Home

Analog System Lab Manual 2E prelims

1. amplifier Output trimmer 12V Zn 1M Vin lt 150 V Two identical circuits reguired for two channels All resistors are 1 4 W 5 unless noted otherwise All capacitors are ceramic discs Oscilloscope probe Adapted from a circuit in by Tim Witham Horowitz P and Hill W 2nd ed 1989 The art of Electronics July 20 1996 Figure C 1 Buffer circuit needed to interface an analog sig Texas Lab Manual tlm 2012 8 14 14 55 page 11 Vour lt 12V to sound card line in buffer nal to oscilloscope 4 138 Appendix C 2 Limitations Not possible to display DC voltages as the input capacitor of sound card blocks DC Low frequency range 10 Hz 20 kHz Measurement is not very accurate Texas Lab Manual tlm 2012 8 14 14 55 page 115 139 Texas Lab Manual tlm 2012 8 14 14 55 page 116 140 2 lt LL A A lt Figure D 1 shows the overall floorplan of the ASLKv2010 Starter kit We have shown the power connections in ASLKv2010 Starter in Figure D 2 Note that the 10 V power and ground connections have to be connected to the power inlets at the side of the kit the power and ground is internally connected to the OPAMPs and ana log multipliers If you wish to carry out an experiment using the DAC integrated circuits on the board you must use an extern 5 V supply and ground connection as shown in Figure D 2 There are th
2. 100 kHz Crystal oscillator N x 100 kHz LPF Amplifier VCO Divided by Figure 7 4 Block diagram of frequency optimizer Texas Lab Manual tlm 2012 8 14 14 55 page 77 101 Texas Lab Manual tlm 2012 8 14 14 55 page 78 102 Me gt LLI j ab 49 AC O 8 1 Goal of the Experiment In the front end electronics of a system we may require that the gain of the amplifier is adjustable since the amplitude of the input keeps varying Such a system can be designed using feedback This experiment demonstrates one such system 8 2 Brief Theory and Motivation The reader will benefit from the recorded lectures at 27 Another useful reference is the application note on Automatic Level Controller for Speech Signals using PID Controllers 2 Texas Lab Manual tlm 2012 8 14 14 55 page 79 103 Figure 8 Automatic Gain Control AGC Automatic Volume Control AVC In the signal chain of an electronic system the output of the sensor can vary depend ing on the strength of the input To adapt to wide variations in the magnitude of the input we can design the amplifier such that its gain can be adjusted dynamically This is pos sible when the input signal has a narrow bandwidth and the control system is called Automatic Gain Control AGC Since we may wish to maintain the output voltage of the amplifier at a constant level we also use the term Automatic Volume Control AV
3. tlm 2012 8 14 14 55 page 95 119 Texas Lab Manual tlm 2012 8 14 14 55 page 96 120 lt gt LL a A lt Texas Instruments Analog ICs used in ASLKv2010 Starter kit A 1 TL082 JFET Input Operational Amplifier A 1 1 Features Low power consumption Wide common mode and differential voltage ranges Input bias and offset currents Output short circuit protection Low total harmonic distortion 0 003 Typ High input impedance JFET input stage Latch up free operation Texas Lab Manual tlm 2012 8 14 14 55 page 97 121 Output A V Inverting input A Output B Inverting input B Non inverting input A Ve Non inverting input B Figure A 1 TLO82 JFET input operational amplifier High slew rate 13 V s Typ Common mode input voltage range includes Ver A 1 2 Applications Instrumentation Amplifiers Filters A 1 3 Description The TL08x JFET input operational amplifier family is designed to offer a wider selection than any previously developed operational amplifier family Each of these JFET input operational amplifiers incorporates well matched high voltage JFET and bipolar tran sistors in a monolithic integrated circuit The devices feature high slew rates low input bias and offset currents and low offset voltage temperature coefficient Offset adjustment and external compensation options are available within th
4. 2012 8 14 14 55 page 37 61 Figure 3 1 Integrator 3 2 1 Integrators An integrator circuitthat uses an Op Amp is shown in Figure 3 1 Assuming A GB s the transfer function of the integrator is given by 1 Vo sR VAHE GB RC GB The output goes to saturation in practice To make it work a high valued resistance across C must be added in order to bring the Op Amp to the active region where it can act as an integrator 3 2 2 Differentiators A differentiator circuit that uses an Op Amp is shown in Figure 3 2 R Vi o Figure 3 2 Differentiator Texas Lab Manual tlm 2012 8 14 14 55 page 38 62 Again assuming that A GB s the transfer function of the differentiator is given by Vo sRC 8 j je 9 GB GB sRC 3 2 The output of the differentiator remains at input offset approximately 0 However any sudden disturbance at the input causes it to go to ringing at natural frequency cg 3 3 Specifications Fix the RC time constant of the integrator or differentiator so that the phase shift and magnitude variation of the ideal block remains unaffected by the active device parameters 3 4 Measurements to be Taken Time response Apply a step input and a square wave input to the integrator and study the output response Apply a triangular and square wave input to the differentiator and study the output response Frequency response Apply the sine wave input and stud
5. In the circuit of Figure 5 1 assume that VW Vi sin wt 0 5 3 Then the output of the multiplier is VV Vo cosp cos lot 5 4 2V Texas Lab Manual tlm 2012 8 14 14 55 page 55 79 b 1 Figure 5 2 Voltage controlled filter with frequency a gt y b x Ve 6 Texas Lab Manual tlm 2012 8 14 14 55 page 56 0 VCP VCF V 1 BPF V 2 BSF Figure 5 3 a A self tuned filter based on a voltage controlled filter or voltage controlled phase generator b a simple voltage controlled phase generator that can become part of a self tuned filter Texas Lab Manual tlm 2012 8 14 14 55 page 57 81 200 0 mV 400 0 mV 100 0 mV 20 0 ms 30 0 ms 40 0 ms 50 0 ms Time Figure 5 4 Output of the self tuned filter based on simulation V corresponds to BPF Vo2 corresponds to BSF is the control voltage and V is the input voltage After passing through the LPF the high frequency component gets filtered out and only the average value of output Vz remains Vay VoVp cos 5 5 2V dVay 5 6 Kod 0 5 6 Kog is called the phase detector sensitivity and is measured in Volts radians Texas Lab Manual tlm 2012 8 14 14 55 page 58 82 For 90 Vay becomes 0 This information is used to tune the voltage controlled filter VCF automatically wp of the VCF is give
6. 6 e 4 090 00000000 0 069068 000000 Texas Lab Manual tlm 2012 8 14 14 55 page 8 2 SL NO 0374 LNe YJ 5 OTOTAMISW 104 WesBelp p Q aunbily HM OLOZAMISV 104 LUBI BIG uld 2012 8 14 14 55 page 9 33 Texas Lab Manual tlm engineering students to perform analog lab experiments The main idea behind ASLKv2010 Starter kit is to provide a cost efficient platform or test bed for students to realize almost any analog system using general purpose ICs such as Op Amps and analog multipliers ASLKv2010 Starter kit comes with four general purpose operational amplifiers TLO82 and three wide bandwidth precision analog multipliers MPY634 from Texas Instruments There is also a provision to include a 12 bit parallel input multiplying digital to analog converter DAC7821 A portion of ASLKv2010 Starter kit is left for general purpose prototyping and can be used for carrying out mini projects The kit has a provision to connect 10 V DC power supplies The kit comes with the necessary short and long connectors as well as connectors for power sup plies Figure D 2 Appendix D shows the way power supply connections are made on ASLKv2010 Starter kit The 10 V supplies are connected internally to all the ICs that require 10 V supplies namely the operational amplifiers and the multipliers Since the DAC requires 5 V supply the student
7. Its differential X Y and Z inputs allow configuration as a multiplier squarer divider square rooter and other functions while maintaining high accuracy The wide band width of this new design allows signal processing at IF RF and video frequencies The internal output amplifier of the MPY634 reduces design complexity compared to other high frequency multipliers and balanced modulator systems It is capable of perform ing frequency mixing balanced modulation and demodulation with excellent carrier rejection An accurate internal voltage reference provides precise setting of the scale factor The differential Z input allows user selected scale factors from 0 1 to 10 using external feedback resistors A 2 4 Download Datasheet http focus ti com lit ds symlink mpy6 34 pdf A 3 DAC 7821 12 Bit Parallel Multiplying DAC A 3 1 Features 2 5V to 5 5 V supply operation Fast parallel interface 17 ns write cycle Update rate of 20 4 MSPS 10 MHz multiplying bandwidth 10V input Low glitch energy 5 nVs Texas Lab Manual tlm 2012 8 14 14 55 page 100 124 lour 1 20 Fes soe T DAC7821 lour2 VREF i 1 Power on Bi lout DB11 MSB R W 4 DB10 cS l A DAC7821 Deo 6 DBO LSB Input latch DB8 DB1 M l DB2 a 1 1 087 8 86 9 DBS Mo A edge cel DB5 DB4 4 DBO eee DB11 GND Figure A 3 DAC 7821 Digital to analog conv
8. 2012 8 14 14 55 page 118 142 U1P6 R10p 10k C8p R9p 47k H AUG R8p 2 2k 0 1 uF C7p iii R7p 1k R6p 1k 0 01 uF C5p iii U1P2 H U1P1 nnn U1P3 Rip 1k 00125 Cip i R2p 1k OtuF C2p it 3p 2 2k 0105 C3p 1 5 rt R4p 47k nnn IN tuF C4p 6 RSp 10k Figure D 3 Op Amp IC 1 Dual Op Amp with two amplifiers 1A and 1B connected in Type 1 configuration Inverting potmeters receives 10 V supply and ground connection The output of a potmeter can be used as a DC reference voltage or even as power supply for the DAC Figure D 3 shows the connections for Op Amp IC 1 which has two Op Amps connected in Type 1 inverting configuration The inverting terminal of Op Amp 1 A is connected to resistors through Berg pin connections Alp A2p R5p and Texas Lab Manual tlm 2012 8 14 14 55 page 119 143 0 01 uF C9p 0 tuF C10p O 1uF Clip U2P5 U2P7 ks jil 1uF 00 Figure 2 4 Op Amp IC 2 Dual Op Amp with two amplifiers 2A and 2B 2A can be connected in Type 1 configuration Inverting 2B is a spare U3P2 U3P1 100 Ii U3P3 Iil U3P5 U3P7 U3P6 ii Figure 2 5 Op Amp IC 3 Dual Op Amp with two spare amplifiers 3A and 3B to capacitors through the Berg pin connections C1p C2p C3p C4p Note that each Berg connection has three
9. Neither Wiley India nor the author shall be liable for any loss of profit or any other commercial damages including but not limited to special incidental consequential or other damages Disclaimer The contents of this book have been checked for accuracy Since deviations cannot be precluded entirely Wiley or its author cannot guarantee full agreement As the book is intended for educational purpose Wiley or its author shall not be responsible for any errors omissions or damages arising out of the use of the information contained in the book This publication is designed to provide accurate and authoritative information with regard to the subject matter covered It is sold on the understanding that the Publisher is not engaged in rendering professional services Trademarks All brand names and product names used in this book are trademarks registered trademarks or trade names of their respective holders Wiley is not associated with any product or vendor mentioned in this book Other Wiley Editorial Offices John Wiley amp Sons Inc 111 River Street Hoboken NJ 07030 USA Wiley VCH Verlag GmbH Pappellaee 3 D 69469 Weinheim Germany John Wiley amp Sons Australia Ltd 42 McDougall Street Milton Queensland 4064 Australia John Wiley amp Sons Asia Pte Ltd 1 Fusionopolis Walk 07 01 Solaris South Tower Singapore 138628 John Wiley amp Sons Canada Ltd 22 Worcester Road Etobicoke Ontario Canada M9W 1 First Edition 20
10. The DAC7821 is available in a 20 lead TSSOP package A 3 4 Download Datasheet http focus ti com lit ds symlink dac7821 pdf A 4 TPS40200 Wide Input Non Synchronous Buck DC DC Controller A 4 1 Features Input voltage range 4 5 to 52 V Output voltage 700 mV to 90 V n Texas Lab Manual tlm 2012 8 14 14 55 page 102 126 TPS40200 FB4 E A and SS SS reference gt 8 VDD GDRV voltage swing limited to V 8V b Figure A 4 TPS40200 DC DC controller 200 mA internal P Channel FET driver Voltage feed forward compensation Under voltage lockout Texas Lab Manual tlm 2012 8 14 14 55 page 103 127 Programmable fixed frequency 35 500 kHz operation Programmable short circuit protection Hiccup overcurrent fault recovery Programmable closed loop soft start O 700 mV 1 reference voltage DB External synchronization PB Small 8 pin SOIC D and QFN DRB packages A 4 2 Applications Industrial control Distributed power systems 6 DSL Cable modems Scanners Telecom A 4 3 Description The TPS40200 is a flexible non synchronous controller with a built in 200 mA driver for P channel FETs The circuit operates with inputs up to 52 V with a power saving feature that turns off driver current once the external FET has been fully turned on This feature extends the flexibility of the device allowing it to operate wi
11. circuits like AGC AVC Ground and power supplies are provided internally to the DAC Pins U9P3 and U8P3 of DAC1 and DAC2 are to be grounded and U9P18 and Texas Lab Manual tlm 2012 8 14 14 55 page 13 37 U8P18 of DAC1 and DAC2 are to be connected to 5 V In order to use the DAC inte grated circuit on the ASLKv2010 Starter kit the external connections shown in Figure 0 6 are required The kit has a provision to connect 10 V power supplies In addition using the potentiometers variable voltage can be obtained if needed for any circuit or IC All the ICs on the board except DAC are internally connected to power supply but in case external connection is required it can be taken easily from Power Distribution Pins Please refer to Appendix D for experimental configurations of ASLKv2010 Starter Kit The top left portion of the kit is a general purpose area which uses a proto board 0 6 Organization of the Manual There are 10 experiments in this manual and the next 10 chapters are devoted to them We recommend that in the first cycle of experiments the instructor introduces the ASLKv2010 Starter kit and ensure that all the students are familiar with a SPICE based simulation program A warm up exercise can be included where the students are asked to use such a simulation program For each of the experiments we have Clarified the goal of the experiment and provided the theoretical background The Ana log System Lab can
12. plugged into laptops so that the laptop can work as an oscilloscope See 30 Alternately we also provide an experiment that helps you build a circuit to directly interface analog outputs to a PC See Appendix C 6 Dual power supply with the operating voltages of 10 V Function generators which can operate in the range on 1 to 10 MHz and capable of generating sine square and triangular waves A computer with simulation software such as TINA 9 or PSPICE 32 and design software from Texas Instruments FilterPro and SwitcherPro installed on it 0 3 1 Important Notes In all the experiments of Analog System Lab please note the following When we do not explicitly mention the magnitude and frequency of the input waveform please use 0 to 1 V as the amplitude of the input and 1 kHz as the frequency Texas Lab Manual tlm 2012 8 14 14 55 page 6 30 Always use sinusoidal input when you plot the frequency response and use square wave input when you plot the transient response 9 s Note to students With every experiment we have included tables that can be used to record the experimental data that you collect during the experiment We have shown four blank entries in every table to illustrate the type of data the student must collect the student must actually record many more data points 0 Precaution Please note that 11082 is a dual Op Amp This means that the IC has two Op Amp circuits If yo
