Analog Circuits (eBook)

Front Cover 1
Analog Circuits: World Class Designs 4
Copyright Page 5
Table of Contents 6
Preface 14
About the Editor 20
About the Authors 22
Chapter 1: Review of Feedback Systems 26
Introduction and Some Early History of Feedback Control 26
Invention of the Negative Feedback Amplifier 27
Control System Basics 29
Loop Transmission and Disturbance Rejection 30
Stability 31
Routh Stability Criterion 33
The Phase Margin and Gain Margin Tests 36
Relationship Between Damping Ratio and Phase Margin 37
Loop Compensation Techniques—Lead and Lag Networks 38
Parenthetical Comment on Some Interesting Feedback Loops 40
Example 1-1: Gain of +1 amplifier 42
Example 1-2: Gain of +10 amplifier 44
Example 1-3: Integral control of reactive load 45
Example 1-4: Photodiode amplifier 50
Example 1-5: MOSFET current source 53
Example 1-6: Maglev example 58
Appendix: MATLAB Scripts 62
References 66
Chapter 2: My Approach to Feedback Loop Design 70
My Approach to Design 71
What Is a V/I Source? 72
An Ideal V/I Source 73
Designing a V/I Source 74
Capacitive Load Compensation 77
Model to Investigate Overshoot 79
Back to the Frequency Domain 81
Range of Compensation Required 84
Phase Margin Approach to Loop Compensation 85
LTX Device Power Source (DPS) Performance 86
Summary of My Method 87
Chapter 3: Basic Operational Amplifier Topologies and a Case Study 88
In This Chapter 88
Basic Device Operation 88
Example 3-1: Case study: Design, analysis, and simulation of a discrete operational amplifier 93
Brief Review of LM741 Op-Amp Schematic 100
Some Real-World Limitations of Operational Amplifiers 101
Example 3-2: Op-amp driving capacitive load 105
References 108
Chapter 4: Finding the Perfect Op-Amp for Your Perfect Circuit 112
Choose the Technology Wisely 114
Fundamental Operational Amplifier Circuits 115
Using These Fundamentals 123
Amplifier Design Pitfalls 126
References 127
Chapter 5: Review of Passive Components and a Case Study in PC Board Layout 128
In This Chapter 128
Resistors 128
Comments on Surface-Mount Resistors 131
Comments on Resistor Types 132
Capacitors 132
Inductors 136
Printed Circuit Board Layout Issues 137
Approximate Inductance of a PCB Trace Above a Ground Plane 140
Example 5-1: Design case study—high-speed semiconductor laser diode driver 141
References 149
Chapter 6: Analog Lowpass Filters 152
In This Chapter 152
A Quick Introduction to Analog Filters 152
Passive Filters 153
Normalization and Denormalization 154
Poles and Zeros 155
Active Lowpass Filters 155
First-Order Filter Section 156
Sallen-Key Lowpass Filters 156
Sallen-Key Rolloff Deficiencies 157
Denormalizing Sallen-Key Filter Designs 161
State Variable Lowpass Filters 162
Cauer and Inverse Chebyshev Active Filters 162
Denormalizing State Variable or Biquad Designs 164
Frequency-Dependent Negative Resistance Filters 166
Denormalization of FDNR Filters 169
References 171
Chapter 7: Highpass Filters 172
In This Chapter 172
Passive Filters 172
Active Highpass Filters 175
First-Order Filter Section 177
Sample-and-Difference Circuit 178
Sallen-Key Highpass Filter 178
Using Lowpass Pole to Find Component Values 179
Using Highpass Poles to Find Component Values 180
Operational Amplifier Requirements 180
Denormalizing Sallen-Key or First-Order Designs 181
State Variable Highpass Filters 182
Cauer and Inverse Chebyshev Active Filters 183
Denormalizing State Variable or Biquad Designs 187
Gyrator Filters 188
References 192
Chapter 8: Noise: The Three Categories—Device, Conducted, and Emitted 194
Types of Noise 194
Definitions of Noise Specifications and Terms 195
References 223
Chapter 9: How to Design Analog Circuits Without a Computer or a Lot of Paper 226
Thoughts on Designing a Circuit 226
My Background 227
Breaking Down a Circuit 230
Equivalent Circuits 230
Stock Parts Values 232
RC Networks 233
Stabilizing a Feedback Loop 237
Circuit Impedance 240
New Parts 241
Breadboarding 241
Testing 242
How Much to Learn 242
Settling Time Tester 242
Final Notes 249
Chapter 10: Bandpass Filters 250
In This Chapter 250
Lowpass-to-Bandpass Transformation 251
Passive Filters 251
Formula for Passive Bandpass Filter Denormalization 255
