Reverse Leakage QANSISZTK BIT 4 Q2NE727 2TX BJT Toinclude this spec in the model To include this spec in the model M2N7000 2TX SUBCKT extraction please enter two or mote extraction please enter two of more M2N7002 2TX SUBCKT data points in the following table data points in the following tabl
162. de gt lt tathode GOES VEIN lt E Q able per 1 5 lt a ct a 1 cathode gt ande erode gt Ca apr c Rout Ce a E SPS Meg T pF ji gathod cathode gt Figure 47 Triode circuit Assumptions In its main operating region the triode s current is proportional to the 3 2 power of a linear combination of the grid and anode voltages ianode ko vg ky va For a typical triode kg 200e 6 and k4 0 12 Looking at the upper left hand portion of the schematic notice the a general purpose ABM part used to take the input voltages from anode grid and cathode Assume the following associations e V anode is associated with V IN1 e V grid is associated with V IN2 e V cathode is associated with V IN3 The expression property EXP1 then represents V grid cathode and the expression property EXP2 represents 0 12 V anode cathode When the template substitution is performed the resulting VALUE is equivalent to the following V V grid cathode 0 12 V anode cathode 171 Chapter 6 Analog behavioral modeling 172 The part would be defined with the following characteristics EXP1 V IN2 IN3 EXP2 0 12 V IN1 IN3 This works for the main operating region but does not model the case in which the current stays 0 when combined grid and anode voltages go negative We can accommodate that situation as follows by adding the LIMIT part with the following characte
163. de the non causal part into a causal region S is theoretically 50 non causal Non causality on the order of 1 or less is usually not critical to the simulation results You can delay S to keep it causal but the separation between the impulses is infinitesimal This means that a very small time step is needed For this reason it is usually better to use a macromodel to implement differentiation Here are some guidelines e Inthe case of a Laplace device ELAPLACE multiply the Laplace expression by e to the s lt the suggested delay gt e Inthe case of a frequency table EFREQ or GFREQ do either of the following e Specify the table with DELAY lt the suggested delay gt e Compute the delay by adding a phase shift 189 Chapter 6 Analog behavioral modeling 190 Chebyshev filters All of the considerations given above for Laplace parts also apply to Chebyshev filter parts However PSpice also attempts to deal directly with inaccuracies due to sampling by applying Nyquist criteria based on the highest filter cutoff frequency This is done by checking the value of TMAX If TMAX is not specified it is assigned a value or if it is specified it may be reduced For low pass and band pass filters TMAX is set to 0 5 FS where FS is the stop band cutoff in the case of a low pass filter or the upper stop band cutoff in the case of a band pass filter For high pass and band reject filters there is no c
164. del and then edit the original model from within the part definition on page 4 117 editor 103 Chapter 4 Creating and editing models press P Di lt Dbreak v1 cot M G9 in ik YW 0 Figure 30 Design for a half wave rectifier 104 press The Model Editor tutorial In this tutorial you will model a simple diode device as follows Create the schematic for a simple half wave rectifier Run the Model Editor from the schematic editor to create an instance model for the diode in your schematic Creating the half wave rectifier design To draw the design 1 Note From the Project Manager from the File menu point to New then choose Project Enter the name of the new project RECTFR and click Create From Capture s Place menu choose Part Place one each of the following parts reference designator shown in parentheses as shown in Figure 30 e Dbreak D1 diode e C C1 capacitor e R R1 resistor e VSIN V1 sine wave source Click the Ground button and place the analog ground From the Place menu choose Wire and draw the connections between parts as shown in Figure 30 From the File menu choose Save If you were to simulate this design using a transient analysis you would also need to set up a transient specification for V1 most likely this would mean defining the VOFF offset voltage VAMPL amplitude and FREQ frequency properties for V1 For
165. devices Part one Simulation primer Part one provides basic information about circuit simulation including examples of common analyses e Chapter 1 Things you need to know provides an overview of the circuit simulation process including what PSpice does descriptions of analysis types and descriptions of important files e Chapter 2 Simulation examples presents examples of common analyses to introduce the methods and tools you ll need to enter simulate and analyze your design Things you need to know Chapter overview This chapter introduces the purpose and function of the OrCAD PSpice circuit simulator e What is PSpice on page 1 2 describes PSpice capabilities e Analyses you can run with PSpice on page 1 3 introduces the different kinds of basic and advanced analyses that PSpice supports e Using PSpice with other OrCAD programs on page 1 9 presents the high level simulation design flow e Files needed for simulation on page 1 10 describes the files used to pass information between OrCAD programs This section also introduces the things you can do to customize where and how PSpice finds simulation information e Files that PSpice generates on page 1 14 describes the files that contain simulation results Chapter 1 Things you need to know The range of models built into PSpice indude not only those for resistors inductors capacitors and bipolar transistors but also these transmission li
166. dify each model characteristic shown in the Model Spec frame with new values from the data sheets The Model Editor takes the new information and fits new model parameter values When updating the entered data the Model Editor expects either e device curve data point pairs or e single valued data depending on the device characteristic For the diode Forward Current Junction Capacitance and Reverse Leakage require device curve data Reverse Breakdown and Reverse Recovery require single valued data Table 1 lists the data sheet information for the Dbreak X model Table1 Sample diode data sheet values For this model characteristic Enter this forward current 1 3 0 2 junction capacitance 1m 120p 1 73p 3 75 45p reverse leakage 6 20n reverse breakdown Vz 7 5 Iz 20m Zz 5 reverse recovery no changes To change the Forward Current characteristic 1 Inthe Spec Entry frame click the Forward Current tab This tab requires curve data 2 Inthe Vfwd text box type 1 3 3 Press to move to the Ifwd text box and then type 0 2 To change the values for J unction Capacitance and Reverse Leakage 1 Follow the same steps as for Forward Current entering the data sheet information listed in Table 1 that corresponds to the current model characteristic To change the Reverse Breakdown characteristic 1 Inthe Spec Editing frame click the Reverse Breakdown tab This tab requires single valued
167. displayed data the extent of the scrolling region and the minimum resolution for each of the axes Displayed Data Range parameters determine what portion of the stimulus data set will be presented on the screen Extent of Scrolling Region parameters set the absolute limits on the viewable range Minimum Resolution parameters determine the smallest usable increment example if it is set to 1 msec then you cannot add a data point at 1 5 msec 255 Chapter 10 Transient analysis 256 Defining stimuli 1 Place stimulus part instances from the symbol set VSTIM ISTIM and DIGSTIMn 2 Click the source instance to select it 3 From the Edit menu choose PSpice Stimulus to start the Stimulus Editor 4 Fill in the transient specification according to the dialogs and prompts 5 From the File menu choose Save to save the edits Example piecewise linear stimulus 1 2 Open an existing schematic or start a new one From the Place menu choose Part and browse the SOURCE OLB part library file for VSTIM and select it Place the part It looks like a regular voltage source with an implementation property displayed Click the implementation label and type vfirst This names the stimulus that you are going to create If you are working in a new schematic use Save from the File menu to save it This is necessary since the schematic name is used to create the default stimulus file name Click the VSTIM part to select it From
168. dow B is loaded with YOURSIM DAT When V 2 is copied from window A to window B the trace looks different because it is determined by data from YOURSIM DAT instead of MYSIM DAT Copying and moving labels Labels can be selected and moved or copied either within the same Probe window or to another Probe window To copy labels 1 Select one or more hift click labels or select multiple labels by drawing a selection rectangle Selected labels are highlighted From the Edit menu choose Copy or Cut to save the labels to the clipboard Cut removes labels from the Probe window User interface features for waveform analysis 3 Switch to the Probe window where labels are to be press Ctri V added and from the Edit menu choose Paste 4 Click on the new location to place the labels To move labels 1 Select one or more hif click labels or select multiple labels by drawing a selection rectangle Selected labels are highlighted 2 Move the labels by dragging them to a new location Tabulating trace data values You can generate a table of data points reflecting one or more traces in the Probe window and use this information in a document or spreadsheet To view the trace data values table 1 Select one or more hift click trace names Selected trace names are highlighted 2 From the Edit menu choose Copy or Cut to save the ir trace data point values to the Clipboard Cut removes traces from the Prob
169. dows 344 Index 403 Index 404
170. e To reconfigure an include file as a library file 1 From the Simulation menu choose Edit Simulation Settings then click the Include Files tab 2 Select the include file that you want to change 3 Click either the Add as Global or the Add to Design button 4 Click Remove to remove the include file entry 121 Chapter 4 Creating and editing models 122 Handling duplicate model names If your model libraries contain duplicate model names PSpice always uses the first model it finds This means you might need to resequence the search order to make sure PSpice uses the model that you want See Changing model library search order on page 4 124 Note PSpice searches design libraries before global libraries so if the new model you want to use is specific to your design and the duplicate definition is global you do not need to make any changes Adding model libraries to the configuration New libraries are added above the selected library name in the Library Files list box To add model libraries to the configuration 1 From the Simulation menu choose Edit Simulation Settings then click the Libraries tab Click the library name positioned one entry below where you want to add the new library In the Filename text box either e type the name of the model library or e click Browse to locate and select the library Do one of the following e If the model definitions are for use in the current design o
171. e temperature analysis is set to analysis is setup as follows Print Step Final Time Enable Fourier Center Frequency Output Vars To start the simulation 35 degrees The transient 20ns 1000ns selected 1Meg V OUT2 1 From Capture s File menu point to Open and choose Project 2 Open the following project in your OrCAD program installation directory Analog example The example project EXAMPLE OP is provided with your OrCAD programs When shipped EXAMPLE OP is set up with multiple analyses For this example the AC sweep DC sweep Monte Carlo worst case and small signal transfer function analyses have been disabled The specification for each of these disabled analyses remains intact To run them from Capture in the future from the PSpice menu choose Edit Simulation Settings and enable the analyses Note When you run a Fourier analysis using PSpice as specified in this example PSpice writes the results to the PSpice output file 0UT You can also use Probe windows to display the Fourier transform of any trace expression by using the FFT capability in PSpice To find out more refer to PSpice A D online Help 341 Chapter 13 Analyzing waveforms If PSpice is set to show traces for all markers on startup you will see the V OUTL and V OUT2 traces when the Probe window displays To clear these traces from the plot from the Trace menu choose Delete All Traces 342 PSPICE SAMPLES
172. e palzarany Diode e wwa mijd ea BASIGZTX Diode BAS19 ZTX Diode Junction Capacitance BASZNZTX Diode BAS2I ZTX Diode Toinclude this spec in the model BAVZO ZTX Diode E Reverse Breakdown extraction please enter two of more BAV 4 ZTX Diode data ponts in the folowing table BAVOIZTX BAWSEZZTX Diode WA BY31 ZTX BBYAUZTX Diod BCIOTBP ZTX BIT Reverse Recovery ol ina r i pea oll ion Ca Reverse Br fa Reverse Re Parameters A tive i 4 d A E E E i Ready T NONI Figure 32 Assorted device characteristic curves for a diode Adding aurves for more than one temperature By default the Model Editor computes device curves at 27 C For any characteristic you can add curves to the plot at other temperatures To add curves for Forward Current at a different temperature 1 Inthe Spec Entry frame click the Forward Current tab 2 From the Plot menu choose Add Trace 3 Type 100 in C 4 Click OK The Forward Current plot should appear as shown in Figure 33 below Using the Model Editor to edit models 6 2U 6 5U 1 6U 1 4U o Ifwd 27 C Ifwd 166 C Forward Voltage Figure 33 Forward Current device curve at two temperatures Completing the model definition You can refine the model definition by e modifying the entered data as described before
173. e Configuring model libraries on mwa A TA 297 Chapter 12 Monte Carlo and sensitivity worst case analyses 298 E PSENSOR lib OrCAD Model Editor Rbreak BEE File Edit View Model Plot Tools Window Help 18 x SCI ile JARRI A mE cE model RMontel RES R 1 DEV 2 LOT 10 a Figure 79 Model definition for RMontel1 PSENSOR LIB Capture also automatically configures the library for local use To have resistors R2 and R4 use the same tolerances as R1 1 In Capture s schematic page editor select R2 and R4 2 From the Edit menu select Properties 3 In the R2 row click in the cell under the Implementation column and type RMontel 4 In the R4 row click in the cell under the Implementation column and type RMontel To assign 5 device tolerance to the resistance multiplier for R3 1 Select R3 2 From the Edit menu select PSpice Model 3 Inthe Model Text frame change the MODEL statement to model RTherm RES R 1 DEV 5 4 From the File menu choose Save Your schematic page should look like Figure 80 Setting up the analyses This section shows how to define and enable a DC analysis that sweeps the pressure value and a Monte Carlo analysis that runs the DC sweep with each change to the resistance multipliers To set up the DC sweep 1 Inthe PSpice menu choose New Simulation Profile or Edit Simulation Settings If this is a new simulation enter the name of the profile and click
174. e 6 the knee of the I V curve would be too sharp for PSpice to maintain its continuity within the power supply step size limit of le 6 Unguarded p n junctions A second consideration is to avoid unguarded p n junctions no series resistance The above diode example also applies to the p n junctions inside bipolar transistors MOSFETs drain bulk and source bulk JFETs and GaAsFETs 385 Chapter B Convergence and time step too small errors 386 No leakage resistance A third consideration is to avoid situations which could have an ideal current source pushing current into a reverse biased p n junction without a shunt resistance Since p n junctions in PSpice have almost no leakage resistance and would cause the junction s voltage to go beyond 1e10 volts The model libraries which are part of PSpice follow these guidelines Typos can cause unrealistic device parameters The following MOSFET M1 3 2 1 0 MMOD L 5 W 3 has a length of five meters and a width of three meters instead of micrometers It should have been M1 3 2 1 0 MMOD L 5u W 3u PSpice flags an error for L too large but cannot for W because power MOSFETs are so interdigitated a zipper like trace that their effective W can be very high The LIST option can show this kind of problem When the devices are listed in the output file their values are shown in scientific notation making it easy to spot unusual values Switches PSpice sw
175. e MODEL or SSUBCKT definition of the simulation model as it appears in the model library LIB Example If your design includes a 2N2222 bipolar transistor with a MODEL name of Q2N2222 then the Implementation name for that part should be Q2N2222 Note Make sure that the model library containing the definition for the attached model is configured in the list of libraries for your project See Configuring model libraries on page 4 120 for more information To attach a model implementation 1 Inthe schematic page editor double click a part to display the Parts spreadsheet of the Property Editor 2 From the Implementation list select PSpice Model 3 Inthe Implementation column type the name of the model to attach to the part 4 Click Apply to update the design then close the Parts spreadsheet Defining part properties needed for simulation If you created your parts using any of the methods discussed in this chapter then your part will have these properties already defined for it e PSpice PSPICETEMPLATE for simulation e PART and REFDES for identification For example if you create a part that has electrical behavior described by the subcircuit definition that starts with SUBCKT 7400 A B Y optional DPWR G_DPWR DGND G_DGND params MNTYMXDLY 0 IO_LEVEL 0 then the appropriate part properties are IMPLEMENTATION 7400 MNTYMXDLY 0 IO_LEVEL 0 PSPICETEMPLATE X REFDES ZA B ZY PWR GND MODEL
176. e available colors in sequence for each y axis e the same color for all the traces that belong to the same waveform data file To configure trace color schemes in the Probe Options dialog box 1 From the Tools menu choose Options to display the Probe Options dialog box 2 Under Trace Color Scheme choose one of the following options Table 2 Choose this option To do this Normal Match Axis Sequential Per Axis Unique by File Use a different color for each trace for up to 12 traces depending on the number of colors set in the PSPICE INI file Use the same color for all the traces that belong to the same y axis The title of the axis by default 1 2 etc is the same color as its traces Use the available colors in sequence for each y axis Use the same color for all the traces in one Probe window that belong to the same waveform data file 3 Click OK View ing waveforms If you are using Capture you can either view waveforms automatically after you run a simulation or you can monitor the progress of the simulation as it is running Setting up waveform display from Capture You can configure the way you want to view the waveforms in PSpice by defining display settings in the Probe Window tab in the Simulation Settings dialog box Simulation Settings Parametric x General Analysis Include Files Libraries Stimulus Options Data Collection Probe Window M Displa
177. e delay is necessary so that the impulse response is causal That is so that the impulse response does not have any significant components before time zero The constant group delay is calculated from the values for a given table entry as follows group delay phase 360 frequency For this example the group delay is 3 2 msec 6912 360 6k 5760 360 6k 3 2m An alternative specification for this table could be 0 0 0 5kHz 0 0 6kHz 60 0 3 2ms MAGUNITS PHASEUNITS This produces a PSpice netlist declaration like this ELOWPASS 5 0 FREQ V 10 0 0 0 5kHz 0 0 6kHz 60 0 DELAY 3 2ms PSpice equivalent parts LOWPASS he OLT Ih DT EFREQ V 96IN 9IN DELAY 0 Figure 53 EFREQ part example 185 Chapter 6 Analog behavioral modeling Figure 54 Voltage multiplier circuit mixer 186 Cautions and recommendations for simulation and analysis Instantaneous device modeling During AC analysis nonlinear transfer functions are handled the same way as other nonlinear parts each function is linearized around the bias point and the resulting small signal equivalent is used Consider the voltage multiplier mixer shown in Figure 54 This circuit has the following characteristics Vin1 DC 0v AC 1v Vin2 DC 0v AC 1v where the output on net 3 is V 1 V 2 During AC analysis V 3 0 due to the 0 volts bias point voltage on nets
178. e following e change definitions and e create new definitions When you are finished the Model Editor automatically configures the model definitions into the model libraries To display the model text 1 From the View menu choose Model Text The Model Editor displays the PSpice syntax for model definitions e MODEL syntax for models defined as parameter sets e SUBCKT syntax for models defined as netlist subcircuits You can edit the definition just as you would in any standard text editor Editing MODEL definitions For definitions implemented as model parameter sets using PSpice MODEL syntax the Model Editor lists one parameter per line This makes it easier to add DEV LOT tolerances to model parameters for Monte Carlo or sensitivity worst case analysis Editing SUBCKT definitions For definitions implemented as subcircuit netlists using PSpice SUBCKT syntax the model editor displays the subcircuit syntax exactly as it appears in the model library The Model Editor also includes all of the comments immediately before or after the subcircuit definition Changing the model name You can change the model name directly in the PSpice MODEL or SUBCKT syntax but double check that the new name does not conflict with models already contained in the libraries Note Ifyou do create a model with the same name as another model and want PSpice to always use your model make sure the configured model libraries
179. e if you want to do any of the entering data sheet information and model following fitting as described in How to fit e create a model and use the model in any design and models on page 4 97 automatically create a part e create a model and have the model definition available to any design without creating a part or e examine or verify the characteristics of a given model without using PSpice Running the Model Editor alone means that the model you are creating or examining is not currently tied to a part instance on your schematic page or to a part editing session Note You can only edit models for device types that the Model Editor supports See Model Editor supported device types on page 4 95 for details Starting the Model Editor To start the Model Editor alone If you have already started the Model Editor from Capture and want to continue 1 From the Start menu point to the OrCAD program working on new models then folder then choose Model Editor 1 Save the opened model library 2 From the File menu choose New or Open and enter an existing or new model library name 2 Open or create a different model library 3 From the Part menu choose New Copy From or Import to load a model 3 Get a model or create a new one 99 Chapter 4 Creating and editing models Instead of using the OrCAD default part set for new models you can have the Model Editor use your own set of standard parts To find out more see
180. e netlist or by making the appropriate choice from the Analysis Setup Options menu When enabled the GMIN stepping algorithm is applied after the circuit fails to converge with the power supplies at 100 percent and if GMIN stepping also fails the supplies are then cut back to almost zero GMIN stepping attempts to find a solution by starting the repeating cycle with a large value of GMIN initially 1 0e10 times the nominal value If a solution is found at this setting it then reduces GMIN by a factor of 10 and tries again This continues until either GMIN is back to the nominal value or a repeating cycle fails to converge In the latter case GMIN is restored to the nominal value and the power supplies are stepped Bias point and DC sweep Bias point and DC sweep Power supply stepping As previously discussed PSpice uses a proprietary algorithm which finds a continuous path from zero power supplies levels to 100 It starts at almost zero 001 power supplies levels and works its way back up to the 100 levels The minimum step size is 1e 6 0001 The first repeating series of the first step starts at zero for all voltages Semiconductors Model parameters The first consideration for semiconductors is to avoid physically unrealistic model parameters Remember that as PSpice steps the power supplies up it has to step carefully through the turn on transition for each device In the diode example above for the setting N 1
181. e this output variable Which is represented by this equation Flicker noise for a device Shot noise for a device Thermal noise for the RB RC RD RE RG or RS constituent of a device respectively Total noise for a device Total output noise for the circuit RMS summed output noise for the circuit Equivalent input noise for the circuit NFID device_name NFIB device_name NSID device_name NSIB device_name NSIC device_name NRB device_name NRC device_name NRD device_name NRE device_name NRG device_name NRS device_name NTOT device_name NTOT ONOISE V ONOISE V INOISE a I ia For diodes and BJTs noise 2q For GaAsFETs JFETs and MOSFETs noise kp dI 2 noise 4kT W 3 noise does R Sum of all contributors in device_name y NTOT device device RMS sum of all contributors JNTOT ONOISE V ONOISE gain To find out more about the equations that describe noise behavior refer to the appropriate device type in the A nalog Devices chapter in the OrCAD PSpice Reference Manual 245 Chapter9 AC analyses For a description of the Interval parameter see page 9 244 246 About noise units Table 9 This type of noise output variable Is reported in these units Device contribution of the form 2 Nxxx volts Hz Total input or output noise of the form V ONOISE or V INOISE volts JHz Example You can ru
182. e using Device Equations must be made to all new PSpice updates you install Device models made with ABM can be used for most cases are much easier to create and are compatible with PSpice updates The ABM OLB part library file The part library ABM OLB contains the ABM components This library contains two sections The first section has parts that you can quickly connect to form control system types of circuits These components have names like SUM GAIN LAPLACE and HIPASS The second section contains parts that are useful for more traditional controlled source forms of schematic parts These PSpice equivalent parts have names like EVALUE and GFREQ and are based on extensions to traditional PSpice E and G device types Implement ABM components by using PSpice primitives there is no corresponding abm 1ib model library A few components generate multi line netlist entries but most are implemented as single PSpice E or G device declarations See ABM part templates on page 6 152 fora description of PSPICETEMPLATE properties and their role in generating netlist declarations See Implementation of PSpice equivalent parts on page 6 175 for more information about PSpice E and G syntax The ABM OLB part library file 149 Chapter 6 Analog behavioral modeling The name of an interface port does not extend to any connected nets To refer to a signal originating at an interface port connect the port to an offpage connector of
183. e window 3 In Clipboard Viewer from the Display menu choose either Text or OEM Text To export the data points to other applications Saving the data directly to a file from Clipboard Viewer can create superfluous 1 Select one or more hift click trace names Selected data at the beginning of the file trace names are highlighted 2 From the Edit menu choose Copy or Cut to save the i trace data point values to the Clipboard Cut removes traces from the Probe window 3 Paste the data from the Clipboard into a text editor a spreadsheet program or a technical computing program such as Mathcad 349 Chapter 13 Analyzing waveforms press Ctrl lt gt Shift C You can move the cursor box any where over the Probe window by dragging the box to another location 350 4 Save the file Using cursors When one or more traces are displayed you can use cursors to display the exact coordinates of two points on the same trace or points on two different traces In addition differences are shown between the corresponding coordinate values for the two cursors Displaying cursors To display both cursors 1 From the Trace menu point to Cursor then choose Display The Probe Cursor window appears showing the current position of the cursor on the x axis and y axis As you move the cursors the values in the cursor box change In the analog area of the plot if any both cursors are initially placed on
184. e window A Probe window is a separately managed waveform display area A Probe window can include multiple analog and digital plots Figure 92 shows two plots displayed together Because a Probe window is a window object you can minimize and maximize windows or move and scale the windows within the PSpice workspace A toolbar can be displayed in the Probe window and applies to the active Probe window E window A window B active Figure 92 Two Probe windows You can display information from one or more waveform data files in one Probe window After the first file is loaded load other files into the same Probe window by appending them in PSpice Overview of waveform analysis Managing multiple Probe windows You can open any number of Probe windows Each Probe window is a tab on the worksheet displayed in the middle of the workspace The same waveform data file can be displayed in more than one Probe window You can tile the windows to compare data Only one Probe window is active at any given time identified by a highlighted title bar or a topmost tab Menu keyboard and mouse operations affect only the active Probe window You can switch to another Probe window by clicking another tab or title bar Printing multiple windows You can print all or selected Probe windows with up to nine windows on a single page When you choose Print from the File menu a list of all open Probe windows appear
185. ear or small signal analysis This means that nonlinear devices must be linearized to run the analysis What s required to transform a device into a linear druit In order to transform a device such as a transistor amplifier into a linear circuit you must do the following 1 Compute the DC bias point for the circuit 2 Compute the complex impedance and or transconductance values for each device at this bias point 3 Perform the linear circuit analysis at the frequenciesof Example Replace a bipolar transistor in interest by using simplifying approximations common emitter mode with a constant transconductance collector current roportional to base emitter voltage and a What PSpice does a of constant impedances i PSpice automates this process for you PSpice computes the partial derivatives for nonlinear devices at the bias point and uses these to perform small signal analysis Example nonlinear behavioral modeling block Suppose you have an analog behavioral modeling block that multiplies V 1 by V 2 Multiplication is a nonlinear operation To run an AC sweep analysis on this block the block needs to be replaced with its linear equivalent To determine the linear equivalent block PSpice needs a known bias point 239 Chapter9 AC analyses Int of Out In2 Vi C ai ke DC 0V DC 2V ACMAG 1V A This is exactly how a double balanced mixer behaves In practice this is a si
186. ections in this chapter that are relevant to the model editing task that you want to complete e Ways to create and edit models on page 4 92 How to use the tools These sections explain how to use different tools to create and edit models on their own and when editing schematic pages or parts e Using the Model Editor to edit models on page 4 93 e Editing model text on page 4 110 e Using the Create Subcircuit command on page 4 115 Other useful information These sections explain how to configure and reuse models after you have created or edited them e Changing the model reference to an existing model definition on page 4 117 e Reusing instance models on page 4 118 e Configuring model libraries on page 4 120 What are models What are models A model defines the electrical behavior of a part On a schematic page this correspondence is defined by a part s Implementation property which is assigned the model name Depending on the device type that it describes a model is defined as on of the following e amodel parameter set e asubcircuit netlist Both ways of defining a model are text based with specific rules of syntax Models defined as model parameter sets PSpice has built in algorithms or models that describe the behavior of many device types The behavior of these built in models is described by a set of model parameters You can define the behavior for a device that is based ona built in model
187. ectrical behavior the model can be e explicitly defined in a model library e built into PSpice or e built into the part for some kinds of analog behavioral parts e A part with modeled pins to form electrical connections in your design e A translation from design part to netlist statement so that PSpice can read it in Note Notall parts in the libraries are set up for simulation For example connectors are parts destined for board layout only and do not have these simulation properties Vendor supplied parts The OrCAD libraries provide an extensive selection of manufacturers analog parts Typically the library name reflects the kind of parts contained in the library and the vendor that provided the models Example MOTOR_RF OLB and MOTOR_RF LIB contain parts and models respectively for Motorola made RF bipolar transistors Part naming conventions The part names in the OrCAD libraries usually reflect the manufacturers part names If multiple vendors supply the same part each part name includes a suffix that indicates the vendor that supplied the model Example The OrCAD libraries include several models for the OP 27 opamp as shown by these entries in the online Library List Generic Mfg Device Type Name Name Symbol Name Library Tech Type Model Operational Amplifier OP 249 Analog OP 249G AD ANLG_DEV SL amp Devices Inc Operational Amplifier OP 260 Analog OP 260 AD ANLG_DEV SLB Devices Inc
188. ed Saving the design Before editing the models for the Rbreak resistors save the schematic To save the design 1 From Capture s File menu choose Save Defining tolerances for the resistor models This section shows how to assign device DEV and lot LOT tolerances to the model parameters for resistors R1 R2 R3 and R4 using the model editor To assign 2 device and 10 lot tolerances to the resistance multiplier for R1 1 Select R1 2 From the Edit menu choose PSpice Model Capture searches the libraries for the Rbreak model definition and makes a copy to create an instance model 3 To change the instance model name from Rbreak to Rmontel1 do the following a Inthe Model Text frame double click Rbreak b Type RMontel 4 To add a 2 device tolerance and a 10 lot tolerance to the resistance multiplier do the following a Add the following to the MODEL statement after R 1 DEV 2 LOT 10 The model editing window should look something like Figure 79 5 From the File menu choose Save By default Capture saves the RMontel MODEL definition to the design_name lib library which is Monte Carlo analysis You can use the model editor to change the MODEL or SUBCKT syntax for a model definition To find out more about the model editor see Editing model text on page 4 110 or refer to the online PSpice Reference Manual To find out more about adding model libraries to the configuration se