13. 1 f f being the input frequency Figure 3 4 shows sample output waveforms obtained through simulation In Figure 3 4 a the input waveform is a square wave the triangular waveform is the output of the integrator and the ringing waveform is Table 3 1 Plot of magnitude and phase w rt input frequency for the integrator S No InputFrequency Magnitude Phase 62 ROUN Texas Lab Manual tlm 2012 8 14 14 55 page 40 4 10 00 VF 40 00 80 00 VF 10 00 90 00 VE 88 00 0 00 VF 300 00 Freguency Hz Figure 3 3 Frequency response of integrator and differentiator Table 3 2 Plot of magnitude and phase w rt input frequency for the differentiator S No Input Frequency Magnitude Phase oFrFwWwWN the output of the differentiator We leave it as an exercise for the student to figure out which are the outputs of the integrator and differentiator in Figure 3 4 b Texas Lab Manual tlm 2012 8 14 14 55 page 41 65 A ndino A nding Time ms b Figure 3 4 Outputs of integrator and differentiator for a square wave b triangular wave inputs 2012 8 14 14 55 page 42 66 em Texas Lab Manual Table 3 3 Variation of peak to peak value of output w rt peak value of input S No Peak Value of Input V Peak to Peak Value of Output 15 O MN 3 6 Exercise Groun
14. 10 0 r 10 0 5 0 0 5 0 10 0 Input voltage V Figure 1 7 Transfer characteristics of unity gain non inverting and inverting amplifiers 1 4 Measurements to be Taken Time response Apply a square wave of fixed magnitude and study the effect of slew rate on the three types of feedback amplifiers namely unity gain inverting and non inverting amplifiers Frequency response Obtain the gain bandwidth product of the three types of feed back amplifiers namely unity gain inverting and non inverting amplifiers from the frequency response If we refer to the gain of the feedback amplifier as A and the bandwidth of the feedback amplifier as notice that 4 0 GB This illustrates the tradeoff between gain and bandwidth in a feedback amplifier Texas Lab Manual tlm 2012 8 14 14 55 page 22 46 b Figure 1 8 Instrumentation amplifier configurations with a three b two operational amplifiers 6 DC transfer characteristics When we increase the gain of the feedback amplifier the input range over which the output of the amplifier remains inear with respect to input voltage will begin to reduce In fact this range is given by 2 4 From the DC transfer characteristic of Table 1 4 determine the input range of the amplifier where the output remains linear with respect to the input voltage Texas Lab Manual tlm 2012 8 14 14 55 page 23 47 Determine the second pole of an Op
15. 11 00 13 00 m 15 00 m 17 00 m Time s Figure 6 3 b Simulation of the function generator of Figure 6 3 a a A digitally controlled oscillator DCO is shown in Figure 6 4 The frequency of oscillation is given by 1 Ao2 1 7 i ARC Ra 4096 R 1 kand C 1 uF Rj M 1k Determine the maximum and minimum frequency of oscillation in the linear range b Design a digitally controlled Band Pass filter with 0 10 using the same integrator with multiplying DAC Ra DAC7821 Vet Figure 6 4 Digitally Controlled Oscillator DCO Texas Lab Manual tlm 2012 8 14 14 55 page 70 94 ab gt ab L ab 49 AS O 7 1 Goal of the Experiment The goal of this experiment is to make you aware of the functionality of the Phase Locked Loop commonly referred to as PLL The PLL is mainly used for generating stable high frequency clocks in the 100 MHz GHz range 7 2 Brief Theory and Motivation Crystals can be used to generate stable clocks in the range of a few hundreds of kilo hertz to a few megahertz If we need stable clocks of much larger frequency we can use the clock waveform from the crystal source as a reference clock and additional analog circuits to multiply the frequency of the reference clock Such a circuit is called Texas Lab Manual tlm 2012 8 14 14 55 page 71 95 a Phase Locked Loop The reader will
16. 55 page 63 87 Texas Lab Manual tlm 2012 8 14 14 55 page 64 88 6 1 Goal of the Experiment The goal of this experiment is to design and build a function generator capable of generating a square wave and a triangular wave of a known frequency f We will also convert a function generator to a Voltage Controlled Oscillator which is a versatile building block that finds numerous applications 6 2 Brief Theory and Motivation The function generator circuit consists of a feedback loop which includes a Schmitt trigger and an integrator Recall that the Schmitt trigger is a two bit A D converter at Vss levels If the integrator in a function generator is replaced by a combination of a Texas Lab Manual tlm 2012 8 14 14 55 page 65 89 Figure 6 1 Voltage Controlled Oscillator VCO multiplier and an integrator we get a Voltage Controlled Oscillator VCO as shown in Figure 6 1 You will benefit from listening to the recorded video lectures from 28 The output of the VCO is shown in Figure 6 2 The function generator produces a square wave at the Schmitt trigger output and a triangular wave at the integrator output with the frequency of oscillation equal to f 1 4RC R2 R1 The function generator circuit can be converted as a linear VCO by using the multiplier integrator combination as shown in Figure 6 1 The frequency of oscillation of the VCO becomes 6 8 Kuco the sensitivity of
17. Description 100 A 2 4 Download Datasheet 100 A 3 DAC 7821 12 Bit Parallel Multiplying DAC 100 A 3 1 Features 100 32 Applications 101 A 3 3 Description 102 A 3 4 Download Datasheet 102 A 4 540200 Wide Input Non Synchronous Buck DC DC Controller 102 A 4 1 Features 102 A 4 2 Applications 104 Texas Lab Manual tlm 2012 8 14 14 55 page xviii 14 A 4 3 Description A44 TPS40200EVM 002 A 4 5 Download Datasheet A 5 TLV700xx 200mA Low IQ Low Dropout Regulator for Portables A 5 1 Features A 5 2 Applications A 5 3 Description A 5 4 TLV70018EVM 503 Evaluation Module A 5 5 Download Datasheet B Introduction to Macromodels B 1 Micromodels B 2 Macromodels C Activity To Convert your PC Laptop into an Oscilloscope C 1 Introduction C 2 Limitations D System Lab Kit ASLKv2010 Starter Kit Connection Diagrams Bibliography Index Texas Lab Manual thm 2012 8 14 14 55 page xix 5 104 105 105 105 105 106 106 107 107 109 110 112 113 113 115 117 125 129 Texas Lab Manual tlm 2012 8 14 14 55 page xx 16 0 1 Signal chain in an electronic system 2 0 2 Dependence among experiments on the ASLKv2010 Starter 5 0 3 Picture of ASLKv2010 Starter kit 8 0 4 Pin diagram for ASLKv2010 Starter kit 9 0 5 External connections needed for using the analog multiplier 13 0 6 External connections needed for using the DAC 13 1 1 An ideal dual input sin
18. Figure 1 6 illustrates the frequency response magnitude and phase of the three different negative feedback amplifier topologies Vai is the frequency response of the unity gain amplifier Vais the frequency response of the non inverting amplifier 6 3 is the frequency response of the inverting amplifier The figure also shows the time domain response of the amplifier Figure 1 7 shows the output of the three types of amplifiers for a square wave input illustrating the limitations due to slew rate 1 3 Specifications Design the following amplifiers a a unity gain amplifier b a non inverting ampli fier with a gain of 2 Figure 1 5 a and an inverting amplifier with the gain of 2 Figure 1 5 b Texas Lab Manual tlm 2012 8 14 14 55 page 20 44 1 0M Frequency Hz x os or T 200 0 200 0 100 0 k Bep eseud gt 5 Q 20 0mV 10 0mV yndino 10 0mV 20 0mV 500 0 300 0 400 0 Time ns 200 0 100 0 b a Frequency response of negative feedback amplifiers b time response Figure 1 6 of negative feedback amplifiers Texas Lab Manual tlm 2012 8 14 14 55 page 21 45 Non inv amp gain 3 10 0 5 0 i ae Unity gain Output Opec sees eet voltage V i 1 i 5 04 sta vallal ee Inv amp gain 2
19. Fundamental Frequency 48 49 53 Gain Bandwidth Product 19 22 Gain Stage 4 Gain Closed Loop 16 Gain Open Loop 16 Gain Bandwidth Product 16 GB 16 Grounded Capacitor 43 Harmonics 49 60 High pass Filter 46 Hysteresis 27 29 INA1xx 27 Instrumentation Amplifier 4 26 Integrator 4 39 55 66 Inverting Amplifier 26 Inverting Schmitt Trigger 30 LC Filter 86 LDO 91 Line Regulation 93 Load Regulation 93 Lock Range 60 72 73 79 Low Noise 82 Low Dropout Regulator 92 111 Low Pass Filter 46 50 53 Macromodel 4 24 112 Magnitude Response 19 46 50 Micromodel 110 Mixed mode 4 Mixer 4 MODEM 66 Modulator 4 Monostable Multivibrator 32 33 MPY634 11 50 99 Multiplier 55 Natural Frequency 18 Negative Feedback 16 Noise 37 Non inverting Amplifier 20 Non inverting Schmitt Trigger 31 OPA3xx 27 OPA7xx 27 Operational Amplifier 4 11 97 101 Oscillation 66 73 Oscillator 4 66 Oscilloscope 6 24 81 113 Output Characteristic 94 Phase Detector 4 51 58 Phase Response 46 51 PID Controller 71 PLL 72 73 Power Supply 13 107 Power Amplifier 29 85 Prototyping 8 PSPICE 9 PWM 27 86 Quality Factor 18 40 Reference Voltage 86 Regenerative Feedback 34 Regulator 82 105 Ringing 18 Ripple Rejection 94 95 Rise Time 4 Sampling 4 Saturation Limit 16 Schmitt Trigger 66 Second Order System 18 Se
20. ON Table 1 3 Plot of magnitude and phase variation w rt input frequency S No Input Frequency Magnitude Variation Phase Variation 15 ON gt Table 1 4 DC transfer characteristic S No DC InputVoltage DC Output Voltage 15 ON gt 1 6 Exercises Design an instrumentation amplifier of a differential mode gain Ag of 3 using three Op Amps Refer to Figure 1 8 a for the circuit diagram and determine the values of the resistors Assume that the resistors have tolerance 6 of 1 and deter mine the Common Mode Rejection Ratio CMRR of the setup using the following equation curr 29 2 5 Estimate the bandwidth of the instrumentation amplifier We invite the reader to view the recorded lecture 20 Texas Lab Manual tlm 2012 8 14 14 55 page 25 49 Design an instrumentation amplifier with a differential mode gain Ag of 5 using two Op Amps Refer to Figure 1 8 b for the circuit diagram and determine the values of the resistors Assume that the resistors have 1 tolerance and determine the CMRR of the setup Estimate the bandwidth of the instrumentation amplifier 9 Figure 1 9 a shows an inverting amplifier whose gain is inversely proportional to the control voltage V3 Show that the gain of the amplifier is 10 5 Remember that the multiplier has a scaling factor of 0 1 V Measure the gain and bandwidth of the amplifier when V3 1V Repeat this experiment for V3 2V and 5 V How is this amplifier topology
21. U8P17 U8P16 U8P15 U8P14 U8P13 U8P12 7821 DAC 1 vlads aalala plom olala alla pla a 7821 DAC 1 15V lt Vp lt 15 V O 10k 0 OV Von Reg ail DAC7821 10 V lt Vour lt 10 V b Figure D 8 a PCB connections for the DAC on ASLKv2010 Starter b external connections needed to use the DAC to make it four quadrant Texas Lab Manual tlm 2012 8 14 14 55 page 123 7 Texas Lab Manual tlm 2012 8 14 14 55 page 124 148 my SL NO 0374 1 ADCPro TM Analog to Digital Conversion Evaluation Software Free Available from http focus ti com docs toolsw folders print adcpro html 2 F Archibald Automatic Level Controller for Speech Signals Using PID Controllers Application Notes from Texas Instruments Available from http focus ti com lit wp spraaj4 spraaj4 pdf 3 High Performance Analog Available from www ti com analog 4 Wide Bandwidth Precision Analog Multiplier MPY634 Burr Brown Products from Texas Instruments Available from http focus ti com lit ds sbfs017a sbfs017a pdft 5 B Carter and T Brown Handbook Of Operational Amplifier Applications Texas Instru ments Application Report 2001 Available from http focus ti com lit an sboa092a sboa092a pdf 6 B Carter Op Amp and Comparators Don t Confuse Them Texas Instruments Application Report 2001 Available from http tinyurl com carter opamp comp 7 B Carter Filter Desig
22. We hope you and your students will find the Analog Systems Lab Kit and the exper iments in this manual rewarding We intend to continue to develop more experiments and learning materials in the future we will share them on the TI India University Pro gram website www uniti in We are eager to know your critique of the kit as well as the manual Do write to us K R K Rao C P Ravikumar November 2010 Texas Instruments India Bagmane Tech Park CV Raman Nagar Bangalore 560093 India Texas Lab Manual tlm 2012 8 14 14 55 page xi 47 Texas Lab Manual tlm 2012 8 14 14 55 page xii 8 0 1 0 2 0 3 0 4 0 5 0 6 Texas Lab Manual tlm 2012 8 14 14 55 page xiii 9 Analog System Lab Organization of the Analog System Lab Course Lab Setup 0 3 1 Important Notes System Lab Kit ASLKv2010 Starter An Overview 0 4 1 Hardware 0 4 2 Software Familiarizing with ASLKv2010 Starter Kit Organization of the Manual 1 Experiment1 Negative Feedback Amplifiers and Instrumentation Amplifier 15 1 1 Goal of the Experiment 15 12 Brief Theory and Motivation 15 1 2 1 Unity Gain Amplifier 15 1 3 Specifications 20 1 4 Measurements to be Taken 22 1 5 What Should you Submit 24 1 6 Exercises 25 1 7 Other Related ICs 28 1 8 Related Reading 28 2 Experiment 2 Regenerative Feedback System Astable and Monostable Multivibrator 29 2 1 Goal of the Experiment 29 2 2 Brief Theory and Motiv
23. a astable multivibrator b monostable multivibrator OFF state for a period equal to t The equation for t is shown below 1 After triggering the monostable at time t the next trigger pulse must be applied after t t The formula for z is given below z RCln 2 6 B Texas Lab Manual thm 2012 8 14 14 55 page 33 57 Figure 2 6 Monostable multivibrator 2 3 Specifications Design a regenerative feedback circuit with a hysteresis of 1 V Refer to Figure 2 3 for the circuit diagram 2 4 Measurements to be Taken Obtain the DC transfer characteristics of the system Estimate the hysteresis and see how it can be controlled by varying the regenerative feedback factor Vary either A or Ro in order to vary 6 Apply the triangular waveform with the peak voltage of 10 V at a given frequency and observe the output waveform Observe the delay between the input and the output waveforms at the zero crossover point Enter the reading of the delay in the rightmost column of the Table 2 1 As you vary the hysteresis the delay must also vary in direct proportion to the hysteresis Texas Lab Manual tlm 2012 8 14 14 55 page 34 58 Table 2 1 Plot of hysteresis w rt regenerative feedback S No Regenerative Feedback Factor 8 Hysteresis Width Delay 15 62 92 2 5 What Should you Submit Use Table 2 1 to note down your readings Submit the DC transfer characteristics obtaine
24. be Taken 68 6 5 What Should you Submit 68 6 6 Exercises 69 7 Experiment 7 Phase Locked Loop 71 7 1 Goal of the Experiment 71 7 2 Brief Theory and Motivation n e Phase Lock Loop 7 3 Specifications 73 7 4 Measurements to be Taken 73 7 5 What Should you Submit 74 7 6 Exercises 75 Texas Lab Manual thm 2012 8 14 14 55 page xvi 12 8 Experiment 8 Automatic Gain Control AGC Automatic Volume Control AVC 79 8 1 Goal of the Experiment 79 8 2 Brief Theory and Motivation 79 e Automatic Gain Volume Control 8 3 Specification 81 8 4 Measurements to be Taken 81 8 5 What Should you Submit 81 8 6 Exercises 82 9 Experiment 9 DC DC Converter 85 9 1 Goal of the Experiment 85 9 2 Brief Theory and Motivation 85 e DC DC Converter e Class D Power Amplifier 9 3 Specification 86 9 4 What Should you Submit 86 9 5 Exercises 89 10 Experiment 10 Low Dropout LDO Linear Regulator 91 10 1 Goal of the Experiment 91 10 2 Brief Theory and Motivation 91 e Linear Regulator 10 3 Specifications 92 Texas Lab Manual tlm 2012 8 14 14 55 page xvii 13 10 4 Measurements to be Taken 94 10 5 What Should you Submit 94 10 6 Exercises 95 A ICs used in ASLKv2010 Starter Kit 97 A 1 TL082 JFET Input Operational Amplifier 97 A 1 1 Features 97 A 1 2 Applications 98 A 1 3 Description 98 A 1 4 Download Datasheet 98 A 2 MPY634 Wide Bandwidth Analog Precision Multiplier 99 A 2 1 Features 99 22 Applications 99 A 2 3
25. be conducted parallel to a theory course on Analog Design or as a separate lab that follows a theory course The student should have the following skills to pursue Analog System Lab Basic understanding of electronic circuits Basic computer skills required to run the tools such as TINA PSPICE FilterPro and SwitcherPro Ability to use the oscilloscope Concepts of gain bandwidth transfer function filters regulators and wave shaping Texas Lab Manual tlm 2012 8 14 14 55 page 14 38 ab ab AC O 1 1 Goal of the Experiment The goal of this experiment is two fold In the first part we will understand the applica tion of negative feedback in designing amplifiers In the second part we will build an instrumentation amplifier 1 2 Brief Theory and Motivation 1 2 1 Unity Gain Amplifier An Op Amp 8 can be used in negative feedback mode to build unity gain amplifiers non inverting amplifiers and inverting amplifiers While an ideal Op Amp is assumed to have infinite gain and infinite bandwidth real Op Amps have finite numbers for these Texas Lab Manual tlm 2012 8 14 14 55 page 15 39 parameters Therefore itis important to understand some limitations of real Op Amps such as finite Gain Bandwidth Product GB Similarly the slew rate and saturation lim its of an operational amplifier are equally important Given an Op Amp how do we measure these par
