Audio power amplifier design handbook

Contents......Page 6
Synopsis......Page 8
Preface......Page 16
The economic importance of power amplifiers......Page 18
The study of amplifier design......Page 20
Misinformation in audio......Page 22
The performance requirements for amplifiers......Page 39
Acronyms......Page 44
A brief history of amplifiers......Page 47
Amplifier architectures......Page 48
Power amplifier classes......Page 50
AC and DC coupled amplifiers......Page 58
Negative feedback in power amplifiers......Page 61
How a generic amplifier works......Page 77
The advantages of convention......Page 79
The eight distortions......Page 80
Open-loop linearity and how to determine it......Page 84
Direct o/l gain measurement......Page 85
Using model amplifiers......Page 87
The concept of the Blameless amplifier......Page 88
The role of the input stage......Page 90
Distortion from the input stage......Page 91
BJTs vs FETs for the input stage......Page 92
The input stage distortion in isolation......Page 93
Input stage balance......Page 96
The joy of current-mirrors......Page 97
Improving input-stage linearity......Page 99
Radical methods of improving input linearity......Page 100
Input noise and how to reduce it......Page 102
Offset and match: the DC precision issue......Page 106
The input stage and the slew-rate......Page 107
The voltage-amplifier stage......Page 108
Measuring VAS distortion in isolation......Page 109
VAS operation......Page 110
Linearising the VAS: active load techniques......Page 112
VAS enhancements......Page 114
The importance of voltage drive......Page 116
The balanced VAS......Page 117
The VAS and manipulating open-loop bandwidth......Page 118
Manipulating open-loop bandwidth......Page 121
Classes and devices......Page 123
The distortions of the output......Page 126
The emitter-follower output......Page 129
The CFP output......Page 131
Quasi-complementary outputs......Page 136
Triple EF output stages......Page 138
Distortion and its mechanisms......Page 139
Large-signal distortion (Distortion 3a)......Page 140
Crossover distortion (Distortion 3b)......Page 156
Thermal distortion......Page 170
Thermal distortion in a power amp IC......Page 173
Selecting an output stage......Page 174
Closing the loop: distortion in complete amplifiers......Page 175
Distortion number 4: VAS loading distortion......Page 180
Distortion number 5: rail decoupling distortion......Page 182
Distortion number 6: induction distortion......Page 185
Distortion number 7: NFB takeoff point distortion......Page 187
Distortion number 8: capacitor distortion......Page 189
Design example: a 50 W Class-B amplifier......Page 192
Frequency compensation in general......Page 200
Dominant-pole compensation......Page 201
Lag compensation......Page 202
Including the output stage: inclusive Miller compensation......Page 203
Nested feedback loops......Page 204
Two-pole compensation......Page 205
Output networks......Page 207
Crosstalk in amplifier output inductors......Page 220
Reactive loads and speaker simulation......Page 226
Loudspeaker loads and output stages......Page 231
Enhanced loudspeaker currents......Page 237
Amplifier instability......Page 239
Speed and slew-rate in audio amplifiers......Page 241
Power supply technologies......Page 252
Design considerations for power supplies......Page 255
An introduction to class-A......Page 272
Class-A configurations and efficiency......Page 273
Output stages in Class-A......Page 276
Quiescent current control systems......Page 280
A novel quiescent current controller......Page 282
A Class-A design......Page 284
The trimodal amplifier......Page 286
Load impedance and operating mode......Page 288
Efficiency......Page 289
On Trimodal biasing......Page 294
Class-A/AB mode......Page 295
The mode-switching system......Page 298
Thermal design......Page 299
A complete Trimodal amplifier circuit......Page 300
The performance......Page 303
The principles of Class-G......Page 307
Introducing series class-G......Page 308
Efficiency of Class-G......Page 310
The biasing requirements......Page 313
The linearity issues of series Class-G......Page 315
The static linearity......Page 316
Controlling small-signal distortion......Page 319
The performance......Page 323
Deriving a new kind of amplifier: Class-A + C......Page 326
Adding two-pole compensation......Page 328
Further variations on Class-G......Page 330
The characteristics of power FETS......Page 331
FET vs BJT output stages......Page 332
IGBTs......Page 333
Power FET output stages......Page 335
FETs in Class-A stages......Page 338
Why quiescent conditions are critical......Page 342
Accuracy required of thermal compensation......Page 343
Basic thermal compensation......Page 348
Thermal simulation......Page 349
Modelling the EF output stage......Page 351
Modelling the CFP output stage......Page 359
The integrated absolute error criterion......Page 361
Improved thermal compensation: the emitter-follower stage......Page 362
Improved compensation for the CFP output stage......Page 365
A better sensor position......Page 366
A junction-temperature estimator......Page 367
A junction estimator with dynamics......Page 369
Variable-tempco bias generators......Page 374
Thermal dynamics in reality......Page 381
Categories of amplifier protection......Page 387
Overload protection......Page 389
Catching diodes......Page 400
DC-offset protection......Page 401
Thermal protection......Page 409
Powering auxiliary circuitry......Page 411
Audio amplifier PCB design......Page 413
Amplifier grounding......Page 421
Ground loops: how they work and how to deal with them......Page 422
Class I and Class II......Page 429
Mechanical layout and design considerations......Page 431
Testing and fault-finding......Page 435
Safety......Page 437
Index......Page 440