189. ed and connected by straight lines which is used to suppress a value until a given amount of time has passed where t is a relational expression using the relational operators shown in Table 9 M x P x R x and IMG x apply to Laplace expressions only Table1l System variables This variable Evaluates to this TEMP TIME Temperature values resulting from a temperature parametric temperature or DC temperature sweep analysis The default temperature TNOM is set in the Options dialog box from the Simulation Settings dialog box choose the Options tab TNOM defaults to 27 C Note TEMP can only be used in expressions pertaining to analog behavioral modelin Time values resulting from a transient analysis If no transient analysis is run this variable is undefined Note TIME can only be used in analog behavioral modeling expressions Using global parameters and expressions for values Note If a passive or semiconductor device has an independent temperature assignment then TEMP does not represent that device s temperature To find out more about customizing temperatures for passive or semiconductor devices refer to the MODEL command in the Commands chapter in the online OrCA D PSpice A D Reference Manual 73 Chapter 3 Preparing a design for simulation To find out how to use these parts and specify their properties see the following 74 Setting up a DC stimulus on p
190. ed as either E or G device types The E part type provides a voltage output and the G device type provides a current output The device s transfer function can contain any mixture of voltages and currents as inputs Hence there is no longer a division between voltage controlled and current controlled parts Rather the part type is dictated only by the output requirements If a voltage output is required use an E part type If a current output is necessary use a G part type Each E or G part type in the ABM OLB part file is defined by a template that provides the specifics of the transfer function Other properties in the model definition can be edited to customize the transfer function By default the template cannot be modified directly choosing Properties from the Edit menu in Capture Rather the values for other properties such as the expressions used in the template are usually edited then these values are substituted into the template However the part editor can be used to modify the template or designate the template as modifiable from within Capture This way custom parts can be created for special purpose application Implementation of PSpice equivalent parts Although you generally use Capture to place and specify PSpice equivalent ABM parts it is useful to know the PSpice command syntax for E and G devices This is especially true when creating custom ABM parts since part templates must adhere to PSpice syn
191. ed in the legend below the x axis V In in this example The Probe Cursor window also appears To display the cursor crosshairs a Position the mouse anywhere inside the Probe window b Click to display the crosshairs for the first cursor C Right click to display the crosshairs for the second cursor In the trace legend the part for V In is outlined in the crosshair pattern for each cursor resulting in a dashed line as shown in Figure 11 Place the first cursor on the V In waveform a Click the portion of the V In trace in the proximity of 4 volts on the x axis The cursor crosshair appears and the current X and Y values for the first cursor appear in the cursor window b To fine tune the cursor location to 4 volts on the x axis drag the crosshairs until the x axis value of the Al cursor in the cursor window is approximately 4 0 You can also press 3 and for tighter control Place the second cursor on the V Mid waveform a Right click the trace legend part diamond for V Mid to associate the second cursor with the Mid waveform The crosshair pattern for the second cursor outlines the V Mid trace part as shown in Figure 12 0 Right click the portion on the V Mid trace that is in the proximity of 4 volts on the x axis The X and Y values for the second cursor appear in the cursor window along with the difference dif between the two cursors X and Y values DC sweep analysis C To fine tune the locat
192. eep analysis Setting up an AC analysis To set up the AC analysis 1 From the PSpice menu choose New Simulation Profile or Edit Simulation Settings If this is a new simulation enter the name of the profile and click OK The Simulation Settings dialog box appears Simulation Settings AC Sweep ix General Analysis Include Files Libraries Stimulus Options Data Collection Probe Window Analysis type AC Sweep Type ACS Noise Linear Start Frequency fi 0 Options Logarithmic End Frequency f1 00K General Settings Monte Carlo Wworst Case Parametric Sweep CTemperature Sweep Noise Analysis I Enabled Total Points fi 0 Cancel Apply Help 2 Choose AC Sweep Noise in the Analysis type list box 3 Under Options select General Settings if it is not already enabled 4 Set the number of sweep points as follows 235 Chapter9 AC analyses If you also want to run a noise analysis then before clicking OK complete the Noise Analysis frame in this dialog box as described in Setting up a noise analysis on page 9 243 236 Table 6 To sweep frequency Do this linearly logarithmically by decades logarithmically by octaves Under AC Sweep Type click Linear and enter the total number of points in the sweep in the Total Points box Under AC Sweep Type click Logarithmic select Decade default and e
193. efault up to five triplets are allowed where n 1 2 3 4 or 5 DELAY group delay increment defaults to 0 if left blank RI table type if left blank the frequency table is interpreted in the input frequency magnitude phase format if defined with any value such as YES the table is interpreted in the input frequency real part imaginary part format MAGUNITS units for magnitude where the value can be DB decibels or MAG raw magnitude defaults to DB if left blank PHASEUNITS units for phase where the value can be DEG degrees or RAD radians defaults to DEG if left blank The FTABLE part is described by a table of frequency responses in either the magnitude phase domain R_I or complex number domain R_I YES The entire table is read in and converted to magnitude in dB and phase in degrees Interpolation is performed between entries Magnitude is interpolated logarithmically phase is interpolated linearly For frequencies outside the table s range 0 zero magnitude is used This characteristic can be used to impose an upper and lower limit on the output The DELAY property increases the group delay of the frequency table by the specified amount The delay term is particularly useful when a frequency table device generates a non causality warning message during a transient analysis The warning message issues a delay Control system parts If more than five values are required the part can be customized
194. efined Part library the Model Editor saves all new parts to the specified file until you change it Saving global models and parts Wh en you save your changes the Model Editor does the following for you Tos 1 Saves the model definition to the model library that you originally opened If you had the automatic part creation option enabled saves the part definition to MODEL_LIBRARY_NAME OLB ave the new model and part From the File menu choose Save to update MODEL_LIBRARY_NAME LIB and if you enabled part creation MODEL_LIBRARY_NAME OLB and save them to disk Using the Model Editor to edit models Running the Model Editor from the schematic page editor If you want to Once you have started the Model Editor you can proceed with entering data sheet e test behavior variations on a part or S i information and model fitting as described e refine a model before making it available to all now to tit modeis n designs page 4 97 then run the Model Editor from the schematic page editor in Capture This means editing models for part instances on your schematic page When you select a part instance and edit its model the schematic page editor automatically creates an instance model that you can then change Note You can only edit models for device types that the Model Editor supports See Model Editor supported device types on page 4 95 for details What is an instance model For more informatio
195. efined as follows EXPR value used for table lookup defaults to V IN IN if left blank TABLE series of either input frequency magnitude phase triplets or input frequency real part imaginary part triplets describing a complex value defaults to 0 0 0 1Meg 10 90 if left blank PSpice equivalent parts 183 Chapter 6 Analog behavioral modeling 184 DELAY group delay increment defaults to 0 if left blank RI table type if left blank the frequency table is interpreted in the input frequency magnitude phase format if defined with any value such as YES the table is interpreted in the input frequency real part imaginary part format MAGUNITS units for magnitude where the value can be DB decibels or MAG raw magnitude defaults to DB if left blank PHASEUNITS units for phase where the value can be DEG degrees or RAD radians defaults to DEG if left blank The DELAY property increases the group delay of the frequency table by the specified amount The delay term is particularly useful when an EFREQ or GFREQ device generates a non causality warning message during a transient analysis The warning message issues a delay value that can be assigned to the part s DELAY property for subsequent runs without otherwise altering the table The output of the device depends on the analysis being done For DC and bias point the output is simply the zero frequency magnitude times the value of EX
196. entifier gt The schematic page editor processes the property according to the special character as shown in the following table Table 4 This syntax Is replaced with this lt id gt Value of lt id gt Error if no lt id gt attribute or if no value assigned amp lt id gt Value of lt id gt if lt id gt is defined lt id gt s s Text between s s separators if lt id gt is defined lt id gt s 8 8 Text between the first s s separators if lt id gt is defined else the second s s clause lt id gt s s Text between s s separators if lt id gt is undefined lt id gt S 8S S Text between the first s s separators if lt id gt is undefined else the second S 5 clause lt id gt s s Text between s s separators if lt id gt is defined but delete rest of template if lt id gt is undefined is a separator character Separator characters include commas periods semi colons forward slashes and vertical bars You must always use the same character to specify an opening closing pair of separators Note You can use different separator characters to nest conditional property clauses Defining part properties needed for simulation Example The template fragment 2G bar if th If G tran G G G 1000 usesthe vertical as the separator between the en else parts of this conditional clause has a value then this fragment slates to G
197. ep variable value at which the collating function was measured are given The parameters are listed in worst output order for example the collating function was its worst when the first parameter printed in the list was varied When you use the YMAX collating function the output file also lists mean deviation and sigma values These are based on the changes in the output variable from nominal at every sweep point in every sensitivity run Manual optimization You can use worst case analysis to perform manual optimization with PSpice The monotonicity condition is usually met if the parameters have a very limited range Performing worst case analysis with tight tolerances on the parameters produces sensitivity and worst case results in the output file You can use these to decide how the parameters should be varied to achieve the desired response You can then make adjustments to the nominal values in the circuit file and perform the worst case analysis again for a new set of gradients Monte Carlo analysis Monte Carlo MC analysis may be helpful when worst case analysis cannot be used Monte Carlo analysis can often be used to verify or improve on worst case analysis results Monte Carlo analysis randomly selects possible parameter values which can be thought of as randomly selecting points in the parameter space The worst case analysis assumes that the worst results occur somewhere on the surface of this space where parameter
198. er thus defining the transfer function Hence the first expression fragment should be assigned to the EXP1 property the second fragment to EXP2 and so on Expression properties can be defined using a combination of arithmetic operators and input designators You may use any of the standard PSpice arithmetic operators see Table 9 on page 3 70 within an expression statement You may also use the EXPn properties as variables to represent nets or constants Table2 ABM expression parts Part Inputs Output ABM none V ABM1 1 V ABM2 2 V ABM3 3 V ABM I none I ABM1 I 1 I ABM2 I 2 I ABM3 I 3 I The following examples illustrate a variety of ABM expression part applications Control system parts Example one Suppose you want to set an output voltage on net 4 to 5 2 By volts times the square root of the voltage between nets 3 em ec LL and 2 You could use an ABM2 part which takes two inputs and provides a voltage output to define a part like the one shown in Figure 43 Figure 43 ABM expression part example one In this example of an ABM device the output voltage is set to 5 volts times the square root of the voltage between net 3 and net 2 The property settings for this part are as follows EXP 1 BY EXP2 SQRT V IN2 IN1 This will produce a PSpice netlist declaration like this ESQROOT 4 0 VALUE 5V SQRT V 3 2 Example two GPSK is an oscillator for a PSK Phase Shift Keyed Tima SIN modu
199. eral character in the netlist type ss in the template Defining part properties needed for simulation PSPICETEMPLATE examples Simple resistor R template The R part has e two pins 1 and 2 e two required properties REFDES and VALUE Template R REFDES 1 2 VALUE Sample translation R_R23 abc def 1k where REFDES equals R23 VALUE equals 1k and R is connected to nets abc and def Voltage source with optional AC and DC specifications VAC template The VAC part has e two properties AC and DC e two pins and Template V REFDES DC DC DC AC AC AC Sample translation V_V6 vp vm DC 5v where REFDES equals V6 VSRC is connected to nodes vp and vm DC is set to 5v and AC is undefined Sample translation V_V6 vp vm DC 5v AC 1v where in addition to the settings for the previous translation AC is set to lv 143 Chapter 5 Creating parts for models Note For clarity the PSPICETEMPLATE property value is shown here in multiple lines in a part definition it is specified in one line no line breaks To find out how to define subcircuits refer to the SUBCKT command in the online OrCA D PSpice A D Reference Manual 144 Parameterized subcircuit call X template Suppose you have a subcircuit Z that has e two pins a and b e asubcircuit parameter G where G defaults to 1000 when no value is supplied To allow the parameter to be changed on the schematic page treat G as an
200. erative process After analyzing simulation results you can refine your design and simulation settings and then perform a new simulation and waveform analysis Analyzing waveforms with PSpice What is waveform analysis After completing the simulation PSpice plots the waveform results so you can visualize the circuit s behavior and determine the validity of your design Perform post simulation analysis of the results This means you can plot additional information derived from the waveforms What you can plot depends on the types of analyses you run Bode plots phase margin derivatives for small signal characteristics waveform families and histograms are only a few of the possibilities You can also plot other waveform characteristics such as rise time versus temperature or percent overshoot versus component value Using PSpice with other OrCAD programs Using PSpice with other OrCAD programs Using Capture to prepare for simulation Capture is a design entry program you need to prepare your circuit for simulation This means e placing and connecting part symbols e defining component values and other attributes e defining input waveforms e enabling one or more analyses and e marking the points in the circuit where you want to see results Capture is also the control point for running other programs used in the simulation design flow What is the Stimulus Editor The Stimulus Ed
201. erent ways e directly in the PSPICETEMPLATE definition e by defining the part s EXPR and related properties if any The PSpice syntax for declaring E and G devices can help you form a PSPICETEMPLATE definition Part three Setting Up and Running Analyses Part Three describes how to set up and run analyses and provides setup information specific to each analysis type e Chapter 7 Setting up analyses and starting simulation explains the procedures general to all analysis types to set up and start the simulation e Chapter 8 DC analyses describes how to set up DC analyses including DC sweep bias point detail small signal DC transfer and DC sensitivity e Chapter 9 AC analyses describes how to set up AC sweep and noise analyses e Chapter 10 Transient analysis describes how to set up transient analysis and optionally Fourier components This chapter also explains how to use the Stimulus Editor to create time based input e Chapter 11 Parametric and temperature analysis describes how to set up parametric and temperature analyses and how to run post simulation performance analysis in Probe on the results of these analyses e Chapter 12 Monte Carlo and sensitivity worst case analyses describes how to set up Monte Carlo and sensitivity worst case analyses for statistical interpretation of your circuit s behavior Setting up analyses and starting simulation Chapter overview This chapter
202. erion for determining the worst values for the relevant model parameters is defined in the WC statement as a function of any standard output variable in a specified range of the sweep Ina given range reduce the measurement to a single value by one of these five collating functions MAX Maximum output variable value MIN Minimum output variable value YMAX Output variable value at the point where it differs the most with the nominal run RISE_EDGE Sweep value where the output value variable value crosses above a given threshold value FALL_EDGE Sweep value where the output value variable value crosses below a given threshold value You can define Worst as the highest HI or lowest LO possible collating function relative to the nominal run Procedure To establish the initial value of the collating function worst case analysis begins with a nominal run using all model parameters at their nominal values Next multiple sensitivity analyses determine the individual effect of each model parameter on the collating function This is accomplished by varying model parameters one at a time in consecutive simulations The Worst case analysis You can define models for nearly all primitive analog circuit parts such as resistors capacitors inductors and semiconductor devices PSpice reads the standard model parameter tolerance syntax specified in the MODEL statement For each model parameter PSpice uses the nominal min
203. es a menu bar and toolbars for controlling the simulation and the waveform display Title bar The title bar of the simulation window the area at the top of the window identifies the name of the currently open simulation either simulation profile or circuit file and the name of the currently active document displayed in the main window area For example the simulation window shown in Figure 56 indicates that simulation profile Example TRAN is currently open and the active document displayed is Example Example TRAN DAT Menus and Toolbars The menus accessed from the menu bar include commands to set up and control the simulator customize the window display characteristics and configure the way the waveforms are displayed The toolbar buttons duplicate many of the more frequently used commands 209 Chapter 7 Setting up analyses and starting simulation 210 I Example TRAN OrCAD PSpice A D_ example Example TRAN dat active Fie Edt View Simulation Trace Plot Tools Window Help zlajxj a SS HS P ree Eeen UUU U a 8293 Oh E Reed AVe ue Ade Z 6 5U 8s 0 2us U OUT1 V OUT2 Bi example xa z EJIE j Time step 19 25E 09 Time 1 000E 06 End 1 000E 06 ETEN Anais Awan Dewees Foia press Fl Time 1 0006 08 CALCE Figure 55 PSpice simulation window Main window section The top central portion by defa
204. es button information and guidelines 5 In the Choose a Goal Function list click Bandwidth then click the Next gt button 6 Click in the Name of Trace to search text box and type Click El then double click V Out V Out 7 Click in the db level down for bandwidth calc text box and type 3 8 Click the Next gt button The wizard displays the gain trace for the first run R 100 and shows how the bandwidth is measured This is done to test the goal function Chapter 2 Simulation examples Double click the x axis or press The Trace list includes goal functions only in performance analysis mode when the x axis variable is the swept parameter 50 10 Click the Next gt button or the Finish button A plot of the 3dB bandwidth vs Rval appears Change the x axis to log scale a From the Plot menu choose Axis Settings b Click the X Axis tab Under Scale choose Log d Click OK To plot gain vs Rval manually 1 2 From the Plot menu choose Add Y Axis From the Trace menu choose Add to display the Add Traces dialog box In the Functions or Macros frame select the Goal Functions list and then click the Max 1 goal function In the Simulation Output Variables list click V out In the Trace Expression text box edit the text to be Max Vdb out then click OK PSpice displays gain on the second y axis vs Rval Figure 26 shows the final performance analysis plot of 3dB bandwidth and gain i
205. es for waveform analysis 2 From the View menu point to Zoom then choose Area PSpice changes the plot to display the region within the selection rectangle 345 Chapter 13 Analyzing waveforms For information about adding labels including text line poly line arrow box circle ellipse and mark refer to the online Help in PSpice 346 Scrolling traces By default when a plot is zoomed standard scroll bars appear to the right or at the bottom of the plot area as necessary These can be used to pan through the data You can configure scroll bars so they are always present or are never displayed To configure scroll bars 1 In PSpice from the Tools menu choose Options 2 Inthe Use Scroll Bars frame choose one of the scroll bars options as described below Table 1 Choose this option To do this Auto Have scroll bars appear when a plot is zoomed or when additional traces are displayed in the plot but are not visible default Never Never display scroll bars This mode provides maximum plot size and is useful on VGA and other low resolution displays Always Display scroll bars at all times However they are disabled if the corresponding axis is full scale Modifying trace expressions and labels You can modify trace expressions text labels and ellipse labels that are currently displayed within the Probe window thus eliminating the need to delete and recreate any of these objects
206. etric analysis 43 Analyzing waveform families 00000 4 45 Finding out more about parametric analysis 48 Performance analysis isas ded e oes Dee Sw Ra ewe OS ee 49 Finding out more about performance analysis 51 Part two Chapter 3 Contents Design entry Preparing a design for simulation 55 Chapter overview 243464 e odu eshte Shee ee se 55 Checklist for simulation setup 20 4 0 445 e4 x ext a eek eee Gare 56 Typical simulation setup steps ase ewe ek ae ek eg we we GH 56 Advanced design entry and simulation setup steps 57 When netlisting fails or the simulation does not start 2 0 ee 58 Things to check in your design 04 58 Things to check in your system configuration 59 Using parts that you can simulate xis 4 a ea ae Kee es OR eS 60 Vendor supplied parts da4 4244405 daa Kee tHe RR eee of 61 Part naming conventions 4 0 2 4 oss ese dae oo Pe he es 61 Finding the part that you want 0 000 62 Passive parts 2 6 4 steve deck se Sny aa ee Oe Be eee 64 Breakout Date coc ee oo ie ak amp Pak ee Ge oe See BA 65 Behavioral parts 24 545 ch bbe Ee bbe Ged webs de ee Stor 66 Using global parameters and expressions for values 67 Global parameters lt i cee ie sds ee EKER S SWE EY EER amp 67 Declaring and using a global parameter 67 EXPICSSIONG 24 8 40 6 R e ee a SE Aw
207. evaluation Load a completed data section 1 From the Plot menu choose Axis Settings In the Processing Options frame select Fourier From the Plot menu choose Axis Settings In the Processing Options frame select Performance Analysis From the Plot menu choose Axis Settings then click the X Axis tab Click the Axis Variable button In the X Axis Variable dialog box specify a new x axis variable From the Trace menu select Eval Goal Function In the Evaluate Goal Function s dialog box specify a goal function From the File menu choose Append Waveform DAT Select a DAT file to append Pausing a simulation and viewing waveforms You can pause a simulation to analyze waveforms before the simulation is finished After you pause the simulation you can either resume the simulation or end it To pause a simulation 1 From PSpice s Simulation menu choose Pause 2 Inthe Probe window view the waveforms generated before you paused the simulation Viewing waveforms 3 Do one of the following e From the Simulation menu choose Run to resume the simulation e From the Simulation menu choose Stop to stop the simulation Using schematic page markers to add traces You can place markers on a schematic page to identify the See Trace expressions on points where you want to see waveform results displayed page 13 356 for ways to add traces You can place markers within PSpice e Before si
208. evising workarounds and manually entering data to keep files in sync Our products will help you build better products faster and at lower cost Before you begin xxiv OrCAD PSpice overview OrCAD PSpice simulates analog only circuits After you prepare a design for simulation OrCAD Capture generates a circuit file set The circuit file set containing the circuit netlist and analysis commands is read by PSpice for simulation PSpice formulates these into meaningful graphical plots which you can mark for display directly from your schematic page using markers How to use this guide How to use this guide This guide is designed so you can quickly find the information you need to use PSpice This guide assumes that you are familiar with Microsoft Windows NT or 95 including how to use icons menus and dialog boxes It also assumes you have a basic understanding about how Windows manages applications and files to perform routine tasks such as starting applications and opening and saving your work If you are new to Windows please review your Microsoft Windows User s Guide Typographical conventions Before using PSpice it is important to understand the terms and typographical conventions used in this documentation This guide generally follows the conventions used in the Microsoft Windows User s Guide Procedures for performing an operation are generally numbered with the following typographical conventions
209. f data These are listed in the Available Sections dialog box From PSpice s Trace menu choose Performance Analysis Click the Select sections button In the Available Sections dialog box click the All button Click OK 6 To display current through the Meter voltage source do the following a From Capture s PSpice menu point to markers and choose Current into Pin b Place a current probe on the left hand pin of the Meter source 7 Switch to the Probe window to see the family of curves for I Meter as a function of P Note For more on analyzing Monte Carlo results in PSpice see the next section on Monte Carlo histograms Monte Carlo Histograms You can display data derived from Monte Carlo waveform families as histograms This is part of the performance analysis feature In this example you simulate a fourth order Chebyshev active filter running a series of 100 AC analyses while randomly varying resistor and capacitor values for each run Then having defined performance analysis goal functions for bandwidth and center frequency you observe the statistical distribution of these quantities for the 100 runs Chebyshev filter example The Chebyshev filter is designed to have a 10 kHz center frequency and a 1 5 kHz bandwidth The schematic page for the filter is shown in Figure 81 The stimulus specifications for V1 V2 and V3 are V1 DC 15 V2 DC 15 V3 AC 1 The parts are rounded to the nearest ava
210. f the whole process is getting started that is finding the bias point PSpice first tries with the power supplies set to 100 A solution is not guaranteed but most of the time the PSpice algorithm finds one If not then the power supplies are cut back to almost zero They are cut to a level small enough that all nonlinearities are turned off When the circuit is linear a solution can be found very near zero of course Then PSpice works its way back up to 100 power supplies using a variable step size Once a bias point is found the transient analysis can be run It starts from a known solution the bias point and steps forward in time The step size is variable and is reduced as needed to find further solutions DC sweep The DC sweep uses a hybrid approach It uses the bias point algorithm varying the power supplies to get started For subsequent steps it uses the previous solution as the initial approximation The sweep step is not variable however If a solution cannot be found at a step then the bias point algorithm is used for that step The whole process relies heavily on continuity It also requires that the circuit be linear when the supplies are turned off 383 Chapter B Convergence and time step too small errors 384 STEPGM IN An alterative algorithm is GMIN stepping This is not obtained by default and is enabled by specifying the circuit analysis option STEPGMIN either using OPTION STEPGMIN in th
211. fied performance analysis goal functions When the simulation is finished a list appears containing all of the sections runs in the data file produced by PSpice To use the data from every run select All and click OK in the Available Selections dialog box In the case of Figure 69 the trace I L1 from the ninth section was added by specifying the following in the Add Traces dialog box I L1 9 Parametric analysis To display the Add Traces dialog box from the Trace menu choose Add Trace or click the Add Trace toolbar button E 275 Chapter 11 Parametric and temperature analysis I amp SCHEMATICI Parametric OrCAD PSpice A D_ rlofiltSCHEMATICI Test dat B Fie Edt View Simulation Trace Plot Tools Window Help ale x eet SN EET Paane pai S Se Umesh med lKM FUR Bee Z 4 58 asanda oa i Os 1 L1 9 Troubleshooting tip Brenson More than one PSpice run or data section is Figure 69 Current of L1 when R1 is 1 5 ohms required for performance analysis Because one data value is derived for each To run performance analysis waveform in a related set of waveforms at least two data points are required to 1 From the Trace menu choose Performance Analysis produce a trace 2 Click OK Use Eval Goal Function from the Trace menu to evaluate a goal function on a single waveform and produce a single data point result PSpi
212. files on page 13 338 and To add traces using output variables on page 13 356 You can also double click a text or ellipse label to modify it or press Ctrl V 347 Chapter 13 Analyzing waveforms When adding a trace to a Probe window you can make the trace display name different from the trace expression 1 From the Trace menu choose Add Trace 2 Inthe Trace Expression text box enter a trace expression using the syntax trace_ expression display_ name 3 Click OK For information about adding labels including text line poly line arrow box circle ellipse and mark refer to the online Help in PSpice alo E 348 e To add traces before a currently displayed trace name select the trace name and then choose Paste from the Edit menu Here are some considerations when copying or moving trace names and expressions into a different Probe window If the new Probe window is reading the same waveform data file the copied or moved trace names and expressions display traces that are identical to the original selection set If the new Probe window is reading a different waveform data file the copied or moved names and expressions display different traces generated from the new data For example suppose two waveform data files MYSIM DAT and YOURSIM DAT each contain a V 2 waveform Suppose also that two Probe windows are currently displayed where window A is loaded with MYSIM DAT and win
213. for definitions e Depending on the configuration model libraries are available either to a specific design or to all global designs Model libraries Device model and subcircuit definitions are organized into model libraries Model libraries are text files that contain one or more model definitions Typically model library names have a LIB extension Most model libraries contain models of similar type For vendor supplied models libraries are also partitioned by manufacturer To find out more about the models contained in a model library read the comments in the file header Model library configuration PSpice searches model libraries for the model names specified by the MODEL implementation for parts in your design These are the model definitions that PSpice uses to simulate your circuit For PSpice to know where to look for these model definitions you must configure the libraries This means e Specifying the directory path or paths to the model libraries e Naming each model library that PSpice should search and listing them in the needed search order e Assigning global or design scope to the model library Global vs design models and libraries Model libraries and the models they contain have either design or global application to your designs Design models Design models apply to one design The schematic page editor automatically creates a design model whenever you modify the model definition for a part
214. g Devices chapter of the online OrCA D PSpice A D Reference Manual XXX New Model Editor interface The Model Editor formerly known as Parts has been improved and modernized for Release 9 It now provides a unified application for editing models either in text form or by modifying their specifications The Model Editor now also supports Darlington modeling EKV version 2 6 MOSFET model The EKV model is a scalable and compact model built on fundamental physical properties of the device Use this model to design low voltage low current analog and mixed analog digital circuits that use sub micron technologies Version 2 6 models the following e geometrical and process related aspects of the device oxide thickness junction depth effective channel length and width and so on e effects of doping profile and substrate effects e weak moderate and strong inversion behavior e mobility effects due to vertical and lateral fields and carrier velocity saturation e short channel effects such as channel length modulation source and drain charge sharing and the reverse short channel effect e thermal and flicker noise modeling e short distance geometry and bias dependent device matching for Monte Carlo analysis Enhanced model libraries The model libraries supplied with PSpice Release 9 have been enhanced to include the latest models from various vendors as well as models for popular optocouplers Darlingtons and DAC and ADC
