Contents

Preface xi

Acknowledgments xv

1 Class AB Amplifiers 1

1.1 Introduction 1

1.2 Classical Class AB Modes 2

1.3 Class AB: A Different Perspective 9

1.4 RF Bipolars: Vive La Difference 16

1.4.1 A Basic RF BJT Model 16

1.5 On Sweet Spots and IM Glitches 29

1.6 Conclusions 31

Reference 32

2 Doherty and Chireix 33

2.1 Introduction 33

2.2 The Doherty PA 34

2.2.1 Introduction and Formulation 34

v

2.2.2 The Classical Doherty Configuration 37

2.2.3 Variations on the Classical Configuration 42

2.2.4 Peaking Amplifier Configurations 49

2.2.5 Doherty PA Matching Topologies 52

2.2.6 The Multiple Doherty PA 56

2.2.7 Doherty PA Conclusions 56

2.3 The Chireix Outphasing PA 58

2.3.1 Introduction and Formulation 58

2.3.2 Discussion, