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Laboratory Experiment 2 EE348L

1. HSpice user manual version 2001 4 is as follows tran resolution duration sweep parameter_name poi number_of_points valuel value University of Southern California EE348L page10 Lab 2 An example is shown below KEKE K K K K K K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK analysis section FR FAS 2g K K K ie K K ig K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK os K K K K K K K KK tran Ins 200ns sweep r2 poi 3 1k 10k 100k Exercise Rerun the SPICE netlist in Figure 2 5 with the modification to sweep the parameter r2 through three values of 1k 10k 100k Plot Vo What should the amplitude for Vo be for each case The transient analysis with the parameter sweep will produce multiple waveforms on the same panel in WaveView Analyzer To view which waveform corresponds to which parameter value you can click on the box next to the waveform name Then you can separate each waveform by right clicking in the panel the waveform names are located in 2 3 4 ALTER Statements In HSPICE embedded sweeps are not allowed Thus the ALTER statement can be used so that the same simulation is repeated for a different value of another parameter We will practice by changing the parameter opamp_gain using the ALTER statement page 3 40 of HSpice user manual version 2001 4 An HSpice simulation with n ALTER statements produces n 1 output files For a transient analys
2. for example options post 1 brief nomod alt999 accurate acct 1 opts 2 3 Voltage Controlled Voltage Sources VCVS In Exercise 2 of the laboratory exercises of laboratory 1 we modeled an operational amplifier using a voltage controlled voltage source VCVS These dependent sources are represented in SPICE using the E element University of Southern California EE348L page5 Lab 2 The syntax of the E element in SPICE is Ename n n p p gain lt MAX val gt lt MIN val gt Exxxis the name of the E element source such as Elor E2 There are four nodes in the dependent source command The first two nodes of the voltage controlled voltage source VCVS n and n represent the node numbers for the positive and negative ports of the output The second set of node numbers in and in represents the positive and negative nodes of source s reference voltage The gain of the VCVS is indicated by the value of gain The value of the output is dependent on the controlling voltage by a factor of the gain lt MAX val gt and lt MIN val gt are optional parameters that determine the maximum and minimum values the E element can assume during the course of the simulation In other words they specify the upper and lower limits on the voltage the dependent source can assume These keywords are very useful in modeling the limits placed by the power supplies on the output voltage of an op amp 2 3 1 Examples of VCVS statements E1231050 In the a
3. Gm expressions for the effective input resistance inductance and capacitance Reff Leff and Ceff respectively R L S Figure 2 12 Tuned circuit for VCCS problem 5 Zin s is the input impedance of the entire circuit to the right of the arrow B C Let the resonant frequency of the input impedance be denoted as What is in terms of inductances L L and capacitance Cin The resonant frequency is the frequency at which the imaginary impedances cancel each other out What design condition must be satisfied at the resonant frequency to achieve a purely real and matched impedance at the input port that is Zin j Rs Determine H s Q o and H and simplify for the case in part B You should be able to show that the transfer function can be cast in the form of a second order bandpass filter University of Southern California EE348L page21 Lab 2 H s H w 2 Ky Ky 1 Qw W What is the low frequency gain What is the high frequency gain What is the phase at resonant frequency in degrees D Model the amplifier in Figure 2 12 in SPICE using the SPICE Voltage Controlled Current Source VCCS element G Represent the core element of the amplifier as outlined by the dotted line box in Figure 2 12 as a sub circuit in your netlist Let G 2 5mmho R 50 Ohms C 50fF L 5nH and L 1nH Let L be a parameter with default value of InH a Perform an ac sweep from 100 MHz to 1THz v
4. K K K K K K K K K K K 2K K K KEEK K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK K K K K K K K K K K K K K K 2 K K begin output form section KKE K K K K K K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK K K K K K K K K K K K K 2k K 2 K K Before saving the file make sure to press return once and only once after END END Note Remember that SPICE is case insensitive 2 2 1 Options statements Options statements options are control statements to specify various parameters associated with the simulator A description of HSPICE options can be found on page 8 14 Chapter 9 pages 10 22 to 10 36 pages 11 24 to 11 26 and page12 7 of the HSPICE manual version 2001 4 December 2001 The following options are a useful set of options for the beginner options post 1 post output data associated with each node in the circuit page 9 14 options brief stop printback of netlist until options brief 0 is encountered page 9 6 options nomod do not print model decks which may be large page 9 9 options alt999 generate up to 1000 unique output run files page 9 5 options accurate useful for accurate simulation of large circuits page 9 40 options acct 1 reports job accounting and runtime statistics page 9 5 options opts print the current settings of all control options page 9 10 Multiple options may be combined on one line See
5. K ok ok KK vl inOac 1 KEKE K K K E K es K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK probe statement section KEEK fe fe 2g E K ae E K K K K fe K K K K 2S 2g K K K K K K K K K K K K K k K K K K K K KK k K K K K K K K og probe ac gain par v out v in probe ac gaindB par 20 log10 v out v in probe ac phase par vp out vp in FEE K K E E K 2 K K K K K K K K k K K K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK specify nominal temperature of circuit in degrees C EKEK K K K E K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K k KK K K K K K K K K KK TEMP 27 EEKE K K KE E K a K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK x analysis section FEE K K 2g E K ae K K K K K fe K K is K 2S ag K K K K K K K K K K K K K k K K K K K K KK k K K K K K K K 2 ac dec 100 10k 10G sweep rpar1 poi 3 100 1e3 1e4 alter param cpar1 100pF END Figure 2 8 HSPICE netlist highlighting ac analysis with parameter variation and user defined expression 2 3 5 6 Printing from HSPICE See Laboratory Experiment 1 section 1 9 3 for printing with Wave View Analyzer Another method is to use ctrl PrintScreen while a window containing the plot is open on your desktop Then the entire window can be pasted and edited before submitting 2 4 Voltage Controlled Current Sources VCCS University of Southern California EE348L page
6. and its phase in the dc ac or the tran analyses we have to be able to specify an expression for the transfer function Vo s Vin s and the phase shift from input to the output We use the PAR command to do so The syntax is described on page 7 8 of the HSpice user manual version 2001 4 The probe statement used to specify the graphical output of node voltages branch current and user defined expressions for a particular analysis is described in page 8 10 of the HSpice user manual version 2001 4 2 3 5 1 Plotting the transfer function We specify the ac plot of the transfer function v out v in where out and in are the output and input node names respectively as follows where gain is the user defined plot parameter probe ac gain par v out v in The ac plot of the transfer function expressed in dB terms is 20 log10 v out v in is probe ac gaindB par 20 log10 v out v in In the above expression log10 is the logarithm to base 10 and gaindB is the user defined plot parameter 2 3 5 2 Plotting the phase of the transfer function The phase of a node voltage or a branch current is specified by using vp node or ip branch_current as described on page 8 30 of the HSpice user manual version 2001 4 Accordingly the phase difference from input to the output is probe ac phase par vp out vp in where phase is the user defined plot parameter Note the type of analysis specified in the probe statements above m
7. n n transresistance current flowing through vname 2 6 1 Examples of CCVS statements H123V150 In the above example the output voltage of the CCVS H1 is between nodes 2and 3 The controlling or reference current is flowing through voltage source V1 in the circuit The gain of the CCVS is 50 Mathematically V 2 3 50 I V1 Note that optional parameter MAX and MIN are absent A CCVS can be used to model a device with finite gain and maximum and minimum limits on the value of the output voltage Hlimited out out V1 MAX 5V MIN 0V 1000 In the above example Hlimited models a device where V out out 1000 0 OI V1 with a maximum voltage of 5 0V and a minimum voltage of OV In many cases it is useful to parameterize the transresistance of a CCVS so that simulations that check the influence of varying transresistance can be run This is specified in HSpice as follows _param transres 2e5 Hlimited out out V1 MAX 5V MIN OV transres In the above example transresis a user defined parameter It is important to note that user defined University of Southern California EE348L page17 Lab 2 parameters should not be the same as SPICE commands or reserved keywords They should also be less than 16 characters in length Unpredictable results can occur if user defined parameters are not different from SPICE commands or reserved keywords Of all the dependent sources the CCVS is the least encountered source you wil
8. 14 Lab 2 Voltage Controlled Current Sources VCCS are dependent sources that are represented in HSpice using the G element page 5 34 of the HSpice user manual version 2001 4 The G element can also be used to describe a Voltage Controlled Resistor VCR or a switch page 5 35 of the HSpice user manual version 2001 4 The syntax of the G element in HSpice is Gxxx n n in in lt MAX val gt lt MIN val gt transconductance Gxxx is the name of the G element source such as G1 or G2 There are four nodes in the dependent source command The first two nodes of the voltage controlled current source VCCS n and n represent the node numbers for the positive and negative ports of the output The second set of node numbers in and in represents the positive and negative nodes of source s reference voltage lt MAX val gt and lt MIN val gt are optional parameters that determine the maximum and minimum values the G element can assume during the course of the simulation In other words they specify the upper and lower limits on the current the dependent source can assume These keywords are very useful in modeling the limits placed by the power supplies on the output current of the device The gain of the VCCS is indicated by the value of transconductance The value of the output is dependent on the controlling voltage by a factor of the transcondutance 2 4 1 Examples of VCCS statements G1231050 In the above example the output curr
9. 2 inm 0 r2 PRS FAS 2g 2g K K 2 E K 2 K K K K K fe K K is K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK k Darameters section KKK K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K K K param r2 1k param opamp_gain 1 FKK K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K 3K K K K K K K K K K K K K K K K K K K K x Sources section 2 2 2 KE K KE K K 2 K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K KK K K K K K K ok ok ok K vl in 0 sin OV 60mV 10x 100ps 0 FEE K K K E E K E K K K K K K K K k K OK K K K K K K K K K K K K K k K K K K K K KK k K K K K K K K KK specify nominal temperature of circuit in degrees C KEKE EK K KE E K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK TEMP 27 KEE KE K KE K E K K K K K K K K K K 2s K K a K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK xxx analysis section EEE K K KE E K 2 K K K K K K K K 2s K K K K K K K K K K K K K K K K K K K K K K Kk k K K K K K K K KK tran 1ns 200ns sweep r2 poi 3 1k 10k 100k alter param opamp_gain 1e2 ealter param opamp_gain 1e4 END Figure 2 6 HSPICE netlist for op amp circuit in Exercise 2 of lab assignment 1 with ALTER statements Exercise Rerun the HSPICE netlist in Figure 2 6 and plot the different output waveforms corresponding to each parameter value You should plot a total of three 3