215. g messages to the output file To view the simulation output file 1 From PSpice s View menu choose Output File Figure 5 shows the results of the bias point calculation as written in the simulation output file tant 10 05 98 12 06 18 t PSpice 9 0 Aug 1998 traretet Dg 3 tererter a circuit file for profile Bias tatt SMALL SIGNAL BIAS SOLUTION TEMPERATURE 27 000 DEG C AAEERERANRREAEAEEAAEA AERA AA EATEN AERA ATER TARTRATE RATE E EEE R EERE REE REET EERE T ET NODE VOLTAGE NODE VOLTAGE NODE VOLTAGE MODE VOLTAGE IN 0 0000 OUT 0 0000 VCC 5 0000 N00744 9434 VOLTAGE SOURCE CURRENTS NNE CURRENT yL 1 229E 03 V in 9 4346 04 TOTAL POWER DISSIPATION 6 15E 03 WATTS Ea idl E pesch Figure Simulation output file 2 When finished close the window Running PSpice PSpice measures the current through a two terminal device into the first terminal and out of the second terminal For voltage sources current is measured from the positive terminal to the negative terminal this is opposite to the positive current flow convention and results in a negative value in the output file Finding out more about bias point calculations Table 2 1 To find out more about this See this bias point calculations Bias point on page 8 223 25 Chapter 2 Simulation examples Note The default settings for DC Sweep simulation are Voltage Source as the swept variable type and L
216. ge 3 74 analog circuits UV Define input Defining stimuli on An overview of DC AC and waveforms page 3 75 time based stimulus parts UY Set up one or more Chapter 7 Setting up Procedures general to all analysis analyses analyses and starting types to set up and start the simulation simulation Chapter 8 through Detailed information about DC AC Chapter 12 see the table of transient parametric temperature contents Monte Carlo and sensitivity worst case 56 For more information on this step Checklist for simulation setup See this WY Place markers Using schematic page markers to add traces on page 13 331 Limiting waveform data file size on page 13 334 How to display results in PSpice by picking design nets How to limit the data file size Advanced design entry and simulation setup steps For more information on this step See this To find out how to WY Create new models UY Create new parts Chapter 4 Creating and editing models Chapter 6 Analo behavioral modeling Chapter 5 Creating parts for models The OrCAD Capture User s Guide Define models using the Model Editor or Create Subcircuit command Define the behavior of a block of analog circuitry as a mathematical function or lookup table Create parts either automatically for models using the part wizard or the Parts utility or by manually defining AKO parts define simulation
217. ge editor does the following things for you e Maps any named interface ports at the active level of hierarchy to terminal nodes in the PSpice SUBCKT statement e Saves the subcircuit definition to a file named DESIGN_NAME SUB Before you can use the subcircuit definition in your design you need to e Create a part for the subcircuit Using the Create Subcircuit command If you verify the model library configuration in the Simulation Settings dialog box click the Libraries tab you see entries for NOM LIB for global use as denoted by the asterisk and MY LIB for design use no asterisk in the Library files list You can change the model reference for this part back to the original Q2N2222 by following the procedure To change model references for part instances on your design on page 4 117 The Create Subcircuit command does not help you create a hierarchical design You need to do this yourself before using the Create Subcircuit command For information on hierarchical designs and how to create them refer to the OrCA D Capture User s Guide 115 Chapter 4 Creating and editing models Refinements can include extending the subcircuit definition using the optional nodes construct OPTIONAL the variable parameters construct PARAMS and the FUNC and local PARAM commands 116 Configure the DESIGN_NAME SUB file so PSpice knows where to find it To create a subcircuit definition for a portion of your
218. ge or current to the output file 1 Place and connect any of the following parts from the PSpice library SPECIAL OLB Table 14 Use this part To plot this VPLOT1 Voltage on the net that the part terminal is connected to VPLOT2 Voltage differential between the two nets that the part terminals are connected to IPLOT Current through a net Insert this part in series like a current meter 2 Double click the part instance to display the Parts spreadsheet 3 Click the property name for the analysis type that you want plotted DC AC or TRAN 4 In the columns for the analysis type that you want plotted DC AC or TRAN type any non blank value such as yY YES or 1 Writing additional results to the PSpice output file To view the PSpice output file after having run a simulation 1 From the Simulation menu choose Examine Output JEL IPLOT 369 Chapter 14 Other output options If you do not enable a format PSpice 5 Ifyou selected the AC analysis type enable an output defaults to MAG format a Click the property name for one of the following output formats MAG magnitude PHASE REAL IMAG imaginary or DB b Type any non blank value such as Y YES or 1 C Repeat the previous steps a and b for as many AC output formats as you want to see plotted 6 Repeat steps 2 through 5 for any additional analysis types you want plotted Note Ifyou do not en
219. hat you can step for each kind of analysis Table4 Parametric and temperature analysis types For this analysis You can step one of these Parametric global parameter model parameter component value DC source operational temperature Temperature operational temperature Analyses you can run with PSpice Monte Carlo and sensitivity worst case Monte Carlo and sensitivity worst case analyses are statistical PSpice changes device model parameter values with respect to device and lot tolerances that you specify and runs a simulation for each value Table 5 summarizes how PSpice runs each statistical analysis type Table5 Statistical analysis types For this statistical analysis PSpice does this Monte Carlo For each simulation randomly varies all device model parameters for which you have defined a tolerance Sensitivity Computes the probable worst case worst case response of the circuit in two steps 1 Computes component sensitivity to changes in the device model parameters This means PSpice nonrandomly varies device model parameters for which you have defined a tolerance one at a time for each device and runs a simulation with each change 2 Sets all model parameters for all devices to their worst case values assumed to be at one of the tolerance limits and runs a final simulation Chapter 1 Things you need to know Taken together simulation and waveform analysis is an it
220. he Model Editor you need to 1 Inthe schematic page editor select Q6 on the schematic page 2 From the Edit menu choose PSpice Model The Model Editor automatically creates a copy of the Q2N2222 base model definition 3 Inthe Model Editor from the View menu choose Model Text The Model Editor displays the PSpice syntax for the copied model in the text editing area Editing the Q2N2222 X model instance Text edits appropriate to this example are as follows e Add the DEV 5 clause to the Rb statement required e Change the model name to 92N2222 mc optional for descriptive purposes only Saving the edits and updating the schematic When you choose Save from the File menu two things happen e The Model Editor saves the model definition to the model library e The schematic page editor updates the Implementation property value to Q2N2222 MC for the Q6 part instance In this example the default model library is MY LIB If MY LIB does not already exist the Model Editor creates and saves it in the current working directory The schematic page editor then automatically configures it as a design model library for use with the current design only Now you are ready to set up and run the Monte Carlo analysis Using the Create Subcircuit command The Create Subcircuit command creates a subcircuit netlist definition for the displayed level of hierarchy and all lower levels in your design The schematic pa
221. he parts Implementation property You can change this assignment by replacing the Implementation property value with the name of a different model that already exists in the library You can do this for e A part instance in your design e lt A part in the part library To change model references for part instances on your design 1 Find the name of the model that you want to use 2 Inthe schematic page editor select one or more parts on your schematic page 3 From the Edit menu choose Properties The Parts spreadsheet appears 4 Click the cell under the column Implementation Type 5 From the Implementation list select PSpice Model 6 Inthe Implementation column type the name of the existing model that you want to use if it is not already listed 7 Click Apply to update the changes then close the spreadsheet To change the model reference for a part in the part library 1 Find the name of the model that you want to use 2 Inthe schematic page editor select the part you want to change 3 From the Edit menu choose Part to start the part editor with that part loaded for editing 117 Chapter 4 Creating and editing models For information on how to create instance models see e Running the Model Editor from the schematic page editor on page 4 101 e Starting the Model Editor from the schematic page editor in Capture on page 4 111 See Changing the model reference to an existing model definit
222. he transform is the value of EXPR where EXPR follows the same rules as for VALUE expressions see EVALUE and GVALUE parts on page 6 176 XFORM is an expression in the Laplace variable s It follows the rules for standard expressions as described for VALUE expressions with the addition of the s variable PSpice equivalent parts Moving back and forth between the time and frequency domains can cause surprising results Often the results are quite different than what one would intuitively expect For this reason we strongly recommend familiarity with a reference on Fourier and Laplace transforms A good one is 1 R Bracewell The Fourier Transform and Its Applications McGraw Hill Revised Second Edition 1986 We also recommend familiarity with the use of transforms in analyzing linear systems Some references on this subject 2 W H Chen The Analysis of Linear Systems McGraw Hill 1962 3 J A Aseltine Transform Method in Linear System Analysis McGraw Hill 1958 4 GR Cooper and C D McGillen Methods of Signal and System Analysis Holt Rinehart and Winston 1967 Voltages currents and TIME cannot appear in a Laplace transform 181 Chapter 6 Analog behavioral modeling 182 The output of the device depends on the type of analysis being done For DC and bias point the output is simply the zero frequency gain times the value of EXPR The zero frequency gain is the value of XFORM with s 0 For AC analy
223. hen VARY BOTH is specified in the WC statement and a model parameter is specified with both DEV and LOT tolerances defined the worst case analysis may produce unexpected results The sensitivity of the collating function is only tested with respect to LOT variations of such a parameter For example during the sensitivity analysis the parameter is varied once affecting all devices referring to it and its effect on the collating function is recorded For the worst case analysis the parameter is changed for all devices by LOT DEV in the determined direction See the example schematic in Figure 89 and circuit file in Figure 90 WCASE VARY BOTH Test Vin 1 0 10V Rs 1 2 1K Rwc1 2 3 Rmod 100 Rwc2 3 0 Rmod 100 MODEL Rmod RES R 1 LOT 10 DEV 5 DC Vin LIST 10 WC DC V 3 MAX VARY BOTH LIST OUTPUT ALL ENDS Figure 90 Circuit file using VARY BOTH In this case V 3 is maximized if e Rwel and Rwc2 are both increased by 10 per the LOT tolerance specification and e Rwel is decreased by 5 and Rwe2 is increased by 5 per the DEV tolerance specification The final values for Rwc and Rwc2 should be 105 and 115 respectively However because Rwc1 and Rwc2 are varied together during the sensitivity analysis it is assumed that both must be increased to their maximum for a maximum V 3 Therefore both are increased by 15 Rwe1 Rmod 100 Vin zO Rwc2 Rmod 100 t Figure 89 Schematic
224. hen a warning is issued but Capture still outputs the resulting netlist When a match is found the original fragment is replaced by the fully qualified name of the net or device For example suppose we have a hierarchical part U1 Inside the schematic representing U1 we have an ABM expression including the term V Reference If Reference is the name of a local net then the fragment written to the netlist will be translated to V U1_Reference If Reference is the name of a global net the corresponding netlist fragment will be V Reference Names of voltage sources are treated similarly For example an expression including the term I Vsense will be output as I V_U1_Vsense if the voltage source exists locally and as I V_Vsense if the voltage source exists at the top level Forcing the use of a global definition If a net name exists both at the local hierarchical level and at the top level the search mechanism used by Capture will find the local definition You can override this and force Capture to use the global definition by prefixing the name with a single quote character For example suppose there is a net called Reference both inside hierarchical part U1 and at the top level Then the ABM fragment V Reference will result in V U1_Reference in the netlist while the fragment V Reference will produce V Reference Placing and specifying ABM parts 151 Chapter 6 Analog behavioral modeling For cl
225. hese are the variables setup to be monitored during simulation The Devices window displays the devices that are being simulated 211 Chapter 7 Setting up analyses and starting simulation 212 DC analyses Chapter overview This chapter describes how to set up DC analyses and includes the following sections e DC Sweep on page 8 214 e Bias point on page 8 223 e Small signal DC transfer on page 8 225 e DC sensitivity on page 8 228 Chapter 8 DC analyses 214 DC Sweep Minimum requirements to run a DC sweep analysis Minimum circuit design requirements Table9 DC sweep circuit design requirements Swept variable type Requirement voltage source temperature current source model parameter global parameter voltage source with a DC specification VDC for example none current source with a DC specification IDC for example PSpice model MODEL global parameter defined with a parameter block PARAM DC Sweep Minimum program setup requirements Simulation Settings Example ix General Analysis Include Files Libraries Stimulus Options Data Collection Probe Window Analysis type r Sweep variable C Voltage source Name fv a Current source AGE tone ro pipet C Global parameter Primary Sweep C Model REESI AG celtics _ Secondary Sweep c a eee eee Ly Monte Carlo Aworst Case Temperature STEM EU MBME Parametric Sweep
226. hows how to run a transient analysis on the clipper circuit This requires adding a time domain voltage stimulus as shown in Figure 14 Di D1N3940 RI ci Ing syOut lt AAN H gt 1k 0 47u D2 Re D1N3940 5 5k lt S o EJ Jml l s 3 as Ol 2 SINE dl Figure 14 Diode clipper circuit with a voltage stimulus Transient analysis To add a time domain voltage stimulus 1 8 9 From Capture s PSpice menu point to Markers and choose Delete All Select the ground part beneath the VIN source From the Edit menu choose Cut Scroll down or from the View menu point to Zoom then choose Out Place a VSTIM part from the PSpice library SOURCESTM OLB as shown in Figure 14 From the Edit menu choose Paste Place the ground part under the VSTIM part as shown in Figure 14 From the View menu point to Zoom then choose All From the File menu choose Save to save the design To set up the stimulus 1 2 Select the VSTIM part V3 From the Edit menu choose PSpice Stimulus The New Stimulus dialog box appears In the New Stimulus dialog box type SINI Click SIN sinusoidal then click OK In the SIN Attributes dialog box set the first three properties as follows Offset Voltage 0 Amplitude 10 Frequency 1kHz BI Click Apply to view the waveform The Stimulus Editor window should look like Figure 15 or press Ctri V Note The S
227. i Vin Al Cnn DO Vbias ik iuF AC 1 Figure 71 RLC filter example circuit 278 Example frequency response vs arbitrary parameter You can view a plot of the linear response of a circuit at a specific frequency as one of the circuit parameters varies such as the output of a band pass filter at its center frequency vs an inductor value In this example the value of a nonlinear capacitance is measured using a 10 kHz AC signal and plotted versus its bias voltage The capacitance is in parallel with a resistor so a trace expression is used to calculate the capacitance from the complex admittance of the R C pair Setting up the druit Enter the circuit in Capture as shown in Figure 71 To create the capacitor model in the schematic editor 1 Place a CBREAK part 2 Select it so that it is highlighted 3 From the Edit menu choose PSpice Model 4 In the Model Text frame enter the following model Cnin CAP C 1 VC1 0 01 VC2 0 05 5 From the File menu choose Save Set up the circuit for a parametric AC analysis sweep Vbias and run PSpice Include only the frequency of interest in the AC sweep Parametric analysis To display the results Use PSpice to display the capacitance calculated at the frequency of interest versus the stepped parameter 1 2 3 Simulate the circuit Load all AC analysis sections From the Trace menu choose Add Trace or click the Add Trace toolb
228. ias Point Output File Options Transient Output File Options xj Start saving data after seconds Cancel IV Perform Fourier Analysis _ Cancel Center Frequency 1Meg he Number of Harmonics Output Variables fio ut2 IV Include detailed bias point information for nonlinear controlled sources and semiconductors OP Figure 63 Transient analysis setup for EXAMPLE OP 263 Chapter 10 Transient analysis The example circuit EXAMPLE OP is provided with the OrCAD program installation 264 During a transient analysis any or all of the independent sources may have time varying values In EXAMPLE OP the only source which has a time varying value is V1 VSIN part with attributes VOFF Ov VAMPL 0 1v FREQ 5Meg V1 s value varies as a 5 MHz sine wave with an offset voltage of 0 volts and a peak amplitude of 0 1 volts In general more than one source has time varying values readme RAIAS RCI RC2 example rdm ak 2 ik croan Pe ik OUTI 4 d 0UT2 RSI YN RS2 S 03 k ERA q212222 ik qd b Qi at a eae eee q212222 of Fa 4212222 C VEE i VEE Figure 64 Example schematic EXAMPLE OPJ The transient analysis does its own calculation of a bias point to start with using the same technique as described for DC sweep This is necessary because the initial values of the sources can be different fr
229. ice parasitics For example a resistor can be used to give a finite output impedance Capacitances between the grid cathode and anode are also needed The lower part of the schematic in Figure 47 shows a possible method for incorporating these effects To complete the example one could add a circuit which produces the family of I V curves shown in Figure 48 0 OU Z200U 400 o I Cuanode vanode Figure 48 Triode subcircuit producing a family of I V curves Control system parts 173 Chapter 6 Analog behavioral modeling There are no equivalent F or H part types in the part library becayse PSpice F and H devices do not support the ABM extensions 174 PSpice equivalent parts PSpice equivalent parts respond to a differential input and have double ended output These parts reflect the structure of PSpiceE and G devices thus having two pins for each controlling input and the output in the part Table 1 summarizes the PSpice equivalent parts available in the part library Table1 PSpice equivalent parts Category Part Description Properties Mathematical EVALUE general purpose EXPR expression GVALUE ESUM special purpose none GSUM EMULT GMULT Table look up ETABLE general purpose EXPR GTABLE TABLE Frequency EFREQ general purpose EXPR table look up GFREQ TABLE Laplace ELAPLACE general purpose EXPR transform GLAPLACE XFORM PSpice equivalent ABM parts can be classifi
230. ide a delay of 100 seconds At a certain threshold a comparator turns on a power MOSFET The overall simulation time is 100 seconds For default RELTOL this gives us a minimum time step of 100 picoseconds If the comparator and other circuitry has portions that switch in a nanosecond then PSpice needs steps of less than 100 picoseconds to calculate the transition accurately Transient analysis 389 Chapter B Convergence and time step too small errors 390 Failure at the first time step If the transient analysis fails at the first time point then usually there is an unreasonably large capacitor or inductor Usually this is due to a typographical error Consider the following capacitor C 1 3 0 10uft 10 has the letter O should have been 10 This capacitor has a value of one farad not 10 microfarads An easy way to catch these is to use the LIST option on the OPTIONS command LIST The LIST option can echo back all the devices into the output file that have their values in scientific notation That makes it easy to spot any unusual values This kind of problem does not show up during the bias point calculation because capacitors and inductors do not participate in the bias point Similar comments apply to the parasitic capacitance parameters in transistor and diode models These are normally echoed to the output file the NOMOD option suppresses the echo but the default is to echo As in the LIST ou
231. ided in various data files Some of these are generated by Capture others come from libraries which can also be generated by other programs like the Stimulus Editor and the Model Editor and still others are user defined Files that Capture generates When you begin the simulation process Capture first generates files describing the parts and connections in your circuit These files are the netlist file and the circuit file that PSpice reads before doing anything else Netlist file The netlist file contains a list of device names values and how they are connected with other devices The name that Capture generates for this file is DESIGN_NAME NET Circuit file The circuit file contains commands describing how to run the simulation This file also refers to other files that contain netlist model stimulus and any other user defined information that apply to the simulation The name that Capture generates for this file is DESIGN_NAME CIR Other files that you can configure for simulation OrCAD Stimulus Editor F L global i model P D l ibraries OrCAD Model Editor model input definitions waveforms a stimulus file simulation primitives ocal model ibraries custom OrCAD include file PSpice Figure 1 User configurable data files that PSpice reads Before starting simulation PSpice needs to read other files that contain simulation information for your circuit The
232. igure 42 Figure 43 Figure 44 Figure 45 Figure 46 Figure 47 Figure 48 Figure 49 Figure 50 Figure 51 Figure 52 Figure 53 Figure 54 Figure 55 Figure 56 Figure 57 Figure 58 Figure 59 Figure 60 Figure 61 Figure 62 Figure 63 Figure 64 Figure 65 Figure 66 Figure 67 Figure 68 Figure 69 Figure 70 Figure 71 Figure 72 Figure 73 Figure 74 Figure 75 xvi Rules for pin callout in subcircuit templates 146 LOPASS filter xample 224464 4b 4 ee HES OE Ow ESS amp 157 HIPASS filter patlexample 2 lt 6404 404 oe ete etene 4 84 158 BANDPASS filter part example e404 c 48 eee Ga we Rie alee ee 159 BAN DEE filter part example 2 24t40 224s EG ESE ORE ES 159 FTABLE part example ca veces oS eee eee OER Se ew Swe eH 162 LAPLACE patt exaniple O e ss s aace av ed ed Sos Kaw e booms 165 Viewing gain and phase characteristics of a lossy integrator 165 LAPLACE part example WO cae awe a eh APE EAL SE REE ED 165 ABM expression part example one 0 0 00 0000048 169 ABM expression part example two 2 2 2 2 0000 ee eee 169 ABM expression part example three 2 2 00 00000 4 170 ABM expression part example four 1 65 6b eee ee eee ee 170 Triode Circuit 22 4 c5 62 24 h 2 222 24445 dea Sea e he ede a 171 Triode subcircuit producing a family of I V curves 173 EVALUE part example 6676 2468 6ORG BARRE ORES 177 CVALUE part example c 24 24 4 eee Oe a
233. ilable 1 resistor and 5 capacitor value In this example note how the Monte Carlo analysis Another way to view the family of curves without using schematic markers is as follows 1 From PSpice s Trace menu choose Add Trace 2 Inthe Simulation Output Variables list double click I Meter Monte Carlo analysis is frequently used to predict yields on production runs of a circuit For more information about performance analysis see RLC filter example on age 11 274 301 Chapter 12 Monte Carlo and sensitivity worst case analyses 302 bandwidth and the center frequency vary when 1 resistors and 5 capacitors are used in the circuit uz L11013 411 Wh Figure 81 Chebyshev filter Creating models for Monte Carlo analysis To vary the resistors and capacitors in the filter circuit create models for these parts on which you can set device tolerances for Monte Carlo analysis The BREAKOUT OLB library contains generic devices for this purpose The resistors and capacitors in this schematic are the Rbreak and Cbreak parts from BREAKOUT OLB Using the Model Editor modify the models for these parts as follows model RMOD RES R 1 DEV 12 model CMOD CAP C 1 DEV 52 Setting up the analysis To analyze the filter set up both an AC analysis and a Monte Carlo analysis The AC analysis sweeps 50 points per decade from 100 Hz to 1 MHz The Monte Carl
234. ill take effect brightyellow darkblue 1 Ina standard text editor such as Notepad open PSPICE INI This file is normally located in the darkcyan darkgray darkgreen P a C Windows directory darkmagenta darkred r Scroll to the PROBE DISPLAY COLORS or oe PROBE PRINTER COLORS section of the file lightgreen 3 Add or modify a color entry See Table 1 on lightblue lightgray green page 13 325 for a description of color entries and their magenta mustard orange default values Valid item names include pink purple red e BACKGROUND brown blue cyan e FOREGROUND white black yellow 324 Setting up waveform analysis e TRACE_1 through TRACE_12 4 If you added or deleted trace number entries set NUMTRACECOLORS n to the new number of traces where n is between 1 and 12 This item represents the number of trace colors displayed on the screen or printed before the color order repeats 5 Save the file Tablel Default waveform viewing colors Item Name Description Default BACKGROUND specifies the color of BLACK When you want to copy Probe plots to the window background dipboard and then paste them into a black FOREGROUND specifies the default WHITE and white document choose the Change All color for items not Colors to Black option under Foreground in explicitly specified the Copy to Clipboard Color Filter dialog TRACE 1 specifies the first color BRIGHTGREEN ae Window menu choose Copy used for trace display 0 Ulpboar
235. imulation specifications Set up the noise simulation specifications and enable the analysis in the AC Sweep Noise portion of the Simulation Settings dialog box Click OK to save the simulation profile From the PSpice menu choose Run to start the simulation Noise analysis To find out how see Setting up an AC stimulus on page 9 233 To find out how see Setting up an AC analysis on page 9 235 To find out how see Setting up a noise analysis on page 9 243 241 Chapter9 AC analyses Example Diodes have separate noise contributions from thermal shot and flicker noise 242 What is noise analysis When running a noise analysis PSpice calculates and reports the following for each frequency specified for the AC Sweep Noise analysis e Device noise which is the noise contribution propagated to the specified output net from every resistor and semiconductor device in the circuit for semiconductor devices the device noise is also broken down into constituent noise contributions where applicable e Total output and equivalent input noise Table 7 This value Means this Output noise RMS sum of all the device contributions propagated to a specified output net Input noise equivalent noise that would be needed at the input source to generate the calculated output noise in an ideal noiseless circuit How PSpice calculates total output and input noise To calculate total noise at an output net
236. imum and maximum probable values and the DEV and or LOT specifiers the probability distribution type such as UNIFORM or GAUSS is ignored You can use analog behavioral models to measure waveform characteristics other than those detected by the available collating functions such as rise time or slope You can also use analog behavioral models to incorporate several voltages and currents into one output variable to which a collating function may be applied See Chapter 6 Analog behavioral modeling for more information This procedure saves time by performing the minimum number of simulations required to make an educated guess at the parameter values that produce the worst results It also has some limitations which are described in the following sections 307 Chapter 12 Monte Carlo and sensitivity worst case analyses 308 direction better or worse in which the collating function changes with a small increase in each model parameter is recorded Finally for the worst case run each parameter value is taken as far from its nominal as allowed by its tolerance in the direction which should cause the collating function to be its worst given by the HI or LO specification Outputs A summary of the sensitivity analysis is printed in the PSpice output file QUT This summary shows the percent change in the collating function corresponding to a small change in each model parameter If a PROBE statement is include
237. in Rb2 but device saturates if Rb2 is maximized Vcc Vcc 0 10 Rc Vcc G 1k Ql C B 0 Q2N2222 Rb1 Vcc B 10k Rb2 B 0 Rbmod 720 model Rbmod res R 1 dev 5 WC analysis results are correct model Rbmod res R 1 1 dev 5 WC analysis misled by sensitivity xxxx x Load and blocking capacitor CoutC Out lu RI Out 0 1k Run with either the STEP or the WC but not both This circuit file is currently set up to run the STEP WC is commented out kkk Parametric Sweep providing plot of Vm LOUT vs Rb2 STEP Res Rbmod R 0 8 1 2 10m xxxx x Worst case analysis run once for each of the model definitions stated above WC AC Vm CLOut min range 99k 101k list output all AC Lin 3 90k 110k probe end Figure 85 Amplifier netlist and circuit file output is not monotonic with a variable parameter see Figure 87 and Figure 88 For demonstration the parametric analysis is run first generating the curve shown in Figure 87 and Figure 88 This curve derived using the YatX goal function shown in Figure 86 illustrates the non monotonic dependence of gain on Rb2 YatX 1 X_value yl 1 sfxv X_value 1 Figure 86 YatX Goal Function To do this yourself place the goal function definition in a PROBE GF file in the circuit directory Then start PSpice load all of the AC sweeps set up the X axis for performance analysis and add the following trace YatxX Vm LOUT 100k
238. inary files When you first open a CSDF data file PSpice converts it back to the DAT format This conversion takes two or more times as long as opening a DAT file PSpice saves the new DAT file for future use 339 Chapter 13 Analyzing waveforms To save simulation results in ASCII format 1 From PSpice s Simulation menu choose Edit Profile to display the Simulation Settings dialog box General Analysis Include Files Libraries Stimulus Options Data Collection Probe Window Schematic Circuit Data All voltages currents and digital states C All but intemal subcircuit data C At Markers only C None Cancel Apply Help 2 Click the Data Collection tab 3 Select Save data in the CSDF format CSD 4 Click OK PSpice writes simulation results to the waveform data file in ASCII format as CSD instead of DAT following the CSDF convention 340 Analog example In this section basic techniques for performing waveform analysis are demonstrated using the analog circuit EXAMPLE OPJ VOU moa readme RAIAS RCI RC2 example rdm ax n cloap zn our 4 dt our ast Ne o RS y y k q212222 4212222 th l a M Ee at ot 212222 ts _p 3 0 VEE Figure 95 Example schematic EXAMPLE OPJ Running the simulation The simulation is run with the Bias Point Detail Temperature and Transient analyses enabled Th
239. inear as the sweep type To use a different swept variable type or sweep type choose different options under Sweep variable and Sweep type 26 DC sweep analysis You can visually verify the DC response of the clipper by performing a DC sweep of the input voltage source and displaying the waveform results in the Probe window in PSpice This example sets up DC sweep analysis parameters to sweep Vin from 10 to 15 volts in 1 volt increments Setting up and running a DC sweep analysis To set up and run a DC sweep analysis 1 In Capture from the PSpice menu choose New Simulation Profile The New Simulation dialog box appears In the Name text box type DC Sweep From the Inherit From list select Schematic1 Bias then click Create The Simulation Settings dialog box appears Click the Analysis tab From the Analysis type list select DC Sweep and enter the values shown in Figure 6 DC sweep analysis Simulation Settings Example Primary Sweep _ Secondary Sweep Monte CarloAworst Case Parametric Sweep Temperature Sweep Save Bias Point Load Bias Point Figure6 DC sweep analysis settings 6 Click OK to close the Simulation Settings dialog box 7 From the File menu choose Save 8 From the PSpice menu choose Run to run the analysis 27 Chapter 2 Simulation examples 28 press press Ctri M Displaying DC analysis results Probe windows can appear during or after the simulation is f
240. ing part properties needed for simulation 139 PSPICETEMPLATE 0 0 0 0 0 000000 eee eens 140 PSPICETEMPLATE syntax 4 0 44 604 9S Rae de Bs 140 PSPICETEMPLATE examples 22 lt 288 0 feebe 2s 143 Analog behavioral modeling 147 Chapter overview 2 2 209 2 444 owes ee RR ERE A REE ES 8 147 Overview of analog behavioral modeling 148 The ABM OLB part library file 3 4 64 b Oe Bake RS we ede he Se 149 Placing and specifying ABM parts sk 4 w sie 4 a4 Ba eee Xe ew 150 Net names and device names in ABM expressions 150 Forcing the use of a global definition 151 ABM part templates 5 ac 0 66s ooh G kee Rew S ER EEERS eR EE 152 Control system parts ia ce bee Sod eee ee ee Ooo ewe eee oe 153 Basic Compo NtS s sios eh epee ted teeth eeha he es 155 LAS 5 ea sa ee SR ERE SOS aw E Re Ee EH HK 156 Chebyshev filters ccud a eS a patsa aop a eee ae Cate Fe 157 Integrator and differentiator 2 sho wag amp Soe heed Boe Re 160 Table look up parts 4deh tS OX eee ee a ek Ek 160 Laplace transform part lt 24 45 eee eee Shee eR 164 Math functions e sens ae bans Od Ha Ree Ree a eee be 167 ABM expression parts gee Os aaa SHEERS Bea 168 An instantaneous device example modeling atriode 171 PSpice equivalent parts 65 065 2 oe aaa SR RO 174 Implementation of PSpice equivalent parts 175 Modeling mathematical or instantaneous relationships