26. benefit from viewing the recorded lecture at 24 The PLL uses the same concept that was introduced earlier in this lab namely self tuned filter Experiment 5 If we replace the voltage controlled phase generator voltage controlled filter with a VCO we obtain a PLL This is shown in Figure 7 1 The sensitivity of the PLL is given by Kyco dw 000 7 1 veo gy 7 1 Lock range b Figure 7 1 a Phase Locked Loop PLL circuit b characteristics of the PLL Texas Lab Manual tlm 2012 8 14 14 55 page 72 96 Here V 4V RC is the frequency of oscillation of the VCO Therefore do 1 K ET E V veo ay Tae T e When no input voltage is applied to the system the system oscillates at the free running frequency of the VCO given by oga with corresponding control voltage of Vcg If an input voltage V with the frequency same as wg is applied the PLL will continue to run at the free running frequency and the phase difference between the two signals W and V gets adjusted to 90 since V is 0 This was explained in Chapter 5 As the frequency of input signal is changed the control voltage will change correspondingly so as to lock the frequency of the output to the input frequency As a result there the phase difference between the input and output signals shifts away from 90 The range of input frequencies for which the output frequency gets locked to the input frequency is called the lock ran
27. generator Build the function generator in ASLKv2010 Starter kit and observe the wave forms generated by the circuit on an oscilloscope Compare the results with simulation results Vary the control voltage of the VCO and see its effect on the frequency of the output waveform Measure the sensitivity Kyco of the VCO Use Table 6 1 to note your readings and compute the sensitivity Texas Lab Manual tlm 2012 8 14 14 55 page 68 92 Table 6 1 Change in frequency as a function of control voltage S No Control Voltage V Change in Frequency 1 2 3 4 6 6 Exercises Design a function generator that can generate square wave and triangular wave outputs of 10 kHz frequency Apply 1V 1 kHz square wave over 2 V DC and observe the FSK for a VCO designed for 10 kHz frequency 9 For the function generator of Figure 6 3 a which uses Deboo s integrator and an inverting Schmitt trigger determine the frequency of oscillation Transform this circuit into a VCO using an analog multiplier a 3 1k NV VIIL J Po 1k Ls 2 VF ene 0 H TL082 Riik U TLO8 AAA VA 12 J VF 8 4 Up TL082 C 1u R 1 k Figure 6 3 a Function generator Texas Lab Manual tlm 2012 8 14 14 55 page 69 93 20 00 10 00 m T J 0 00 Output 10 00 20 00 m
28. http tinyurl com ti macromodels 35 How to use PC as Oscilloscope Available from www trickswindows com 36 Zelscope Oscilloscope and Spectrum Analyzer Available from www zelscope com Texas Lab Manual tlm 2012 8 14 14 55 page 127 151 Texas Lab Manual tlm 2012 8 14 14 55 page 128 152 Kpa 58 73 Kycr 59 Kyco 3 0 18 38 wai 17 og2 17 8 FilterPro 6 10 50 SwitcherPro 6 TINA TI 6 9 A D Converter 65 AGC 13 79 80 Analog Comparator 4 Analog Multiplier 11 99 Astable Multivibrator 33 Automatic Level Controller 79 AVC 79 Band Pass Filter 46 70 Band Stop Filter 46 Bandwidth 25 Buck Controller 105 Buck Converter 105 Buffer Amplifier 114 Butterworth Filter 50 CCCS 16 Class D 29 66 85 88 Clock Generator 11 CMRR 25 Communication Circuits 4 Control Voltage 58 73 81 Crystal 71 DAC 12 65 DAC7821 63 101 Damping Factor 18 DC Analysis 110 DC DC Converter 85 86 87 91 92 Delay Time 4 Demodulator 4 Differential Equation 35 Differentiator 4 39 Digital to Analog Converter 102 Distortion Analyzer 49 Dominant Pole 17 Fall Time 4 Feedback 16 Filter 4 49 Filter Design 50 FM 4 66 Frequency Compensation 17 Texas Lab Manual tlm 2012 8 14 14 55 page 129 153 Frequency Response 18 24 50 Frequency Synthesizer 68 78 FSK 66 Function Generator 4 65 65 66 81
29. pins and the user can use any one of them for making an electrical connection The Op Amp 1 B is connected to resistors through Berg pin connections R6p A7p R10p and to capacitors through Berg pin connections Texas Lab Manual tlm 2012 8 14 14 55 page 120 144 R27p 1k 1uF C20p R28p 47k R29p 10k 0 1uF C21p How E R30p 2 2k R3ip ik 0 01 uF C22p 0 01 uF C25p U4P2 R16p 01 R17p 0 1 uF C19p R18p 0 1 WF C15p R19p R22p 10k 0 1 uF C18p R20p 1uF C14p R23p 22k 105 C17p Figure D 6 Op Amp IC 4 Dual Op Amp with amplifiers 4A and 4B Op Amp 4A and 4B can be used in inverting or non inverting configuration C5p C6p C7p C8p The Berg pin connection U1P1 can be used to connect the output of Op Amp 1 A Similarly connnection U1P7 can be used to connect the output of Op Amp 1 B Texas Lab Manual tlm 2012 8 14 14 55 page 121 145 U5P14 U5P12 U5P11 U5P10 U5P8 U5P14 U5P12 U5P11 U5P10 U5P8 U5P14 U5P12 U5P11 U5P10 U5P8 N T T n T A MPY634 8 8 p p U6P1 U6P2 U6P4 U6P6 U6P7 0501 0502 0504 0506 7 8 Input 1 MPY 634 b Figure D 7 a PCB connections for analog multipliers 1 2 and 3 on ASLKv2010 Starter b External connections needed to use the multiplier MPY634 Texas Lab Manual tlm 2012 8 14 14 55 page 122 146 U9P19 U9P18 U9P17 U9P16 U9P15 U9P14 U9P13 U9P12 U8P19 U8P18
30. the VCO is an important parameter and is given by df 2 f K H It 1 VO y O s 101 VCO is an important analog circuit and finds many applications It is used in the generation of FSK FM waveforms and constitutes the modulator part ofthe MODEM In this role the VCO is also called mod of modem As a VCO it finds use in the Phase Locked Loop PLL which we will study in Chapter 7 The VCO can also be used as a reference oscillator for a Class D amplifier and the Switched Mode Power Supply SMPS Texas Lab Manual tlm 2012 8 14 14 55 page 66 90 10 0 5 0 fo Output V 10 0 1 T T T T T T T T T T T 70 0 72 5 75 0 5 80 0 Time ms a Ks sall II DT ae Time ms b Figure 6 2 Simulation outputs for a function generator b FSK generator Texas Lab Manual tlm 2012 8 14 14 55 page 67 91 Experiment 6 6 3 Specifications Design a function generator to generate both sguare and triangular waveforms for a frequency of 1 kHz 6 4 Measurements to be Taken Determine the frequency of oscillations of square and triangular waves Theoretically the frequency of oscillation should be ee LNA ARC Convert the function generator into a VCO Measure the sensitivity of the VCO defined df as dV 6 5 What Should you Submit Simulate the circuits and obtain the print out of the waveforms generated by the function
31. the board The Op Amps marked TYPE 1 can be connected in the inverting configuration only With the help of con nectors either resistors or capacitors can be used in the feedback loop of the amplifier There are three TYPE 1 amplifiers There are three spare Op Amps and two TYPE 2 amplifiers TYPE 2 amplifiers can be connected in inverting or non inverting configurations All the Op Amps ICs operate on 10 V the power supply and ground connections are internally provided and the user need not worry about these Texas Lab Manual tlm 2012 8 14 14 55 page 12 36 Input 1 Output MPY 634 Input 2 Figure 0 5 External connections needed for using the analog multiplier 10k O Vout 10 V lt VoupS 10V Figure 0 6 External connections needed for using the DAC 15 V lt V lt 15V Three analog multipliers are included in the kit These are wide bandwidth pre cision analog multipliers from Texas Instruments MPY634 Each multiplier is a 14 pin IC and operates on 10 V supply The power supply connections for the multipliers are provided internally In order to use the analog multiplier IC on the ASLKv2010 Starter kit the external connections shown in Figure 0 5 are required Two digital to analog converters DAC labeled DAC1 and DAC2 are provided in the kit Both the DACs are DAC7821 from Texas Instruments They are 12 bit parallel input multiplying DACs that can be used in place of analog multipliers in
32. ti com Also refer to the application notes 7 12 and 13 Texas Lab Manual tlm 2012 8 14 14 55 page 52 6 ab LL ab Aes O 5 1 Goal of the Experiment The goal of this experiment is to learn the concept of tuning a filter The idea is to adjust the RC time constants of the filter so that given in phase response of a Low Pass filter the output phase w r t input is exactly 90 at the incoming frequency This principle is utilized in distortion analyzers and spectrum analyzers Such self tuned filters are used to lock on to the fundamental frequency and harmonics of the input 5 2 Brief Theory and Motivation In order to design self tuned filters and other analog systems in subsequent experi ments we need to introduce one more building block the analog multiplier The reader Texas Lab Manual tlm 2012 8 14 14 55 page 53 77 will benefit from viewing the recorded lecture at 23 Inthe ASLKv2010 Starter kit we have used the MPY634 analog multiplier from Texas Instruments Figure 5 1 shows the symbol of an analog multiplier In our experiments we will use V 10 V We also show the output of the multiplier when two sinusoidal waveforms are multiplied note that the output of the multiplier depends on the phase difference between the two inputs and can therefore be used as a measure of the phase difference Vo Vottset Kx x Vx Ky x Vy Ko x Vx x Vy 8 5
33. transient analysis and steady state analysis Simulators such as SPICE require the user to specify the model for the transistor There are many different models available today for the MOS transis tor depending on the desired accuracy The level 1 model captures the dependence of the drain to source current on the gate to source and drain to source voltages the mobility of the majority carrier the width and length of the channel and the gate oxide thickness It also considers non idealities such as channel length modulation in the saturation region and the dependence of the threshold voltage on the source to bulk voltage More complex models for the transistor are available which have more than 50 parameters B 1 Micromodels If you have built an operational amplifier using transistors a straight forward way to analyze the performance of the Op Amp is to come up with the micromodel of the Op Amp where each transistor is simply replaced with its corresponding simulation model Micromodels will lead to accurate simulation but will prove computationally intensive As the number of nodes in the circuit increases the memory requirement will be higher and the convergence of the simulation can take longer A macromodel is a way to address the problem of space time complexity mentioned above In today s electronic systems we make use of analog circuits such as opera tional amplifiers data converters PLL VCO voltage regulators and so on The
34. when we were working on this manual It is our pleasure to acknowledge their contribution We acknowledge the encouragement and sup port from Syd Coppersmith WW Manager TI Analog University Program throughout this endeavor A number of colleagues at Texas Instruments India have helped us and encouraged us at different stages of the development of the kit and the manual Our sincere thanks are due to all of them Mr Krishnamurthy Bhat of Basaveshwara Texas Lab Manual tlm 2012 8 14 14 55 page x 6 Engineering College Bagalkot Karnataka India spent several months with us help ing us realize the kit as a product He was ably helped by Sagar Juneja then a student intern at TI India Sagar has also read various drafts of this manual and provided helpful comments Ullas Taneja another student intern helped in recording the video lectures that provide more information on these experiments Pulkit Jain also an intern helped us by drawing many of the diagrams in this manual We thank the faculty members who attended the faculty development programs where initial drafts of this manual and the Analog System Lab Kit were used their feedback has been useful in improving the kit as well as the manual We thank Mr E S Kannan of YEE YES and Mr Ashfag Ibrahim of Cranes Software for their support We thank Mr Praveen Settigere of Wiley India for his interest in this project and for all the help he provided in publishing the manual
35. 1 Vi Vo 7 Vo a 1 0 V 500 0 mV Output 500 0 mv 4 1 0 V Time ms b Figure 5 1 a Symbol of an analog multiplier b multiplier as a phase detector Texas Lab Manual tlm 2012 8 14 14 55 page 54 78 where 5 is a non linear term in Vx and Vy Kx and Ky are called feedthrough components and Ko is called the normalizing component We define 1 Ko For a precision multiplier V lt Vx and V lt V where V is the parameter defined above Hence for precision amplifiers Vo Vy x Vy V In Experiment 4 if we replace the integrator with a multiplier followed by integrator then the circuit becomes a Voltage Controlled Filter or a Voltage Controlled Phase Generator shown in Figure 5 2 This forms the basic circuit for self tuned filter See Figure 5 3 a The output of the self tuned filter for a square wave input including the control voltage waveform is shown in Figure 5 4 The figure brings out the aspect of automatic control and self tuning A simpler version of the voltage controlled phase generator which can be part of a self tuned filter is shown in Figure 5 3 b You may use this simpler circuit which uses only two Op Amps note that the circuit of Figure 5 3 a uses four Op Amps In the simpler circuit you can study the variation of the phase in direct proportion to Vier for a given sine wave input frequency 5 2 1 Multiplier as a Phase Detector
36. 11 Second Edition 2012 ISBN 978 81 265 3742 6 www wileyindia com Printed at Paras Printers Delhi The first version of this manual released in 2011 has been received with great enthusiasm by teachers and students We thank everyone for this warm reception We are happy to place in your hands the revised version of the Analog System Lab Manual The Analog System Lab Kit and the associated manual were created to help colleges in India in updating their curriculum for courses related to analog Ana log electronics occupies a very special and significant place in modern day systems In the past decade India has seen the emergence of a number of system design com panies Manufacturing of electronic products has also received a significant boost These companies look for system level design skills in both analog and digital domains Unfortunately analog system design is not emphasized in the conventional way of teaching analog Our attempt is to help bridge this gap at an early stage in undergradu ate coursework We believe that the ASLK can be adopted by both undergraduate and postgraduate students Texas Lab Manual tlm 2012 8 14 14 55 page v 1 Since ASLK Starter kit was introduced close to 100 colleges in India have intro duced it in their teaching curriculum We have interacted with hundreds of Indian teachers in the faculty development programs on Analog System Design that were con ducted in the last year Several
37. 15 O MN Table 7 2 Control voltage as a function of input frequency S No Input Frequency Control Voltage 15 62 92 the actual waveforms Observe what happens to the output frequency when the system is not locked What do you see as the control voltage waveform then Measure the change in the phase of the output signal as input frequency is varied within the lock range Vary the input frequency and obtain the change in the control voltage Use Table 7 2 to record your readings 7 6 Exercises For the PLL FLL shown in Figure 7 3 a determine the free running frequency Determine the lock ranges when the input is a square wave of amplitude 0 5 V Repeat the experiment when the input amplitude is 1 V Texas Lab Manual tlm 2012 8 14 14 55 page 75 99 1 V square wave J C 100 n J Up 100 k i 610 U Up 9 paa U TL082 A VE Figure 7 3 a Phase locked loop 10 00 5 00 2 0 00 6 5 00 10 00 4 a 7 10 00 m 12 50 m 15 00 m 17 50 m 20 00 m Time 5 Figure 7 3 b Simulation of the PLL at free running frequency when input amplitude is 1V Texas Lab Manual tlm 2012 8 14 14 55 page 76 100 Design a frequency synthesizer to generate a waveform of 1 MHz frequency from a 100 kHz crystal as shown in Figure 7 4
38. 2 8 14 14 55 page 81 5 8 0 00 0 0 20 4 0 6 0 Time ms Output V Figure 8 3 Output of AGC circuit 8 6 Exercises Determine the lock range for the AGC that was built as part of the experiment The lock range is defined as the range of input values for which output voltage remains constant Oo The AGC AVC circuit of Figure 8 4 a is designed for W 0 2 V Determine the peak amplitude of the output VF and control voltage VF when the input VG 0 1 V Repeat for VG 1V 2V 4V and 8V Texas Lab Manual tlm 2012 8 14 14 55 page 82 106 U4 TL082 U TL082 Figure 8 4 a AGC circuit 8 00 6 00 4 00 2 00 0 00 Output 2 00 4 00 6 00 8 00 __ __ ay ___ 110 00 m 112 50 m 115 00 m 117 50 m 120 00 m Time s Figure 8 4 b Simulation of the AGC circuit for output voltage 2 V peak Texas Lab Manual thm 2012 8 14 14 55 page 83 107 Texas Lab Manual tlm 2012 8 14 14 55 page 84 108 ab L ab O Aes O 9 1 Goal of the Experiment The goal of this experiment is to design a DC DC converter using a general purpose Op Amp and a comparator and to study its characteristics We also aim to study the characteristics of a DC DC converter integrated circuit we select the wide input non synchronous buck DC DC conv
39. 5 page 18 42 5 1 5 1 00 4 amp J 5 500 00 m gt Pae oo oon enne eee ee eee eee ee 0 00 4 0 00 250 00 n 500 00 n 750 00 n 1 00 pi Time s Figure 1 4 Time response of an amplifier for a step input of size V If we apply a step voltage of amplitude V to the unity gain amplifier and if Vp GB gt slew rate then the output appears as shown in Figure 1 4 if 0 gt 1 2or lt 1 Q is approximately equal to the total number of visible peaks in the step response Figure 1 4 and the frequency of ringing is oo 1 1 40 Slew rate is known as the maximum rate at which the output of the Op Amps is capable of rising in other words slew rate is the maximum value that dVo dt can attain In this experiment as we increase the amplitude of the step input at some value of V the rate at which the output starts rising remains constant and no longer increases with V this rate is called slew rate The slew rate can therefore be deter mined by applying a square wave of amplitude V at certain high frequency close to gain bandwidth product and increasing the magnitude of the input Texas Lab Manual tlm 2012 8 14 14 55 page 19 43 a Figure 1 5 a Non inverting amplifier of gain 2 b inverting amplifier of gain 2 A non inverting amplifier with a gain of 2 is shown in Figure 1 5 a An inverting amplifier with a gain of 2 is shown in Figure 1 5 b
40. ANALOG SYSTEM LAB MANUAL ANALOG SYSTEM LAB MAN Learning to Design Analog Systems using Analog System Lab Starter Kit Dr K R K Rao and Dr C P Ravikumar Texas Instruments India Bagmane Tech Park CV Raman Nagar Bangalore 560093 India vi TEXAS INSTRUMENTS WILEY Analog System Lab Manual secona tuition Learning to Design Analog Systems using Analog System Lab Starter Kit Copyright 2012 by Texas Instruments All rights reserved No part of this book may be reproduced stored in a retrieval system or transmitted in any form or by any means electronic mechanical photocopying recording or scanning without the written permission of Texas Instruments Limits of Liability While the publisher and the author have used their best efforts in preparing this book Wiley and the author make no representation or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for any particular purpose There are no warranties which extend beyond the descriptions contained in this paragraph No warranty may be created or extended by sales representatives or written sales materials The accuracy and completeness of the information provided herein and the opinions stated herein are not guaranteed or warranted to produce any particular results and the advice and strategies contained herein may not be suitable for every individual
41. Amp and develop the macromodel for the given Op Amp IC TL082 See Appendix B for an introduction to the topic of analog macromodels 1 5 What Should you Submit Submit the simulation results for time response frequency response and DC transfer characteristics Take the plots of time response frequency response and DC transfer characteris tics from the oscilloscope and compare them with your simulation results 6 Apply a square wave of amplitude 1 V at the input Change the input frequency and study the peak to peak amplitude of the output Take the readings in Table 1 1 and compute the slew rate Hint for calculating the slew rate After the slew rate has been achieved the peak to peak amplitude of output starts falling Apply a high frequency square wave and increase the peak to peak amplitude of the input Compute the slew rate Take the readings in Table 1 2 Frequency response Apply sine wave input to the system and study the magnitude and phase response Take your readings in Table 1 3 DC transfer characteristics Vary the DC input voltage and study its effect on the output voltage Take your readings in Table 1 4 Table 1 1 Measurement of slew rate Method 1 S No Input Frequency Peak to Peak Amplitude of Output Vpp 15 ON Texas Lab Manual tlm 2012 8 14 14 55 page 24 8 Table 1 2 Measurement of slew rate Method 2 S No Input Voltage Peak to Peak Amplitude of Output V 15
42. C Figure 8 1 shows an AGC system The typical I O characteristic of AGC AVC system is shown in Figure 8 2 As shown in Figure 8 2 the output value of the system remains constant at 2V Vef beyond input voltage Vp 2V Vier Figure 8 2 Input output characteristics of AGC AVC Texas Lab Manual tlm 2012 8 14 14 55 page 80 104 Experiment 8 8 3 Specification Design an AGC AVC system to maintain a peak amplitude of sine wave output at 2 V 8 4 Measurements to be Taken Transfer Characteristics Plot the input versus output characteristics for the AGC AVC 8 5 What Should you Submit Simulate the system of Figure 8 1 and plot the output of the AGC system Assume that the input comes from a function generator use a sine wave input of a single frequency Build the AGC system of Figure 8 1 using ASLKv2010 Starter kit Note the output of the AGC system from the oscilloscope and compare the output with simulation result 6 Plot the output as a function of input voltage Take sufficient number of readings Does the output remain constant as the magnitude of the input is increased Beyond what value of the input voltage does the gain begin to stabilize Use Table 8 1 to record your readings We have included sample output waveform for the AGC system in Figure 8 3 Table 8 1 Transfer characteristic of the AGC system S No Input Voltage Output Voltage Control Voltage 15 62 2 Texas Lab Manual tlm 201
43. Figure 4 3 Table 4 2 Frequency response of a BPF with Fy 1 kHz 0 1 Band Pass Band Stop S No Input Phase Magnitude Phase Magnitude frequency 1 2 3 4 Table 4 3 Frequency response of a BSF with Fy 10 kHz Q 10 Band Pass Band Stop S No Input Phase Magnitude Phase Magnitude frequency 1 2 3 4 Texas Lab Manual tlm 2012 8 14 14 55 page 49 73 30 0 Gain dB 40 0 T t 100 125 t t 150 175 200 Freguency Hz Figure 4 3 Magnitude response of BPF BSF 4 6 Exercises Higher order filters are normally designed by cascading second order filters and if needed one first order filter Design a third order Butterworth Low Pass Filter using FilterPro and obtain the frequency response as well as the transient response of the filter The specifications are bandwidth of the filter oo 2 x 10 rad s and Hy 10 Design a notch filter Band Stop filter to eliminate the 50 Hz power line fre quency In order to test this circuit synthesize a waveform v t sin 100zt 0 1 sin 200z t Volts and use it as the input to the filter What output did you obtain 9 A third order Butterworth filter is designed as shown It realizes a transfer function 1 1 2 sCR 2 sCR 2 sCR 3 with C 1pFand R 1k Determine its bandwidth The desired transfer function is realized using cascading of a second order filter with Q of 1 and a first order filter Te
44. Magnitude response of BPF BSF 50 Texas Lab Manual tlm 2012 8 14 14 55 page xxii 18 4 4 a Third order Butterworth filter 51 4 4 b Frequency response of the Butterworth filter 51 4 5 a Tow Thomas biguad filter 52 4 5 b Frequency response of the filter 52 5 1 a Symbol of an analog multiplier b multiplier as a phase detector 54 5 2 Voltage controlled filter with frequency a x b x Ve 56 5 3 a A self tuned filter based on a voltage controlled filter or voltage controlled phase generator b a simple voltage controlled phase generator that can become part of a self tuned filter 57 5 4 Output of the self tuned filter based on simulation V corresponds to BPF Vo2 corresponds to BSF V is the control voltage and V is the input voltage 8 5 5 a Simulation of the self tuned filter shown in Figure 5 5 b when VG 0 1 V 61 5 5 b Self tuned filter 62 6 1 Voltage Controlled Oscillator VCO 66 6 2 Simulation outputs for a function generator b FSK generator 67 6 3 a Function generator 69 6 3 b Simulation of the function generator of Figure 6 3 a 70 6 4 Digitally Controlled Oscillator DCO 70 7 1 a Phase Locked Loop PLL circuit b characteristics of the PLL 72 7 2 Sample output waveform for the Phase Locked Loop PLL for a square wave input waveform 74 7 3 a Phase locked loop 76 Texas Lab Manual tlm 2012 8 14 14 55 page xxiii 19 7 3 b Simulation of the PLL at free r
45. Regulation Vary the load such that load current varies and obtain the output voltage see the point till where output voltage remains constant After that the output will fall as the load current increases Obtain the Ripple Rejection Apply the input ripple voltage and see the output ripple voltage with the input ripple voltage the output ripple voltage will rise Obtain the Line Regulation Vary the input voltage and plot the output voltage as a function of the input voltage Until the input reaches a certain value the output voltage remains constant after this point the output voltage will rise as the input voltage is increased Calculate the Output Impedance 10 5 What Should you Submit Simulate the systems and compute the output characteristics transfer character istics and ripple rejection Take the plots of output characteristics transfer characteristics and ripple rejection from the oscilloscope and compare them with simulation results Texas Lab Manual tlm 2012 8 14 14 55 page 94 118 Table 10 2 Variation of line regulation with input voltage in an LDO S No Input Voltage Output Voltage 1 62 92 Table 10 3 Ripple rejection 0 No Ripple Input Voltage Ripple Output Voltage 1 O MN gt 10 6 Exercises Perform the same experiment with the specialized IC for LDO from Texas Instru ment TLV700xx family and compare the characteristics of both the systems Texas Lab Manual
46. able 9 2 to take your readings Is the plot linear Table 9 1 Variation of output voltage with control voltage ina DC DC converter S No Control Voltage Controlled Voltage Texas Lab Manual tlm 2012 8 14 14 55 page 88 112 Table 9 2 Variation of duty cycle with control voltage ina DC DC converter S No Control Voltage Duty Cycle T R O MN 9 5 Exercises Explain how a PMOS switch can be used to achieve Class D operation for the DC DC converter system we studied Show the block diagram You may need a diode in your system why Perform the same experiment with the specialized IC for DC DC converter from Texas Instrument TPS40200 and compare the characteristics of both the systems Texas Lab Manual tlm 2012 8 14 14 55 page 89 113 Texas Lab Manual tlm 2012 8 14 14 55 page 90 114 ab j ab O 10 1 Goal of the Experiment The goal of this experiment is to design a Low Dropout Linear regulator using a general purpose Op Amp and study its characteristics We will also see that an integrated circuit family of regulators called TLV700xx is available for the purpose and study their characteristics Our aim is to design a linear voltage regulator with high efficiency used in Jow noise high efficiency applications 10 2 Brief Theory and Motivation Please view the recorded lectures at 25 for a detailed description of voltage
47. ameters Since the frequency and transient response of an ampli fier are affected by these parameters we can measure the parameters if we have the frequency and transient response of the amplifier You can obtain these response characteristics by applying sinusoidal and square wave input respectively We invite the reader to view the recorded lecture 18 An Op Amp may be considered as a Voltage Controlled Voltage Source VCVS with the voltage gain tending toward oo or a Current Controlled Current Source CCCS with current gain tending toward oo For finite output voltage the input voltage is practi cally zero This is the basic theory of Op Amp in the negative feedback configuration Figure 1 1 shows a differential input single ended output Op Amp which uses dual supply Vss for biasing so that the output offset voltage can be made zero when the input offset voltage is zero Vo A Vj Vo 1 1 Vo Vi V 1 2 1 2 In the above equations Ap is the open loop gain for real amplifiers Ap is in the range of 10 to 106 and hence Vj V i Vss V2 Vo Ao V4 Va v 8 Figure 1 1 An ideal dual input single output Op Amp Texas Lab Manual tlm 2012 8 14 14 55 page 16 40 Figure 1 2 A unity gain system A unity feedback circuit is shown in Figure 1 2 It is easy to see that Vo Ao 1 3 a 2 0 Le ener 1 4 Vi In Op Amps closed loop gain A is frequency depende
48. anagement processing Humidity Sound Light D A Figure 0 1 Signal chain in an electronic system Embedded The digital data is processed by a CPU such as a DSP a microprocessor or a microcontroller The choice of the processor depends on how intensive the computation is A DSP may be necessary when real time signal processing is needed and the computations are complex Microprocessors and microcon trollers may suffice in other applications Digital to analog conversion DAC is necessary to convert the stream of 05 and 1s back into analog form The output of the DAC has to be amplified before the analog signal can drive an external actuator A Power Management block is needed to provide power to the various blocks In modern day VLSI chips power dissipation is a major consideration so that we can keep the power density under control Since the source of power can be a battery itis important to ensure long battery life through techniques such as clock gating power gating etc The Power Management block is responsible for these functions It is evident that analog circuits play a crucial role in the implementation of an electronic system Texas Lab Manual tlm 2012 8 14 14 55 page 2 26 The goal of the Analog System Lab Course is to provide students an exposure to the fascinating world of analog and mixed signal signal processing The course can be adapted for an undergraduate or a postgraduate c
49. and 4B can be used in inverting or non inverting configuration a PCB connections for analog multipliers 1 2 and 3 on ASLKv2010 Starter b External connections needed to use the multiplier MPY634 a PCB connections for the DAC on ASLKv2010 Starter b external connections needed to use the DAC to make it four quadrant Texas Lab Manual tlm 2012 8 14 14 55 page xxv 21 120 120 121 122 123 Texas Lab Manual tlm 2012 8 14 14 55 page xxvi 22 1 1 Measurement of slew rate Method 1 24 1 2 Measurement of slew rate Method 2 25 1 3 Plot of magnitude and phase variation w rt input frequency 25 1 4 DC transfer characteristic 25 2 1 Plot of hysteresis w rt regenerative feedback 35 3 1 Plot of magnitude and phase w r t input frequency for the integrator 40 3 2 Plot of magnitude and phase w rt input frequency for the differentiator 41 3 3 Variation of peak to peak value of output w r t peak value of input 43 4 1 Transfer functions of active filters 46 4 2 Frequency response of a BPF with fy 1 kHz Q 1 49 4 3 Frequency response of a BSF with Fy 10 kHz 0 10 49 Texas Lab Manual tlm 2012 8 14 14 55 page xxvii 23 5 1 6 1 7 1 7 2 8 1 9 1 9 2 10 1 10 2 10 3 B 1 Variation of output amplitude with input frequency Change in frequency as a function of control voltage Output phase as a function of input frequency Control voltage as a function of input frequ
50. ation 29 2 2 1 Inverting Regenerative Comparator 29 2 2 2 Astable Multivibrator 32 2 2 3 Monostable Multivibrator Timer 32 2 3 Specifications 34 2 4 Measurements to be Taken 34 2 5 What Should you Submit 35 2 6 Exercises 35 Texas Lab Manual thm 2012 8 14 14 55 page xiv 10 3 Experiment 3 Integrators and Differentiators 37 3 1 Goal of the Experiment 37 3 2 Brief Theory and Motivation 37 3 2 1 Integrators 38 322 Differentiators 38 3 3 Specifications 39 3 4 Measurements to be Taken 39 3 5 What Should you Submit 40 3 6 Exercise Grounded Capacitor Topologies of Integrator and Differentiator 43 4 Experiment4 Analog Filters 45 4 1 Goal of the Experiment 45 42 Brief Theory and Motivation 45 4 2 1 Frequency Response of Filters 47 43 Specifications 47 44 Measurements to be Taken 48 4 5 What Should you Submit 49 46 Exercises 50 4 7 Related ICs 52 5 Experiment5 Self tuned Filter 53 5 1 Goal of the Experiment 53 5 2 Brief Theory and Motivation 53 5 2 1 Multiplier as a Phase Detector 55 Texas Lab Manual tlm 2012 8 14 14 55 page xv 11 5 3 Specification 60 5 4 Measurements to be Taken 60 5 5 What Should you Submit 60 5 6 Exercises 61 5 7 Related ICs 63 6 Experiment 6 Function Generator and Voltage Controlled Oscillator 65 6 1 Goal of the Experiment 65 6 2 Brief Theory and Motivation 65 e VCO e Function Generator e FM FSK Generator 6 3 Specifications 68 6 4 Measurements to
51. ation results in these exercises The starred exercises can be good starting points when one begins to use ASLK However we emphasize the importance of the other exercises which involve design We suggest that a teacher assigns a mix of starred and the other exercises in the lab work We are pleased to acknowledge the help from several persons in preparing this manual Ms Meenakshi Sehrawat of Wiley India has done a creditable job of editing We thank Praveen Settigere of Wiley India for his continued support Joyan Gratian Sanctis of TI India has taken the excellent picture of the ASLK included in this manual We are indebted to Sagar Juneja for his constant help in all aspects of ASLK promotion Texas Lab Manual tlm 2012 8 14 14 55 page vi 2 We thank Cranes Software for their manufacturing and promotion of ASLK We thank all our colleagues in TI India for their constant support and encouragement As always we are eager to know your feedback K R K Rao C P Ravikumar July 2012 Texas Instruments India Bagmane Tech Park CV Raman Nagar Bangalore 560093 India Texas Lab Manual tlm 2012 8 14 14 55 page vii 3 Texas Lab Manual tlm 2012 8 14 14 55 page viii 4 Although digital signal processing is the most common way to process signals ana log signal processing cannot be completely avoided since the real world is analog in nature The goal of the Analog System Lab is to provide studen
52. better than that of Figure 1 5 a Can you think of an application for this amplifier VF U TL082 IX V 12V Figure 1 9 a An inverting amplifier with analog gain control Texas Lab Manual tlm 2012 8 14 14 55 page 26 50 10 00 Voltage V Q 5 00 10 00 ALAMA SKK KK A LK 0 00 250 00 u 500 00 u 750 00 u 1 00 m Time 5 Figure 1 9 b Simulation of the circuit for Figure 1 9 a when V3 1V A digitally controlled programmable amplifier is shown in Figure 1 10 It is an inverting amplifier whose gain magnitude G is given by Vout _ R2 4096 Vi SA2 0 Determine the maximum and minimum limits of the gain G Note that the input to the DAC is a 12 bit binary word A11 Ap Can you think of an application for such an amplifier Compare the circuits of Figure 1 9 a and Figure 1 10 Rip DAC7821 Vier Figure 1 10 Digitally controlled amplifier Texas Lab Manual tlm 2012 8 14 14 55 page 27 51 Experiment 1 1 7 Other Related ICs Specific ICs from Texas Instruments that can be used as instrumentation amplifiers are INA114 INA118 and INA128 Additional ICs from Texas Instruments that can be used as general purpose Op Amps are OPA703 OPA357 etc See 3 1 8 Related Reading Datasheets of all these ICs are available at www ti com An excellent reference about operational ampl
53. cation of analog ICs used in electronic systems You will learn how to develop a macromodel for an IC based on its terminal char acteristics I O characteristics DC transfer characteristics frequency response stability characteristics and sensitivity characteristics Exp 1 Exp 2 Negative feedback Regenerative feedback amplifiers and systems astable and instrumentation amplifier monostable multivibrators Exp 3 Integrators and differentiators Exp 8 Exp 10 Automatic gain Low dropout regulator control Exp 6 Function generator and voltage controlled oscillator Exp 4 Analog filters Exp 7 Phase locked loop Exp 9 Frequency locked DC DC converter loop Class D amplifier Exp 5 Self tuned filter Figure 0 2 Dependence among experiments on the ASLKv2010 Starter Texas Lab Manual tlm 2012 8 14 14 55 page 5 29 You will be able to make the right choice for an IC for a given application You will be able to perform basic fault diagnosis of an electronic system 0 3 Lab Setup The setup for the Analog System Lab is very simple and requires the following ASLKv2010 Starter kit and the associated Lab Manual from Texas Instru ments India the lab kit comes with required connectors Refer to Section 0 4 for an overview of the kit 6 Alow frequency operation oscilloscope which can operate in the frequency range of 1 to 10 MHz Texas Instruments also offers an oscilloscope card which can be
54. cks Manufacturers of semiconductors provide macromodels for their products to help system designers in the process of system configuration selection You can download the models for TI analog ICs from http tinyurl com ti macromodels these files have a tsm extension As you can guess there is no single macromodel for an IC A number of macro models can be derived based on the level of accuracy desired and the computational complexity that one can afford A recommended design methodology is to start with a simple macromodel for the system components and simulate the system A step wise refinement procedure may be adopted and more accurate models can be used for selected components when the results are not satisfactory Texas Lab Manual tlm 2012 8 14 14 55 page 112 136 oO gt lt LL A A lt C 1 Introduction In any analog lab an oscilloscope is required to display waveforms at different points in the circuit under construction in order to verify circuit operation and if neces sary redesign the circuit High end oscilloscopes are needed for measurements and characterization in labs Today solutions are available to students for converting a PC into an oscilloscope 31 These solutions require some additional hardware to route the analog signals to the PC for observation they also require software that provides the graphical user interface to convert a PC display into an oscilloscope Since most student
55. colleges have independently conducted such hands on workshops for teachers as well as students We are encouraged by the acceptance of the kit as an educational tool that is easy to use We are grateful to all the comments and feedback we have received from academia Several teachers have told us that they have designed new experiments in the areas of communications and controls Several companies used ASLK in their in house training programs To see the reaction from students we made it mandatory for participants of TI India Analog Design Contest to carry out a challenging experiment on the ASLK We could not have expected a more positive response Some students even surprised us by using ASLK for new experi ments such as motor control and simulation of chaos in oscillators We encourage students and teachers to explore such innovative applications of ASLK TI has a vast portfolio of analog ICs to select from Please make use of TI s free samples program to carry out additional experiments on ASLK Based on the feedback we received we have introduced a few changes in this ver sion of the manual We are sure you will like the aesthetic improvements to the manual including the colored illustrations A pin diagram of the ASLK is included with the kit to facilitate the connections We have added several additional exercises in almost all chapters These additional exercises are marked with a star we have provided the component values and typical simul
56. cond order Filter 45 46 Self Tuned Filter 51 53 73 Sensitivity 58 59 66 73 Signal Chain 2 Signal Processing 2 Signal to Noise Ratio 37 Simulation 110 112 Slew Rate 20 SMPS 66 85 Spare 11 SPICE 110 Square Wave 40 Standard Linear Amplifiers 111 Steady state Analysis 110 Steady state Response 50 Step Response 18 Switching Circuit 29 Time Constant 53 Time Response 39 Texas Lab Manual tlm 2012 8 14 14 55 page 130 154 Timer 32 TINA 6 TLO82 24 98 TLV70018 107 TLV700xx 95 TPS40200 104 TPS40200EVM 105 Transfer Characteristic 25 35 81 94 Transfer Function 18 Transient Analysis 110 Triangular Wave 67 UAF42 52 Unity Gain Amplifier 20 Unity Gain 16 Universal Active Filter 52 VCA820 63 VCF 57 59 VCO 4 66 62 73 68 VCVS 16 Voltage Controlled Voltage Source 16 Voltage Gain 16 Texas Lab Manual tlm 2012 8 14 14 55 page 131 155 Texas Lab Manual tlm 2012 8 14 14 55 page 132 156
57. d linear amplifier these include the number of operational amplifiers in a sin gle package the Gain Bandwidth Product of the amplifier the CMRR Vs min Vs max and so on See http tinyurl com ti std linear The website allows you to specify these parameters and narrow your choices Texas Lab Manual tlm 2012 8 14 14 55 page 111 135 But how does one specify the parameters for the components The overall system performance will depend on the way the parameters for the individual components have been selected For example the gain bandwidth product of an operational ampli fier B1 will influence a system level parameter such as the noise immunity or stability If one has n components in the system and there are m choices for each compo nent there are m n possible system configurations Even if we are able to narrow the choices through some other considerations we may still have to evaluate several system configurations Performing simulations using micromodels will be a painstaking and non productive way of selecting system configurations B 2 Macromodels A macromodel is a mathematical convenience that helps reduce simulation com plexity The idea is to replace the actual circuit by something that is simpler but is nearly equivalent in terms of input characteristics output characteristics and feed forward characteristics Simulation of a complete system becomes much more simple when we use macromodels for the blo
58. d using simulation Take the plot of DC transfer characteristics from the oscilloscope and compare it with simulation result Vary the regenerative feedback and observe the variation in the hysteresis Is the hysteresis directly proportional to regenerative feedback factor 6 2 6 Exercises Design an astable multivibrator using charging and discharging of capacitor C through resistance R between input and output of the Schmitt trigger See Figure 2 4 Assume that frequency f 1 T 1 kHz Design a monostable multivibrator Timer for rt 10 ms and estimate RC using Equation 2 5 Texas Lab Manual tlm 2012 8 14 14 55 page 35 59 Texas Lab Manual tlm 2012 8 14 14 55 page 36 60 ab ab L ab 49 AS O 3 1 Goal of the Experiment The goal of the experiment is to understand the advantages and disadvantages of using integrators or differentiators as building blocks in building NY order filters 3 2 Brief Theory and Motivation Integrators and differentiators can be used as building blocks for filters Filters are essential blocks in analog signal processing to improve signal to noise ratio An Op Amp can be used to construct an integrator or a differentiator This experiment is to understand the advantage of using integrators instead of differentiators as building blocks Differentiators are rejected because oftheir good response to noise Texas Lab Manual tlm
59. ded Capacitor Topologies of Integrator and Differentiator Determine the function of the circuits shown in Figure 3 5 What are the advan tages and disadvantages of these circuits when compared to their conventional counterparts Deboo s integrator a Figure 3 5 Circuits for Exercise Texas Lab Manual tlm 2012 8 14 14 55 page 43 67 Texas Lab Manual tlm 2012 8 14 14 55 page 44 68 i S ab AS O 4 1 Goal of the Experiment To understand the working of four types of second order filters namely Low Pass High Pass Band Pass and Band Stop filters and study their frequency characteristics phase and magnitude 4 2 Brief Theory and Motivation Second order filters or biquard filters are important since they are the building blocks in the construction of N order filters for N gt 2 When N is odd the N order filter can be realized using N 1 2 second order filters and one first order filter When N Texas Lab Manual tlm 2012 8 14 14 55 page 45 69 is even we need N 2 second order filters Please listen to the recorded lecture at 21 for a detailed explanation of active filters Second order filter can be used to construct four different types of filters The trans fer functions for the different filter types are shown in Table 4 1 where wp 1 RC and Hp is the low frequency gain of the transfer function The filter na
60. e TLO8x family The C suffix devices are characterized for operation from 0 C to 70 C The I suffix devices are characterized for operation from 40 C to 85 C The Q suffix devices are characterized for operation from 40 C to 125 C A 1 4 Download Datasheet http focus ti com lit ds symlink t1082 pdf Texas Lab Manual tlm 2012 8 14 14 55 page 98 2 A 2 MPY634 Wide Bandwidth Analog Precision Multiplier A 2 1 Features Wide bandwidth 10 MHz Typ 0 5 max four quadrant accuracy Internal wide bandwidth Op Amp A 2 2 Applications Precision analog signal processing Modulation and demodulation Voltage controlled amplifiers Video signal processing Voltage controlled filters and oscillators Voltage SF o _ reference and bias X0 2 Multiplier core zoll 0 75 Atten Z 270 Transfer function MV 7 A A 4 4 gt 5 Precision output Op Amp Vout Figure A 2 MPY634 Analog multiplier Texas Lab Manual tlm 2012 8 14 14 55 page 99 123 Vs NC Output Z Input Z Input NC Appendix A A 2 3 Description The MPY634 is a wide bandwidth high accuracy four guadrant analog multiplier Its accurately laser trimmed multiplier characteristics make it easy to use in a wide variety of applications with a minimum of external parts often eliminating all external trimming
61. ency Transfer characteristic of the AGC system Variation of output voltage with control voltage in a DC DC converter Variation of duty cycle with control voltage in a DC DC converter Variation of load regulation with load current in an LDO Variation of line regulation with input voltage in an LDO Ripple rejection Operational amplifiers available from Texas Instruments Texas Lab Manual tlm 2012 8 14 14 55 page xxviii 24 60 69 75 75 81 88 89 94 95 95 111 O Si ab N ab 27 AS O 0 1 Analog System Lab Although digital signal processing is the most common form of processing signals ana log signal processing cannot be completely avoided since the real world is analog in nature Consider a typical signal chain Figure 0 1 A sensor converts the real world signal into an analog electrical signal This analog signal is often weak and noisy Amplifiers are needed to strengthen the signal Analog filtering may be necessary to remove noise from the signal This front end processing improves the signal to noise ratio Three of the most important building blocks used in this stage are a Operational Amplifiers b Analog Multipliers and c Analog Comparators An analog to digital converter transforms the analog signal into a stream of 5 and 18 Texas Lab Manual tlm 2012 8 14 14 55 page 1 25 A D Temperature Pressure Position Speed Flow Power m
62. erter Extended temperature range 40 C to 125 C C 20 lead TSSOP packages 12 Bit monotonic O 1LSB INL DB Four quadrant multiplication Power on reset with brownout detection Read back function O Industry standard pin configuration A 3 2 Applications Portable battery powered instruments Waveform generators Analog processing Programmable amplifiers and attenuators Texas Lab Manual tlm 2012 8 14 14 55 page 101 125 Digitally controlled calibration Programmable filters and oscillators Composite video Ultrasound A 3 3 Description The DAC7821 is a CMOS 12 bit current output digital to analog converter DAC This device operates from a single 2 5V to 5 5V power supply making it suitable for battery powered and many other applications This DAC operates with a fast parallel interface Data read back allows the user to read the contents of the DAC register via the DB pins On power up the internal register and latches are filled with zeroes and the DAC outputs are at zero scale The DAC7821offers excellent 4 quadrant multiplication char acteristics with a large signal multiplying and width of 10 MHz The applied external reference input voltage V ef determines the full scale output current An integrated feedback resistor Arg provides temperature tracking and full scale voltage output when combined with an external current to voltage precision amplifier
63. erter TPS40200 from Texas Instruments Our aim is to design a DC DC converter with high efficiency using a general purpose Op Amp for a variety of applications like Switched Mode Power Supply SMPS audio amplifier Class D Power Amplifier etc 9 2 Brief Theory and Motivation The reader will benefit from viewing the recorded lecture at 26 Also refer to the application note Design Considerations for Class D Audio Power Amplifiers 17 Texas Lab Manual tlm 2012 8 14 14 55 page 85 109 The function generator which we studied in Chapter 6 is a basic building block in a DC DC converter The triangular output of the function generator with peak amplitude V and frequency f is fed as an input to a comparator whose second input comes from a reference voltage Vier The output of the comparator is a Pulse Width Modulation PWM waveform whose duty cycle is given by Viet Vo 1 where 7 1 f is the time period of the triangular waveform The duty cycle is directly proportional to reference voltage Vref If we connect a lossless Low Pass filter LC filter at the output of the comparator as shown in Figure 9 1 it is possible to get 8 stable DC voltage Vay given by Vay ref Vss Vp 9 1 We thus get a converter with high conversion efficiency We can also insert a PMOS switch in between the comparator and the LC filter to achieve Class D operation 9 3 Specification Design a DC DC converter us
64. ge of the system If K q denotes the sensitivity of the phase detector the lock range is given by Lock Range Kpa x x Ap x Kyco 7 2 on either side of wq 7 3 Specifications Design a PLL to get locked to frequency of 1 59 kHz when the free running frequency is 1 59 kHz 7 4 Measurements to be Taken Measure the lock range of the system Measure the change in the phase of the output signal as input frequency is varied within the lock range Texas Lab Manual tlm 2012 8 14 14 55 page 73 97 Output V 5 0 10 0 r 8 0 8 5 9 0 9 5 10 0 Time ms Figure 7 2 Sample output waveform for the Phase Locked Loop PLL for a square wave input waveform Vary the input frequency and obtain the change in the control voltage and plot the output A sample output characteristic of the PLL is shown in Figure 7 2 In the diagram the square wave of 10 V is the input waveform the square wave of 8 V is the output waveform The slow varying waveform in thick line is the control voltage 7 5 What Should you Submit Simulate the system and predict the output waveforms of the PLL Build the PLL system using ASLKv2010 Starter kit and take the plots of the output waveform on the oscilloscope Compare the simulation results with Texas Lab Manual tlm 2012 8 14 14 55 page 74 98 Table 7 1 Output phase as a function of input frequency S No Input Frequency Output Phase
65. gle output Op Amp 16 1 2 A unity gain system 17 1 3 Magnitude response of a unity gain system 18 1 4 Time response of an amplifier for a step input of size W 19 1 5 a Non inverting amplifier of gain 2 b inverting amplifier of gain 2 20 Texas Lab Manual tlm 2012 8 14 14 55 page xxi 17 1 6 a Frequency response of negative feedback amplifiers b time response of negative feedback amplifiers 21 1 7 Transfer characteristics of unity gain non inverting and inverting amplifiers 22 1 8 Instrumentation amplifier configurations with a three b two operational amplifiers 23 1 9 a An inverting amplifier with analog gain control 26 1 9 b Simulation of the circuit for Figure 1 9 a when 1V 27 1 10 Digitally controlled amplifier 7 2 1 Inverting Schmitt trigger and its hysteresis characteristic 30 2 2 Symbols for a inverting b non inverting Schmitt trigger circuits 31 2 3 Non inverting Schmitt trigger and its hysteresis characteristic 31 2 4 Astable multivibrator 32 2 5 Simulation results for a astable multivibrator monostable multivibrator 33 2 6 Monostable multivibrator 34 3 1 Integrator 38 3 2 Differentiator 38 3 3 Frequency response of integrator and differentiator 41 3 4 Outputs of integrator and differentiator for a square wave b triangular wave inputs 42 3 5 Circuits for Exercise 43 4 1 A second order universal active filter 47 4 2 Simulation waveform for a universal active filter 48 4 3
66. goal Texas Lab Manual tlm 2012 8 14 14 55 page 110 134 Table B 1 Operational amplifiers available from Texas Instruments Characteristic Number of Varieties 1 Standard Linear Amplifier 240 2 Fully Differential Amplifier 28 3 Voltage Feedback 68 4 Current Feedback 4 5 Rail to Rail 14 6 JFET CMOS 23 7 DSL Power Line 19 8 Precision Amplifier 641 9 Low Power 144 10 High Speed Amplifier gt 50 MHz 182 11 Low Input Bias Current FET Input 38 12 Low Noise 69 13 Wide Bandwidth 175 14 Low Offset Voltage 121 15 High Voltage 4 16 High Output Current 54 17 LCD Gamma Buffer 22 of the system designer is not only to get a functionally correct design but also to optimize the cost and performance of the system The system level cost and perfor mance depend on the way the building blocks B1 Bo Bn have been implemented For example if B is an Op Amp we may have several choices of operational ampli fiers Texas Instruments offers a large number of operational amplifiers that a system designer can choose from Refer to Table B 1 As you will see there are close to 2000 types of operational amplifiers available These are categorized into 17 different bins to make the selection simpler However you will notice that 240 varieties are avail able in the category of Standard Linear amplifiers How does a system designer select from this large collection To understand this you must look at the characteristics of a standar
67. has three options to use the output from one of the potmeters to provide 5 V supply to generate a 5 V supply see the DC DC converter experiment in this manual or to use an external 5 V supply This comprehensive user manual included with the kit gives complete insight of how to use ASLKv2010 Starter kit The manual covers exercises of analog sys tem design along with brief theory and simulation results obtained using simulation software Refer to Appendix A for the details of the integrated circuits that are included in ASLKv2010 Starter kit Refer to Appendix D for additional details of ASLKv2010 Starter kit 0 4 2 Software The following softwares are necessary to carry out the experiments suggested in this manual ASPICE based simulation software such as TINA 9 Multisim 15 or PSPICE 32 FilterPro a software program for designing analog filters Texas Lab Manual tlm 2012 8 14 14 55 page 10 34 6 switcherPro a software program for designing switched mode power sup plies Q mpacBuf ferPro 8 software for designing multiplying D A converters aDpcPro a software for designing A D converters ClockPro a software for synthesizing clock generators Several SPICE based simulation software 9 32 are available today to verify the behavior of circuits before they are implemented These are powerful and easy to use simulators for electronic circuits It allows the simulation of circuits wi
68. hmitt trigger circuit is shown in Figure 2 3 Voltage V 10 0 i 7 i r i 10 0 5 0 0 5 0 10 0 Input voltage V Figure 2 3 Non inverting Schmitt trigger and its hysteresis characteristic Texas Lab Manual tlm 2012 8 14 14 55 page 31 55 Experiment 2 2 2 2 Astable Multivibrator An astable multivibrator is shown in Figure 2 4 The first two waveforms Vo and 2 shown in Figure 2 5 namely square and the triangular waveforms are generated using the astable multivibrator We refer to 6 as the regenerative feedback factor The time period of the square waveform generated by the multivibrator is given by T 2 RC n 7 2 4 l BVss refers to the peak amplitude of the triangular waveform 2 2 3 Monostable Multivibrator Timer The circuit diagram for a monostable multivibrator is shown in Figure 2 6 The trigger waveform is applied to the monostable multivibrator at the positive terminal which produces the outputs V 3 and Vo4 at the output as shown in Figure 2 5 The monostable remains in the ON state until it is triggered at this time the circuit switches to the Figure 2 4 Astable multivibrator Texas Lab Manual tlm 2012 8 14 14 55 page 32 56 20 00 6 00 6 00 20 00 m 22 50 m 25 00 m 27 50 m 30 00 m Time s 10 0 V 5 0 V 150 0 160 0 170 0 180 0 190 0 200 0 Time ms Figure 2 5 Simulation results for
69. ifiers is the Handbook of Operational Amplifier Applications by Carter and Brown 5 The book OPAMPS For Everyone by Carter and Mancini is also an excellent resource 8 Texas Lab Manual tlm 2012 8 14 14 55 page 28 52 5 L ab ES O 2 1 Goal of the Experiment This experiment illustrates the use of positive regenerative feedback used in all ON OFF control systems such as temperature controllers pulse width modulators and Class D amplifiers The goal of this experiment is to understand the basics of hysteresis and the need of hysteresis in switching circuits 2 2 Brief Theory and Motivation 2 2 1 Inverting Regenerative Comparator In the earlier experiment we had discussed the use of only negative feedback Let us now introduce the case of regenerative positive feedback as shown in the Figure 2 1 Texas Lab Manual tlm 2012 8 14 14 55 page 29 53 V Vo 10 05 5 04 0 Ro Voltage V 5 5 0 10 0 4 1 i i r 10 0 5 0 0 5 0 10 0 Input voltage V Figure 2 1 Inverting Schmitt trigger and its hysteresis characteristic The reader will benefit by listening to the recorded lecture at 22 The relation between the input voltage V and output voltage V is given by Equation 2 3 where 6 KAR Vo AlV BVo 2 1 V V My 22 1 8 2 3 AB There are three cases to be considered Case 1 A lt 1 In this case the circu
70. ing a switching frequency of 10 kHz and 100 kHz using an available reference voltage for an output voltage of 5 V 9 4 What Should you Submit Simulate the system and plot the output waveforms of the comparator and the Low Pass filter output as shown in Figure 9 1 We have included a DC DC converter and typical simulation results in Figure 9 2 Vss in the system is the unregulated input Vo is the converted output Texas Lab Manual tlm 2012 8 14 14 55 page 86 110 Triangular waveform generator 1 1 1 0 V 7 0V Vo2 3 0V 8 0 V 2 0V 1 0 V Vo 1 0 V EHTE tates Len III T TTT 10 0 10 5 11 0 11 5 12 0 Time ms b Figure 9 1 a DC DC converter b waveforms from simulation Texas Lab Manual tlm 2012 8 14 14 55 page 87 111 9 0 7 0 5 0 Output V 3 0 1 0 10 0 10 25 10 5 10 75 10 Time ms Figure 9 2 PWM and Class D output waveforms Build the DC DC converter using ASLKv2010 Starter kit and observe the waveforms mentioned above Compare with simulation results 6 Plot the average output voltage Vay as a function of control voltage V and obtain the plot Use a table similar to Table 9 1 to take your readings Is the plot linear Determine the peak to peak ripple at the output of the LPF Plot the duty cycle 7 as a function of control voltage V Use a table similar to T
71. it behaves as an amplifier and the output voltage has a linear relation to the input voltage However the gain is very sensitive to variations in Ag S Case 2 A B 1 In this case the amplifier becomes unstable and its output saturates Case 3 A 6 lt lt 1 The output voltage is no longer related linearly to input voltage This configuration is useful in interface circuits where the output voltage behaves in a digital way and shows two stable states namely Vss and Vss Texas Lab Manual thm 2012 8 14 14 55 page 30 54 When the input is a large negative value the output saturates at Vss As the input is increased the output remains constant at Vss and when the input reaches Vss the device enters into the regenerative feedback mode and the output changes from Vss to Vss Now when the input is decreased the circuit can change state only when the input becomes 2 Vss See Figure 2 1 Thus there is a hysteresis of Vss on either side of origin and there is a total hysteresis of 2 B Vss This kind of comparator is required when driving 8 MOSFET as a switch in ON OFF controllers SMPS Switched Mode Power Supply pulse width modulators and Class D audio power amplifiers The symbol for this inverting type Schmitt trigger is shown in Figure 2 2 a One can similarly construct a non inverting Schmitt trigger for which the symbol is shown in Figure 2 2 b The non inverting Sc
72. l com krkrao nptel ic lec27 25 K R K Rao Electronics for Analog Signal Processing Part II Voltage Regulators Recorded lecture available through NPTEL http tinyurl com krkrao nptel 26 http tinyurl com krkrao nptel 27 http tinyurl com krkrao nptel 28 26 K R K Rao Electronics for Analog Signal Processing Part II Converters Recorded lecture available through NPTEL http tinyurl com krkrao nptel 28 27 K R K Rao Electronics for Analog Signal Processing Part II AGC AVC http tinyurl com krkrao nptel 33 http tinyurl com krkrao nptel 34 http tinyurl com krkrao nptel 35 http tinyurl com krkrao nptel 36 28 K R K Rao Analog ICs Voltage Controlled Oscillator Recorded lectures available from http tinyurl com krkrao vco 1 http tinyurl com krkrao vco 2 29 Thomas Kugesstadt Active Filter Design Technigues Texas Instruments Available from http focus ti com lit ml sloa088 sloa088 pdf 30 Oscilloscope Solutions from Texas Instruments Available from http focus ti com docs solution folders print 437 html 31 PC Based Test and Instrumentation Available from http www pctestinstruments com 32 PSpice http en wikipedia org wiki PSpice 33 SwitcherPro TM Switching Power Supply Design Tool http focus ti com docs toolsw folders print switcherpro html 34 Texas Instruments Analog eLAB SPICE Model Resources Macromodels for TI analog ICs are downloadable from
73. ltage or current controlled amplifier finds applications in communication circuits in the form of mixer modulator demod ulator and phase detector We use the multiplier in building Voltage Controlled Oscillators VCO Frequency Modulated Waveform Generators or Frequency Shift Key Generators in modems Automatic Gain Controllers Amplitude Stabi lized Oscillators Self tuned Filters and Frequency Locked Loop Voltage controlled phase generators and VCOs that use multiplier as a phase detector are built and their lock range and capture range estimated and verified In the Analog System Lab the frequency range of all applications has been restricted to 1 10 kHz with the following in mind a Simple macromodels can be used for active devices in simulation b A PC can be used in place of an oscilloscope We have also included an experiment that can help the student use a PC as an oscilloscope We also suggest an experiment on the development of macromodels for an Op Amp Texas Lab Manual tlm 2012 8 14 14 55 page 4 28 Figure 0 2 shows the dependence among the experiments included in Analog Sys tem Lab The sequence in which the experiments are carried out can be altered using this dependence graph We believe that the students must carry out all the experiments At the end of Analog System Lab we believe you will have the following know how about analog system design You will learn about the characteristics and specifi
74. mes are often abbre viated as LPF Low Pass Filter HPF High Pass Filter BPF Band Pass Filter and BSF Band Stop Filter In this experiment we will describe a universal active filter that pro vides all four filter functionalities Figure 4 5 b shows a second order universal filter Table 4 1 Transfer functions of active filters Low Pass Filter 2 High Pass Filter a Band Pass Filter Band Stop Filter el Texas Lab Manual tlm 2012 8 14 14 55 page 46 70 Figure 4 1 A second order universal active filter realized using two integrators Note that there are different outputs of the circuit that realize LPF HPF BPF and BSF functions 42 1 Freguency Response of Filters The magnitude response of two ofthe filters BPF and BSF are shown in Figure 4 3 The phase sensitivity 60 66 is maximum at 0 and is given by 2Q ap This information about phase variation can be used to tune the filter to a desired freguency wo This is demonstrated in the next experiment For the BPF the magnitude response peaks at wy and is given by 450 The BSF shows a null magnitude response at w 09 4 3 Specifications Design a Band Pass and a Band Stop filter For the BPF assume Fp 1 kHz and Q 1 For the BSF assume Fy 10 kHz and 0 10 Texas Lab Manual tlm 2012 8 14 14 55 page 47 71 4 4 Measurements to be Taken Steady state response Apply a square wave inp
75. n by VRC Therefore dao V 0 TT V We v re VC The sensitivity of VCF is radians sec Volts Now 6 d db don dV dwg dV If we consider the low pass output then dp 20 don ap 0 Hence sensitivity of VCF Kycr is equal to 20 Ve H For varying input frequency the output phase will always lock to the input phase with 90 phase difference between the two if Vay 0 Texas Lab Manual tlm 2012 8 14 14 55 page 59 83 Table 5 1 Variation of output amplitude with input frequency Input Voltage S No Input Freguency Output Amplitude 15 ON gt 5 3 Specification Assuming that the input frequency is 1 kHz design a high Q BPF whose center freguency gets tuned to 1 kHz 5 4 Measurements to be Taken Apply a square wave input and observe the amplitude of the Band Pass output for fundamental and its harmonics 5 5 What Should you Submit Simulate the circuits and obtain the transient response of the system Take the plots of transient response from oscilloscope and compare them with simulation results Measure the output amplitude of the fundamental Band Pass output at varying input frequency at fixed input amplitude Output amplitude should remain constant for varying input frequency within the lock range of the system Texas Lab Manual tlm 2012 8 14 14 55 page 60 84 Experiment 5 5 6 Exercises Determine the lock ra
76. n in Thirty Seconds Application Report from Texas Instruments Downloadable from http focus ti com lit an sloa093 sloa093 pdf 8 B Carter and R Mancini OPAMPS For Everyone Elsevier Science Publishers 2009 Texas Lab Manual tlm 2012 8 14 14 55 page 125 149 9 DesignSoft TINA the complete analog lab www tina com 10 FilterPro TM Active Filter Design Application Free software Available from http tinyurl com filterpro download 11 Thomas Kuehl and Faisal Ali Active Filter Synthesis Made Easy With FilterPro V3 0 Tutorial presented in TI Technology Days 2010 May USA Available from http www ti com ww en techdays 2010 index shtml 12 J Molina DESIGN A 60Hz Notch Filter with the UAF42 Application note from Burr Brown Texas Instruments 2000 Available from http focus ti com lit an sbfa012 sbfa012 pdf 13 J Molina Digitally Programmable Time Continuous Active Filter 2000 Application note from Burr Brown Texas Instruments http focus ti com lit an sbfa005 sbfa005 pdf 14 George S Moschytz From Printed Circuit Boards to Systems on a chip IEEE Circuits and Systems magazine Vol 10 Number 2 2010 15 National Instruments www ni com multisim 16 Phase locked loop Wikipedia entry http en wikipedia org wiki Phase locked loop 17 R Palmer Design Considerations for Class D Audio Amplifiers Application Note from Texas Instruments Available from http focus
77. nge of the self tuned filter you designed The lock range is defined as the range of input frequencies where the amplitude of the output voltage remains constant at Hy x Q x Vp Repeat the experiment above with other periodic input waveforms such as the triangular waveform 9 A self tuned filter is shown in Figure 5 5 b Determine its lock range Estimate the output at VF and the control voltage VF for a square wave input VG of 0 1 V magnitude Repeat for VG 0 2V 2 00 1 00 4 0 00 Output 1 00 2 00 337 00 m 339 00 m 341 00 m 343 00 m Time s Figure 5 5 a Simulation of the self tuned filter shown in Figure 5 5 b when VG Texas Lab Manual tlm 2012 8 14 14 55 page 61 85 HA a o 8 Ip 06 o ep OL SY EJA JLH Z801L N A 28011 2801 n iN 7 6 is il 6 N x I 05 6 28 ka iy 0 u 001 ALH u 00L 29 ZL ip H kull Figure 5 5 b Self tuned filter Texas Lab Manual tlm 2012 8 14 14 55 page 62 86 Experiment 5 5 7 Related ICs Texas Instruments also manufactures the following related ICs Voltage controlled amplifiers e g VCA820 and multiplying DAC e g DAC7821 that can be used in place of analog multiplier Refer to www ti com for application notes Texas Lab Manual thm 2012 8 14 14
78. nt as shown in Equation 1 5 where wg and wg wg lt wg are known as the dominant poles of the operational amplifier This transfer function is typical in an Op Amp that has internal frequency compensation Please view the recorded lecture 19 to get to know more about frequency compensation Ao iz 1 5 001 1 5 002 al We can now write the transfer function T for a unity gain amplifier as 1 T N 1 1 A 1 6 1 1 1 40 s Ap og1 s 40 042 52 40 01 w42 1 17 1 s GB s Ao wd2 s GB a The term GB Apwg1 known as the gain bandwidth product of the operational amplifier is one of the most important parameters in Op Amp negative feedback circuits Texas Lab Manual tlm 2012 8 14 14 55 page 17 41 The transfer function in Equation 1 7 can be rewritten as 1 1 s o 9 6 T where 0 vVod2 GB 1 A GB wa2 We can approximate 0 as GB 1 0 AS y q2 GB 12 Also w VGB aq Q is the Quality Factor 1 20 is the Damping Factor and wp is the natu ral frequency of the second order system Figure 1 3 shows the frequency response magnitude vs w c of a unity gain amplifier 10 00 E Vi TT Gain dB 8060 A Po ak ene ae Se 100 00 k 1 00 M 10 00 M Freguency Hz Figure 1 3 Magnitude response of a unity gain system Texas Lab Manual tlm 2012 8 14 14 5
79. o use the resistor in a DC circuit But if the resistor is used in a high frequency application we may have to think about the parasitic inductances and Capacitances associated with the resistor Similarly the voltage and current may not have a strict linear relation due to the dependence of the resistivity on temperature of operation skin effect and so on This example illustrates that there is no single model for an electronic component Depending on the application and the accuracy desired we may have to use simpler or more complex mathematical models Texas Lab Manual tlm 2012 8 14 14 55 page 109 133 We will use another example to illustrate the above point The MOS transistor which is the building block of most integrated circuits today is introduced at the beginning of a course on VLSI design In a digital circuit the transistor may be simply modeled as an ideal switch that can be turned on or off by controlling the gate voltage This model is sufficient if we are only interested in understanding the functionality of the circuit If we wish to analyze the speed of operation of the circuit or the power dissipation in the circuit we will need to model the parasitics associated with the transistors If the same transistor is used in an analog circuit the model that we use in the analy sis would depend on the accuracy which we want in the analysis We may perform different kinds of analysis for an analog circuit DC analysis
80. oach to teaching analog design start with analog systems and then move to circuits Analog systems are part of every electronic system today and we believe they must be taught in the building block spirit that has worked well for digital design There are many system design companies today looking for engineers who can design using analog ICs they hardly ever design or even use a common emitter amplifier or a Wien bridge oscillator There are 10 experiments in the Analog System Lab which can be carried out either individually or by groups of two or three students In the first phase of experiments two basic analog building blocks are introduced namely Operational Amplifiers and Analog Multipliers In the second phase we explain how larger analog systems such as integrators differentiators filters function generators VCO PLL DC DC converters and regulators can be constructed using the basic building blocks The emphasis is on learning by paper design simulation through SPICE hardware construction and analysis of results With each experiment we provide brief theoretical background references to literature mostly online and easy to access the specification of the design experiment measurements to be taken and the documents to be submitted at the end of the experiment A teacher s manual can be made available on request This manual is the result of almost a year s effort We have received support from a number of individuals
81. of devices ideal for most battery operated handheld equipment All device ver sions have thermal shutdown and current limit for safety Furthermore these devices are stable with an effective output capacitance of only 0 1 uF This feature enables the use of cost effective capacitors that have higher bias voltages and temperature derating A 5 4 TLV70018EVM 503 Evaluation Module The evaluation module TLV70018EVM 503 facilitates evaluation of the IC TLV70018 from Texas Instruments which is a Low Dropout Regulator 200mA low IQ LDO regulator in the DCK 2 0 x 2 1mm SC70 5 package A5 5 Download Datasheet http focus ti com lit ds symlink tlv70012 pdf Texas Lab Manual tlm 2012 8 14 14 55 page 107 131 Texas Lab Manual tlm 2012 8 14 14 55 page 108 132 mM as LL a A lt Simulation models are very useful in the design phase of an electronic system Before a system is actually built using real components it is necessary to perform a software breadboarding exercise through simulation to verify the functionality of the system and to measure its performance If the system consists of several building blocks B B2 Bn the simulator requires a mathematical representation of each of these building blocks in order to predict the system performance Let us consider a very sim ple example of a passive component such as a resistor Ohm s law can be used to model the resistor if we intend t
82. ound the following two components e The Op Amp TL082 a general purpose JFET input Operational Amplifier made by Texas Instruments e Wide bandwidth precision Analog Multiplier MPY634 from Texas Instruments Texas Lab Manual tlm 2012 8 14 14 55 page 3 27 Using these components the student will build gain stages buffers instru mentation amplifiers and voltage regulators These experiments bring out several important issues such as measurement of gain bandwidth product slew rate and saturation limits of the operational amplifiers We then introduce the analog comparator which is a mixed mode device its input is analog and output is digital In a comparator the rise time fall time and delay time are important apart from input offset Part II The second part concentrates on building analog systems using the blocks mentioned in the previous point First we introduce integrators and differentiators that are essential for imple menting filters that can band limit a signal prior to the sampling process to avoid aliasing errors A function generator is also a mixed mode system that uses an integrator and a regenerative comparator as building blocks The function generator is capable of producing a triangular waveform and square waveform as outputs It is also useful in Pulse Width Modulation in DC to DC converters switched mode power supplies and Class D power amplifiers The analog multiplier which is a vo
83. ree potmeters included in the kit each of which is connected across 10 V and ground The output of the potmeter can be used to derive a voltage in the range 0 to 10 V this can be useful in generating a reference voltage or even in generating a 5 V power supply for the DAC The student must become familiar with the general floorplan of the kit Begin by understanding the power and ground connections to the kit Note that 10 V and ground connections must be fed to the kit from the inlets at the left hand side This automatically powers the operational amplifiers and the analog multipliers Each of the Texas Lab Manual tlm 2012 8 14 14 55 page 117 141 7821 DAC 1 7821 DAC 2 MOSFET 5 MPYOTe MULTIPLIER 1 MULTIPLIER 2 MULTIPLIER 3 Power z POTMETER TONNE CTIDNS INDICATOR LEDs OPAMP 4 082 OPAMP 3 082 OPAMP 1 TLO82 OPAMP 2 082 1A TYPE 1 2A TYPE 1 3A SPARE 4A TYPE2 TYPE 1 2B SPARE 3B SPARE 48 TYPE 2 18 Figure D 1 Floorplan of the ASLKv2010 Starter kit 5V General purpose prototype board t 30010 c 30014 Multiplier 2 Multiplier 3 2024 4777 TL082 Dual OPAMP IC 4 Dual OPAMP IC 1 ae eae i 4A TYPE 2 JA TYPE 1 5 R d 18 TYPE 1 2B TYPE 1 SS Sonne 4B TYPE 2 Figure D 2 Power connections in ASLKv2010 Starter kit Only connect 10 V and ground connections Texas Lab Manual tlm
84. reg ulators In the case of the DC DC converter studied in the previous experiment the Texas Lab Manual tlm 2012 8 14 14 55 page 91 115 Vun PMOS Transistor Figure 10 1 Low Dropout Regulator LDO switching activity exemplified by the PWM waveform is a source of noise As a result DC DC converter of the previous chapter is not suitable for ow noise applications An LDO is better suited in such cases An LDO system is shown in Figure 10 1 It uses a PMOS current amplifier along with an Op Amp so that power dissipation in Op Amp and PMOS combination is minimal The efficiency of the LDO defined as the ratio of the output voltage to input voltage is high The regulated output voltage is given by R Vo Vef 4 7 10 1 1 10 3 Specifications Generate a 3 V output when input voltage is varying from 4 V to 5 V Texas Lab Manual tlm 2012 8 14 14 55 page 92 116 Voltage V ee mi 500 0 600 0 700 0 800 0 900 0 1 0k Input resistance ohms b Voltage V 16 0 18 0 20 0 Input voltage V 12 05 14 0 c Figure 10 2 a A regulator system with startup b load regulation output c line regulation output Texas Lab Manual thm 2012 8 14 14 55 page 93 117 Table 10 1 Variation of load regulation with load current in an 0 S No Load Current Output Voltage 15 O 92 10 4 Measurements to be Taken Obtain the Load
85. resistors for some common output voltages A 4 5 Download Datasheet http focus ti com lit ds symlink tps40200 pdf A 5 TLV700xx 200mA Low IQ Low Dropout Regulator for Portables 4 5 Features Very low dropout 43 mV at lut 50 MA Vour 2 8 V 6 85 mV at lur 100 MA Voyz V 175 mV at lur 200 MA Voyr 2 35 V 2 accuracy Texas Lab Manual tlm 2012 8 14 14 55 page 105 129 Figure A 5 TLV700XX Low dropout regulators Low 10 31 pA Available in fixed output voltages from 0 7 V to 4 8 V High PSRR 68 dB at 1 kHz Stable with effective capacitance of 0 1 uF 6 6 6 6 6 Thermal shutdown and overcurrent protection D Available in 1 5mm x 1 5 mm SON 6 SOT23 5 and SC 70 packages A 5 2 Applications Wireless handsets Smart phones PDAs 6 MP3 players ZigBee Networks Bluetooth Devices Li lon operated handheld products WLAN and other PC add on cards A 5 3 Description The TLV700xx TLV701xx series of low dropout LDO linear regulators from Texas Instruments are low quiescent current devices with excellent line and load Texas Lab Manual tlm 2012 8 14 14 55 page 106 130 transient performance These LDOs are designed for power sensitive applications A precision bandgap and error amplifier provides overall 2 accuracy Low output noise very high power supply rejection ratio PSRR and low dropout voltage make this series