10. K K K K K K 2 K K K K K K K K K K K K KK k K K K K K K K 2 options section FKK K K K K K K K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K K K options post 1 brief nomod alt999 accurate acct 1 opts FEE K K KE K K 2 K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K KK k K K K K K K K KK subcircuit section 2 2 2 KE K K K K K K K K K K K K K K K K E K K K K K K K K K K K K K K K K K K K K K of K K K K K K K ok ok KK subckt my_opamp in in out gain opamp_gain Rin in in 1G Rout out AOv Im University of Southern California EE348L page9 Lab 2 E1 AOv 0 in in gain MAX 5 MIN 5 ends FE AS 2g 2g K K ie K K ie K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK os K K K K K K K KK Circuit description KEEK K K K K K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK rs in inp 50 rl inp 0 1k x1 inp inm out my_opamp gain opamp_gain rf out inm 100K r2 inm 0 r2 KEKE K K K K K K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK Darameters section KEEK K K K K K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K 2 param r2 1k param opamp_gain 2e5 KEKE K K K K K K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK k Sources section 2 2k of KE KE KE K K E K K K K K K K K K K K K K K K K K K K K K K K
11. K K K K K K K K K K K K K K K K K K K K KK K K K K K K K 2K KK K K K K K K K K K K KK K 2 K K K begin description of top level circuit netlist KKE K K K K K K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK K K K K K K K K K K K K K 2K 2 K K KEEK K K ie K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K KK K 2s K K K K K K KK K K K K K K K K K K K K K K 2K K K begin parameters section KK K K K K K K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K 2K KK K K K K K K K K K K KK K 2K 2 K K KEKE K K K ie 2s K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K 2s K K K K K 2K KK K K K K K K K K K K K K 2k K 2K K K begin source section KKE K K K K K K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K 2K K K K K K 2K KK K K K K K K K K K K K K K 2K K K K KK K K K K K K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK K K K K K K K K K K K K K 2K 2K K K begin analysis section KEKE K K K K K K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK K K K K K K K K K K KK 2k K 2K K K KKK K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K K K K K 2k K 2 K K begin Model section KKE K K K ie K K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK K K K
12. K K K K K K K K K K KK K K K K K K K ok K K vl in 0 sin OV 60mV 10x 100ps 0 EKEK K K K K K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK xk specify nominal temperature of circuit in degrees C KEEK K K K K K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K K K TEMP 27 KEEK K K K K K K K K K K K K K K 2 K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK analysis section KEEK K K 2s K K K K K K K K K K K is K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK tran Ins 200ns END Figure 2 5 HSPICE netlist for op amp circuit in Exercise 2 of lab assignment 1 with supply limit of 5V for the op amp 2 3 3 Parameter sweep in DC AC TRAN analysis In this section we investigate parameter sweeping in the example netlist shown in Figure 2 5 for the circuit in Figure 2 4 Our goal is to determine how the transient waveforms in the example netlist changes as a function of the op amp gain that we parameterized using the parameter opamp_ gain in the subcircuit my opamp This kind of analysis is called sweeping a parameter or sweeping a variable Although this example is done using a transient analysis it can be done in both AC and DC analyses as well We change the analysis section in the above example to sweep the parameter r2 through three values 1k 10k and 100k The syntax page 11 4 transient sweep
13. Laboratory Experiment 2 EE348L B Madhavan Revised by Aaron Curry University of Southern California EE348L page1 Lab 2 Table of Contents 2 Experiment 2 SPICE Simulations IL cccsccssssscssssccssssccssssccsssscssssssssssees 4 2 1 Introductionis hada chaise ane the cee ee a aun ial 4 2 2 Good SPICE netlist writing practice 0 0 cee eeceeeeseecseceseceeceseceseeeseecsaecaeeeeeseeseeeeaeeeaeee 4 221 Options statements enei eiee e enea E E RE E A E A O A aE E 5 2 3 Voltage Controlled Voltage Sources VCVS ccccccessecsseceeseceeaeeceaeeceseeecaeceeaaeceeaeenaeeeaes 5 2 3 1 Examples of VCVS statement eresie cee esceseceseceeeesecneceseceseeeseceseseneecaaeaeeaeeees 6 2 3 2 Subcircuit representations sosen icsse i iiini i ia 8 2 3 3 Parameter sweep in transient analysis see eeeceeceseeereeeeeeseecaeeseeeseeeeeeenaeenaes 10 23 4 ALTER St tementS ennn esi eal ede er ih Gas a 11 2 3 5 Using the PAR expression cee n RE EE a a EE a E EE 12 2 3 5 1 Plotting the transfer fUNction cece cee ee eee e erence e te eneeneenaes 13 2 3 5 2 Plotting the phase of the transfer function e cece eee ener e eee eens 13 2 3 5 3 Printing from HSPICE 0 cece EEE ATE ERNES 15 2 4 Voltage Controlled Voltage Sources VCCS oo cee eeescssecsseceseceseeeseeeseeeseesaeceaeeeseeeaeenaees 15 2 4 1 Examples of VCCS statement iieis iiia ieat n nna 15 25 Current Controlled Current Sources CCCS ccccccccccsscccs
14. ain by using the following probe tran gain par v out v s What is the problem with plotting the gain this way Hint What vale does the input equal periodically C Now plot the gain by performing an AC sweep with Vs having a magnitude of 1 i If we want to sweep within 3 decades before and after frequencies of interest what frequency range should we sweep NOTE you should sweep 3 decades before the pole and 3 decades after the zero Vee Figure 2 10 A regular 741 op amp Figure 2 11 Equivalent circuit model of an op amp University of Southern California EE348L page20 Lab 2 5 The linear small signal model of a tuned amplifier which includes the input signal source is in Figure 2 12 The output or response Vo to the input signal Vs is developed across the output inductance Lo Gm models the transconductance of the amplifier The inductance L is a circuit element that is exploited to achieve maximum power transfer between the applied input signal and the amplifier input port whose input impedance is delineated as Zin s The inductance L is a circuit element that is used to tune the resonant frequency of the amplifier The output inductance L controls the gain at resonant frequency A Show that the indicated input impedance Zin s the input impedance of the entire circuit to the right of the arrow in Figure 2 12 can be expressed as Zin s R eet Let st Cof S Give in terms of Cin Ls Lg and
15. arying the value of L over three 3 values 1nH 5nH 10nH Plot gaindB phase zin and pin input power versus frequency on a logarithmic scale on separate panels As we alter L which plots should change refer to your answers in part C How should they change Do your simulations agree with your responses Make sure you zoom in on the Rin vertical axis so that the max value is 5000 b Calculate the values of the resonant frequency gain dB at resonant frequency phase at resonant frequency zin at resonant frequency and pin at resonant frequency for the default values the sweeps with L L 1nH Verify these values in HSpice with a cursor on your sweep NOTE zin and pin can be calculated as probe ac zin par v vs i vs rs probe ac pin par v inpAmp i vs Where vs is an AC source named vs between nodes vs and 0 and rs is a parameter that defines the value for R You should know that these are complex values whose magnitudes will be plotted Zin and Pin are only real at resonant frequency As shown below use a 1000 point decade sweep for the ac analysis ac dec 1000 1OOMEG 1T 6 Switched capacitor circuits are very important circuits for analog design They are used in filter applications and also for analog to digital conversion In these circuits transistors are turned on and off like switches In this exercise we will use the G element as a VCR model for transistors Figure 2 13 shows the circuit of a sw
16. ay be ac dc noise or tran permitting the graphical display of user defined expression in ac analysis dc analysis noise analysis and transient analysis SPICE netlist of circuit to demonstrate parameter sweep in ac analysis Written Jan 24 2005 for EE348L by Bindu Madhavan Edited July 10 2012 for EE348L by Aaron Curry KEKEKE K K 2s E K K K K K K K K K K k K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K 2 xk options section University of Southern California EE348L page13 Lab 2 FES AS 2k E K K 2g E K 2 E E K K K K K K K K 2S 2g K K K K K K K 2g K K K K K k K K K K K k Kk k K K K K K K K 2 options post 1 brief nomod alt999 accurate acct 1 opts EEK fe K 2 K K 2 K K K K K K K K K K 2S ag K K K K K K K K K K K K K K K K K K K K KK k K K K K K K K KK Circuit description KEKEE K K 2k E K ag is K K K K K K K K K KK K K K K K K K ig K K K K K K K K K K K K KK K K K K K K K K 2 R1 in out rpar1 C1 out 0 cpar1 FES FAS 2g 2s K fe 2 E K 2 K K K K K fe K K k K 2S 2s K K K K K K K K K K K K K k K K K K K k Kk k K K K K K K K 2 parameters section KEE KE K K KE E K K K K K K K K K K 2s K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK param rparl 1k param cparl 10pF KEEK K K K E K K K K K K K K K K 2s K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK x Sources section 2 2 2 KE K KE K K KE K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K KK K K K K K
17. bove example the output voltage of the VCVS E1 is between nodes 2and 3 The controlling or reference voltage is between nodes land 0 The gain of the VCVS is 50 Mathematically V 2 3 50 V 1 0 Note that the optional parameters MAX and MIN are absent A VCVS can be used to model an op amp with finite gain and maximum and minimum limits on the value of the output voltage Eopamp1 out out in in 200000 0 MAX 5V MIN 0V In the above example Eopamp1 models an op amp where V out out 200000 0 V in in with a maximum voltage of 5 0V and a minimum voltage of OV In many cases it is useful to parameterize the gain of a VCVS so that simulations that check the influence of varying gain can be run This is specified in HSpice as follows param opamp_gain 2e5 Eopamp out out in in opamp_gain MAX 5V MIN 0V In the above example opamp_gain is a user defined parameter It is important to note that user defined parameters should not be the same as SPICE commands or reserved keywords They should also be less than 16 characters in length Unpredictable results can occur if user defined parameters are not different from SPICE commands or reserved keywords University of Southern California EE348L page6 Lab 2 Rout wv Vo D t I 7 ma ee NA i AVK Rin gt VS e 5 I Rin gt A o Rout 0 a Figure 2 1 a VCVS conceptual representation of op amp b schematic representation Conceptually an ideal
18. d C1l 5pF Let tstep 1n and tstop 201n a Ifwe want to have a delay of Ins what should the delay of be We want no overlap and maximum separation between the on states of each phase What is the gain of this circuit What amplitude should V have b Plot Vin and Vou in separate panels Does Vin look like you expect What about Vou What happens to Vow in between opening up and closing Why Now you can see why it is important to have a reset on the output voltage It is also important that your output is able to settle to the desired value before opens Figure 2 13 A switched capacitor amplifier for problem 6 University of Southern California EE348L page23 Lab 2 closed Figure 2 14 Timing diagram for the switched capacitor circuit in problem 6 C P v a Vo Figure 2 15 Switched capacitor circuit during phase C P C p Mo Figure 2 16 Switched capacitor circuit during phase University of Southern California EE348L page24 Lab 2 29 General Report Format Guidelines 1 Introduction Explain what the lab is about Describe the circuits being built in terms of structure and purpose Also talk about what is being investigated 2 Procedure Step by step talk about what was done and show diagrams of the circuits 3 Data Present all data taken during the lab It should be organized and easy to read 4 Questions Answer all the questions in the lab 5 Discussion Discuss the
19. d all panels in the same window 3 Use the netlist in Figure 2 8 section 2 3 5 AC sweep example plot the user defined gaindB and phase plot parameters on separate panels on the same page for cpar1 100pF and rparl values of 100 1000 and 10000 ohms A What should the 3db frequency be for each rpar1 value B What should the phase at the 3db frequency be C Measure the 3 dB frequency of each LPF and the value of the phase of the transfer function of the circuit at the 3 dB frequency of each LPF Do your simulations agree with your hand calculations 4 Recall the circuit used from lab 1 exercise 2 with an added feedback capacitor University of Southern California EE348L page19 Lab 2 Figure 2 9 Feedback amplifier circuit schematic for problem 4 A Determine the new transfer function i How does the addition of C alter the transfer function Let R gt gt R and A gt gt Aj ii What is the low frequency gain in dB iii What is the high frequency gain in dB iv What is the time constant associated with pole caused by C y What is the time constant associated with the zero caused by C B Model the op amp using the models shown below Let Vcc Vee 10V Let A 80dB 100e6 Perform a transient analysis with Vs having amplitude of 100mV and a frequency of 1MHz i If we want to plot 10 periods what should tstop be ii If we want 100 points per period what should tstep be iii Attempt to plot the g
20. d keywords They should also be less than 16 characters in length Unpredictable results can occur if user defined parameters are not different from HSpice commands or reserved keywords See Chapter 7 of the HSpice user manual version 2001 4 Parameters and Functions 2 5 Current Controlled Current Sources CCCS Current Controlled Current Sources CCCS are dependent sources that are represented in HSpice using the F element page 5 46 of the HSpice user manual version 2001 4 In order to specify a current controlled dependent source we have to be able to specify the controlling current This is done in HSpice by using a voltage source of OV to measure the controlling current The syntax of the F element in HSpice is Fxxx n n vsens lt MAX val gt lt MIN val gt currentgain Fxxx is the name of the F element source such as F1 or F2 There are two nodes in the dependent source command The two nodes of the current controlled current source CCCS n and n represent the node numbers for the positive and negative ports of the output current source The parameter vsens represents the name of the voltage source element through which the controlling current flows lt MAX val gt and lt MIN val gt are optional parameters that determine the maximum and minimum values of output current the F element can assume during the course of the simulation In other words they specify the upper and lower limits on the current the depende
21. eaaaeseneeeseseaeeesaees 13 Figure 2 8 SPICE netlist highlighting ac analysis with parameter variation and user defined ERAIK EL L PEETS A TE sot ties AT S N IA A E E A AE 14 Figure 2 9 Tuned circuit for VCCS problem 5 ccccceeeeeeceeeeeeeeceaeeeeeeeeeeseaeeseeneeeseaaeeseaeeeseaeeeseaeeeees 19 Figure 2 10 A regular 741 OP AMD cee eeeceeeeeeeeneeeeeeeeaeeeeeeaaeeeeeeeaaaeeeeeeseaaeeeeeeeaaaeeeeseeaeeeeeeeaaeeeeeseaas 20 Figure 2 11 Equivalent circuit model Of AN OP AMP eee eeeeeee cece eeee ee ee ee teen ee eee eeaaeeeeeetaeeeeeeeaeeeeene 20 Figure 2 12 Tuned circuit for VCCS problem 5 Zin s is the input impedance of the entire circuit to the right Of the anw nesenie aa e E E A es ane EE AOAN Lear AENEA 21 Figure 2 13 A switched capacitor amplifier for problem 6 ssssssssssssssssssserisssssrrrsssrirrssriirnssrnennsssrennnns 23 Figure 2 14 Timing diagram for the switched capacitor circuit in problem 6 sssseesssessersssesrsssree 24 Figure 2 15 Switched capacitor circuit during phase Dy eeescccessesceeeeeeeeeeeeessneeeeeeseeesaeeeseesnsaeess 24 Figure 2 16 Switched capacitor circuit during phase Do ceeecececeeeceeeeeeeeeeeeaeeeseeeeseaaeseeeeeeeeeeeeaas 24 University of Southern California EE348L page3 Lab 2 2 Experiment 2 SPICE Simulations Part II 2 1 Introduction The objective of this laboratory assignment is to familiarize the student with 1 Good netlist writing practice A netlist is a text
22. ent of the VCCS G1 is between nodes 2 and 3 The controlling or reference voltage is between nodes 1 and 0 The gain of the VCVS is 50 Mathematically I 2 3 50 xV 1 0 Note that optional parameter MAX and MIN are absent A VCCS can be used to model a device such as a MOSFET with finite transconductance and maximum and minimum limits on the value of the output current GMOSFET1 out out in in MAX 5e 6A MIN 0A 200000 0 In the above example GMOSFET1 models a MOSFET where I out out 200000 0x V in in with a maximum current of 5e 6A and a minimum current of 0A The G element can also be used as a switch by making it a Voltage Controlled Resistor VCR Gswitch 2 0 VCR PWL 1 1 0 Ov 10meg 1v 1m The resistance between nodes 2 and 0 varies linearly from 10 meg to 1 m ohms when voltage across nodes 1 and 0 varies between 0 and 1 volt Beyond the voltage limits the resistance remains at 10 meg and 1 m ohms respectively In many cases it is useful to parameterize the transconductance of a VCCS so that simulations that check the influence of varying transconductance can be run This is specified in HSpice as follows _param transconductance 2e5 GMOSFET1 out out in in MAX 5e 6A MIN 0A transconductance University of Southern California EE348L page15 Lab 2 In the above example transconductance is a user defined parameter It is important to note that user defined parameters should not be the same as HSpice commands or reserve
23. file that contains a description of the circuit including all the sources in the circuit the type of analysis ac dc transient noise etc simulator control options to obtain a reasonable simulation of the circuit under consideration A netlist is generated by hand using a text editor in this course Dependent sources Subcircuit command DC AC TRAN sweep command Use of the ALTER command Use of PAR to define and plot user defined expressions for plotting gain and phase across arbitrary nodes in a circuit 7 Use of the measure command in WaveView Analyzer Ra i ee ed This laboratory assignment will use the small signal linear models discussed in class as the vehicle for highlighting the above Please ensure that you read the lab questions carefully and turn in all the requested material derivations SPICE simulation plots and explanations 2 2 Good SPICE netlist writing practice It is useful to learn to quickly get to the relevant section and page of the HSPICE manuals using the index and the search function available in adobe acrobat when a pdf file is being viewed The HSPICE user manual and the HSPICE models manual are posted on the class web site It is best to think of the netlist as comprising multiple sections The first line is the one line description of the circuit Following this line it is best to have a section that serves as the revision history of the netlist Each line begins with a comment character and end
24. is of netlist file mycircuit spice with 4 ALTER statements transient output files mycircuit trO mycircuit trl and mycircuit tr4 are produced Figure 2 6 shows the revised netlist of Figure 2 5 with ALTER statements The modified netlist statements are shown in bold blue text HSPICE netlist of Op amp circuit in Exercise 2 of lab 1 Written Jan 24 2005 for EE348L by Bindu Madhavan Edited July 10 2012 for EE348L by Aaron Curry KEEK K K ie K K ie K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK os K K K K K K K KK options section KEKE K K K K K K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK options post 1 brief nomod alt999 accurate acct 1 opts KEKE K K K K K K ig K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK os K K K K K K K 2 xk subcircuit section KEKE K K K K K K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK subckt my_opamp in in out gain opamp_gain Rin in in 1G Rout out AOv Im E1 AOv 0 in in gain MAX 5 MIN 5 ends PES FAS 2g 2g K K K K K ie K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK os K K K K K K K 2 circuit description KEKE K K K K K K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK rs in inp 50 rl inp 0 1k University of Southern California EE348L page11 Lab 2 xl inp inm out my_opamp rf out inm 100K r
25. itched capacitor amplifier During phase the switches are closed and the switches are open See Figure 2 15 During phase the switches are open and the switches are closed See Figure 2 16 The two phases do not overlap Their timing diagram is shown in Figure 2 14 For analysis assume the op amp is ideal A During phase what is the charge stored across C Use figure 2 15 B During phase what is the charge stored across C2 Use figure 2 16 C Using the conservation of charge what is the gain of this amplifier University of Southern California EE348L page22 Lab 2 D During phase the current in C flows to ground to the left to discharge the capacitor This current flows through capacitor C in the same direction At the end of 5 is V positive or negative Is this an inverting or non inverting amplifier E During phase what does V equal F During phase what does V equal Note this value is sampled at the end of phase G Verify your answers by simulating the circuit using HSPICE Use the model of an op amp from problem 4 Perform a transient analysis with V being a SIN wave with amplitude of 1V anda frequency of 1OMHz Let and be pulses with periods of Ins on times of 4ns and rise and fall times of lps Use voltage controlled resistors to model the switches with impedances going from 1MQ to 1mQ in the off and on states respectively Let C2 1pF an
26. l find The other three sources are encountered by the listed elements VCVS Op Amp VCCS MOSFET CCCS BJT 2 7 References 1 HSPICE user manual posted on EE348L class web site 3 EE348L Laboratory Experiment 1 Spring 2005 posted on EE348L class web site 4 J Choma EE348L Lecture Supplement 1 University of Southern California EE348L page18 Lab 2 2 8 Lab Exercises Note In your lab report include a clean printout of the SPICE netlist for each Lab question and its parts Take care that you do not make typographical errors as this can result in erroneous results and increase your debugging time Ensure that you use the correct dependent source Refer to section 1 9 of laboratory assignment 1 HSPICE Guidelines Review to refresh up on the HSPICE Guidelines When doing an AC sweep make sure the horizontal axis frequency is logarithmic 1 Perform the exercise in Section 2 3 3 Parameter sweep in DC AC TRAN analysis Calculate the gain for these three resistance values Justify that the results of the transient analysis simulations for the three r2 values of 1k 10k and 100k agree with your calculations by including a cursor Submit the plot of the transient analysis 2 Perform the exercise in section 2 3 4 ALTER Statements using the netlist in Figure 3 6 Submit a plot of the transient analysis results with the transient analysis for each value of parameter opamp_gain in a separate panel an