241. ing simulation 200 schematic page is referred to as Y1 R34 when used in an output variable A lt pin id gt from line 4 is uniquely distinguished by specifying the full part name as described above followed by a colon and the pin name For example the pins on a capacitor with reference designator C31 placed on a top level page and pin names 1 and 2 would be identified as C31 1 and C31 2 respectively Current Specify current in the following format i modifiers lt out device gt modifiers where lt out device gt is a fully qualified device name Modifiers The basic syntax for output variables can be modified to indicate terminals of semiconductors and AC specifications The modifiers come before lt out id gt or lt out device gt Or when specifying terminals such as source or drain the modifier is the pin name contained in lt out id gt or is appended to lt out device gt separated by a colon Modifiers can be specified as follows e For voltage v AC suffix lt out id gt out id v terminal lt out device gt e For current iL AC suffix lt out device gt terminal i terminal AC suffix lt out device gt where terminal specifies one or two terminals for devices with more than two terminals such as D drain G gate S source AC suffix specifies the quantity to be reported for an AC analysis such as M magnitude P phase G group delay out id specifies either the
242. inished Z SCHEMATIC1 DC Sweep OrCAD PSpice A D clipper SCHEMATIC1 DC Sweep dat Bi Fie Edt View Simulation Trace Plot Tools Window Help 18 x a gt S ren Eea 4 fsouwancrocsnees y u 8 3 amp h OM Fer 96 FS KEE ot Sh a E 2 100 5u ou SU 10u 15u UU E clipper sth I Smmuaton Profle SEMATI DC Sweep x F oi C Sweep E ae TE i Stat 10 VVin 15 End 15 oc hed Simulation complete 4 Analysis Wach A Devices For Help press Fi VVin 15 100 ee Figure 7 Probe window To plot voltages at nets In and Mid 1 From PSpice s Trace menu choose Add Trace 2 Inthe Add Traces dialog box select V In and V Mid 3 Click OK To display a trace using a marker 1 From Capture s PSpice menu point to Markers and choose Voltage Level 2 Click to place a marker on net Out as shown in Figure 8 Veco A R2 ZA Di 3 3k D1N3940 R1 c1 In X AAA 4 Mid 4 4H out 1k 0 47u v R3 ZS D R4 3 3k D1N3940 5 6k Veco In f A A o V1 Vin E 5V sT Ov p p Figure 8 Clipper circuit with voltage marker on net Out 3 Right click and choose End Mode to stop placing markers 4 From the File menu choose Save 5 Switch to PSpice The V Out waveform trace appears as shown in Figure 9 IE SCHEMATICI DC Sweep OrCAD PSpice A D clipper SCHEMATIC1 DC Sweep dat Fle Edt View Si
243. instance on your schematic page You can also create models externally and then manually configure the new libraries for a specific design Global models Global models are available to all designs you create The part editor automatically creates a global model whenever you create a part with a new model definition The Model Editor also creates global models You can also create models externally and then manually configure the new libraries for use in all designs How are models organized To optimize the search PSpice uses indexes To find out more about this and how to add delete and rearrange configured libraries see Configuring model libraries on page 4 120 To find out how to change the design and global configuration of model libraries see Changing design and global scope on page 4 123 Example usage To set up device and lot tolerances on the model parameters for a particular part instance when running a Monte Carlo or sensitivity worst case analysis PSpice searches design libraries before global libraries To find out more see Changing model library search order on page 4 124 89 Chapter 4 Creating and editing models For a list of device models provided by OrCAD refer to the online Library List 90 Nested model libraries Besides model and subcircuit definitions model libraries can also contain references to other model libraries using the PSpice LIB syntax When searching model librarie
244. int analog node values as follows 1 Under the Options tab in the Simulation Settings dialog box select Output file in the Category box 2 Uncheck the box for Bias point node voltages NOBIAS Simulation Settings Bias Point x General Analysis Include Files Libraries Stimulus Options Data Collection Probe Window Category Include the following in the output OUT file OPTION Analog Simulation IV Detailed summary and accounting information ACCT Gate level Simulation IV Subcircuit expansion and Load Bias files EXPAND Vv LIBRARY Statements included from libraries LIST NOBIAS NODE I Circuit file statements NOECHO IV Model parameter values NOMOD IV Digital timing and hazard messages NOOUTMSG IV Page breaks and banners for each section NOPAGE IV Value of each PSpice option OPTS Number of digits in printed values fa NUMDG Output file with 80 z characters Reset Cancel Apply Help Small signal DC transfer Small signal DC transfer Minimum requirements to run a small signal DC transfer analysis Minimum circuit design requirements e The circuit should contain an input source such as VSRC Minimum program setup requirements 1 Under Analysis type in the Simulation Settings dialog box select Bias Point 2 Specify the name of the input source desired See Output variables on page 7 199 for a description of output variable formats 3 Click OK t
245. interface features for waveform analysis For more information about the cursor commands refer to the online Help in PSpice For a family of curves such as from a nested DC sweep you can use the mouse or the arrow Keys to move the cursor to one of the other curves in the family You can also click the desired curve To place a label dick Plot point to Label and then choose the desired type of object you want to place 351 Chapter 13 Analyzing waveforms To position a cursor on the next trough of a waveform from the Trace menu point to Cursor then choose Trough To position a cursor on the next peak of a waveform from the Trace menu point to Cursor then choose Peak For more information about cursors refer to the online Help in PSpice 352 Table3 Key combinations for cursor control continued Us this key combination To do this with the cursors Home Move the first cursor to the beginning of the trace Shift Home Move the second cursor to the beginning of the trace End Move the first cursor to the end of the trace Shift End Move the second cursor to the end of the trace Example using cursors Figure 97 shows both cursors on the V 1 waveform in the analog area of the plot digital cursor 1 signal results w cursors z cursor 2 results analog waveform w cursors Figure 97 Cursors positioned on a trough and peak of V 1 Cursor 1 is positi
246. ion of the second cursor to 4 volts on the x axis drag the crosshairs until the x axis value of the A2 cursor in the cursor window is approximately 4 0 You can also press shif gt and Shift for tighter control Figure 13 shows the Probe window with both cursors There are also ways to display the placed difference between two voltages as a trace TS cee e In PSpice add the trace expression a gt S mS e mmm V In V Mid 88a 9 M e E A met Pees 2 e In Capture from the PSpice menu point to Markers and choose Voltage Differential Place the two markers on different pins or wires For Help press FT a V in 15 100 SRR ZIS Figure 13 Voltage difference at V In 4 volts To delete all of the traces You can also delete an individual trace by selecting its name in the trace legend and h Delete All T i 1 From the Trace menu choose Delete races then pressing Delt At this point the design has been saved Ifneeded E ample To delete the V In trac dick the OAE i PSN we ae eae as lt text V In located under the plot s eee ana YSIS exercises later using e Save x axis and then press Delete Finding out more about DC sweep analysis Table 2 1 To find out more about this See this DC sweep analysis DC Sweep on page 8 214 31 32 Chapter 2 Simulation examples Transient analysis This example s
247. ion on page 4 117 118 4 From the Options menu choose Part Properties to display the User Properties dialog box 5 Select Implementation Type 6 From the Implementation list select PSpice Model 7 Inthe Implementation text box type the name of the existing model that you want to use if it is not already listed 8 Click OK to close the Edit Part dialog box Reusing instance models If you created instance models in your design and want to reuse them there are two things you can do e Attach the instance model implementation to other part instances in the same design e Change the instance model to a global model and create a part that corresponds to it Reusing instance models in the same schematic There are two ways to use the instance model elsewhere in the same design To use the instance model elsew here in your design 1 Do one of the following e Change the model reference for other part instances to the name of the new model instance e From the Edit menu use the Copy and Paste commands to place more part instances Reusing instance models Making instance models available to all designs If you are refining model behavior specific to your design and are ready to make it available to any design then you need to link the model definition to a part and configure it for global use To make your instance model available to any design 1 Create a part and assign the instance model name to See Chap
248. ioral Modeling ABM feature of PSpice to make flexible descriptions of electronic components in terms of a transfer function or lookup table In other words a mathematical relationship is used to model a circuit segment so you do not need to design the segment component by component The part library contains several ABM parts that are classified as either control system parts or as PSpice equivalent parts See Basic controlled sources on page 6 192 for an introduction to these parts how to use them and the difference between parts with general purpose application and parts with special purpose application Control system parts are defined with the reference voltage preset to ground so that each controlling input and output are represented by a single pin in the part These are described in Control system parts on page 6 153 PSpice equivalent parts reflect the structure of the PSpice E and G device types which respond to a differential input and have double ended output These are described in PSpice equivalent parts on page 6 174 You can also use the Device Equations option described in the online OrCA D PSpice A D Reference Manual for modeling of this type but OrCAD recommends using the ABM feature wherever possible With Device Equations the PSpice source code is actually modified While this is more flexible and produces faster results it is also much more difficult to use and to troubleshoot Also any changes you mak
249. is no memory penalty for having large model libraries Loading time is kept to a minimum Search order When searching for model definitions PSpice scans the model libraries using these criteria design model libraries before global model libraries model library sequence as listed in the Libraries tab of the Simulation Settings dialog box local directory where the current design resides first then the list of directories specified in the library search path in the order given see Changing the library search path on page 4 125 Configuring model libraries Caution When you use include files instead PSpice treats model library and include files differently as follows e For model library files PSpice reads in only the definitions it needs to run the current simulation e For include files PSpice reads in the file in its entirety This meansif you configure a model library LIB extension as an include file using the Add to Design or Add as Global button PSpice loads every model definition contained in that file If the model library is large you may overload the memory capacity of your system However when developing models you can do the following 1 Initially configure the model library as an include file this avoids rebuilding the index files every time the model library changes 2 When your models are stable reconfigure the include file containing the model definitions as a library fil
250. is produces a PSpice netlist declaration like this EPWR 3 0 VALUE V 5 4 I VSENSE Example four The output of a component GRATIO is a current whose value in amps is equal to the ratio of the voltages at nets 13 and 2 If V 2 0 the output depends upon V 13 as follows if V 13 0 output 0 if V 13 gt 0 output MAXREAL if V 13 lt 0 output MAXREAL where MAXREAL is a PSpice internal constant representing a very large number on the order of 1e30 In general the result of evaluating an expression is limited to MAXREAL This is modeled with an ABM2 I two input current output part like this one in Figure 46 This part is characterized by the following properties EXPL V ZIN2 V IN1 Note that output of GRATIO can be used as part of the controlling function This produces a PSpice netlist declaration like this GRATIO 2 3 VALUE V 13 V 2 Note Letting a current approach 1 30 will almost certainly cause convergence problems To avoid this use the limit function on the ratio to keep the current within reasonable limits Control system parts An instantaneous device example modeling a triode This section provides an example of using various ABM parts to model a triode vacuum tube The schematic of the triode subcircuit is shown in Figure 47 lt ame VENEEN Tr m DASWIN IINE a am
251. is the output voltage between two nets a and b Entering I VDRIV as the output variable specifies that the output variable is the current through a voltage source VDRIV 226 Small signal DC transfer Specify the input source name in the Calculate small signal DC gain TF portion of the Bias Point dialog box The gain from the input source to the output variable is calculated along with the input and output resistances For example if you enter V OUT2 as the output variable and v1 as the input source the input resistance for V1 is calculated the output resistance for V OUT2 is calculated and the gain from V1 to V OUT2 is calculated All calculations are reported to the simulation output file 227 Chapter 8 DC analyses 228 DC sensitivity Minimum requirements to run a DC sensitivity analysis Minimum circuit design requirements None Minimum program setup requirements 1 Inthe Bias Point dialog box select Perform Sensitivity analysis SENS 2 Enter the required value s in the Output variable s box 3 Click OK to save the simulation profile Be sure you give the new profile an appropriate name under the General tab prior to saving 4 In Capture from the PSpice menu select Run to start the simulation DC sensitivity Overview of DC sensitivity DC sensitivity analysis calculates and reports the sensitivity of one node voltage to each device parameter for the following device types res
252. is types including AC sweep Table 3 For current input Use this When you are running IAC An AC sweep analysis only ISRC Multiple analysis types including AC sweep 2 Double click the symbol instance to display the Parts spreadsheet AC sweep analysis Note Unlike DC sweep the AC Sweep Noise dialog box not indude an input source option Instead each independent source in your circuit contains its own AC specification for magnitude and phase If you are planning to run a DC or transient analysis in addition to an AC analysis see If you want to specify multiple stimulus types on page 3 77 for additional information and source symbols that you can use 233 Chapter9 AC analyses 3 Click in the cell under the appropriate property column to edit its value Depending on the source symbol that you placed define the AC specification as follows Table 4 For VAC or IAC Set this property To this value ACMAG AC magnitude in volts for VAC or amps for IAC units are optional ACPHASE Optional AC phase in degrees Table 5 For VSRC or ISRC Set this property To this value If you are also planning to run a transient AC Magnitude_value phase_value analysis see Using VSRC or ISRC where magnitude_value is in volts or parts on page 3 78 to find out how to amps units are optional and the specify the TRAN property optional phase_value is in degrees 234 AC sw
253. istors independent voltage and current sources voltage and current controlled switches diodes bipolar transistors The sensitivity is calculated by linearizing all devices around the bias point 229 Chapter 8 DC analyses 230 AC analyses Chapter overview This chapter describes how to set up AC sweep and noise analyses e AC sweep analysis on page 9 232 describes how to set up an analysis to calculate the frequency response of your circuit This section also discusses how to define an AC stimulus and how PSpice treats nonlinear devices in an AC sweep e Noise analysis on page 9 241 describes how to set up an analysis to calculate device noise contributions and total input and output noise Chapter9 AC analyses To find out how see Setting up an AC stimulus on page 9 233 To find out how see Setting up an AC analysis on page 9 235 To find out more see How PSpice treats nonlinear devices on page 9 239 232 AC sweep analysis Setting up and running an AC sweep The following procedure describes the minimum setup requirements for running an AC sweep analysis For more detail on any step go to the pages referenced in the sidebars To set up and run an AC sweep 1 Place and connect a voltage or current source with an AC input signal 2 From the PSpice menu select New Simulation Profile or Edit Simulation Settings If this is a new simulation enter the name of the profile and click OK
254. it as a single PSpice run For the circuit shown in Figure 57 you can set up a DC sweep analysis with an outer sweep of the voltage source VD and an inner sweep of the voltage source VG as listed in Table 1 Tablel Curve family example setup Outer sweep Nested sweep Swept Var Type voltage source voltage source Sweep Type linear linear Name VD VG Start Value 0 0 End Value 5 2 Increment 0 1 0 5 When the DC sweep analysis is run add a current marker at the drain pin of M1 and display the simulation results in PSpice The result will look like Figure 58 To add a load line for a resistor add a trace that computes the load line from the sweep voltage Assume that the X axis variable is the sweep voltage V_VD which runs from 0 to 5 volts The expression which will add a trace that is the load line for a 50 kohm resistor is 5V V_VD 50K This can be useful for determining the bias point for each member of a curve family as shown in Figure 59 DC Sweep M Mbreakh m Figure 57 Curve family example schematic In Capture from the PSpice menu point to Markers then choose Mark Current Into Pin to add a current marker V_VD is the hierarchical name for VD created by netlisting the schematic 221 Chapter 8 DC analyses 150uA 168uA 5 uA au 1 60 2 0U 3 00 4 0u 5 8U a ID M1 Figure 58 Device curve family SOK Resistor Load Line 166u Se hess Sea i te 2 AE
255. itches have gain in their transition region If several are cascaded then the cumulative gain can easily exceed the derivative limit of 1e14 This can happen when modeling simple logic gates using totem pole switches and there are several gates in cascaded in series Usually a cascade of two switches works but three or more can cause trouble Bias point and DC sweep Behavioral modeling expressions Range limits Voltages and currents in PSpice are limited to the range 1e10 Care must be taken that the output of expressions fall within this range This is especially important when one is building an electrical analog of a mechanical hydraulic or other type of system Source limits Another consideration is that the controlled sources must turn off when the supplies are almost 0 001 There is special code in PSpice which squelches the controlled sources in a continuous way near 0 supplies However care should still be taken using expressions that have denominators Take for example a constant power load GLOAD 3 5 VALUE 2Watts V 3 5 The first repeating series starts with V 3 5 0 and the current through GLOAD would be infinite actually the code in PSpice which does the division clips the result to a finite value The squelching code is required to be a smooth and well behaved function Note The squelching code cannot be strong enough to suppress dividing by 0 The result is that GLOAD d
256. ition with a device while the IC1 and IC2 pseudocomponents allow the association to be with a node or node pair In the case of initial currents through inductors the association is only with a device and so there are no corresponding pseudocomponents The internal implementation is analogous to the capacitor PSpice attaches a current source with a 1 Gohm parallel resistance in series with the inductor Convergence and time step too small errors Appendix overview This appendix discusses common errors and convergence problems in PSpice e Introduction on page B 380 e Bias point and DC sweep on page B 385 e Transient analysis on page B 388 e Diagnostics on page B 393 Chapter B Convergence and time step too small errors The ACand noise analyses are linear and do not use an iterative algorithm so the following discussion does not apply to them 380 Introduction In order to calculate the bias point DC sweep and transient analysis for analog devices PSpice must solve a set of nonlinear equations which describe the circuit s behavior This is accomplished by using an iterative technique the Newton Raphson algorithm which starts by having an initial approximation to the solution and iteratively improves it until successive voltages and currents converge to the same result In a few cases PSpice cannot find a solution to the nonlinear circuit equations This is generally called a convergence problem
257. itor alone on page 4 99 To find out more see Running the Model Editor from the schematic page editor on page 4 101 To find out more see Running the Model Editor alone on page 4 99 94 Ways to use the Model Editor You can use the Model Editor five ways To define a new model and then automatically create a part Any new models and parts are automatically available to any design To define a new model only no part You can optionally turn off the part creation feature for new models The model definition is available to any design for example by changing the model implementation for a part instance To edit a model definition for a part instance on your schematic This means you need to start the Model Editor from the schematic page editor after selecting a part instance on your schematic The schematic editor automatically attaches the new model implementation that the Model Editor creates to the selected part instance To examine or verify the electrical characteristics of a model without running PSpice This means you can use the Model Editor alone to e check characteristics of a model quickly given a set of model parameter values or e compare characteristic curves to data sheet information or measured data Model Editor supported device types Table 17 summarizes the device types supported in the Model Editor Table 17 Models supported in the Model Editor Uses this And this
258. itor is a graphical input waveform editor that lets you define the shape of time based signals used to test your circuit s response during simulation Using the Stimulus Editor you can define e analog stimuli with sine wave pulse piecewise linear exponential pulse single frequency FM shapes The Stimulus Editor lets you draw analog piecewise linear stimuli by clicking at the points along the timeline that correspond to the input values that you want at transitions Chapter 1 Things you need to know 10 What is the Model Editor The Model Editor is a model extractor that generates model definitions for PSpice to use during simulation All the Model Editor needs is information about the device found in standard data sheets As you enter the data sheet information the Model Editor displays device characteristic curves so you can verify the model based behavior of the device When you are finished the Model Editor automatically creates a part for the model so you can use the modeled part in your design immediately Files needed for simulation To simulate your design PSpice needs to know about e the parts in your circuit and how they are connected e what analyses to run e the simulation models that correspond to the parts in your circuit and e the stimulus definitions to test with This information is prov
259. ivalent parts 174 175 simulation status window 208 368 starting 206 using with other programs 9 viewing in progress output values 368 waveform data file DAT 14 PSPICE INI file editing 324 Index R real part 361 regulator 95 RELTOL simulation option 191 resistors 203 363 S schematic page editor starting other tools from Model Editor 101 111 112 scrolling Probe windows 346 semiconductor problems 385 shot noise 245 simulation about 2 analysis execution order 198 setup 197 types 196 batch jobs 207 bias point 374 failure to start 58 initial conditions 374 378 output file OUT 24 setup checklist 56 starting 206 status window 208 troubleshooting checklist 58 simulation control parts 60 ICn 376 NODESETn initial conditions 376 PARAM 67 small signal DC transfer analysis 196 225 introduction 3 Stimulus Editor 33 253 about 9 creating new stimulus parts 259 defining analog stimuli 76 defining stimuli 256 editing a stimulus 260 manual stimulus configuration 261 starting 254 stimulus files 253 254 stimulus files 11 configuring 13 120 stimulus generation 252 401 Index manually configuring 261 stimulus adding 33 AC sweep 233 DC sweep 218 for multiple analysis types 77 transient analog mixed signal 252 subcircuits 87 creating SUBCKT definitions from designs 91 creating SUBCKT definitions from schematics 115 tools to create 91 w
260. l Configuring stimulus files The Include Files tab in the Simulation Settings dialog box allows you to view the list of stimulus files pertaining to your current schematic You can also manually add delete or change the stimulus file configuration in this tab dialog box The list box displays all of the currently configured stimulus files One file is specified per line Files can be configured as either global to the Capture environment or local to the current design Global files are marked with an asterisk after the file name When starting the Stimulus Editor from Capture stimulus files are automatically configured added to the list as local to the current design Otherwise new stimulus files can be added to the list by entering the file name in the Filename text box and then clicking the Add to design local configuration or Add as global global configuration button Starting the Stimulus Editor The Stimulus Editor is fully integrated with Capture and can be run from either the schematic editor or symbol editor You can start the Stimulus Editor by doing the following 6 Select one or more stimulus instances in the schematic 71 From the Edit menu choose PSpice Stimulus The Stimulus Editor utility When you first start the Stimulus Editor you may need to adjust the scale settings to fit the trace you are going to add You can use Axis Settings on the Plot menu or the corresponding toolbar button to change the
261. l D Drain terminal VG JFET G Gate terminal I JFET G S Source terminal Setting up analyses 203 Chapter 7 Setting up analyses and starting simulation Table6 Element definitions for 3 or 4 terminal devices lt out id gt or lt out a Output variable Deve type device lt P id gt examples device indicator MOSFET M B Bulk substrate VDG M1 terminal ID M1 D Drain terminal G Gate terminal S Source terminal bipolar Q B Base terminal V Q1 B transistor C Collector terminal 1 Q1 C E Emitter terminal S Source terminal IGBT Z C Collector terminal V Z1 C E Emitter terminal I Z1 C G Gate terminal Table Element definitions for transmission line devices lt out id gt or Device type lt out device gt lt z gt rei nae bee device indicator p transmission T A Port A V T32 A line B PortB I T32 B 204 Setting up analyses Table8 Element definitions for AC analysis specific elements lt ac suffix gt Output variable device symbol Meaning examples none magnitude default V V1 I V1 M magnitude VM CAP1 1 IM CAP1 1 DB magnitude in decibels VDB R1 phase IP R1 R real part VR R1 I imaginary part VI R1 The INOISE ONOISE DB INOISE and DB ONOISE output variables are predefined for use with noise AC sweep analysis 205 Chapter 7 Setting up analyses and starting simulation Starting a simulation After you have used Capture
262. late is shown indicating the order in which the inputs are processed if applicable Tablel ABM math function parts For this device Output is the ABS SORT PWR PWRS LOG LOG10 EXP SIN COS TAN ATAN ARCTAN absolute value of the input square root of the input result of raising the absolute value of the input to the power specified by EXP result of raising the signed input value to the power specified by EXP LOG of the input LOG 9 of the input result of e raised to the power specified by the input value e where x is the input sin of the input where the input is in radians cos of the input where the input is in radians tan of the input where the input is in radians tan of the input where the output is in radians Math function parts are based on the PSpice E device type Each provides one or more inputs and a mathematical function which is applied to the input The result is output on the output net 167 Chapter 6 Analog behavioral modeling 168 ABM expression parts The expression parts are shown in Table 2 These parts can be customized to perform a variety of functions depending on your requirements Each of these parts has a set of four expression building block properties of the form EXPn where n 1 2 3 or 4 During netlist generation the complete expression is formed by concatenating the building block expressions in numeric ord
263. lator Current is pumped from net 11 through the a B26 TOH T V IN source to net 6 Its value is a sine wave with an amplitude of 15 mA and a frequency of 10 kHz The voltage at net 3 can shift the phase of GPSK by 1 radian volt Note the use Figure 44 ABM expression part of the TIME parameter in the EXP2 expression This isthe example two PSpice internal sweep variable used in transient analyses For any analysis other than transient TIME 0 This could be represented with an ABM1 I part single input current output like the one shown in Figure 44 This part is characterized by the following properties EXP1 15ma SIN EXP2 6 28 10kKHzZ T IME EXP3 V ZIN This produces a PSpice netlist declaration like this GPSK 11 6 VALUE 15MA SIN 6 28 10kHz TIME V 3 169 Chapter 6 Analog behavioral modeling 4 5 IV SENSE VW S6IN2 SoIN 1 Figure 45 ABM expression part example three 2 13 VINZI EINT ab Figure 46 ABM expression part example four 170 Example three A device EPWR computes the instantaneous power by multiplying the voltage across nets 5 and 4 by the current through VSENSE Sources are controlled by expressions which may contain voltages or currents or both The ABM2 part two inputs current output in Figure 45 could represent this This part is characterized by the following properties EXP1 V IN2 IN1 EXP2 I VSENSE Th
264. lear way to apply the Nyquist criterion directly so an additional factor of two is thrown in as a safety margin Thus TMAX is set to 0 25 FP where FP is the pass band cutoff for the high pass case or the upper pass band cutoff for the band reject case It may be necessary to set TMAX to something smaller if the filter input has significant frequency content above these limits Frequency tables For frequency response tables the maximum frequency is twice the highest value It will be reduced to 10 RELTOL TSTOP or 8192 times the frequency resolution if either value is smaller The frequency resolution for frequency response tables is taken to be either the smallest frequency increment in the table or the fastest rate of phase change whichever is least PSpice then checks to see if it can be loosened without inducing sampling errors Cautions and recommendations for simulation and analysis Trading off computer resources for accuracy There is a significant trade off between accuracy and computation time for parts modeled in the frequency domain The amount of computer time and memory scale approximately inversely to RELTOL Therefore if you can use RELTOL 01 instead of the default 001 you will be ahead However this will not adversely affect the impulse response You may also wish to vary TMAX and TSTOP since these also come into play Since the trade off issues are fairly complex it is advisable to first simulate a small
265. lem if the junction is inadvertently forward biased it can create a very large capacitance The capacitance goes as a power of the junction voltage Normal junctions cannot sustain much forward voltage because a large current flows The collector substrate junction is an exception because it has no DC current If this happens it usually shows up at the first time step It can be spotted turning on the detailed operating point information TRAN OP and looking at the calculated value of CJS for bipolar transistors The whole problem can be prevented by using the PSpice model parameter ISS This parameter turns on DC current for the substrate junction Diagnostics Diagnostics If PSpice encounters a convergence problem it inserts into the output file a message that looks like the following ERROR Convergence problem in transient analysis at Time 7 920E 03 Time step 47 69E 15 minimum allowable step size 300 0E 15 These voltages failed to converge V x2 23 1230 23 68 4137 V x2 25 1211 94 86 6888 These supply currents failed to converge 1 X2 L1 36 6259 2 25682 I X2 L2 36 5838 2 29898 These devices failed to converge X2 DCR3 X2 DCR4 x2 ktr X2 Q1 X2 02 Last node voltages tried were NODE VOLTAGE NODE VOLTAG NODE VOLTAGE NODE VOLTAGE E 1 25 2000 3 4 0000 4 0 0000 6 25 2030 X2 23 1230 200 X2 24 9 1441 x2 25 1211 900 X2 26 256 970 0 0 0 X2 28 206 610 X2 29 75 4
266. low filtering of the signal based on a set of frequency characteristics The output of a Chebyshev filter depends upon the analysis being performed Note PSpice computes the impulse response of each Chebyshev filter used in a transient analysis during circuit read in This may require considerable computing time A message is displayed on your screen indicating that the computation is in progress For DC and bias point the output is simply the DC response of the filter For AC analysis the output for each frequency is the filter response at that frequency For transient analysis the output is then the convolution of the past values of the input with the impulse response of the filter These rules follow the standard method of using Fourier transforms Note To obtain a listing of the filter Laplace coefficents for each stage choose Setup from the Analysis menu click on Options and enable LIST in the Options dialog box Each of the Chebyshev filter parts is described in the following pages LOPASS FS stop band frequency FP pass band frequency RIPPLE pass band ripple in dB STOP stop band attenuation in dB The LOPASS part is characterized by two cutoff frequencies that delineate the boundaries of the filter pass band and stop band The attenuation values RIPPLE and STOP define the maximum allowable attenuation in the pass band and the minimum required attenuation in the stop band respectively The LOPASS part provides one in