86. s If you wish to carry out an experiment using the DAC integrated Texas Lab Manual tlm 2012 8 14 14 55 page 11 35 circuits on the board you must use an external 5 V supply and ground connection as shown in Figure D 2 There are three potmeters included in the kit each of which is connected across 10 V and ground The output of the potmeter can be used to derive a voltage in the range of 0 to 10 V this can be useful in generating a reference voltage or even in generating a 5 V power supply for the DAC There are four 11082 Op Amp ICs labeled 1 2 3 and 4 ASLKv2010 Starter kit Each of these ICs has two amplifiers which are labeled A and B Thus 1A and 1B are the two Op Amps in the Op Amp IC 1 etc The eight Op Amps are categorized as shown in the following table Op Amp IC Op Amp Label on Kit Type Purpose 1 1A TYPE 1 1 TYPE 1 Inverting Configuration only 1B TYPE 1 2 1 Inverting Configuration only 2 2A TYPE 1 3 TYPE 1 Inverting Configuration only 2B TYPE SPARE 1 SPARE Spare 3 3A TYPE SPARE 2 SPARE Spare 3B TYPE SPARE 3 SPARE Spare 4 4A TYPE 2 1 TYPE 2 Inverting or Non inverting 4B TYPE 2 2 TYPE 2 Inverting or Non inverting Refer to the floorplan of the kit and identify the Op Amp ICs Figure D 1 It will also be helpful to refer to the power connections shown in Figure D 2 Please see connection diagrams shown in Figures D 3 D 4 D 5 and D 6 The Op Amps are marked TYPE 1 TYPE 2 or SPARE on
87. s have access to a PC or laptop today we have designed the Ana log System Lab such that a PC based oscilloscope solution can be used along with ASLKv2010 Starter kit We believe this will reduce the dependence of the student Texas Lab Manual tlm 2012 8 14 14 55 page 113 137 on a full fledged lab In this chapter we will review a solution for a PC based oscil loscope The components on the ASLKv2010 Starter 0 interface circuit needed to convertthe PC into an oscilloscope an be used to build the One ofthe solutions for a PC oscilloscope is Zelscope 36 which works on per sonal computers running MS Windows XP The hardware regu irements for the PC are modest 300 MHz clock 64 MB memory It uses the sound card in the PC for convert ing the analog signals into digital form The Zelscope software which requires about 1 MB space is capable of using the digitized signal to display waveforms as well as the frequency spectrum of the analog signal At the line in jack of the sound card the typical voltage s hould be about 1 V AC hence it is essential to protect the sound card from over voltages A buffer amplifier circuit is required to protect the sound card from over voltages Two copies of such a circuit are needed to implement a dual channel oscilloscope The buffer amplifier circuit is shown in Figure C 1 and has been borrowed from 35 AC coupling 1 M impedance 150 V input protection 10
88. th an input voltage up to 52 V without dissipating excessive power The circuit operates with voltage mode feedback and has feed forward input voltage compensation that responds instantly to input voltage change The integral 700 mV reference is trimmed to 2 providing the means to accurately control low voltages The TPS40200 is available in an 8 pin SOIC and supports many of the features of more complex controllers Texas Lab Manual tlm 2012 8 14 14 55 page 104 128 Append A A 4 4 7 The TPS40200EVM 002 evaluation module EVM uses the 540200 non synchronous buck controller to provide a resistor selected 3 3 V output voltage that delivers up to 2 5 A from a 24 V input bus The EVM operates from a single supply and uses a sin gle P channel power FET and Schottky Diode to produce a low cost buck converter The part operates at a 200 kHz clock frequency as determined by an external resis tor and capacitor TPS40200EVM 002 is designed to operate with an 18 to 36 V input and to produce a regulated 3 3 V output with a load current from 0 125 to 2 5 A The TPS40200EVM 002 demonstrates using the TPS40200 in a typical buck converter appli cation The ASLKv2010 Starter kitsacrifices some layout density to provide ample test points for module evaluation This EVM can be modified to support output voltages from 0 7 V to 5 V and above by changing a single feedback resistor A table is included in the User Guide that lists specific 1
89. th passive components such as resistors capacitors and inductors as well as active components like transistors and analog integrated circuits Texas Instruments makes macromodels of integrated circuits available for the users of the simulation programs Appendix B explains what macromodels are We will assume that you are familiar with the concept of simulation and are able to simulate a given circuit in TINA or PSPICE FilterPro is a program for designing active filters At the time of writing this manual FilterPro Version 3 0 is the latest It supports the design of different types of filters namely Bessel Butterworth Chebychev Gaussian and linear phase filters The software can be used to design Low Pass filters High Pass filters Band Stop filters and Band Pass filters with up to 10 poles The software can be downloaded from 10 0 5 Familiarizing with ASLKv2010 Starter Kit The Analog System Lab ASLKv2010 Starter kit is divided into many sections Refer to the picture in Figure 0 5 when you read the following description Please also refer to the floorplan of the chip shown in Figure D 1 Appendix D Figure D 1 shows the overall floorplan of the ASLKv2010 Starter kit We have shown the power connections in ASLKv2010 Starter in Figure D 2 Note that the 10 V power and ground connections have to be connected to the power inlets at the side of the kit the power and ground are internally connected to the Op Amps and analog multiplier
90. ti com lit an sloa031 108031 5 18 K R K Rao Electronics for Analog Signal Processing Part Il Op Amp in Nega tive Feedback Recorded lecture available through NPTEL http tinyurl com krkrao nptel lec7 and http tinyurl com krkrao nptel lecs8 19 K R K Rao Electronics for Analog Signal Processing Part Il Frequency Compensation in Negative Feedback Recorded lecture available through NPTEL http tinyurl com krkrao nptel lec16andhttp tinyurl com krkrao nptel lec17 20 K R K Rao Electronics for Analog Signal Processing Part Il Instrumentation Amplifier Recorded lecture available through NPTEL http tinyurl com krkrao nptel lec11 21 K R K Rao Electronics for Analog Signal Processing Part II Active Filters Recorded lecture available through NPTEL http tinyurl com krkrao nptel lec12 22 K R K Rao Electronics for Analog Signal Processing Part II Positive Feedback Regenerative Recorded lecture available through NPTEL http tinyurl com krkrao nptel lec9 Texas Lab Manual thm 2012 8 14 14 55 page 126 150 23 K R K Rao Analog ICs Self Tuned Filter Recorded lecture available through NPTEL http tinyurl com krkrao nptel ic lec23 24 K R K Rao Analog ICs Phase Locked Loop Recorded lecture available through NPTEL http tinyurl com krkrao nptel ic lec24 http tinyurl com krkrao nptel ic lec25 http tinyurl com krkrao nptel ic lec26 and http tinyur
91. ts an exposure to the fascinating world of analog and mixed signal signal processing The course can be adapted for an undergraduate or a postgraduate curriculum As part of the lab course the student will build analog systems using analog ICs and study their macro models characteristics and limitations Our philosophy in designing this lab course has been to focus on system design rather than circuit design We feel that many Analog Design classes in the colleges focus on the circuit design aspect ignoring the issues encountered in system design In the real world a system designer uses the analog ICs as building blocks The focus of the system designer is to optimize system level cost power and performance IC manufacturers such as Texas Instruments offer a large number of choices of integrated circuits keeping in mind the diverse requirements of system designers A designer must Texas Lab Manual tlm 2012 8 14 14 55 page ix 5 be aware of these diverse offerings of semiconductors and select the right IC for the right application We have tried to emphasize this aspect in designing the experiments in this manual We believe that there is a need to make a significant change to the way analog design is taught in the engineering colleges today The conventional way of starting with device physics and moving on to the design and analysis of analog circuits at the transistor level needs rethinking What is proposed is a two tier appr
92. unning frequency when input amplitude is 1V 76 7 4 Block diagram of frequency optimizer TI 8 1 Automatic Gain Control AGC Automatic Volume Control AVC 80 8 2 Input output characteristics of AGC AVC 80 8 3 Output of AGC circuit 82 8 4 a AGC circuit 83 8 4 b Simulation of the AGC circuit for output voltage 2V peak 83 9 1 a DC DC converter b waveforms from simulation 87 9 2 PWM and Class D output waveforms 88 10 1 Low Dropout Regulator LDO 92 10 2 a A regulator system with startup b load regulation output c line regulation output 93 A 1 TL082 JFET input operational amplifier 98 A 2 MPY634 Analog multiplier 99 A 3 DAC 7821 Digital to analog converter 101 A 4 TPS40200 DC DC controller 103 A 5 TLV700XX Low dropout regulators 106 C 1 Buffer circuit needed to interface an analog signal to oscilloscope 114 D 1 Floorplan of the ASLKv2010 Starter kit 118 D 2 Power connections in ASLKv2010 Starter kit Only connect 10 V and ground connections 118 D 3 Op Amp IC 1 Dual Op Amp with two amplifiers 1A and 1B connected in Type 1 configuration Inverting 119 Texas Lab Manual tlm 2012 8 14 14 55 page xxiv 20 D 4 D 5 D 6 D 7 D 8 Op Amp IC 2 Dual Op Amp with two amplifiers 2A and 2B 2A can be connected in Type 1 configuration Inverting 2B is a spare Op Amp IC 3 Dual Op Amp with two spare amplifiers 3A and 3B Op Amp IC 4 Dual Op Amp with amplifiers 4A and 4B Op Amp 4A
93. ur experiment requires only one of the two Op Amp circuits do not leave the inputs and output of the other Op Amp open instead place the second Op Amp in unity gain mode and ground the input 6 A Precaution Never connect any point from the board to the oscilloscope Instead use a probe that is connected to the oscilloscope to investigate different points on the board 0 N Advisory to Students and Instructors We strongly advise that the student performs the simulation experiments outside the lab hours The student must bring a copy of the simulation results from SPICE simulation to the class and show itto the instructor atthe beginning of the class The lab hours must be utilized only for the hardware experiment and comparing the actual outputs with simulation results 0 4 System Lab Kit ASEKv2010 Starter An Overview 0 4 1 Hardware ASLKv2010 Starter kit see Figure 0 3 Pin diagram is shown in Figure 0 4 has been developed at Texas Instruments India This kit is designed for undergraduate Texas Lab Manual tlm 2012 8 14 14 55 page 7 31 J 12ITEIS OTOTANTISV 9INIDIg 0 91 4 Wy aues 7 SLNIWAULSN J SVX 730000 j E 4 7 SIDE TOF COP 0 t 0 0000000000 w 95 900000000 900000000000 00000000000 9090000900000 40000000001 j 0 k0000000000 0 1 1 1 A 1 1 1 1 1 1 4 1 1 1 1 1 1 000000000 E 09 090 00 1 jH00000000000000000000
94. urriculum As part of the lab course the student will build analog systems using analog ICs and study their macro models characteristics and limitations Our philosophy in designing this lab course has been to focus on system design rather can circuit design We feel that many Analog Design classes in the colleges focus on the circuit design aspect ignoring the issues encountered in system design In the real world a system designer uses the analog ICs as building blocks The focus of the system designer is to optimize system level cost power and performance IC manufacturers such as Texas Instruments offer a large number of choices of integrated circuits keeping in mind the diverse requirements of system designers As a student you must be aware of these diverse offerings of semiconductors and select the right IC for the right application We have tried to emphasize this aspect in designing the experiments in this manual 0 2 Organization of the Analog System Lab Course In designing the lab course we have assumed that there are about 12 lab sessions during a semester We have designed 10 experiments that can be carried out either individually or by groups of two or three students The experiments in Analog System Lab can be categorized as follows Part I In the first part the student will be exposed to the operation of the basic building blocks of analog systems Most of the experiments in the Analog System Lab Course are centered ar
95. ut try f 1 kHz and f 10 kHz to both BPF and BSF circuits and observe the outputs A sample output is shown in Figure 4 2 e Band Pass output will output the fundamental frequency of the square wave multiplied by the gain at the center frequency The amplitude at this frequency 4 V is given by g where Vp is the peak amplitude of the input square wave My 0 200 0 mV Vo2 J 200 0 mV 10 0 mV 10 0 mV 10 0 mV gt E a E 80 0 ms 85 0 ms 90 0 ms 95 0 ms 100 0 ms Time Figure 4 2 Simulation waveform for a universal active filter Texas Lab Manual tlm 2012 8 14 14 55 page 48 72 e The BSF output will carry all the harmonics of the square wave other than the fundamental frequency This illustrates the application of BSF as a distortion analyzer Frequency response Apply a sine wave input and obtain the magnitude and the phase response 4 5 What Should you Submit Simulate the circuits in using a simulator software and obtain the steady state response and frequency response for both the filters Take the plots of the steady state response and frequency response from the oscilloscope for both the filters and compare the results with simulation results 6 Frequency response Apply a sine wave input and vary its input frequency to obtain the phase and magnitude error Use Tables 4 2 and 4 3 to note your readings The nature of graphs should be as shown in
96. xas Lab Manual tlm 2012 8 14 14 55 page 50 74 J 2 Figure 4 4 a Third order Butterworth filter 10 00 0 00 Gain dB 10 00 4 20 00 10 100 1k Frequency Hz Figure 4 4 b Frequency response of the Butterworth filter Texas Lab Manual tlm 2012 8 14 14 55 page 51 75 The filter of Figure 4 5 a is known as Tow Thomas Biquad Filter It is designed for a pole Q of 10 and pole frequency of 10 krad sec Obtain its frequency response VF VG and VR VG R 10 kOhm C 100 nF R4 1 kOhm U TL082 A VG V5V U3 TLO82 Figure 4 5 0 Tow Thomas biquad filter 30 00 15 00 g 0 00 oO 15 00 30 00 0 00 8 100 00 2 oO 8 200 00 i a 300 00 10k 100 1k Frequency Hz Figure 4 5 b Frequency response of the filter 47 Related Circuits The circuit described in Figure 4 5 b is a universal active filter circuit While this circuit can be built with Op Amps a specialized IC called UAF42 from Texas Instruments provides the functionality of the universal active filter We encourage you to use this circuit and understand its function Datasheet of UAF42 is available from www
97. y the phase error and magnitude error for integrator and differentiator Texas Lab Manual tlm 2012 8 14 14 55 page 39 63 Experiment 3 3 5 What Should you Submit Simulate the integrator and differentiator using a simulator software and obtain the transient response Take the plots of transient response on an oscilloscope and compare them with simulation results 6 Frequency response Apply a sine wave to the integrator similarly to the differen tiator and vary the input frequency to obtain phase and magnitude errors Prepare a table of the form Table 3 1 Figure 3 3 shows the typical frequency response for integrators and differentiators The first two plots VF and VF are the magnitude responses of the integrator and differentiator respectively The next two plots VF and VF are the phase responses of the integrator and differentiator respectively For an integrator the plot shows a phase lag proportional to w GB The magnitude decreases with increasing frequency For the differentiator the phase will change rapidly at natural frequency in direct proportion to Quality Factor The magnitude peaks at natural frequency and is directly proportional to the Quality Factor Time response Apply a square wave input of amplitude V to the integrator Vary the peak amplitude of the square wave and obtain the peak to peak value Vpp of the output Vp is directly proportional to V and is given by Vpp VpT 2RC where T

Analog System Lab Manual 2E prelims

Contents

Download Pdf Manuals

Related Search

Related Contents