27. ned parameters should not be the same as HSpice commands or reserved keywords They should also be less than 16 characters in length Unpredictable results can occur if user defined parameters are not different from HSpice commands or reserved keywords See Chapter 7 of the HSpice user manual version 2001 4 Parameters and Functions 2 6 Current Controlled Voltage Sources CCVS Current Controlled Voltage Sources CCVS are dependent sources that are represented in SPICE using the H element page 5 42 of the HSpice user manual version 2001 4 In order to specify a current controlled dependent source we have to be able to specify the controlling current This is done in SPICE by using a voltage source of OV to measure the controlling current The syntax of the H element in SPICE is Hxxx n n vsens transresistance lt MAX val gt lt MIN val gt Hxxxis the name of the H element source such as Hlor H2 There are two nodes in the dependent source command The two nodes of the current controlled voltage source CCVS n and n represent the node numbers for the positive and negative ports of the output The parameter vsens represents the name of the voltage source element through which the controlling current flows The gain of the CCVS is indicated by the value of transresistance The value of the output is dependent on the controlling voltage by a factor of the transresistance The mathematical representation of the CCVS is V
28. nputs less than 200 uV the output voltage falls below 200 uV x 60000 12V and is limited by the MIN statement to 12V Revisiting exercise 2 of laboratory assignment 1 we would like to write a SPICE netlist incorporating University of Southern California EE348L page7 Lab 2 good netlist writing principles and the VCVS element we have reviewed so far In addition we would like to add the condition that its power supplies which are 5V and 5V limit the output of the op amp The idealized small signal model of op amp is shown in Figure 2 3 Figure 2 3 Idealized small signal model of op amp in Exercise 2 of lab assignment 1 The model in Figure 2 3 is represented as follows with in and in being the input terminals and out being the output terminal The gain of the op amp is opamp _gain _param opamp_gain 2e5 Rin in in 1G Rout out vZ Im El VZ 0 in in opamp_gain MAX 5V MIN 5V 2 3 2 Subcircuit representation An element like the op amp can be used many times in a circuit A hierarchical representation of the circuit netlist is facilitated by the notion of a subcircuit which is very similar to the concept of a function in programming languages The syntax of the subcircuit with terminal n1 n2 n3 etc is shown below pages 3 12 to 3 19 HSpice user manual version 2001 4 subckt subcircuit_name n1 n2n3 lt parameter_name value gt subcircuit description ends Very Important Point N
29. nt source can assume These keywords are very useful in modeling the limits placed on the output current The gain of the CCCS is indicated by the value of currentgain The value of the output is dependent on the controlling voltage by a factor of the currentgain The mathematical representation of the CCCS is I n n currentgain X current flowing through vsens currentgain X I vsens 2 5 1 Examples of CCCS statements F123 V150 In the above example the output current of the CCCS F1 is between nodes 2 and 3 The controlling or reference current is flowing through voltage source V1 in the circuit The current gain of the CCCS is 50 Mathematically 1 2 3 50 xI V1 Note that optional parameter MAX and MIN are absent A CCCS can be used to model a device with finite gain and maximum and minimum limits on the value of the output voltage Flimited out out V1 MAX 5A MIN 0A 1000 In the above example Flimited models a device where I out out 1000 0 xI V 1 with a maximum current of 5 0A and a minimum current of OA In many cases it is useful to parameterize the currentgain of a CCCS so that simulations that check the influence of varying currentgain can be run This is specified in HSpice as follows University of Southern California EE348L page16 Lab 2 param currentgain 2e5 Flimited out out V1 MAX 5A MIN 0A currentgain In the above example currentgain is a user defined parameter It is important to note that user defi
30. op amp is nothing more than a voltage controlled voltage source VCVS with infinite gain infinite input impedance and zero output impedance as shown in Figure 2 1 The op amp is usually represented schematically as a triangle with two input terminals and one output terminal the internal VCVS is implied Figure 2 2 Behavior of op amp output voltage assuming power supply 12V Practical op amps have finite but large gain with finite but large input impedances and finite but small output impedances In addition the power supplies of the op amp limit the maximum and minimum steady state output voltage that the op amp can assume The power supply is limited to a few volts for op amps in the lab this may be 12 V on integrated circuits perhaps as low as 1V The very large gain is true only for very small inputs signals and for input voltages greater than a certain value greater than 200 uV or less than 200 uV in Figure 2 2 the output simply clips at one of the supply rails determined by whether the input signal is positive or negative This value is determined by the open loop gain of the operational amplifier The SPICE model of the op amp in Figure 2 1 whose transfer characteristic is shown in Figure 2 2 is represented below E1 out 0 in in 60000 0 MAX 12V MIN 12V An input greater than 200 uV results in the output voltage greater than 200 uV x 60000 12V which is limited by the MAX statement to 12V Similarly for i
31. ote that the subcircuit ends with a ends statement The optional parameter_name value specifies the default value of a parameter specified in the subcircuit description The model in Figure 2 3 may be represented as a subcircuit as follows subckt my_opamp in in out ref gain opamp_gain Rin in in 1G Rout out A0Ov 1 El AOv ref in in gain MAX 5V MIN 5V ends A subcircuit is instantiated in a circuit as follows Xyyy nl n2 n3 lt parameter_name value gt University of Southern California EE348L pages Lab 2 Where Xyyyis the name of the subcircuit nl n2 n3etc are the node names or node numbers of the particular instantiation of the subcircuit in the top level circuit The optional parameter_name value sets the value of a parameter in the subcircuit definition for that particular subcircuit instantiation The subcircuit my_opamp is instantiated as follows X1 in in out vss my_opamp gain opamp_gain Where in in out and vss correspond to the terminals in in out and ref of the subircuit definition of my_opamp Figure 2 4 Op amp circuit in Exercise 2 of lab assignment 1 Using the subcircuit definition called my_opamp we can write down the SPICE netlist of the op amp circuit in Figure 2 4 as follows HSPICE netlist of Op amp circuit in Exercise 2 of lab 1 Written Jan 24 2005 for EE348L by Bindu Madhavan Edited July 10 2012 for EE348L by Aaron Curry FEE fe fe 2 K K 2 K K K K K K K K k K 2S a K