267. lt gt amp a Is 1 434e 014 BF 2559 NF 1 VAF 74 03 KF 0 2847 ISE 14346 014 NE 1307 BR 6 092 Ready 12 020 1 a8 o Oot o 7 aa 1e 006 1500 12 1000 20 1 500 1e 014 100 aaa a Figure 29 Model Editor workspace with data for a bipolar transistor Using the Model Editor to edit models For more information about the characteristics of devices supported by the Model Editor refer to the online OrCA D PSpice A D Reference Manual 97 Chapter 4 Creating and editing models 98 g To fit the model 1 For each device characteristic that you want to set up a Inthe Spec Entry frame click the tab of the device characteristic b Enter the device information from the data sheet 2 From the Tools menu choose Extract Parameters to extract all relevant model parameters for the current specification A check mark appears in the Active column of the Parameters frame for each extracted model parameter 3 Repeat steps 1 2 until the model meets target behaviors To view updated performance curves 1 On the toolbar click the Update Graph button Note If you view performance curves before fitting then your data points and the curve for the current model specification may not match Using the Model Editor to edit models Running the Model Editor alone After you have selected the part that you want to model you can proceed with Run the Model Editor alon
268. lt G property value gt Otherwise this fragment translates to G 000 141 Chapter 5 Creating parts for models Caution Recommended scheme for netlist templates Templates for devices in the part library start with a PSpice device letter followed by the hierarchical path and then the reference designator REFDES property OrCAD recommends that you adopt this scheme when defining your own netlist templates Example R REFDES for a resistor 142 The character in templates The schematic page editor replaces the character with the complete hierarchical path to the device being netlisted The n character sequence in templates The part editor replaces the character sequence n with a new line Using n you can specify a multi line netlist entry from a one line template The character and pin names in templates Pin names are denoted as follows o lt pin name gt where pin name is one or more regular characters The schematic page editor replaces the lt pin name gt clause in the template with the name of the net connected to that pin The end of the pin name is marked with a separator see Property names in templates on page 5 141 To avoid name conflicts in PSpice the schematic page editor translates the following characters contained in pin names Table 5 This pin name character Is replaced with this lt 1 L 8 e XXX XXXbar Note To include a lit
269. mic range of time 389 inductors and transformers 391 Newton Raphson requirements 380 parasitic capacitances 391 semiconductors 385 switches 386 transient analysis 388 Create Subcircuit command 91 115 current source controlled 174 192 cursors waveform analysis 350 custom part creation for models 133 using the Model Editor 100 131 D Darlington model transistors 95 DC analyses displaying simulation results 28 see also DC sweep analysis bias point detail analysis small signal DC transfer analysis DC sensitivity analysis DC sensitivity analysis 196 228 introduction 3 DC stimulus property 219 DC sweep analysis 196 214 about 216 curve families 221 example 26 introduction 3 nested 219 setting up 26 stimulus 218 derivative problems 382 design preparing for simulation 9 56 device noise 242 245 total 245 diagnostic problems 393 differentiators ABM 153 160 digital parts vendor supplied 61 digital simulation waveform display 344 364 diodes 95 202 363 dynamic range of time 389 E EGND ground part 83 examples and tutorials AC sweep analysis 37 237 analog waveform analysis 339 bias point detail analysis 22 DC sweep analysis 26 example circuit creation 16 frequency response vs arbitrary parameter 278 mixed analog digital waveform analysis 344 modeling a triode ABM 171 Monte Carlo analysis 293 parametric analysis 42 performance analysis 49 274 transient analy
270. most message conditions a Probe window appears that contains the waveforms associated with the simulation condition along with detailed message text Persistent hazards If a PERSISTENT HAZARD message is displayed two plots appear see Figure 98 containing the following e the waveforms that initially caused the timing violation or hazard lower plot e the primary outputs or internal state devices to which the condition has propagated upper plot E OrCAD PSpice A D Msg1_d dat a File Edit View Simulation Trace Plot Tools Window Help 18 x esas reperar n SS aQ Gree mzta kirane Z TUL feat ri a M a M iti 1 Louons oios i 40 6ns 56 6ns ans rmz 86 6ns 90 8ns 100 6ns 189 5ns ime E J ISEL gt gt ee aa jot S p jon 16ns 12ns 16ns 26ns 24ns 28ns 32ns 36ns Time iol _ il gt Simulation Error Message x PERSISTENT Hazard at time 73ns On OUTPUT Port p15 anret reas Violation at tine 21ns 1 xO B1 26 686 8 Minimum low WIDTH 5ns B2 25 006n 1 NODE clock1 measured WIDTH 1ns dif 5 6006n clock1 width too short BR Mogl_ddat Figure 98 Waveform display for a persistent hazard 355 Chapter 13 Analyzing waveforms You can display a subset of the available simulation output variables by selecting or dearing the variable type check boxes in the Simulation Output Variables frame Variable ty
271. mple multiplier Note A double balanced mixer with inputs at the same frequency would produce outputs at DC at twice the input frequency but these terms cannot be seen with a linear small signal analysis 240 Using a DC source Consider the circuit shown here At the DC bias point PSpice calculates the partial derivatives which determine the linear response of the multiplier as follows dV Out 9V Out avant V2 Wana V In1 V In2 V In2 V In1 V Out V In1 For this circuit this equation reduces to V Out V In1 2 V In2 0 This means that the multiplier acts as an amplifier of the AC input with a gain that is set by the DC input Caution multiplying AC sources Suppose that you replace the 2 volt DC source in this example with an AC source with amplitude 1 and no DC value DC 0 When PSpice computes the bias point there are no DC sources in the circuit so all nodes are at 0 volts at the bias point The linear equivalent of the multiplier block is a block with gain 0 which means that there is no output voltage at the fundamental frequency Noise analysis Setting up and running a noise analysis The following procedure describes the minimum setup requirements for running a noise analysis For more detail on any step go to the pages referenced in the sidebars To set up and run an AC sweep 1 Place and connect a voltage or current source with an AC input signal Set up the AC sweep s
272. mulation to limit results written to the waveform data file and automatically display those traces in PSpice e During or after simulation with PSpice running to automatically display traces in the active Probe window The color of the marker you place is the same as its corresponding waveform analysis trace If you change the color of the trace the color of the marker on the schematic page changes accordingly The Markers submenu also provides options for controlling the display of marked results in PSpice after initial marker placement and during or after simulation To place markers on a schematic page 1 From Capture s PSpice menu point to Markers then choose the marker type you want to place Some of the markers are from the Advanced submenu 331 Chapter 13 Analyzing waveforms B X The color of the marker is the same as its corresponding waveform analysis trace If you change the color of the trace the color of the marker changes accordingly 332 Table 5 Waveform Markers menu command Advanced submenu command voltage Voltage Level not required voltage Voltage Differential not required differential current Current Into Pin not required digital signal Voltage Level not required dB Advanced db Magnitude of Voltage db Magnitude of Current phase Advanced Phase of Voltage Phase of Current group delay Advanced Group Delay of Voltage Group Delay of Current real Advanced Real Part of Voltage Real
273. mulation Trace Plot Toole Window Help 218 x IE sBbuS AIEEE E Il SCHEMATICT DC Sweep pu s8aelGkeS Rae od kyra e e 260 10v Tm 10049 160 5U UCIN 9 U MID A U OUT v_vin Bi clipper SCH 4 es Simulation Profile SCHEMATICT DC Sweep l Simulation running circuit fle for profile DC Sweep Reading and checking circuit Circuit read in and checked no eors DC Analysis DC Analysis finished Simulation complete Stat 10 VVin 15 End 15 ED Analisis K Watch Devices 7 For Help press FT VVin 15 100 EMRE RAS Figure9 Voltage at In Mid and Out F ScrollLock DC sweep analysis 29 Chapter 2 Simulation examples This example uses the cursors feature to view the numeric values for two traces and the difference between them by placing a cursor on each trace Table 10 Association of cursors with mouse buttons cursor 1 left mouse button cursor 2 right mouse button ioiU In U Mid v U Out Figure 11 Trace legend with cursors activated Your ability to get as close to 4 0 as possible depends on screen resolution and window size PoiUCIn o U Mid U Out Figure 12 Trace legend with V Mid symbol outlined 30 1 To place cursors on V In and V Mid From PSpice s Trace menu point to Cursor and choose Display Two cursors appear for the first trace defin
274. n a noise analysis on the circuit shown in Figure 60 on page 9 237 To run a noise analysis on the example In Capture open the EXAMPLE DSN circuit provided with your OrCAD programs in the ORCAD CAPTURE SAMPLES subdirectory 1 From the PSpice menu choose New Simulation Profile or Edit Simulation Settings If this is a new simulation enter the name of the profile and click OK The Simulation Settings dialog box appears 2 Choose AC Sweep Noise in the Analysis type list box 3 Under Options select General Settings if it is not already enabled 4 Enable the Noise Analysis check box 5 Enter the following parameters for the noise analysis Output Voltage V OUT2 I V Source V1 Interval 30 These settings mean that PSpice will calculate noise contributions and total output noise at net OUT2 and equivalent input noise from V1 Figure 63 shows Probe traces for Q1 s constituent noise sources as well as total nose for the circuit after simulating Notice that the trace for RMSSUM at the top of the plot which is a macro for the trace expression SQORT NTOT Q1 NTOT Q2 NTOT Q3 exactly matches the total output noise V ONOISE calculated by PSpice 8 O U ONDISE o RMSSUH 20f 22 2 22 22 22 22222222 222222 nnn 22222 Wicdesnencnssese doses oo oceee een ste E AA ERE es See ie o SEL gt gt 6 0 V A0 0O O y ad so O V 4
275. n dB vs the swept input resistance s 368 1 6K 41 o Bandwidth u Out 3 Z m Max Udb Out Ruval Figure 26 Performance analysis plots of bandwidth and gain vs Reval Performance analysis Finding out more about performance analysis Table 2 4 To find out more about this See this how to use performance RLC filter example on analysis page 11 274 Example Monte Carlo analysis of a pressure sensor on page 12 293 how to use search PSpice A D online Help commands and create goal functions 51 Chapter 2 Simulation examples 52 Part two Design entry Part two provides information about how to enter circuit designs in OrCAD Capture that you want to simulate Chapter 3 Preparing a design for simulation outlines the things you need to do to successfully simulate your schematic including troubleshooting tips for the most frequently asked questions Chapter 4 Creating and editing models describes how to use the tools to create and edit model definitions and how to configure the models for use Chapter 5 Creating parts for models explains how to create symbols for existing or new model definitions so you can use the models when simulating from your schematic Chapter 6 Analog behavioral modeling describes how to model analog behavior mathematically or using table lookups Preparing a design for simulation Chapter overview This chapter pro
276. n is 50 dB This will produce a PSpice netlist declaration like this EBANDPASS 5 0 CHEBYSHEV V 10 BP 800 1 2K 2K 3K 1dB 50dB BAN DRE RIPPLE _ is the pass band ripple in dB STOP is the stop band attenuation in dB FO F1 are the cutoff frequencies F2 F3 The BANDRE part is characterized by four cutoff frequencies The attenuation values RIPPLE and STOP define the maximum allowable attenuation in the pass band and the minimum required attenuation in the stop band respectively The BANDRE J part provides one input and one output Figure 38 shows an example of a BANDRE filter device This is a band reject or notch filter with the stop band between 1 2 kHz and 2 kHz and pass bands below 800 Hz and above 3 kHz The pass band ripple is 0 1 dB and the minimum stop band attenuation is 50 dB This will produce a PSpice netlist declaration like this ENOTCH 5 0 CHEBYSHEV V 10 BR 1 2K 800 3K 2K 1dB 50dB Control system parts Aw 1 2kHz 0 1dE50gp500Hz 3kHz RT te Figure 37 BANDPASS filter part example 4 RS Tiiz 0 1dE50gp500Hz AkHz Az 2kHz Figure 38 BANDREJ filter part example 159 Chapter 6 Analog behavioral modeling If more than five values are required the part can be customized through the part editor Insert additional row variables into the template using the same form as the first five and add ROWn properties as needed to the list of properties 160 I
277. n on instance models see Reusing instance models on An instance model is a copy of the part s original model The copied model is local to the design You can page 4 118 customize the instance model without impacting any other design that uses the original part from the library When the schematic editor creates the copy it assigns a unique name that is by default original_model_name Xn where nis lt blank 1 2 gt depending on the number of different instance models derived from the original model for the current design 101 Chapter 4 Creating and editing models Starting the Model Editor To start editing an instance model 1 In Capture select one part on your schematic page 2 From the Edit menu choose PSpice Model To find out how Capture searches the The schematic page editor searches the model libraries library see Changing model library for the instance model search order on page 4 124 e If found the schematic page editor starts the Model Editor which opens the model library that contains the instance model and loads the instance model e If not found the schematic page editor assumes that this is a new instance model and does the following makes a copy of the original model definition names it original_model_name Xn and starts the Model Editor with the new model loaded Saving design models When you save your edits the Model Editor saves the model definition to DESIGN_NAME LIB
278. nd IN by the current through a a VSENSE This device s behavior is built in to the Sun o property as follows appears on one ine TEMPLATE E REFDES OUT ZOUT VALUE V IN1 IN1 V IN2 IN2 Figure 51 EMULT part example You can use the part editor to change the characteristics of the template to accommodate additional mathematical functions or to change the nature of the transfer function itself For example you may want to create a voltage divider rather than a multiplier This is illustrated in the following example Example 2 Consider the device in Figure 52 178 PSpice equivalent parts Gratio H2 AT div G REFDES OUT SOQUT VALU Figure 52 GMULT part example With this device the output is a current is equal to the ratio of the voltages at input pins 1 and input pins 2 If V IN2 IN2 0 the output depends upon V IN1 IN1 as follows if V IN1 IN1 0 output 0 if V IN1 IN1 gt 0 output MAXREAL if V IN1 IN1 lt 0 output MAXREAL where MAXREAL is a PSpice internal constant representing a very large number on the order of 130 In general the result of evaluating an expression is limited to MAXREAL Note that the output of the part can also be used as part of the controlling function PESIN T S6IN1 JAVE6IN2 96IN2 To create this device you would first make a new part GDIV based
279. nd SUBCKT command syntax Remember to configure the new model library 92 Using the Model Editor to edit models Using the Model Editor to edit models The Model Editor converts information that you enter from the device manufacturer s data sheet into either e model parameter sets using PSpice MODEL syntax or e subcircuit netlists using PSpice SUBCKT syntax The Normal view in the Model Editor does and saves these definitions to model libraries that PSpice ead Bie coHowmng Surat can search when looking for simulation models e optional nodes construct OPTIONAL e variable parameters construct PARAMS OrCAD PSpice e local PARAM command model libraries OrCAD OrCAD Model Editor e local FUNC command To refine the subcircuit definition for these constructs use the Model Text view in Model Editor described in Editing model text on page 4 110 exported model file Figure 27 Relationship of the Model Editor to Capture and PSpice Note By default the Model Editor creates or updates model libraries To create an exported model file choose the Export command from the Model menu and configure it as an include file For more information see How PSpice uses model libraries and the companion sidebar on page 4 121 93 Chapter 4 Creating and editing models To find out more see Running the Model Editor alone on page 4 99 To find out more see Running the Model Ed
280. nd increments within the range The example circuit EXAMPLE OP is provided with the OrCAD program installation 282 Overview of temperature analysis For a temperature analysis PSpice reruns standard analyses set in the Simulation Settings dialog box at different temperatures You can specify zero or more temperatures If no temperature is specified the circuit is run at 27 C If more than one temperature is listed the simulation runs once for each temperature in the list Setting the temperature to a value other than the default results in recalculating the values of temperature dependent devices In EXAMPLE OP see Figure 73 the temperature for all of the analyses is set to 35 C The values for resistors RC1 and RC2 are recomputed based upon the CRES model which has parameters TC1 and TC2 reflecting linear and quadratic temperature dependencies Likewise the Q3 and Q4 device values are recomputed using the Q2N2222 model which also has temperature dependent parameters In the simulation output file these recomputed device values are reported in the section labeled TEMPERATURE ADJUSTED VALUES readme Raids RCH RC2 example rdm 2 ik ik a CLOAD oun d Jout RSI YN RS2 S o2 03 y Gee 4212222 tk T q J ba 4 aa a4 at 2 SERS 202222 ad 4212222 CS m E o VEE Figure 73 Example schematic EXAMPLE OPJ
281. nd vice versa The maximum time is the length of the transient analysis TSTOP Therefore the frequency resolution is 1 TSTOP Laplace transforms For Laplace transforms PSpice starts off with initial bounds on the frequency resolution and the maximum frequency determined by the transient analysis parameters as follows The frequency resolution is initially set below the theoretical limit to 25 TSTOP and is then made as large as possible without inducing sampling errors The maximum frequency has an initial upper bound of 1 RELTOL TMAX where TMAX is the transient analysis Step Ceiling value and RELTOL is the relative accuracy of all calculated voltages and currents If a Step Ceiling value is not specified PSpice uses the Transient Analysis Print Step TSTEP instead Note TSTOP TMAX and TSTEP values are configured using Transient on the Setup menu The RELTOL property is set using Options on the Setup menu PSpice then attempts to reduce the maximum frequency by searching for the frequency at which the response has fallen to RELTOL times the maximum response For instance for the transform 1 1 s the maximum response 1 0 is at s j 0 DC The cutoff frequency used when RELTOL 001 is approximately 1000 2m 159 Hz At 159 Hz the response is down to 001 down by 60 db Since some 187 Chapter 6 Analog behavioral modeling 188 transforms do not have such a limit there is also a limit of 1
282. ne models including delay reflection loss dispersion and crosstalk nonlinear magnetic core models induding saturation and hysteresis six MOSFET models including BSIM3 version 3 1 and EKV version 2 6 five GaAsFET models including Parker Skellern and TriQuint s TOM2 model IGBTs W hat is PSpice OrCAD P Spice is a simulation program that models the behavior of a circuit containing analog devices Used with OrCAD Capture for design entry you can think of PSpice as a software based breadboard of your circuit that you can use to test and refine your design before ever touching a piece of hardware Run basic and advanced analyses PSpice can perform e DC AC and transient analyses so you can test the response of your circuit to different inputs e Parametric Monte Carlo and sensitivity worst case analyses so you can see how your circuit s behavior varies with changing component values Use parts from OrCAD s extensive set of libraries The model libraries feature over 11 300 analog models of devices manufactured in North America Japan and Europe Vary device characteristics without creating new parts PSpice has numerous built in models with parameters that you can tweak for a given device These include independent temperature effects Model behavior PSpice supports analog behavioral modeling so you can describe functional blocks of circuitry using mathematical expressions and functions Analyses you
283. nected to a resistor of one micro ohm This circuit does not have a solution within the dynamic range of currents 1e10 amps Here is another example V1 l 0 5v D1 1s 0 DMOD MODEL DMOD IS le 16 The problem here is that the diode model has no series resistance It can be shown that the current through a To find out more about the diode equations diode is refer to the A nalog Devices chapter in T ISteveres the online OrCAD PSpice A D Reference Manual N defaults to one and k T at room temperature is about 025 volts So in this example the current through the diode would be I 1e 16 e 7 22e70 amps This circuit also does not have a solution within the limits of the dynamic range of PSpice In general be careful of components without limits built into them Extra care is needed when using the expressions for controlled sources such as for behavioral modeling It is easy to write expressions with very large values 381 Chapter B Convergence and time step too small errors Avoid unrealistic model parameters Behavioral modeling expressions need extra care 382 Are the Equations Continuous The device equations built into PSpice are continuous The functions available for behavioral modeling are also continuous there are several functions such as int x which cannot be added because of this So for physically realistic circuits the equations can also be continuous Exceptions that come are usuall
284. nly click the Add to Design button e If the model definitions are for global use in any schematic click the Add as Global button instead Click OK Configuring model libraries Note If the model libraries reside in a directory that is not on the library search path and you use the Browse button in step 3 to select the libraries you want to add then the schematic editor automatically updates the library search path Otherwise you need to add the directory path yourself See Changing the library search path on page 4 125 Changing design and global scope There are times when you might need to change the scope Example If you have an instance model of a model library from design to global or vice versa that you now want to make available to any design then you need to change the To change the scope of a design model to global local model library that contains it to have 1 From the Simulation menu choose Edit Simulation atone hae Settings then click the Libraries tab For more information see Global vs i design models and libraries on 2 Select the model library that you want to change Jage 4 89 3 Do one of the following e Click the Add as Global button to add a global entry e Click the Add to Design button to add a design entry 4 Click the Delete toolbar button to remove the local entry 123 Chapter 4 Creating and editing models See Handling duplicate model names on page 4 122 for more information
285. nsient analysis Print Step 01ms and Final Time 2ms sweeping VIN from 1 8 volts to 1 0 volts and back down to 1 8 volts very slowly This has two advantages e it avoids convergence problems e it covers both the upward and downward transitions in one analysis After the simulation in the Probe window in PSpice the X axis variable is initially set to be Time By selecting X Axis Settings from the Plot menu and clicking on the Axis Variable button you can set the X axis variable to be V 1 Then use Add on the Trace menu to display V 7 and change the X axis to a user defined data range from 1 8V to 1 0V Axis Settings on the Plot menu This plots the output of the Schmitt trigger against its input which is the desired outcome The result looks similar to Figure 67 267 Chapter 10 Transient analysis Note You must do a transient analysis in order to do a Fourier analysis The sampling interval used during the Fourier transform is equal to the print step specified for the transient analysis 268 WMS ae ae SS ae I I 4 204 Pe z i I i I I I I I I I I I I 1 60 I I I if I I 4 I I 2 80 t 1 n l 1 8U 1 6U 1 4U 1 2U 1 8U UC u t Figure 67 Hysteresis curve example Schmitt trigger Fourier components Fourier analysis is enabled through the Output File Options dialog box under the Time Domain
286. nt analysis can fail to complete if the time step gets too small This can have two different effects 1 The Newton Raphson iterations would not converge even for the smallest time step size or 2 Something in the circuit is moving faster than can be accommodated by the minimum step size The message PSpice puts into the output file specifies which condition occurred Skipping the bias point The SKIPBP option for the transient analysis skips the bias point calculation In this case the transient analysis has no known solution to start from and therefore is not assured of converging at the first time point Because of this its use is not recommended It inclusion in PSpice is to maintain compatibility with UC Berkeley SPICE SKIPBP has the same meaning as UIC in Berkeley SPICE UIC is not needed in order to specify initial conditions The dynamic range of TIME TIME the simulation time during transient analysis is a double precision variable which gives it about 15 digits of accuracy The dynamic range is set to be 15 digits minus the number of digits of accuracy required by RELTOL For a default value of RELTOL 001 1 or 3 digits this gives 15 3 12 digits This means that the minimum time step is the overall run time TSTOP divided by 1e12 The dynamic range is large but finite It is possible to exceed this dynamic range in some circuits Consider for example a timer circuit which charges up a 100uF capacitor to prov
287. nte Carlo Worst Case The waveform analyzer calculates and displays the results of PSpice simulations for swept analyses The waveform analyzer also generates supplementary analysis information in the form of lists and tables and saves this in the simulation output file Setting up analyses To set up one or more analyses 1 From the PSpice menu choose New Simulation Profile 2 Enter the name of the profile and click OK 3 Click the Analysis tab if it is not already the active tab in the dialog box Simulation Settings New ix General Analysis Include Files Libraries Stimulus Options Data Collection Probe Window 1000ns seconds TSTOP Print values in the output file every fi Ons seconds r Iransient options Maximum step size seconds I Skip the initial transient bias point calculation SKIPBP Dutput File Options Analysis type Time Domain Transient Suncare Options General Settings Monte Carlo Worst Case OParametric Sweep Temperature Sweep Save Bias Point CLoad Bias Point 4 Enter the necessary parameter values and select the appropriate check boxes to complete the analysis specifications Setting up analyses See Part four Viewing results for information about using waveform analysis in PSpice specific intormation tor setting up each type of analysis is discussed in the following chapters See Output variables on page 7 199 for a descrip
288. ntegrator and differentiator The integrator and differentiator parts are described below INTEG IC initial condition of the integrator output GAIN gain value The INTEG part implements a simple integrator A current source capacitor implementation is used to provide support for setting the initial condition DIFFER GAIN gain value The DIFFER part implements a simple differentiator A voltage source capacitor implementation is used The DIFFER part provides one input and one output Table look up parts TABLE and FTABLE parts provide a lookup table that is used to correlate an input and an output based on a set of data points These parts are described below and on the following pages TABLE ROWn is an input output pair by default up to five triplets are allowed where n 1 2 3 4 or 5 The TABLE part allows the response to be defined by a table of one to five values Each row contains an input and a corresponding output value Linear interpolation is performed between entries For values outside the table s range the device s output is a constant with a value equal to the entry with the smallest or largest input This characteristic can be used to impose an upper and lower limit on the output The TABLE part provides one input and one output FTABLE ROWn either an input frequency magnitude phase triplet or an input frequency real part imaginary part triplet describing a complex value by d
289. nter the total number of points per decade in the Total Points box Under AC Sweep Type click Logarithmic select Octave and enter the total number of points per octave in the Total Points box 5 Inthe Start Frequency and End Frequency text boxes enter the starting and ending frequencies respectively for the sweep 6 Click OK to save the simulation profile AC sweep setup in example op If you look at the example circuit EXAMPLE OP provided with your OrCAD programs you ll find that its AC analysis is set up as shown in Figure 61 VOU ieee ok a q 202222 VEE REIS t p readme RCI Z RC2 example rdm ik n cloaD outi d Jour RS2 RSI p YN 0 4 k yee 4212222 tk st a4 n Fa q212222 O B R QO E Figure 60 Circuit diagram for EXAMPLE OPJ Frequency is swept from 100 kHz to 10 GHz by decades with 10 points per decade The V1 independent voltage source is the only input to an amplifier so it is the only AC stimulus to this circuit Magnitude equals 1 V and relative phase is left at zero degrees the default All other voltage sources have zero AC value AC sweep analysis Note The source V1 is a VSIN source that is normally used for setting up sine wave signals for a transient analysis It also has an AC property so that you can use it for an AC analysis To find out more about VSIN and other sour
290. o analysis is set to take 100 runs The analysis type is AC and the output variable is V OUT Monte Carlo analysis To set up the analysis 1 From PSpice s Trace menu choose Performance Analysis In the Save data from list box choose All Click OK Creating histograms Because the data file can become quite large when running a Monte Carlo analysis to view just the output of the filter you place a voltage probe at the output of the filter To collect data for the marked node only 1 3 From the PSpice menu choose New Simulation Profile or Edit Simulation Settings from the PSpice menu If this is a new simulation enter the name of the profile and click OK The Simulation Settings dialog box appears On the Data Collection tab choose the At Probes only option Click OK To run the simulation and load Probe with data 1 From Capture s PSpice menu choose Run to start the simulation When the simulation is complete PSpice automatically displays the selected waveform Because PSpice ran a Monte Carlo analysis it saved multiple runs or sections of data These are listed in the Available Sections dialog box From PSpice s Trace menu choose Performance Analysis Click the Select sections button In the Available Sections dialog box click All 303 Chapter 12 Monte Carlo and sensitivity worst case analyses 5 Click OK To display a histogram for the 1 dB bandwidth 1 From PSpice
291. o save the simulation profile 4 In Capture from the PSpice menu select Run to start the simulation 225 Chapter 8 DC analyses Overview of small signal DC transfer The small signal DC transfer analysis calculates the small signal transfer function by transforming the circuit around the bias point and treating it as a linear circuit The small signal gain input resistance and output resistance are calculated and reported For N and O devices in the analog interface subcircuits has a well defined linear equivalent To calculate the small signal gain input resistance and output resistance Simulation Settings Small Signal ix General Analysis Include Files Libraries Stimulus Options Data Collection Probe Window Analysis type m Output File Options Biss Point E T Include detailed bias point information for nonlinear controlled sources and semiconductors 0P Options Tones I Perform Sensitivity analysis SENS Temperature Sweep Output yaretlels _ Load Bias Point Save Bias Point M Calculate small signal DC gain TF From Input source name fia To Output variable Mo ut 1 In the Bias Point dialog box select Calculate small signal DC gain TF 2 Specify the value for either an output voltage or the current through a voltage source in the To Output variable box For example entering V a b as the output variable specifies that the output variable
292. oaaa aaa a 30 Voltage difference at V In 4 volts naaa aaa 31 Diode clipper circuit with a voltage stimulus 32 Stimulus Editor window 64d oe ee dK Re PO ES eH aS 34 Transient analysis simulation settings 0 2000 34 Sinusoidal input and clipped output waveforms 35 Clipper circuit with AC stimulus 3 sae ada P ee FAP Rae OH 37 AC sweep and noise analysis simulation settings 38 dB magnitude curves for gain at Mid and Out 40 Bode plot of clipper s frequency response ooo a 41 Clipper circuit with global parameter Rval ouaaa aaa 42 Parametric simulation settings oo dbe cea uaaa adds 44 Small signal response as R1 is varied from 1002 to10kQ 45 Small signal frequency response at 100 and 10 kQ input resistance 47 Performance analysis plots of bandwidth and gain vs Rval 50 Relationship of the Model Editor to Capture and PSpice 93 Process and data flow for the Model Editor 96 Model Editor workspace with data for a bipolar transistor 97 Design for a half wave rectifier aooaa 104 Model characteristics and parameter values for DbreakX 105 Assorted device characteristic curves foradiode 108 Forward Current device curve at two temperatures 109 Figures Figure 34 Figure 35 Figure 36 Figure 37 Figure 38 Figure 39 Figure 40 Figure 41 F
293. odel parameter values reports To produce a list of the model parameters actually used for each run 1 Inthe Simulation Settings dialog box click the Analysis tab From the Analysis type list select an analysis type Under Options select Monte Carlo Worst Case Click the More Settings button ua A WwW N Select List model parameter values 6 Click OK to close the Simulation Settings dialog box This list is written to the simulation output file at the beginning of the run and contains the parameters for each device as opposed to the parameters for each MODEL statement This is because devices can have different parameter values when using a model statement containing a DEV tolerance Note that for midsize and large circuits the List option can produce a large output file 285 Chapter 12 Monte Carlo and sensitivity worst case analyses In excess of about 10 runs the waveform display can look more like a band than a set of individual waveforms This can be useful for seeing the typical spread for a particular output variable As the number of runs increases the spread more closely approximates the actual worst case limits for the circuit 286 Waveform reports For Monte Carlo analyses there are five variations of the output that you can specify in the Save data from text box on the Monte Carlo dialog box Options lt none gt No output is generated All Forces all output to be generated including nominal