Active Bandpass Filters 256
Bandpass Poles and Zeros 257
Bandpass Filter Midband Gain 260
Multiple Feedback Bandpass Filter 261
Dual-Amplifier Bandpass Filter 263
Denormalizing DABP Active Filter Designs 265
State Variable Bandpass Filters 266
Denormalization of State Variable Design 267
Cauer and Inverse Chebyshev Active Filters 268
Denormalizing Biquad Designs 270
References 270
Chapter 11: Bandstop (Notch) Filters 272
A Closer Look at Bandstop Filters 272
Passive Filters 273
Formula for Passive Bandstop Filter Denormalization 277
Active Bandstop Filters 279
Bandstop Poles and Zeros 279
The Twin Tee Bandstop Filter 283
Denormalization of Twin Tee Notch Filter 284
Practical Implementation of Twin Tee Notch Filter 285
Bandstop Using Multiple Feedback Bandpass Section 285
Denormalization of Bandstop Design Using MFBP Section 286
Bandstop Using Dual-Amplifier Bandpass Section 286
Denormalization of Bandstop Design Using DABP Section 288
State Variable Bandstop Filters 288
Denormalization of Bandstop State Variable Filter Section 288
Cauer and Inverse Chebyshev Active Filters 289
Denormalization of Bandstop Biquad Filter Section 291
References 292
Chapter 12: Current–Feedback Amplifiers 294
The Current-Feedback Concept 294
The Conventional Op-Amp 296
Gain-Bandwidth Tradeoff 297
Slew-Rate Limiting 298
The Current-Feedback Amplifier 300
No Gain-Bandwidth Tradeoff 303
Absence of Slew-Rate Limiting 304
Second-Order Effects 305
CF Application Considerations 307
CF Amp Integrators 308
Stray Input-Capacitance Compensation 309
Noise in CF Amp Circuits 310
Low Distortion for Fast Sinewaves Using CF Amps 311
Drawbacks of Current-Feedback Amplifiers vs. Conventional Op-Amps 312
References 312
Chapter 13: The Basics Behind Analog-to-Digital Converters 314
In This Chapter 314
The Key Specifications of Your ADC 315
The CMOS SAR Topology 329
Delta-Sigma (& #916
Decimation Filter 345
References 350
Chapter 14: The Right ADC for the Right Application 352
In This Chapter 352
Classes of Input Signals 352
Temperature Sensor Signal Chains 357
Using an RTD for Temperature Sensing: SAR Converter or & #916
The RTD Current Excitation Circuit for the SAR Circuit 362
RTD Signal Conditioning Path Using the SAR ADC 363
RTD Signal Conditioning Path Using the & #916
Measuring Pressure: SAR Converter or & #916
The Piezoresistive Pressure Sensor 367
The Pressure Sensor Signal Conditioning Path Using a SAR ADC 368
Pressure Sensor Signal Conditioning Path Using a & #916
Photodiode Applications 370
Photosensing Signal Conditioning Path Using a SAR ADC 370
Photosensing Signal Conditioning Path Using a & #916
Motor Control Solutions 372
A Few Final Words 377
References 378
Chapter 15: Working the Analog Problem From the Digital Domain 380
In This Chapter 380
Pulse Width Modulator (PWM) Used as a Digital-to-Analog Converter 381
Looking at This Reference in the Time Domain 381
Changing This Digital Signal to Analog 383
Defining Your Analog Lowpass Filter for Your PWM-DAC 384
Pulling the Time Domain and Frequency Domain Together 387
Using the Comparator for Analog Conversions 388
Input Range of a Comparator (V[sub(IN+)] and V[sub(IN–)]) 389
Input Hysteresis 389
Window Comparator 390
Combining the Comparator with a Timer 391
Using the Timer and Comparator to Build a & #916
& #916
The Controller Implementation 395
Error Analysis of This & #916
RDS[sub(ON)] Error 398
RA0 Port Leakage Current 398
Nonsymmetrical Output Port (RA3) 398
Voltage Reference 398
Other Input Ranges 399
Input Range of 2V to 3V 399
Input Range of 10V to 15V 400
Input Range of ±500 mV 401
Final Thoughts 402
References 403
Chapter 16: What's All This Error Budget Stuff, Anyhow? 404
Chapter 17: What's All This V[sub(BE)] Stuff, Anyhow? 408
Part 1 408
Part 2 414
Next Topic 415
Chapter 18: The Zoo Circuit 418
History, Mistakes, and Some Monkeys Design a Circuit 418
References 437
Appendix A: Analog-to-Digital Converter Specification Definitions and Formulas 440
References 449
Appendix B: Capacitor Coefficients for Lowpass Sallen-Key Filters 450
Index 454
A 454
B 455
C 455
D 456
E 457
F 457
G 458
H 458
I 458
J 458
L 458
M 458
N 459
O 459
P 459
Q 460
R 460
S 460
T 460
U 461
V 461
W 461
Z 461