32. output waveforms one for each of the three opamp_gain parameter values of 1 100 and 2e5 Do the results match with your expectations 2 3 5 Using the PAR expression In this example we will review the use of the PAR expression in HSpice see page 7 8 of the HSpice user manual version 2001 4 to plot user defined expressions in the netlist R ValS C Vs University of Southern California EE348L page12 Lab 2 Figure 2 7 First order RC Low Pass Filter The circuit used in Laboratory 1 exercise 4 is shown in Figure 2 7 The HSPICE netlist for the ac analysis of Figure 2 7 is shown in Figure 2 8 Parameters rpar and cparlare used in the netlist to parameterize the value of resistance R and capacitance C in the first order RC LPF in Figure 2 7 These parameters are shown in quotes to highlight that expressions within quotes may be used instead of simple parameters where each expression involves multiple parameters see page 7 8 of the HSpice user manual version 2001 4 Analyzing the circuit we see that the circuit has a pole at o 1 RC radians per second rps 1 2mRC Hz In a first order LPF this is the 3 dB bandwidth of the circuit The transfer function of the circuit Vo s Vin s has a phase shift that begins to change from 0 to 45 degrees 7 4 radians at approximately o0 10 rps becomes 45 degrees 2 4 radians at o rps and 90 degrees at approximately 10 o rps In order to plot the transfer function
33. results you obtained What significance is there in the results How do they help your investigation Explain the meaning the numbers alone aren t good enough 6 Conclusion Wrap up the report by giving some comments on the lab Do the results clearly agree with what the lab was trying to teach Did you have any problems Suggestions 7 Attachments Attach all hand calculations and SPICE plots necessary NOTE You are turning in lab reports that are to be graded If you want good marks be sure to make the reports as neat and aesthetically appealing as possible If you refer to an attached plot include the page number If you refer to a hand calculation be sure to highlight what you are referring to on the page containing the hand calculation However including equations plots figures etc in the body of your report is good practice Be sure to include plot titles Be sure to include axis titles and units Lab reports are to be typed HANDWRITTEN REPORTS WILL NOT BE ACCEPTED LAB REPORTS ARE DUE AT THE BEGINNING OF THE NEXT LAB THEY WILL NOT BE ACCEPTED IF THEY ARE MORE THAN 15 MINUTES LATE University of Southern California EE348L page25 Lab 2
34. s with a carriage return obtained when the Enter key on the keyboard is pressed It is best to include a time date and time for each revision section This will help in debugging and communicating your circuit problems to another circuit designer This is a model of a typical SPICE input file Title This must be the first line It is used by WaveVeiw Analyzer when the results are displayed Description of the circuit s function including revision notes time and date KEKE K K K 2g K K K K K K K K K K K K K KK K K K K K K K ig K K K K K K K K K K K K KK K K K K K K K K KK K K K K K K K K K K K K K K K K K HSPICE options statements to control HSPICE simulator behavior Description of HSPICE options can be found on page 8 14 Chapter 9 pages 10 22 to 10 36 pages 11 24 to 11 26 and page12 7 of the HSPICE manual version 2001 4 December 2001 KKE K K K K K K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K KK K K K K K K K 2K KK K K K K K K K K K K K K K K K K K options post brief nomod alt999 KEE K K K E K K K K K K K K K K K K K KK K K K K K K K K K K K K K K K K K K K K K K K K K K K K K 2K KK K K K K K K K K K K K K K K 2K K K begin description of sub circuits KEK K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K K KK K K K K K K K K KK K K K K K K K K K K K K K K 2K K K University of Southern California EE348L page4 Lab 2 PRS AS 2g K K K K K K K K K K K K K K K K K KK
35. sssececsesseecsessececssseeeessseeeseneeeenes 16 2 5 1 Examples of CCCS statements 0 ec ceeceeesseeeseeeseceseceeeeeeeeeeeeeneeeseceaecaeenseeeeeeees 16 2 6 Voltage Controlled Current Sources CCVS o cccecccccececsseeeeseceeaceeeeeeceeeeeaeceeaeceeaeseaeeeeaes 17 2 6 1 Examples of CCVS statement oeeie poia ai E V aaiae 17 2 7 Referentes sits sanen cc sti Bas E T eee eens eae Mee a ea eae 18 2 8 Lab Exercises icsvecs csvaciteecesteateieeey ined asthe wei eles neds Shalala a ea eae 19 2 9 General Report Format Guidelines 0 0 0 ee eecseceeeceseeeeeeseeeseecsaeeseceseceseeeseeeaaecsaeneeeneeeaes 25 University of Southern California EE348L page2 Lab 2 Table of Figures Figure 2 1 a VCVS conceptual representation of op amp b schematic representation 7 Figure 2 2 Behavior of op amp output voltage assuming power supply 12V oe eeeeeeeeeeeees 7 Figure 2 3 idealized small signal model of op amp in Exercise 2 of lab assignment 1 8 Figure 2 4 Op amp circuit in Exercise 2 of lab assignment 1 cccccceseeeeeeeeeeeeeeeeseeeseeeeessaaeeeeees 9 Figure 2 5 SPICE netlist for op amp circuit in Exercise 2 of lab assignment 1 ccceeeeeee 10 Figure 2 6 SPICE netlist for op amp circuit in Exercise 2 of lab assignment 1 with ALTER st teme tS e a a a SEAT eds E E A cubes Che EA E EE 12 Figure 2 7 First order RC Low Pass Filter cccccccececeseeeeeeeeeeeeeeeeeeeeeceaeeeseaeesecaeee

Laboratory Experiment 2 EE348L

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