294. oes not turn off near 0 power supplies A better way is described in the application note Modeling Constant Power Loads The squelching code is sufficient for turning off all expressions except those having denominators In general though it is good practice to constrain expressions having the LIMIT function to keep results within physically realistic bounds 387 Chapter B Convergence and time step too small errors 388 Example A first approximation to an opamp that has an open loop gain of 100 000 is VOPAMP 3 5 VALUE V Cint in 1le5 This has the undesirable property that there is no limit on the output A better expression is VOPAMP 3 5 VALUE LIMIT VCint in 1le5 15v 15v where the output is limited to 15 volts Transient analysis The transient analysis starts using a known solution the bias point It then uses the most recent solution as the first guess for each new time point If necessary the time step is cut back to keep the new time point close enough that the first guess allows the Newton Raphson repeating series to converge The time step is also adjusted to keep the integration of charges and fluxes accurate enough In theory the same considerations which were noted for the bias point calculation apply to the transient analysis However in practice they show up during the bias point calculation first and hence are corrected before a transient analysis is run The transie
295. om their DC values To report the small signal parameters for the transient bias point use the Transient command and enable Detailed Bias Point Otherwise if you simply want the result of the transient run itself you should only enable the Transient command In the simulation output file EXAMPLE OUT the bias point report for the transient bias point is labeled INITIAL TRANSIENT SOLUTION Internal time steps in transient analyses During analog analysis PSpice maintains an internal time step which is continuously adjusted to maintain accuracy while not performing unnecessary steps During periods of inactivity the internal time step is increased During active regions it is decreased The maximum internal step size can be controlled by specifying it in the Step Ceiling text box in the Transient dialog box PSpice will never exceed either the step ceiling value or two percent of the total transient run time whichever is less The internal time steps used may not correspond to the time steps at which information has been requested to be reported The values at the print time steps are obtained by second order polynomial interpolation from values at the internal steps Intemal time steps in transient analyses 265 Chapter 10 Transient analysis This technique is described in V Bello Computer Program Adds SPICE to Switching Regulator Analysis Electronic Design March 5 1981 266 Switching circuits in transient
296. ominal analyses are finished PSpice performs the additional specified analysis runs in this example DC sweep Subsequent runs use the same analysis specification as the nominal run with one major exception instead of using the nominal parameter values the tolerances are applied to set new parameter values and thus new part values There is a trade off in choosing the number of Monte Carlo runs More runs provide better statistics but they require more time The amount of time scales directly with the number of runs 20 transient analyses take 20 times as long as one transient analysis During Monte Carlo runs the PSpice status display includes the current run number and the total number of runs left Monte Carlo analysis Reading the summary report The summary report generated in this example see Figure 76 specifies that the waveform generated from V OUT1 OUT2 should be the subject of the collating function YMAX In each of the last four runs the new V OUT1 OUT2 waveform is compared to the nominal V OUT1 OUT2 waveform for the first run calculating the maximum deviation in the Y direction YMAX collating function The deviations are printed in order of size along with their run number HERE SORTED DEVIATIONS OF UCOUT1 0OUT2 TEMPERATURE 35 000 DEG C MONTE CARLO SUMMARY HHA JE E JE KH FE JE FE JE E KE KR KKK JE JE JE JE E PE JE DE JE JE JE JE JE JE JE JE JEJE JE PEJE JE JE JE JE DE FE JE JE JE JE JE ME IE JE JE KE K
297. on display name 4 Click OK Basic output variable form This form is representative of those used for specifying some PSpice analyses lt output gt A C suffix lt name gt name Table 4 This placeholder Means this lt output gt type of output quantity V for voltage or I for current A C suffix quantity to be reported for an AC analysis For a list of valid AC suffixes see Table 8 on page 13 361 lt name gt name specifies either the net or net net pair for which the voltage is to be reported or the device for which a current is reported where e net specifies either the net or pin id lt fully qualified device name gt lt pin name gt e device name specifies the fully Afully qualified device name consists of the qualified device name for a list of full hierarchical path followed by the device types see Table 9 on device s reference designator For page 13 361 and Table 10 on information about syntax see the voltage page 13 362 output variable naming rules 357 Chapter 13 Analyzing waveforms 358 Output variable form for device terminals This form can only be specified for trace expressions The primary difference between this and the basic form is that the terminal symbol appears before the net or device name specification whereas the basic form treats this as the pin name within the pin id lt output gt terminal A C suffix lt name gt name Table 5
298. on the GMULT part Edit the GDIV template to divide the two input values rather than multiply them Lookup tables ETABLE and GTABLE The ETABLE and GTABLE parts use a transfer function described by a table These device models are well suited for use with measured data The ETABLE and GTABLE parts are defined in part by the following properties default values are shown ETABLE TABLE 15 15 15 15 EXPR V IN IN GTABLE 179 Chapter 6 Analog behavioral modeling 180 TABLE 15 15 15 15 EXPR V IN IN First EXPR is evaluated and that value is used to look up an entry in the table EXPR is a function of the input current or voltage and follows the same rules as for VALUE expressions The table consists of pairs of values the first of which is an input and the second of which is the corresponding output Linear interpolation is performed between entries For values of EXPR outside the table s range the device s output is a constant with a value equal to the entry with the smallest or largest input This characteristic can be used to impose an upper and lower limit on the output An example of a table declaration using the TABLE property would be the following TABLE 0 0 02 2 690E 03 04 4 102E 03 06 4 621E 03 08 4 460E 03 10 3 860E 03 12 3 079E 03 14 327E 03 16 1 726E 03 18 1 308E 03 20 1 042E 03 22 734E 04 24 7 544E 04 26 6 56
299. oned on the first trough dip of the V 1 waveform Cursor 2 is positioned on the second peak of the same waveform In the Probe Cursor window cursor 1 and cursor 2 coordinates are displayed A1 and A2 respectively with their difference shown in the bottom line dif The logic state of the Out signal is also displayed to the right of the cursor coordinates User interface features for waveform analysis The mouse buttons are also used to associate each cursor with a different trace by clicking appropriately on either the analog trace symbol in the legend These are outlined in the pattern corresponding to the associated cursor s crosshair pattern Given the example in Figure 97 right clicking the V 2 symbol will associate cursor 2 with the V 2 waveform The analog legend now appears as shown below cursor 1 cursor 2 The Probe Cursor window also updates the A2 coordinates to reflect the X and Y values corresponding to the V 2 waveform 355 Chapter 13 Analyzing waveforms Simulation Message Summary R ix Time Message Type Device 47 000ns PERSISTENT On OUTPUT Port p4 52 000ns PERSISTENT On OUTPUT Port p12 52 000ns PERSISTENT On OUTPUT Port pS 1 000ns PERSISTENT On OUTPUT Port p15 73 000ns WIDTH MIN LOW x0 uval 80 000ns PERSISTENT On OUTPUT Port pt 80 000ns PERSISTENT On OUTPUT Port p16 Sort i Tj Minimum Severity Level Section WARNING z Time C Type Close a EE Boe
300. or models Contents Contents Setting up the analyses w ak one ees eS ew ee be Gs 299 Running the analysis and viewing the results 300 Monte Carlo Histograms 42 aeisis242 24 248eh0n 40404 301 Chebyshev filter example sc 4 eae eee eo Paden ee ee ee 301 Creating models for Monte Carlo analysis 302 Setting up the analysis 66a 6 ese ee Swed see Es 302 Creating histograms s lt ss c ss 4h 24 te td eee eee ee 303 Worst case analysis 24664 ed eos Ra ee OSH EK SE ERT EEO 306 Overview of worst case analysis 2 020202 eae 306 MPU sae hs doe ee eS Pek oS Raw oe ew bars oe OS OE 307 Procedu wae a a sas es a eo Be ams Ge ee ees 307 OUPUTS 4 6 PR wR Ee deed bags tet u tes canes 308 Caution An important condition for correct worst case analysis 6 6 ee ee ee 308 Worst case analysis example 6 ce ee a 309 Tips and other useful information 040 313 VARY BOTH VARY DEV and VARY LOT 313 Gaussian distributions 0 0000 eee 314 YMAX collating function 2 2 ee ee 314 REE TOR zaa Aha bene ee ee ee a eg tech es be ee 314 Sensitivity analysis 64 444 044 456 644 2s a 314 Manual optimization 24 45 02 66 68a hoe kag eee ed 314 Monte Carlo analysis 8 ci amp 6 ee OR ERR ee HRS ees 315 Partfour Viewing results Chapter 13 Analyzing waveforms 319 Chapter overview os soot ee soa pare Re ee Re ee a a a 319 Overview of waveform analysis
301. ording to Figure 2 18 To connect the parts 1 From the Place menu choose Wire to begin wiring parts The pointer changes to a crosshair Click the connection point the very end of the pin on the off page connector at the input of the circuit Click the nearest connection point of the input resistor R1 Connect the other end of R1 to the output capacitor Connect the diodes to each other and to the wire between them a Click the connection point of the cathode for the lower diode Move the cursor straight up and click the wire between the diodes The wire ends and the junction of the wire segments becomes visible Click again on the junction to continue wiring d Click the end of the upper diode s anode pin Continue connecting parts until the circuit is wired as shown in Figure 2 on page 2 16 To assign names labels to the nets 1 From the Place menu choose Net Alias to display the Place Net Alias dialog box In the Name text box type Mid Click OK Place the net alias on any segment of the wire that connects R1 R2 R3 the diodes and the capacitor The lower left corner of the net alias must touch the wire Right click and choose End Mode to quit the Net Alias function Example circuit creation eos To stop wiring right click and choose End Wire The pointer changes to the default arrow Clicking on any valid connection point ends a wire A valid connection point is shown
302. out grid spacing and pin placement refer to the OrCA D The part edit id ins that t placed at part editor considers pins that are not placed a Capture User Gilde integer multiples of the grid spacing from the origin as off grid and a warning appears when you try to save the part Here are two guidelines e Make sure Pointer Snap to Grid is enabled when editing part pins and editing schematic pages so you can easily make connections e Make sure the Part and Symbol Grid spacing matches the Schematic Page Grid spacing 137 Chapter 5 Creating parts for models For more information on model editing in general see Chapter 4 Creating and editing models For specific information on changing model references see Changing the model reference to_an existing model definition on page 4 117 You do not need to enter an Implementation Path because PSpice searches for the model in the list of model libraries you configure for this project 138 Attaching models to parts If you create parts and want to simulate them you need to attach model implementations to them If you created your parts using any of the methods discussed in this chapter then your part will have a model implementation already attached to it MODEL The Implementation property defines the name of the model that PSpice must use for simulation When attaching this implementation this rule applies e The Implementation name should match the name of th
303. ox Enter the noise analysis parameters as follows Noise analysis 243 Chapter9 AC analyses Table 8 In this text box Type this To find out more about valid syntax see Output Voltage Output variables on page 7 199 I V Source Example U1 V2 Note In the Probe window you can view Interval the device noise contributions at every frequency specified in the AC sweep The Interval parameter has no effect on what PSpice writes to the Probe data file A voltage output variable of the form V node node where you want the total output noise calculated The name of an independent current or voltage source where you want the equivalent input noise calculated Note f the source is in a lower level of a hierarchical schematic separate the names of the hierarchical devices with periods An integer n designating that at every n frequency you want to see a table printed in the PSpice output file out showing the individual contributions of all of the circuit s noise generators to the total noise 7 Click OK to save the simulation profile 244 Analyzing Noise in the Probe window You can use these output variable formats to view traces for device noise contributions and total input or output noise at every frequency in the analysis Noise analysis For a break down of noise output variables by supported device type see Table 6 on page 13 358 To view this Us
304. part 76 J JFET 95 203 362 363 L Laplace transform parts ABM 154 164 174 181 187 188 libraries configuring 120 footprint 13 model 88 package 13 part OLB 13 searching for models 121 see also model libraries Library List using the 63 limiters ABM 153 156 M magnetic core nonlinear 95 magnitude 361 markers 334 displaying traces 28 398 for limiting waveform data file size 334 for waveform display 331 math function parts ABM 154 167 mathematical expressions ABM 174 mixed analog digital circuits waveform display 344 364 Model Editor about 10 110 analyzing model parameter effects 97 changing MODEL definitions 110 SUBCKT definitions 111 model names 111 creating parts for models 100 131 custom 133 example 114 fitting models 97 starting stand alone 99 startng from the schematic page editor 101 supported device types 95 testing and verifying models 96 tutorial 104 using data sheet information 96 viewing performance curves 98 ways to use 94 model editor running from the schematic page editor 111 model libraries 11 88 adding to the configuration 122 analog list of 80 and duplicate model names 122 configuration 89 configured as include files 121 configuring 13 81 120 directory search path 125 global vs design 89 123 how PSpice searches them 121 nested 90 OrCAD provided 90 preparing for part creation 130 search order 121
305. pe each file name in the File Name text box separated by a space e Use the combination keystrokes and mouse clicks in the list box as follows Ctrl click to select file names one at a time and hift click to select groups of files Method 2 1 From the Start menu point to the OrCAD program group then choose PSpice Update the command line in the following way e Include a list of circuit file names separated by spaces Circuit file names can be fully qualified or can contain the wild card characters and The PSpice simulation window The PSpice Simulation Window is an MDI Multiple Document Interface application This implies that you can open and display multiple files at the same time in this Starting a simulation window For instance you can have a waveform file DAT a circuit file CIR and a simulation output file OUT open and displayed in different child windows within this one window The PSpice Simulation Window consists of three sections the main window section where the open files are displayed the output window section where output information such as informational warning and error messages from the simulator are shown and the simulation status window section where detailed status information about the simulation are shown These three sections are shown in Figure 56 The windows in these sections may be resized moved and reordered as needed The simulation window also includ
306. pe of a file that is whether the file applies to one design only local or to any design global e Change the search order Files needed for simulation Note Not all stimulus definitions require a stimulus file In some cases like DCand AC sources you must use a schematic symbol and set its attributes See What is the Stimulus Editor on page 1 9 for a description Example An include file that contains definitions using the PSpice FUNC command for functions that you want to use in numeric expressions elsewhere in your design More on libraries Configuration for model libraries is similar to that for other libraries that Capture uses including part libraries To find out more refer to your Capture user s guide 13 Chapter 1 Things you need to know For a description of how to display simulation results see Part four Viewing results For a description of the waveform analyzer program see What is waveform analysis on page 1 8 There are two ways to add waveforms to the display e From within PSpice by specifying trace expressions e From within Capture by cross probing Example Each instance of a VPRINT1 symbol placed in your schematic causes PSpice to generate a table of voltage values for the connecting net and to write the table to the PSpice output file 14 Files that PSpice generates After reading the circuit file netlist file model libraries and any other required inputs
307. pecial characteristics e a link toa simulation model For information on adding simulation models to a model library see Chapter tlist translation x Se 4 Creating and editing models e modeled pins Ways to create parts for models If you want to Then do this To find out more see this Create parts for a setof Use the Model Editor to Basing new parts on a custom set vendor or user defined create parts from a model of parts on page 5 133 models saved in a model library library Change the graphic standard for an existing model library Automatically create Use the Model Editor and Using the Model Editor to create one part each time you enable automatic creation parts on page 5 131 extract a new model of parts Using the Model Editor to edit models on page 4 93 Basing new parts on a custom set of parts on page 5 133 For a list of device types that the Model Editor supports see Model Editor supported device types on page 4 95 129 Chapter 5 Creating parts for models Model libraries typically have a LIB extension However you can use a different file extension as long as the file format conforms to the standard model library file format For information on managing model libraries including the search order PSpice uses see Configuring model libraries on page 4 120 130 Preparing your models for part creation If you already have model definitions and want to
308. pes not generated by the circuit simulation are dimmed For more information about trace expressions see Analog trace expressions on page 13 364 356 Message tracking from the waveform Trace segments with associated diagnostics are displayed in the foreground color specified in your PSPICE INI file This color is different from those used for standard state transitions To display explanatory message text 1 Double click within the tagged region of a trace Trace expressions Traces are referred to by output variable names Output variables are similar to the PSpice output variables specified in the Simulation Settings dialog box for noise Monte Carlo worst case transfer function and Fourier analyses However there are additional alias forms that are valid for trace expressions Both forms are discussed here To add traces using output variables 1 From the Trace menu choose Add Trace to display the Add Traces dialog box 2 Construct a trace expression using any combination of these controls e Inthe Simulation Output Variables frame click output variables e Inthe Functions or Macros frame select operators functions constants or macros e Inthe Trace Expression text box type in or edit output variables operators functions constants or macros 3 If you want to change the name of the trace expression as it displays in the Probe window use the following syntax Trace expressions trace expressi
309. play of the cursors Delete the trace 47 Chapter 2 Simulation examples Finding out more about parametric analysis Table 2 3 To find out more about this See this parametric analysis Parametric analysis on age 11 272 using global parameters Using global parameters and expressions for values on page 3 67 48 Performance analysis Performance analysis Performance analysis is an advanced feature in PSpice that you can use to compare the characteristics of a family of waveforms Performance analysis uses the principle of search commands introduced earlier in this chapter to define functions that detect points on each curve in the family After you define these functions you can apply them to a family of waveforms and produce traces that are a function of the variable that changed within the family This example shows how to use performance analysis to view the dependence of circuit characteristics on a swept parameter In this case the small signal bandwidth and gain of the clipper circuit are plotted against the swept input resistance value To plot bandwidth vs Rval using the performance analysis wizard 1 In Capture open CLIPPER OPJ 2 From PSpice s Trace menu choose Performance Analysis The Performance Analysis dialog box appears with information about the currently loaded data and performance analysis in general 3 Click the Wizard button At each step the wizard provides i Clich
310. property in the template Template X REFDES a b Z PARAMS G G G G G 1000 Equivalent template using the if else form X REFDES a b Z PARAMS G G G G 1000 Sample translation X_U33 101 102 Z PARAMS G 1024 where REFDES equals U33 G is set to 1024 and the subcircuit connects to nets 101 and 102 Sample translation X_U33 101 102 Z PARAMS G 1000 where the settings of the previous translation apply except that G is undefined Pin callout in subcircuit templates The number and sequence of pins named in a template for a subcircuit must agree with the definition of the subcircuit itself that is the node names listed in the SUBCKT statement which heads the definition of a subcircuit These are the pinouts of the subcircuit Example Consider the following first line of a hypothetical subcircuit definition SUBCKT SAMPLE 10 3 27 2 The four numbers following the name SAMPLE 10 3 27 and 2 are the node names for this subcircuit s pinouts Defining part properties needed for simulation Now suppose that the part definition shows four pins IN OUT IN OU T The number of pins on the part equals the number of nodes in the subcircuit definition If the correspondence between pin names and nodes is as follows Table 6 This node name Corresponds to this pin name 10 IN 3 IN 27 OUT 2 OUT then the template looks like this X QREF
311. put and one output Figure 35 shows an example of a LOPASS filter device The filter provides a pass band cutoff of 800 Hz and a stop Control system parts OrCAD Capture recommends looking at one or more of the references cited in Frequency domain device models on page 6 181 as well as some of the following references on analog filter design 1 Ghavsi M S amp Laker K R Modern Filter Design Prentice Hall 1981 Gregorian R amp Temes G Analog MOS Integrated Circuits Wiley Interscience 1986 Johnson David E Introduction to Filter Theory Prentice Hall 1976 Lindquist Claude S Active Network Design with Signal Filtering Applications Steward amp Sons 1977 Stephenson F W ed RC Active Filter Design Handbook Wiley 1985 Van Valkenburg M E Analog Filter Design Holt Rinehart amp Winston 1982 Williams A B Electronic Filter Design Handbook McGraw Hill 1981 1 2kHz 2 les Booz 0 1dE 50dB Figure 35 LOPASS filter example 157 Chapter 6 Analog behavioral modeling band cutoff of 1 2 kHz The pass band ripple is 0 1 dB and the minimum stop band attenuation is 50 dB Assuming that the input to the filter is the voltage at net 10 and output is a voltage between nets 5 and 0 this will produce a PSpice netlist declaration like this ELOWPASS 5 0 CHEBYSHEV V 10 LP 800 1 2K 1dB 50dB HIPASS FS stop band frequency FP pass band frequency RIPPLE pass
312. r design that you want to set up as an equivalent part with behavior described as a subcircuit netlist SUBCKT syntax Note Ifyou created a subcircuit definition using the Create Subcircuit command and want to alter it use the Model Editor to edit the definition or modify the original hierarchical schematic and run Create Subcircuit again to replace the definition Tools to create and edit models For a description of models supported by the Model Editor see Model Editor supported device types on page 4 95 Note The Create Subcircuit command does not help you create a hierarchical design You need to create this yourself before using the Create Subcircuit command For information on hierarchical designs and how to create them refer to the OrCA D Capture User s Guide 91 Chapter 4 Creating and editing models Ways to create and edit models This section is a roadmap to other information in this chapter Find the task that you want to complete then go to the referenced sections for more information If you want to Then do this To find out more see this Create or edit the model for an existing part and have it affect all designs that use that part Create a model from scratch and automatically create a part for it to use in any design Create a model from scratch without a part and have the model definition available to any design View model characteristics for a part
313. r to be investigated A Monte Carlo analysis performs a Monte Carlo statistical analysis of the circuit A worst case analysis performs a sensitivity and worst case analysis of the circuit Sensitivity worst case analyses are different from Monte Carlo analyses in that they compute the parameters using the sensitivity data rather than using random numbers You can run either a Monte Carlo or a worst case analysis but you cannot run both at the same time Multiple runs of the selected analysis are done while parameters are varied You can select only one analysis type AC DC or transient per run The selected analysis is repeated in subsequent passes of the analysis Statistical analyses Output control for statistical analyses Monte Carlo and sensitivity worst case analyses generate the following types of reports e Model parameter values used for each run that is the values with tolerances applied e Waveforms from each run as a function of specifying data collection or by specifying output variables in the analysis set up e Summary of all the runs using a collating function Output is saved to the data file for use by the waveform For information about performance analyzer For Monte Carlo analyses you can use the analysis see RLC filter example on performance analysis feature to produce histograms of page 11 274 derived data For information about histograms see Creating histograms on page 12 303 M
314. rchical parts if used are properly The OrCA D Capture User s Guide defined Ports that connect to the same nethave the The OrCAD Capture User s Guide same name Checklist for simulation setup Things to check in your system configuration Table 6 Make sure that To find out more see this Vv Vv Path to the PSpice programs is correct Directory containing your design has write Your operating system manual permission Your system has sufficient free memory Your operating system manual and disk space 59 Chapter 3 Preparing a design for simulation The OrCAD part libraries also include special parts that you can use for simulation only These include 60 stimulus parts to generate input signals to the circuit see Defining stimuli on page 3 75 ground parts required by all analog circuits which need reference to ground simulation control parts to do things like set bias values see Appendix A Setting initial state output control parts to do things like generate tables and line printer plots to the PSpice output file see Chapter 14 Other output options Using parts that you can simulate The OrCAD part libraries supply numerous parts designed for simulation These include e vendor supplied parts e passive parts e breakout parts behavioral parts At minimum a part that you can simulate has these properties e A simulation model to describe the part s el
315. rcuit design requirements 272 Collating functions used in statistical analyses 287 294 295 300 Default waveform viewing colors 2 0 0 0000000048 325 326 328 330 332 333 346 Mouse actions for cursor control o oo e a 351 Key combinations for cursor control aaoo 351 357 358 Output variable formats aoaaa bee eas ee ee BES oO 358 Table 7 Table 8 Table 9 Table 10 Table 11 Table 12 Table 13 Table 14 Table 15 Examples of output variable formats Output variable AC suffixes Device names for two terminal device types Terminal IDs by three amp four terminal device type Noise types by device type Analog arithmetic functions for trace expressions Output units for trace expressions Tables 360 361 361 362 363 364 366 369 370 xxi Tables xxii Before you begin Welcome to OrCAD OrCAD offers a total solution for your core design tasks schematic and VHDL based design entry FPGA and CPLD design synthesis digital analog and mixed signal simulation and printed circuit board layout What s more OrCAD s products are a suite of applications built around an engineer s design flow not just a collection of independently developed point tools PSpice is just one element in OrCAD s total solution design flow With OrCAD s products you ll spend less time dealing with the details of tool integration d
316. ressions Trace expression aliases Analog trace expressions vary from the output variables used in simulation analyses because analog net values can be specified by lt output variable gt display name as opposed to the lt output variable gt format used in analyses With this format the analog trace expression can be displayed in the analog legend with an optional alias Arithmetic functions Arithmetic expressions of analog output variables use the same operators as those used in simulation analyses by means of part property definitions in Capture You can also include intrinsic functions in expressions The intrinsic functions available for trace expressions are similar to those available for PSpice math expressions but with some differences as shown in Table 12 A complete list of PSpice arithmetic functions can be found in Table 10 on page 3 71 Table12 Analog arithmetic functions for trace expressions Probe Description Available in function PSpice ABS x Ixl YES SGN x 1 if x gt 0 0 if x 0 1 if x lt 0 YES SQRT x xl 2 YES EXP x ex YES LOG x In x YES LOG10 x log x YES M x magnitude of x YES P x phase of x degrees YES R x real part of x YES IMG x imaginary part of x YES Table 12 Analog arithmetic functions for trace expressions Probe Desaintion Available in function P PSpice G x group delay of x seconds NO PWR x y Ixly YES SIN x sin x YES COS x COS x Y
317. ristics HI 1E3 LO 0 This part instance LIMIT1 converts all negative values of V 12 v to 0 and leaves all positive values up to 1 kV alone For a more realistic model we could have used TABLE to correctly model how the tube turns off at 0 or at small negative grid voltages We also need to make sure that the current becomes zero when the anode alone goes negative To do this we can use a DIFF device immediately below the ABM3 device to monitor the difference between V anode and V cathode and output the difference to the TABLE part The table translates all values at or below zero to zero and all values greater than or equal to 30 to one All values between 0 and 30 are linearly interpolated The properties for the TABLE part are as follows ROWL 00 ROW2 301 The TABLE part is a simple one and ensures that only a zero value is output to the multiplier for negative anode voltages The output from the TABLE part and the LIMIT part are combined at the MULT multiplier part The output of the MULT part is the product of the two input voltages This value is then raised to the 3 2 or 1 5 power using the PWR part The exponential property of the PWR part is defined as follows EXP 1 5 The last major component is an ABM expression component to take an input voltage and convert it into a current The relevant ABM1 I part property looks like this EXP1 200E 6 V IN A final step in the model is to add dev
318. rlo Worst Case eee lhe Parametric Sweep Temperature Paremata nane E Temperature Sweep OSave Bias Point 7 Sweep type Load Bias Point ali Start value fos Ae End value fis C Logarithmic Decade Increment fo C Value list 4 Click OK to save the simulation profile 5 From the PSpice menu choose Run to start the simulation Note Do not specify a DC sweep and a parametric analysis for the same variable Overview of parametric analysis Parametric analysis performs multiple iterations of a specified standard analysis while varying a global parameter model parameter component value or operational temperature The effect is the same as running the circuit several times once for each value of the swept variable See Parametric analysis on page 2 42 for a description of how to set up a parametric analysis Parametric analysis 273 Chapter 11 Parametric and temperature analysis 274 RLC filter example This example shows how to perform a parametric sweep and analyze the results with performance analysis Use performance analysis to derive values from a series of simulator runs and plot these values versus a parameter that varies between the simulator runs For this example the derived values are the overshoot and the rise time versus the damping resistance of the filter Entering the design The schematic representation for the RLC filter RLCFILT OPJ is
319. rt generation o oo a 133 139 141 142 145 Control system parts aoaaa a 153 Tables Table 1 Table 2 Table 1 Table 1 Table 2 Table 3 Table 4 Table 5 Table 6 Table 7 Table 8 Table 9 Table 10 Table 11 Table 12 Table 1 Table 2 Table 3 Table 4 Table 5 Table 6 Table 7 Table 8 Table 9 Table 10 Table 1 Table 1 Table 1 Table 2 Table 3 Table 1 Table 2 Table 3 Table 4 Table 5 Table 6 Table 1 Table 2 Table 3 Table 4 Table 5 Table 6 XX ABM math function parts 04s 6440s ee ev teen w en ae een 167 ABM expression parts 2 lt 4445 aed es ieds kha en ene hes 168 PSpice equivalent parts 64 24 54 54 44 245 eS Kee Howe ee 174 Basic controlled sources in ANALOG OLB 192 Classes of PSpice analyses et ea tae PAE SSR REG ERE HERS 196 Execution order for standard analyses 20000 198 PSpice output variable formats 1 244452 4 bab oe ee ee we 201 Element definitions for 2 terminal devices 008 4 202 Element definitions for 3 or 4 terminal devices 0 203 Element definitions for transmission line devices 204 Element definitions for AC analysis specific elements 205 DC sweep circuit design requirements 0 214 218 218 219 Curve family example setup 4442854 24444242444 R044 8 221 233 233 234 234 236 242 244 246 Stimulus symbols for time based input signals 252 Parametric analysis ci
320. rt multiplies the input by the constant specified by the GAIN property then outputs the result This part provides one input and one output DIFF The DIFF part evaluates the voltage difference between two inputs then outputs the result This part provides two inputs and one output 155 Chapter 6 Analog behavioral modeling 156 Limiters The Limiters can be used to restrict an output to values between a set of specified ranges These parts are described below LIMIT HI upper limit value LO lower limit value The LIMIT part constrains the output voltage to a value between an upper limit set with the HI property and a lower limit set with the LO property This part takes one input and provides one output GLIMIT HI upper limit value LO lower limit value GAIN constant gain value The GLIMIT part functions as a one line opamp The gain is applied to the input voltage then the output is constrained to the limits set by the LO and HI properties This part takes one input and provides one output SOFTLIM IT HI upper limit value LO lower limit value GAIN constant gain value A B V internal variables used to define the TANH limiting function The SOFTLIMIT part provides a limiting function much like the LIMIT device except that it uses a continuous curve limiting function rather than a discontinuous limiting function This part takes one input and provides One output Chebyshev filters The Chebyshev filters al
321. rtical bars that make up the histogram mean sigma minimum maximum 10th percentile median and 90th percentile You can also show the distribution of the center frequency of the filter To display the center frequency From the Trace menu choose Goal Functions Choose CenterFreq Click Eval Enter VDB OUT in the Name of trace to search text box a Ww N FF 5 Enter 1 in the db level down for measurement text box 6 Click OK then click Close to view the histogram The new histogram replaces the previous histogram To display both histograms at once choose Add Plot to Window on the Plot menu before choosing Add from the Trace menu The histogram of the center frequency is as shown in Figure 83 Monte Carlo analysis If needed you can turn off the statistical data display as follows 1 From the Tools menu choose Options 2 Clear the Display Statistics check box 3 Click Save and then OK Ten percent of the goal function values is less than or equal to the 10th percentile number and 90 of the goal function values is greater than or equal to that number If there is more than one goal function value that satisfies this criteria then the 10th percentile is the midpoint of the interval between the goal function values that satisfy the criteria Similarly the median and 90th percentile numbers represent goal function values such that 50 and 90 respectively of the goal function values are less than or eq
322. run First Generates output only during the first n runs Every Generates output for every nth run Runs list Does specified analysis and generates outputs only for the listed runs up to 25 values can be specified in the list The indicates that you can set the number of runs in the runs text box Values for the output variables specified in the selected analyses are saved to the simulation output file and data file Note Even a modest number of runs can produce large output files Statistical analyses Collating functions You can further compress the results of Monte Carlo and worst case analyses If you use the collating function a single number represents each run Click the Output File Options button and select a function from the Find list A table of deviations per run is reported in the simulation output file Collating functions are listed in Table 1 Tablel Collating functions used in statistical analyses Function Description YMAX Find the greatest difference in each waveform from the nominal MAX Find the maximum value of each waveform MIN Find the minimum value of each waveform RISE_EDGE Find the first occurrence of the waveform crossing above a specified threshold value FALL EDGE Find the first occurrence of the waveform crossing below a specified threshold value 287 Chapter 12 Monte Carlo and sensitivity worst case analyses Refer to Temperature Effects on Monte Carlo Analysi
323. run an AC or transient analysis in addition to a DC analysis see the following e Using time based stimulus parts with AC and DC properties on page 3 77 for other source symbols that you can use e Using VSRC or ISRC parts on page 3 78 to find out how to specify the TRAN attribute for a time based input signal when using VSRC or ISRC symbols 218 Setting up a DC stimulus To run a DC sweep or small signal DC transfer analysis you need to place and connect one or more independent sources and then set the DC voltage or current level for each source To set up a DC stimulus 1 Place and connect one of these symbols in your schematic Table 10 For voltage input Use this When you are running VDC A DC Sweep and or Bias Point transfer function analysis only VSRC Multiple analysis types including DC Sweep and or Bias Point transfer function Table 11 For current input Use this When you are running IDC A DC Sweep and or Bias Point transfer function analysis only ISRC Multiple analysis types including DC Sweep and or Bias Point transfer function 2 Double click the symbol instance to display the Parts spreadsheet appears 3 Click in the cell under the DC column to edit its value 4 Define the DC specification as follows Table 12 Set this attribute To this value DC DC _level where DC_level is in volts or amps units are optional
324. s to which the output is sensitive are at one of their extreme values If this is not true the Monte Carlo analysis may find a point at which the results are worse To try this replace WC in the circuit file with MC lt runs gt where lt runs gt is the number of simulations you want to perform More runs provide higher confidence results The Monte Carlo summary in the output file lists the runs in decreasing order of collating function value Next add the following option to the MC statement and simulate again OUTPUT LIST RUNS lt worst_run gt This performs only two simulations the nominal and the worst Monte Carlo run The parameter values used during the worst run are written to the output file and the results of both simulations are saved Using Monte Carlo analysis with YMAX is a good way to obtain a conservative guess at the maximum possible deviation from nominal since worst case analysis usually cannot provide this information Worst case analysis Parametric sweeps STEP like the one performed in the circuit file shown in Figure 85 can be used to augment this procedure To save disk space do not specify any OUTPUT options 315 Chapter 12 Monte Carlo and sensitivity worst case analyses 316 Part four Viewing results Part four describes the ways to view simulation results Chapter 13 Analyzing waveforms describes how to perform graphical waveform analysis of simulation results
325. s Each Probe window is identified by the unique identifier in parentheses in its title bar The arrangement of Probe windows on the page can be customized using the Page Setup dialog box You can print in either portrait vertical or landscape horizontal orientation You can also use Print Preview to view all of the Probe windows as they will appear when printed 323 Chapter 13 Analyzing waveforms Setting up waveform analysis Setting up colors You can configure Probe display and print colors in e The configuration file PSPICE INI For information on how to use the available e The Probe Options dialog box colors and color order in a Probe window see Configuring trace color ee s i schieinesian Hace 19 396 ae display and print colors in the PSPICE INI In the PSPICE INI file you can control the following print and display color settings for Probe windows e The colors used to display tra Colors for all items are specified as eres lt item name gt lt color gt The item names e The colors used for the Probe window foreground and and what they represent are listed in background Table 1 e The order colors are used to display traces Here are the color names you can specify The number of colors used to display traces brightcyan brightblue a dien biped To edit display and print colors in the PSPICE INI file brightmagenta Note After editing PSPICE INI you must restart PSpice before your brightwhite changes w
326. s dialog box click the Analysis tab 2 Under Options select Save Bias Point 3 Complete the Save Bias Point dialog box 4 Click OK Save and load bias point Load bias point Load bias point is a simulation control function that allows you to set the bias point as an initial condition A common reason for giving PSpice initial conditions is to select one out of two or more stable operating points set or reset for a flip flop for example To use load bias point 1 Runa simulation using the Save Bias Point option in See Setting up analyses on the Simulation Settings dialog box page 7 197 for a description of the 2 Before running another simulation click the Analysis a tab in the Simulation Settings dialog box 3 Under Options select Load Bias Point 4 Specify a bias point file to load Include the path if the file is not located in your working directory or use the Browse button to find the file 5 Click OK 375 Chapter A Setting initial state 376 Setpoints Pseudocomponents that specify initial conditions are called setpoints These apply to the analog portion of your circuit NODESET 3 4 NODESET 5 Ic Ic2 NODESETI NODESET2 Figure A 1 Setpoints The example in Figure A 1 includes the following IC1 a one pin symbol that allows you to set the initial condition on a net for both small signal and transient bias points IC2 a two pin symbol that allows you to set initial condition between two nets
327. s for matches PSpice also scans these referenced libraries Example Suppose you have two custom model libraries MYDIODES LIB and MYOPAMPS LIB that you want PSpice to search any time you simulate a design Then you can create a third model library MYMODELS LIB that contains these two statements LIB mydiodes lib LIB myopamps 1ib and configure MYMODELS LIB for global use Because MYDIODES LIB and MYOPAMPS LIB are referenced from MYMODELS LIB they are automatically configured for global use as well OrCAD provided models The model libraries that you initially install with your OrCAD programs are listed in NOM LIB This file demonstrates how you can nest references to other libraries and models If you click the Libraries tab in the Simulation Settings dialog box immediately after installation you see the NOM LIB entry in the Library Files list The asterisk means that this model library and any of the model libraries it references contain global model definitions Tools to create and edit models There are three tools that you can use to create and edit model definitions Use the e Model Editor when you want to e derive models from data sheet curves provided by manufacturers or e modify the behavior of a Model Editor supported model e edit the PSpice command syntax text for MODEL and SUBCKT definitions e Create Subcircuit command in the schematic page editor when you have a hierarchical level in you
328. s in the Application Notes manual for more information The example schematic EXAMPLE DSN is provided on the OrCAD installation CD 288 Temperature considerations in statistical analyses The statistical analyses perform multiple runs as does the temperature analysis Conceptually the Monte Carlo and worst case loops are inside the temperature loop However since both temperature and tolerances affect the model parameters OrCAD recommends not using temperature analysis when using Monte Carlo or worst case analysis Also you cannot sweep the temperature in a DC sweep analysis or put tolerances on temperature coefficients while performing one of these statistical analyses In EXAMPLE DSN the temperature value is fixed at 35 C VOU aera readme RalaS RCI RC2 example rdm Z ik ok a CLOAD OUT d Jour RS2 ga a2 N 93 mmm y k q212222 q212222 k 4 1 oi at d R 4202222 ad Ha q212222 o E o VEE Figure 74 Example schematic EXAMPLE DSN Monte Carlo analysis Monte Carlo analysis The Monte Carlo analysis calculates the circuit response to changes in part values by randomly varying all of the model parameters for which a tolerance is specified This provides statistical data on the impact of a device parameter s variance With Monte Carlo analysis model parameters are given Monte Carlo analysis is frequently used
329. s over a range of frequencies Outputs include voltages and currents with magnitude and phase you can use this information to obtain Bode plots Noise For each frequency specified in the AC analysis e Propagated noise contributions at an output net from every noise generator in the circuit e RMS sum of the noise contributions at the output e Equivalent input noise Note To run a noise analysis you must also run an AC sweep analysis Analyses you can run with PSpice Transient and Fourier These time based analyses evaluate circuit performance in response to time varying sources Table 3 summarizes what PSpice calculates for each time based analysis type Table3 Time based analysis types For this time based analysis PSpice computes this Transient Voltages and currents tracked over time Fourier DC and Fourier components of the transient analysis results Note To run a Fourier analysis you must also run a transient analysis Chapter 1 Things you need to know Advanced multi run analyses The multi run analyses parametric temperature Monte Carlo and sensitivity worst case result in a series of DC sweep AC sweep or transient analyses depending on which basic analyses you enabled Parametric and temperature For parametric and temperature analyses PSpice steps a circuit value in a sequence that you specify and runs a simulation for each value Table 4 shows the circuit values t
330. se are model files and if required stimulus files and include files Files needed for simulation Refer to the online OrCA D PSpice Reference Manual for the syntax of the statements in the netlist file and the circuit file The circuit file QR that Capture generates contains references to the other user configurable files that PSpice needs to read 11 Chapter 1 Things you need to know A subcircuit sometimes called a macromodel is analogous to a procedure call in a software programming language See What is the Model Editor on page 1 10 for a description 12 You can create these files using OrCAD programs like the Stimulus Editor and the Model Editor These programs automate file generation and provide graphical ways to verify the data You can also use the Model Text view in the Model Editor or another text editor like Notepad to enter the data manually Model library A model library is a file that contains the electrical definition of one or more parts PSpice uses this information to determine how a part will respond to different electrical inputs These definitions take the form of either a e model parameter set which defines the behavior of a part by fine tuning the underlying model built into PSpice or e subcircuit netlist which describes the structure and function of the part by interconnecting other parts and primitives The most commonly used models are available in the OrCAD model libr
331. shown in Figure 68 PARAMETERS r 0 5 Figure 68 Passive filter schematic This series of PSpice runs varies the value of resistor R1 from 0 5 to 1 5 ohms in 0 1 ohm steps Since the time constant of the circuit is about one second perform a transient analysis of approximately 20 seconds Create the circuit in OrCAD Capture by placing a piecewise linear independent current source IPWL from SOURCE OLB Set the current source properties as follows AC la T1 Os I1 Oa T2 10ms I2 Oa T3 10 1ms I3 la Place an instance of a resistor and set its VALUE property to the expression R To define R as a global parameter place a PARAM pseudocomponent and use the Property Editor to create a new property R and set its value to 0 5 Place an inductor and set its value to 1H place a capacitor and set its value to 1 and place an analog ground symbol 0 from SOURCE OLB Wire the schematic symbols together as shown in Figure 68 Running the simulation Run PSpice with the following analyses enabled transient print step 100ms final time 20s parametric swept var type global parameter sweep type linear name R start value 0 5 end value 1 5 increment 0 1 After setting up the analyses start the simulation by choosing Run from the PSpice menu Using performance analysis to plot overshoot and rise time After performing the simulation that creates the data file RLCFILT DAT you can calcualte the speci
332. sient analysis You can create and edit voltage sources and current sources for your circuit Menu prompts guide you to provide the necessary parameters such as the rise time fall time and period of an analog repeating pulse Graphical feedback allows you quickly verify the waveform Stimulus files The Stimulus Editor produces a file containing the stimuli with their transient specification These stimuli are defined as simulator device declarations using the V voltage source and I current source forms Since the The Stimulus Editor utility OrCAD program versions without the Stimulus Editor must use the characterized by property sources listed in Table 10 on page 10 252 253 Chapter 10 Transient analysis tings Transient n General Analysis Include Files Libraries Stimulus Options Data Collection Probe Window Filename Analysis Include Files Include files ate loaded before the circuit They can include most valid PSpice commands such as PARAM and FUNC definitions Browse Add as Global Add to Design Remove Cancel Apply Help 254 Stimulus Editor produces these statements automatically you will never have to be concerned with their syntax However if you are interested in a detailed description of their syntax see the descriptions of V and I devices in the Analog Devices chapter of the the online OrCA D PSpice A D Reference Manua
333. sient or DC response However such poles will make the actual device oscillate Non causality and Laplace transforms PSpice applies an inverse FFT to the Laplace expression to obtain an impulse response and then convolves the impulse response with the dependent source input to obtain the output Some common impulse responses are inherently non causal This means that the convolution Cautions and recommendations for simulation and analysis must be applied to both past and future samples of the input in order to properly represent the inverse of the Laplace expression For example the expression S corresponds to differentiation in the time domain The impulse response for S is an impulse pair separated by an infinitesimal distance in time The impulses have opposite signs and are situated one in the infinitesimal past the other in the infinitesimal future In other words convolution with this corresponds to applying a finite divided difference in the time domain The problem with this for PSpice is that the simulator only has the present and past values of the simulated input so it can only apply half of the impulse pair during convolution This will obviously not result in time domain differentiation PSpice can detect but not fix this condition and issues a non causality warning message when it occurs The message tells what percentage of the impulse response is non causal and how much delay would need to be added to sli
334. signal DC transfer function require you to specify output variables for voltages and currents at specific points on the schematic Depending upon the analysis type you may need to specify the following e Voltage on a net a pin or at a terminal of a semiconductor device e Current through a part or into a terminal of a semiconductor device e Adevice name If output variables or other information are required select Output File Options in the Monte Carlo Worst Case dialog box and enter the required parameters Voltage Specify voltage in the following format v modifiers lt out id gt lt out id gt 1 where lt out id gt is lt net id gt or lt pin id gt 2 6 gt lt net id gt is a fully qualified net name lt pin id gt is lt fully qualified device name gt lt pin name gt 4 A fully qualified net name as referred to in line 3 above is formed by prefixing the visible net name from a label applied to one of the segments of a wire or bus or an offpage port connected to the net with the full hierarchical path separated by periods At the top level of hierarchy this is just the visible name A fully qualified device name from line 4 above is distinguished by specifying the full hierarchical path followed by the device s part reference separated by period characters For example a resistor with part reference R34 inside part Y1 placed on a top level 199 Chapter 7 Setting up analyses and start
335. sis 32 using the Model Editor 104 114 worst case analysis 309 expression parts ABM 154 168 expressions 69 70 Index see also parameters ABM 174 functions 71 specifying 69 system variables 73 waveform analysis 364 F files generated by Capture 10 user configurable 11 with simulation results 14 flicker noise 245 Fourier analysis 196 introduction 5 FREQUENCY output variable 359 frequency response vs arbitrary parameter 278 frequency table parts ABM 174 183 190 functions PSpice A D 71 waveform analysis 364 G GaAsFET 203 362 363 goal functions 275 in performance analysis 276 single data point 276 grid spacing part graphics 136 part pins 136 ground missing 83 missing DC path to 84 parts 60 group delay 361 H histograms 301 hysteresis curves 266 IAC stimulus part 233 IC property 378 ICn initial conditions parts 376 397 Index IDC stimulus part 74 218 IGBT 95 204 362 imaginary part 361 include files 11 configuring 13 120 with model definitions 121 inductors 202 problems 391 initial conditions 374 378 input noise total 245 instance models and the Model Editor 101 112 changing model references 117 editing 103 reusing 118 saving for global use instead using the Model Editor 113 integrators ABM 153 160 IPLOT write current plot part 369 IPRINT write current table part 370 ISRC stimulus part 74 218 233 ISTIM stimulus
336. sis EXPR is linearized around the bias point similar to the VALUE parts The output is then the input times the gain of EXPR times the value of XFORM The value of XFORM at a frequency is calculated by substituting j w for s where w is 2p frequency For transient analysis the value of EXPR is evaluated at each time point The output is then the convolution of the past values of EXPR with the impulse response of XFORM These rules follow the standard method of using Laplace transforms We recommend looking at one or more of the references cited in Frequency domain device models on page 6 181 for more information Example The input to the Laplace transform is the voltage across the input pins or V IN IN The EXPR property may be edited to include constants or functions as with other parts The transform 1 1 001 s describes a simple lossy integrator with a time constant of 1 millisecond This can be implemented with an RC pair that has a time constant of 1 millisecond Using the part editor you would define the XFORM and EXPR properties as follows XFORM 1 1 001 s EXPR V ZIN IN The default template remains appears on one line TEMPLATE E REFDES ZOUT 0UT LAPLACE EXPR XFORM After netlist substitution of the template the resulting transfer function would become V OUT BOUT LAPLACE V IN IN 1 1 001 s The output is a voltage and is applied between pins OUT and OUT
337. specific properties Create and edit part graphics pins and properties in general 57 Chapter 3 Preparing a design for simulation When netlisting fails or the simulation does not start If you have problems starting the simulation there may be problems with the design or with system resources If there are problems with the design PSpice displays errors and warnings in the Simulation Output window You can use the Simulation Output window to get more information quickly about the specific problem To get online information about an error or warning shown in the Simulation Output window 1 Select the error or warning message 2 Press F1 The following tables list the most commonly encountered problems and where to find out more about what to do Things to check in your design Table 5 Make sure that To find out more see this XX NS NNN N NN The model libraries stimulus files and Configuring model libraries on page 4 120 include files are configured The parts you are using have models Unmodeled parts on page 3 79 and Defining part properties needed for simulation on page 5 139 You are not using unmodeled pins Unmodeled pins on page 3 82 You have defined the grounds Missing ground on page 3 83 Every analog net has a DC path to ground Missing DC path to ground on page 3 84 The part template is correct Defining part properties needed for simulation on page 5 139 Hiera
338. sus bias voltage 280 Temperature analysis Minimum requirements to run a temperature analysis Minimum circuit design requirements None Minimum program setup requirements 1 In the Simulation Settings dialog box from the Analysis type list box select Time Domain Transient Under Options select Temperature Sweep if it is not already enabled Specify the required parameters for the sweep General Analysis Include Files Libraries Stimulus Options Data Collection Probe Window Analysis type Time Domain Transient gt Run the simulation at temperature 35 9 C Repeat the simulation for each of the temperatures Options a T General Settings Monte Carlo Worst Case Enter a list of temperatures separated by spaces For example 0 27 125 Parametric Sweep Temperature Sweep Save Bias Point Load Bias Point WKS Click OK to save the simulation profile From the PSpice menu choose Run to start the simulation Temperature analysis See Setting up analyses on page 7 197 for a description of the Simulation Settings dialog box 281 Chapter 11 Parametric and temperature analysis Running multiple analyses for different temperatures can also be achieved using parametric analysis see Parametric analysis on page 11 272 With parametric analysis the temperatures can be specified either by list or by range a
339. tax The general forms for PSpice E and G extensions are E lt name gt lt connecting nodes gt lt ABM keyword gt lt ABM function gt G lt name gt lt connecting nodes gt lt ABM keyword gt lt ABM function gt where lt name gt is the device name appended to the E or G device type character lt connecting specifies the lt node name node nodes gt name gt pair between which the device is connected PSpice equivalent parts 175 Chapter 6 Analog behavioral modeling 176 lt ABM specifies the form of the transfer keyword gt function to be used as one of VALUE arithmetic expression TABLE lookup table LAPLACE Laplace transform FREQ frequency response table CHEBYSHEV Chebyshev filter characteristics lt ABM specifies the transfer function as a function gt formula or lookup table as required by the specified lt ABM keyword gt Refer to the online OrCA D PSpice A D Reference Manual for detailed information Modeling mathematical or instantaneous relationships The instantaneous models using VALUE and TABLE extensions to PSpice E and G devices in the part templates enforce a direct response to the input at each moment in time For example the output might be equal to the square root of the input at every point in time Such a device has no memory or a flat frequency response These techniques can be used to model both linear and nonlinear responses Note For AC analysis
340. ter 5 Creating parts for the Implementation property models for more information 2 Ifneeded move the instance model definition to an See Configuring model libraries appropriate model library and make sure the library on page 4 120 for more information is configured for global use Note If you use the part wizard to create the part automatically from the model definition then this step is completed for you 119 Chapter 4 Creating and editing models General Analysis Include Files Libraries Stimulus Options Data Colection Probe Window Filename Browse Library fies xiti Tachi ib ri Add as Global Add to Design Edit Library Path C Program Files OrCAD Capture Libramy PSpice Browse The Include Files tab contains include files You can manually add design and global indude files to your configuration using the Add to Design and Add as Global buttons respectively The Stimulus tab contains stimulus files See Configuring stimulus files on page 10 254 for more information 120 Configuring model libraries Although model libraries are usually configured for you there are things that you sometimes must do yourself These are e adding new model libraries that were created outside of Capture or the Model Editor e changing the global or design scope of a model library e changing the library search order e changing or adding directory search paths
341. the Edit menu choose PSpice Stimulus This starts the Stimulus Editor and displays the New Stimulus dialog box You can see that the stimulus already has the name of Vfirst Select PWL in the dialog box and click OK The cursor looks like a pencil The message in the status bar at the bottom of the screen lets you know that you are in the process of adding new data points to the stimulus The left end of the bottom status bar displays the current coordinates of the cursor The Stimulus Editor utility 9 Move the cursor to 200ns 1 and click the left mouse button This adds the point Notice that there is automatically a point at 0 0 Ignore it for now and continue to add a couple more points to the right of the current one 10 Click right to stop adding points 11 From the File menu choose Save If you make a mistake or want to make any changes reshape the trace by dragging any of the handles to anew location The dragged handle cannot pass any other defined data point To delete a point click its handle and press Del To add additional points either choose Add Point from the Edit menu press Alt JHA or click the Add Point toolbar button At this point you can return to Capture edit the current stimulus or go on to create another Example sine wave sweep This example creates a 10 k sine wave with the amplitude parameterized so that it can 1 Open an existing schematic or start a new one a Mare be swept during
342. the passive device models built into PSpice These are summarized in the following table Table7 Passive parts These parts are Which is this PSpice available For this device type device letter C capacitor C C_VAR L inductor L R resistor R R_VAR XFRM_LINEAR transformer Kand L K_LINEAR T ideal transmission line T TLOSSY Lossy transmission line T TnCOUPLED coupled transmission line T and K TnCOUPLEDX KCOUPLEn For these device types the OrCAD libraries supply several parts Refer to the online OrCA D PSpice A D Reference Manual for the available parts Breakout parts The OrCAD libraries supply passive and semiconductor parts with default model definitions that define a basic set of model parameters This way you can easily e assign device and lot tolerances to model parameters for Monte Carlo and sensitivity worst case analyses e define temperature coefficients and e define device specific operating temperatures These are called breakout parts and are summarized in the following table Table8 Breakout parts Use this Which is this PSpice breakout part For this device type device letter BBREAK GaAsFET B CBREAK capacitor C DBREAKx diode D JBREAKx JFET J KBREAK inductor coupling K LBREAK inductor L MBREAKx MOSFET M QBREAKx bipolar transistor Q RBREAK resistor R SBREAK voltage controlled S switch TBREAK transmission line T WBREAK current controlled W s
343. this tutorial however you will not perform a simulation so you can skip this step Using the Model Editor to edit the D1 diode model To create a new model and model library 1 Inthe Model Editor from the Model menu choose New 2 Inthe New dialog box do the following a Inthe Model text box type Dbreakx b From the From Model list select Diode Click OK 3 From the File menu choose Save As 4 Inthe File name text box type rect fr 1ib to save the library as RECTFR LIB Entering data sheet information As shown in Figure 31 the Model Editor initially displays e diode model characteristics listed in the Models List frame and e DbreakX model parameter values listed in the Parameters frame 24 ModelLib1 lib Dbreakx OrCAD Model Editor Forward Current Gi Fie Edt View Model Plot Tools Window Help 218 x olsjalsja me eee WE ef ef Model Name Type Forward Current GEESE Diode a wiwa wwa l Foward Cur JE Junction Ca G Reverse Le fE Reverse Br E Reverse Re OAAAAAAAAAAAN AN FERRERS EB 0 3333 manmanan Tn TRA z FREESFS z Figure 31 Model characteristics and parameter values for Dbreakx Using the Model Editor to edit models 105 Chapter 4 Creating and editing models 106 You can mo
344. through the part editor Insert additional row variables into the template using the same form as the first five and add ROWn properties as needed to the list of properties 161 Chapter 6 Analog behavioral modeling FTABLE Freq dB Deg OHz 0 0 5kHz 0 5760 BkHz 60 8912 DELAY 0 Figure 39 FTABLE part example 162 value that can be assigned to the part s DELAY property for subsequent runs without otherwise altering the table The output of the part depends on the analysis being done For DC and bias point the output is the zero frequency magnitude times the input voltage For AC analysis the input voltage is linearized around the bias point similar to EVALUE and GVALUE parts Modeling mathematical or instantaneous relationships on page 6 176 The output for each frequency is then the input times the gain times the value of the table at that frequency For transient analysis the voltage is evaluated at each time point The output is then the convolution of the past values with the impulse response of the frequency response These rules follow the standard method of using Fourier transforms We recommend looking at one or more of the references cited in Frequency domain device models on page 6 181 for more information Note The table s frequencies must be in order from lowest to highest The TABLE part provides one input and one output Example A device ELOFILT is used as a frequen
345. timulus Editor and click the Parametric Sweep button Select Global Parameter in the Swept Var Type frame Select Linear in the Sweep type frame Enter AMP in the Name text box Specify values for the Start Value End Value and Increment text boxes You can now set up your usual Transient AC or DC analysis and run the simulation The Stimulus Editor utility Creating new stimulus symbols 1 Use the Capture part editor to edit or create a part with the following properties Implementation Type PSpice Stimulus Implementation name of the stimulus model STIMTYPE type of stimulus valid values are ANALOG if this property is nonexistent the stimulus is assumed to be ANALOG 259 Chapter 10 Transient analysis PWL stimuli are a little different since they are a series of time value pairs This provides a fast way to scale a PWL stimulus 260 Editing a stimulus To edit an existing stimulus 1 Start the Stimulus Editor and select Get from the Stimulus menu 2 Double click the trace name at the bottom of the X axis for analog This opens the Stimulus Attributes dialog box where you can modify the attributes of the stimulus directly and immediately see the effect of the changes To edit a PWL stimulus 1 Double click the trace name This displays the handles for each defined data point 2 Click any handle to select it To reshape the trace drag it to anew location To delete the data point press Del
346. timulus Editor is not included in PSpice Basics A If you do not have the Stimulus Editor 1 Place a VSIN partinstead of VSTIM and double click it 2 In the Edit Part dialog box click User Properties 3 Set values for the VOFF VAMPL and FREQ properties as defined in step 5 When finished click OK 33 Chapter 2 Simulation examples press Shif F12 Transient options Bun totime ams seconds TSTOP Bint values in the output file every 20ns seconds Maximum step size seconds T Skip the initial transient bias point calculation SKIPBP Cees e e Output File Options Figure 16 Transient analysis simulation settings 34 Stimulus Editor chppert stl l lojx 2 Ele Edit Stimulus Plot View Tools Window Help lajxi 1 Bg Stimulus Attributes ES Name SINE Type SIN Otfsetvaue 0 i Amplitude 10 Frequency fm Time Delay pooo Damping Factor pooo Phase Angle ct Cancel Figure 15 Stimulus Editor window 7 Click OK 8 From the File menu choose Save to save the stimulus information Click Yes to update the schematic 9 From the File menu choose Exit to exit the Stimulus Editor To set up and run the transient analysis 1 From Capture s PSpice menu choose New Simulation Profile The New Simulation dialog box appears 2 Inthe Name text box type Transient 3 From the Inherit From list select Schemati
347. tion property is non blank Things to watch for For a roadmap to other commonly encountered problems and solutions see When netlisting fails or the simulation does not start on page 3 58 The libraries listed in the tables that follow all contain parts that you can simulate Some files also contain parts that you can only use for board layout That s why you need to check the Pspice TEMPLATE property if you are unsure or still getting warnings when you try to simulate your druit 79 Chapter 3 Preparing a design for simulation To find out more about a particular library refer to the online Library List or read the header of the model library file itself 80 Table 16 Analog libraries with modeled parts installed in Capture Library PSpice 1_SHOT ABM ADV_LIN AMP ANALOG ANA_SWIT ANLG_DEV ANL_MISC APEX BIPOLAR BREAKOUT BUFFER BURR_BRN CD4000 COMLINR DIODE EBIPOLAR EDIODE ELANTEC EPWRBJT FILTSUB FWBELL HARRIS IGBT JBIPOLAR JDIODE JFET JJFET JOPAMP JPWRBJT JPWRMOS LIN_TECH MAGNETIC MAXIM MOTORAMP MOTORMOS MOTORSEN MOTOR_RF NAT_SEMI OPAMP OPTO PHIL_BJT PHIL_FET PHIL_RF POLYFET PWRBJT PWRMOS SIEMENS SWIT_RAV SWIT_REG TEX_INST THYRISTR TLINE XTAL ZETEX Check for this if the part in question is custom built Are there blank or inappropriate values for the part s Implementation and PSPICETEMPLATE properties If so load this part into the part editor an
348. tion of the output variables that can be entered in the Simulation Settings dialog box displayed for an analysis type Specific information for setting up each type of analysis is discussed in the following chapters 197 Chapter 7 Setting up analyses and starting simulation 198 5 Setup any other analyses you want to perform for the circuit by selecting any of the remaining analysis types and options then complete their setup dialog boxes Execution order for standard analyses For normal simulations that are run from a simulation profile or in batch mode only the particular analysis type that is specified will be executed During simulation of a circuit file the analysis types are performed in the order shown in Table 3 Each type of analysis is conducted only once per run Several of the analyses small signal transfer DC sensitivity and frequency response depend upon the bias point calculation Because so many analyses use the bias point PSpice calculates this automatically PSpice s bias point calculation computes initial states of analog components Table3 Execution order for standard analyses 1 DC sweep 2 Bias point 3 Frequency response 4 Noise 5 DC sensitivity 6 Small signal DC transfer 7 Transient response 8 Fourier components Setting up analyses Output variables Certain analyses such as noise Monte Carlo sensitivity worst case DC sensitivity Fourier and small
349. tions RELTOL 191 output control parts 60 369 output file OUT 24 control parts 369 tables and plots 369 output noise total 245 output variables arithmetic expressions 364 noise waveform analysis 245 363 PSpice A D 199 waveform analysis 356 waveform analysis functions 364 P PARAM global parameter part 67 parameters 67 parametric analysis 196 272 analyzing waveform families 45 example 42 frequency response vs arbitrary parameter 218 introduction 6 performance analysis 274 setting up 43 temperature analysis 196 281 parasitic capacitance 391 part wizard using custom parts 133 parts creating for models using the Model Editor 100 131 creating new stimulus parts 259 editing graphics 135 grid spacing graphics 136 pins 136 ground 60 non simulation 140 output control 60 399 pins 82 136 preparing model libraries for part creation 130 properties for simulation 139 saving as global using the Model Editor 100 131 simulation control 60 simulation properties 129 stimulus 60 ways to create for models 129 AGND ground 83 BBREAK GaAsFET 65 behavioral 66 breakout 65 C capacitor 64 CBREAK capacitor 65 creating for models custom parts 133 using the Model Editor 131 CVAR capacitor 64 D diode 64 DBREAK diode 65 EGND ground 83 finding 62 IAC AC stimulus 233 ICn initial conditions 376 IDC DC stimulus 74 218 ISRC analog stimulus 74 218
350. to enter your circuit design and have set up the analyses to be performed you can start a simulation by choosing Run from the PSpice menu When you enter and set up your circuit this way Capture automatically generates the simulation files and starts PSpice There may be situations however when you want to run PSpice outside of Capture You may want to simulate a circuit that was not created in Capture for example or you may want to run simulations of multiple circuits in batch mode This section includes the following e Starting a simulation from Capture below e Starting a simulation outside of Capture on page 7 207 e Setting up batch simulations on page 7 207 e The PSpice simulation window on page 7 208 Starting a simulation from Capture After you have set up the analyses for the circuit you can start a simulation from Capture in either of the following ways e From the PSpice menu select Run gt e Click the Simulate button on the PSpice toolbar 206 Starting a simulation Starting a simulation outside of Capture To start PSpice outside of Capture 1 From the Start menu point to the OrCAD program group then choose PSpice From the File menu choose Open Simulation Do one of the following e Double click on the simulation profile filename SIM in the list box e Enter the simulation profile filename SIM in the File name text box and click Open From the Simulation menu choose Edit
351. tput the model parameters are echoed in scientific notation making it easy to spot unusual values A further diagnostic is to ask for the detailed operating bias point TRAN OP information TRAN OP This lists the small signal parameters for each semiconductor device including the calculated parasitic capacitances Transient analysis Parasitic capacitances It is important that switching times be nonzero This is assured if devices have parasitic capacitances The semiconductor model libraries in PSpice have such capacitances If switches and or controlled sources are used then care should be taken to assure that no sections of circuitry can try to switch in zero time In practice this means that if any positive feedback loops exist such as a Schmidt trigger built out of switches then such loops should include capacitances Another way of saying all this is that during transient analysis the circuit equations must be continuous over time just as during the bias point calculation the equations must be continuous with the power supply level Inductors and transformers While the impedance of capacitors gets lower at high frequencies and small time steps the impedance of inductors gets higher Note The inductors in PSpice have an infinite bandwidth Real inductors have a finite bandwidth due to eddy current losses and or skin effect At high frequencies the effective inductance drops Another way to say this is that ph
352. u Configuring update intervals You can define the frequency at which PSpice updates the waveform display as follows e At fixed time intervals every n sec e According to the percentage of simulation completed every n where n is user defined The default setting Auto updates traces each time PSpice gets new data from a simulation To change the update interval 1 From the Tools menu choose Options 2 Inthe Auto Update Interval frame choose the interval type sec or then type the interval in the text box Interacting with waveform analysis during simulation The functions that change the x axis domain that set a new x axis variable can not be accessed while the simulation is running If you have enabled the display of Viewing waveforms During a multi run simulation such as Monte Carlo parametric or temperature PSpice displays only the data for the most recent run in the Probe window E or press insert For more information see Using schematic page markers to add 329 Chapter 13 Analyzing waveforms 330 waveforms during simulation and wish to reconfigure the x axis settings as explained below you must wait until the simulation run has finished The following table shows how to enable the functions that change the x axis domain Table 4 Enable this function By doing this Fast Fourier transforms Performance analysis New x axis variable Goal function
353. ual to those numbers Sigma is the standard deviation of the goal function values 305 Chapter 12 Monte Carlo and sensitivity worst case analyses tra Pate nS WPT Se we 8 4K 8 8K 9 2K 9 6K 10 0K 10 4K 10 8K CenterFreq YDBCOUT 13 n samples 166 sigma 265 376 median 9987 8 n divisions 20 minimum 9109 8 96th gile 180242 5 mean 9955 4 16th Zile 9537 52 maximun 180354 9 Figure 83 Center frequency histogram Worst case analysis This section discusses the analog worst case analysis feature of PSpice The information provided in this section explains how to use worst case analysis properly and with realistic expectations Overview of worst case analysis Worst case analysis is used to find the worst probable output of a circuit or system given the restricted variance of its parameters For instance if the values of R1 R2 and R3 can vary by 10 then the worst case analysis attempts to find the combination of possible resistor values which result in the worst simulated output As with any other analysis there are three important parts inputs procedure and outputs 306 Inputs In addition to the circuit description you need to provide two pieces of information e the parameter tolerances e a definition of what worst means You can set tolerances on any number of the parameters that characterize a model The crit
354. uation for the diode model which includes a term involving the reverse characteristic parameters such as ISR NR These parameters could have a significant effect at low current This means that the curve displayed in the Model Editor does not exactly match whatis displayed in PSpice after a simulation Be sure to test and verify models using PSpice If needed fine tune the models Note When specifying operating characteristics for a model you can use typical values found on data sheets effectively for most simulations To verify your design you may also want to use best and worst case values to create separate models and then swap them into the circuit design 96 Ways To Characterize Models Figure 28 shows two ways to characterize models using the Model Editor device data from data sheets parts estimation PSpice model simplified graph of device parameters equation characteristic t evaluation user data entry what if model data Figure 28 Process and data flow for the Model Editor Creating models from data sheet information The most common way to characterize models is to enter data sheet information for each device characteristic After you are satisfied with the behavior of each characteristic you can have the Model Editor estimate or extract the corresponding model parameters and generate a graph showing the behavior of the characteristic This is called the fitting process
355. ulation examples Finding out more about transient analysis Table 2 1 To find out more about this See this transient analysis for analog Chapter 10 Transient designs analysis Includes how to set up time based stimuli using the Stimulus Editor 36 AC sweep analysis AC sweep analysis The AC sweep analysis in PSpice is a linear or small signal frequency domain analysis that can be used to observe the frequency response of any circuit at its bias point Setting up and running an AC sweep analysis In this example you will set up the clipper circuit for AC analysis by adding an AC voltage source for a stimulus signal see Figure 18 and by setting up AC sweep parameters om D1N3940 c1 O47u D2 R4 D1N3940 5 6k lt o F vin 2s lt H u Z m KOO Figure 18 Clipper circuit with AC stimulus To change Vin to include the AC stimulus signal 1 In Capture open CLIPPER OPJ 2 Select the DC voltage source Vin and press to remove the part from the schematic page 37 Chapter 2 Simulation examples Note PSpice simulation is not case sensitive so both M and m can be used as milli and MEG Meg and meg can all be used for mega However waveform analysis treats M and m as mega and milli respectively 38 From the Place menu choose Part In the Part text box type vac from the PSpice library SOURCE OLB and click OK Place
356. ult of the simulation window is the main window section where documents such as waveforms circuit description output information etc are displayed within child windows These windows are tabbed by default The tabs at the bottom left show the names of the documents that each child window contains Clicking on a tab brings that child window to the foreground Figure 56 shows the tabbed document windows for Example Example TRAN DAT and Example Example TRAN OUT You can configure the display of these windows to suit your preferences and to make the analysis of the circuit quick and readily understandable These windows can also be resized moved and reordered to suit your needs Output window section The lower left portion of the simulation window provides a listing of the output from the simulation It shows informational warning and error messages from the simulation You can resize and relocate this window to make it easier to read Starting a simulation Simulation status window section The lower right portion of the simulation window presents a set of tabbed windows that show detailed status about the simulation There are three tabbed windows in this section the Analysis window the Watch Variable window and the Devices window The Analysis window provides a running log of values of simulation variables parameters such as Temperature Time Step and Time The Watch Variable window displays watch variables and their values T
357. ummarized in Table 10 Table 10 Stimulus symbols for time based input signals Specified by Symbol name Description Using the VSTIM voltage source Sauls Pet ISTIM current source Defining symbol VSRC voltage sources attribute VEXP VPULSE VPWL VPWL_RE_FOREVER VPWL_F_RE_FOREVER VPWL_N_TIMES VPWL_F_N_TIMES VSFFM VSIN ISRC current sources IEXP IPULSE IPWL IPWL_RE_FOREVER IPWL_F_RE FOREVER IPWL_N_TIMES IPWL_F_N_TIMES ISFFM ISIN To use any of these source types you must place the symbol in your schematic and then define its transient behavior Each property characterized stimulus has a distinct set of attributes depending upon the kind of transient behavior it represents For VPWL_F_xxx IPWL_F_xxx and FSTIM a separate file contains the stimulus specification As an alternative the Stimulus Editor utility automates the process of defining the transient behavior of stimulus devices The Stimulus Editor allows you to create analog stimuli which generate sine wave repeating pulse exponential pulse single frequency FM and piecewise linear waveforms The stimulus specification created using the Stimulus Editor is saved to a file automatically configured into the schematic and associated with the corresponding VSTIM or ISTIM part instance or symbol definition The Stimulus Editor utility The Stimulus Editor is a utility that allows you to quickly set up and verify the input waveforms for a tran
358. using VARY BOTH The purpose of the technique is to reduce the number of simulations For a more accurate worst case analysis you should first perform a worst case analysis with VARY LOT manually adjust the nominal model parameter values according to the results then perform another analysis with VARY DEV specified 313 Chapter 12 Monte Carlo and sensitivity worst case analyses This may result in maximizing or minimizing the output variable value over the entire range of the sweep This collating function is useful when you know the direction in which the maximum deviation occurs 314 Gaussian distributions Parameters using Gaussian distributions are changed by 30 three times sigma for the worst case analysis YMAX collating function The purpose of the YMAX collating function is often misunderstood This function does not try to maximize the deviation of the output variable value from nominal Depending on whether HI or LO is specified it tries to maximize or minimize the output variable value itself at the point where maximum deviation occurred during sensitivity analysis RELTOL During the sensitivity analysis each parameter is varied multiplied by 1 RELTOL where RELTOL is specified in a OPTIONS statement or defaults to 0 001 Sensitivity analysis The sensitivity analysis results are printed in the output file OUT For each varied parameter the percent change in the collating function and the swe
359. value and then click Apply f Close the property editor spreadsheet To change stimulus references globally for a part a Select the part you want to edit a From the Edit menu choose Part to start the part editor Transient time response b Create or change the part definition making sure See Chapter 5 Creating parts for to define the following properties models for a description of how to create Implementation stimulus name as defined in and edit parts the Stimulus Editor Transient time response The Transient response analysis causes the response of the circuit to be calculated from TIME 0 to a specified time A transient analysis specification is shown for the circuit EXAMPLE OPJ in Figure 63 EXAMPLE OP is shown in Figure 64 The analysis is to span the time interval from 0 to 1000 nanoseconds and values should be reported to the simulation output file every 20 nanoseconds Simulation Settings Transient Analysis x General Analysis Include Files Libraries Stimulus Options Data Collection Probe Window Analysis type Time Domain Transient E Bun to time fi O00ns seconds TSTOP Options Print values in the output file every fi Ons seconds General Settings Transient options Monte Carlo Worst Case Maximum step size seconds Parametric Sweep Temperature Sweep I Skip the initial transient bias point calculation SKIPBP Save Bias Point C Load B
360. value the syntax you need to use is as follows Table 15 This property Has this syntax DC DC_value units AC magnitude_value units phase_value TRAN time based_type parameters where time based_type is EXP PULSE PWL SFFM or SIN and the parameters depend on the time based_type Note OrCAD recommends that if you are running only a transient analysis use a VSTIM or ISTIM part if you have the standard package or one of the other time based source parts that has properties specific for a waveform shape Things to watch for This section includes troubleshooting tips for some of the most common reasons your circuit design may not netlist or simulate Unmodeled parts If you see messages like this in the PSpice Simulation Output window Warning Part part_name has no simulation model then you may have done one of the following things e Placed a part from the OrCAD libraries that is not available for simulation used only for board layout e Placed a custom part that has been incompletely defined for simulation Do this if the part in question is from the OrCAD libraries e Replace the part with an equivalent part from one of the libraries listed in the tables below e Make sure that you can simulate the part by checking the following e ThatithasaPSPICETEMPLATE property and that its value is non blank e That it has an Implementation Type PSpice MODEL property and that its Implementa
361. ven if this does not cause a problem with disk space large waveform data files take longer to read in and take longer to display traces on the screen You can limit waveform data file size by e placing markers on your schematic before simulation and having PSpice restrict the saved data to these markers only e excluding data for internal subcircuits e suppressing simulation output Limiting file size using markers One reason that waveform data files are large is that by default PSpice stores all net voltages and device currents for each step for example time or frequency points However if you have placed markers on your schematic prior to simulation PSpice saves only the results for the marked wires and pins Viewing waveforms To limit file size using markers 1 From Capture s PSpice menu choose Edit Simulation Settings to display the Simulation Settings dialog box Simulation Settings Parametric x General Analysis Include Files Libraries Stimulus Options Data Collection Probe Window r Schematic Circuit Data C All voltages currents and digital states All but internal subcircuit data T Save data in the CSDF format CSD Cancel Apply Help 2 Click the Data Collection tab 3 In the Schematic Circuit Data frame choose At Markers only and click OK 4 From the PSpice menu point to Markers then choose The color of the marker on the schematic the marker type you want to pl
362. vides introductory information to help Refer to your OrCA D Capture you enter circuit designs that simulate properly If you User s Guide for general schematic want an overview use the checklist on page 3 56 to guide entry information you to specific topics Topics include e Checklist for simulation setup on page 3 56 e Using parts that you can simulate on page 3 60 e Using global parameters and expressions for values on page 3 67 e Defining power supplies on page 3 74 e Defining stimuli on page 3 75 e Things to watch for on page 3 79 Chapter 3 Preparing a design for simulation Checklist for simulation setup This section describes what you need to do to set up your circuit for simulation 1 Find the topic that is of interest in the first column of any of these tables 2 Go to the referenced section For those sections that provide overviews you will find references to more detailed discussions Typical simulation setup steps For more information on this step See this To find out this VU Setcomponent values Using parts that you can An overview of vendor passive and other properties simulate on page 3 60 breakout and behavioral parts Using global parameters and How to define values using variable expressions for values on parameters functional calls and page 3 67 mathematical expressions UY Define power Defining power supplies on An overview of DC power for supplies pa
363. which is already configured for local use see What happens if you don t save the instance model on page 4 103 To save instance models 1 From the File menu choose Save to update DESIGN_NAME LIB and save it to disk 102 Using the Model Editor to edit models What happens if you don t save the instance model Before the schematic page editor starts the Model Editor it does these things e Makes a copy of the original model and saves it as an instance model in SCHEMATIC_NAME LIB e Configures SCHEMATIC_NAME LIB for design use if not already done e Attaches the new instance model name to the Implementation property for the selected part instance This means that if you e quit the Model Editor or e return to Capture to simulate the design without first saving the model you are editing the part instance on your schematic page is still attached to the instance model implementation In this case the instance model is identical to the original model If you decide to edit this model later be sure to do one of the following e Ifyou want the changes to remain specific to the current design edit the instance model in the design library using the Model Editor e Ifyou want the change to be global change the model To find out how to change model implementation for the part instance in your design references see Changing the model back to the original model name in the global library reference to an existing mo
364. wing e Change the resistor values for R3 R5 R6 and R7 from their default value of 1 k e Set the DC value for the V1 voltage source To change resistor values 1 Double click the value for a resistor 2 Type the new value Depending on the resistor you are changing set its value to one of the following refer to Figure 78 Table 1 If you are changing this resistor Type this R3 1k 1 P Pcoeff Pnom R5 2k R6 470 R7 25 3 Repeat steps 1 2 for each resistor on your schematic page To set the DC value for the V1 source and make it visible 1 Double click the V1 source part 2 Inthe Parts Spreadsheet click in the cell under the DC column 3 Type1 35v Monte Carlo analysis Click the Display button In the Display Format frame choose the Value Only option to make the DC value 1 35v visible on the schematic Click OK then click Apply to apply the changes you have made to the part Close the Parts Spreadsheet Setting up the parameters To complete the value specification for R3 define the global parameters Pcoeff P and Pnom To define and initialize Pcoeff P and Pnom 1 2 Place a PARAM part on the schematic page Double click the PARAM part to display the Parts Spreadsheet For each parameter create a new property by clicking New and typing its name Enter its corresponding value by clicking in the cell under the new property name and typing its value Specify the par
365. witch XFRM_NONLINEAR transformer Kand L ZBREAKN IGBT Z For this device type the OrCAD libraries supply several breakout parts Refer to the online OrCA D PSpice Reference Manual for the available parts Using parts that you can simulate To find out more about models see What are models on page 4 87 To find out more about Monte Carlo and sensitivity worst case analyses see Chapter 12 Monte Carlo and sensitivity worst case analyses To find out more about setting temperature parameters see the A nalog Devices chapter in the online OrCA D PS pice A D Reference Manual andfind the device type that you are interested in To find out more about how to use these parts and define their properties look up the corresponding PSpice device letter in the Analog Devices chapter of the online OrCA D PSpice A D Reference Manual and then look in the Capture Parts section 65 Chapter 3 Preparing a design for simulation For more information see Chapter 6 Analog behavioral modeling 66 Behavioral parts Behavioral parts allow you to define how a block of circuitry should work without having to define each discrete component Analog behavioral parts These parts use analog behavioral modeling ABM to define each part s behavior as a mathematical expression or lookup table The OrCAD libraries provide ABM parts that operate as math functions limiters Chebyshev filters integrators differentiators and others
366. y Probe window during simulation after simulation has completed Show All markers on open schematics Last plot Cancel Aol Help The display settings in the Probe Window tab are explained in the following table Viewing waveforms You do not need to exit PSpice if you are finished examining the simulation results for one circuit and want to begin a new simu ation from within Capture However PSpice unloads the old waveform data file for a simu simu drcuit each time that you run a new ation of the circuit After the ation is complete the new or updated waveform data file is loaded for viewing 327 Chapter 13 Analyzing waveforms If you open a new Probe window from the Window menu choose New Window while monitoring the data the new window also starts in monitor mode because it is associated with the same waveform data file 328 Table 3 This setting Enables this type of waveform display Display Probe Waveforms are displayed only when a window when profile is opened Display Probe window during simulation Display Probe window after simulation has completed Show all markers on open schematics Show last plot DAT file is opened from within PSpice Waveforms are displayed as the simulation progresses marching waveforms Waveforms are displayed only after the full simulation has completed and all data has been c
367. y from exceeding the limits of the numerics in PSpice This example tries to approximate an ideal switch using the diode model MODEL DMOD IS le 16 N le 6 The current through this diode is 1e 16 ev 025 1e 16 ev 25e9 Because the denominator in the exponential is so small the current I is essentially zero for V lt 0 and almost infinite for V gt 0 Even if there are external components that limit the current the knee of the diode s I V curve is so sharp that it is almost a discontinuity Are the derivatives correct The device equations built into PSpice include the derivatives and these are correct Depending on the device the physical meaning of the derivatives is small signal conductance transconductance or gain Unrealistic model parameters can exceed the limit of 1e14 but it requires some effort The main thing to look at is the behavioral modeling expressions especially those having denominators Introduction Is the initial approximation close enough Newton Raphson is guaranteed to converge only if the analysis is started close to the answer Also there is no measurement that can tell how close is close enough PSpice gets around this by making heavy use of continuity Each analysis starts from a known solution and uses a variable step size to find the next solution If the next solution does not converge PSpice reduces the step size falls back and tries again Bias point The hardest part o
368. you want to see tabulated 6 Repeat steps 2 through 5 for any additional analysis types you want plotted Note If you do not enable an analysis type PSpice reports the transient results 371 Chapter 14 Other output options 372 Setting initial state Appendix overview This appendix includes the following sections e Save and load bias point on page A 374 e Setpoints on page A 376 e Setting initial conditions on page A 378 Chapter A Setting initial state If the circuit uses high gain components or if the circuit s behavior is nonlinear around the bias point this feature is not useful See Setting up analyses on page 7 197 for a description of the Analysis Setup dialog box 374 Save and load bias point Save Bias Point and Load Bias Point are used to save and restore bias point calculations in successive PSpice simulations Saving and restoring bias point calculations can decrease simulation times when large circuits are run multiple times and can aid convergence Save Load Bias Point affect the following types of analyses e transient e DC e AC Save bias point Save bias point is a simulation control function that allows you to save the bias point data from one simulation for use as initial conditions in subsequent simulations Once bias point data is saved toa file you can use the load bias point function to use the data for another simulation To use save bias point 1 Inthe Simulation Setting
369. ype Use this part name For this device type Use this part name Bipolar transistor LPNP Bipolar transistor NPN Bipolar transistor PNP Capacitor Diode GaAsFET IGBT N channel Inductor JFET N channel JFET P channel Magnetic core LPNP NPN PNP CAP DIODE GASFET NIGBT IND NJF PIF CORE MOSFET N channel MOSFET P channel OPAMP 5 pin OPAMP 7 pin Resistor Switch voltage controlled Transmission line Voltage comparator Voltage comparator 6 pin Voltage reference Voltage regulator NMOS PMOS OPAMP5 OPAMP7 RES VSWITCH TRN VCOMP VCOMP6 VREF VREG Does not apply to the Model Editor 2 For each custom part set its MODEL property to M where is a back single quote or grave character 133 Chapter 5 Creating parts for models This tells the Model Editor to substitute the correct model name To base new parts on custom parts using the Model Editor 1 Inthe Model Editor from the Options menu choose Part Creation Setup and enable automatic part creation as described in To automatically create parts for new models on page 5 132 2 Inthe Base Parts On frame enter the name of the existing part library OLB that contains your custom parts 3 Click OK 134 Editing part graphics If you created parts using the Model Editor and you want to make further changes the following sections explain a few important things to remember when you edit the
370. ysical inductors have a frequency at which their Q begins to roll off The inductors in PSpice have no such limit This can lead to very fast spikes as transistors and diodes connected to inductors turn on and off The fast spikes in turn can force PSpice to take unrealistically small time steps Note OrCAD recommends that all inductors have a parallel resistor series resistance is good for modeling DC effects but does not limit the inductor s bandwidth The parallel resistor gives a good model for eddy current loss and limits the bandwidth of the inductor The size of 391 Chapter B Convergence and time step too small errors 392 resistor should be set to be equal to the inductor s impedance at the frequency at which its Q begins to roll off Example A common one millihenry iron core inductor begins to roll off at no less than 100KHz A good resistor value to use in parallel is then R 2 2 100e3 001 628 ohms Below the roll off frequency the inductor dominates above it the resistor does This keeps the width of spikes from becoming unreasonably narrow Bipolar transistors substrate junction The UC Berkeley SPICE contains an unfortunate convention for the substrate node of bipolar transistors The collector substrate p n junction has no DC component If the capacitance model parameters are specified e g CJS then the junction has voltage dependent capacitance but no DC current This can lead to a sneaky prob
371. ysis setup for EXAMPLE DSN 290 Figure 76 Figure 77 Figure 78 Figure 79 Figure 80 Figure 81 Figure 82 Figure 83 Figure 84 Figure 85 Figure 86 Figure 87 Figure 88 Figure 89 Figure 90 Figure 91 Figure 92 Figure 93 Figure 94 Figure 95 Figure 96 Figure 97 Figure 98 Figure A 1 Figures Summary of Monte Carlo runs for EXAMPLE OPJ 291 Parameter values for Monte Carlo pass three 292 Pressure sensor circuit o oo ee 293 Model definition for RMontel aaa 000000048 298 Pressure sensor circuit with RMonte1 and RTherm model definitions 299 Chebyshey filter 2 oc es ke ee we eee OE Be Se EG bee ew a 302 1 dB bandwidth histogram 4 lt 6248 ee Soke aa eee deen 305 Center frequency histogram i i 66 bee eee ee ee ee eH 306 Simple biased BJT amplifier lt 6 b hd ee eae He Le es 309 Amplifier netlist and circuit fle 6 ek ee Se ee ew OS 310 YatX Goal Function 2 a a a 311 Correct worst case results 2 312 Incorrect worst case results 2 o oo ee 312 Schematic using VARY BOTH gt lt o4 kee be ene4 ek oa Se oe RS 313 Circuit file using VARY BOTH dso aud eee eee KS ees 313 Analog and digital areasofaplot 0004 321 Two Probe windows 0 0 00 00 ee a 322 Trace legend symbols oo Boe eRe A ee ee de ERS eS 338 Section information message box 2 6 eee ee ee 339 Example schematic EXAMPLE OP 52 ea ee

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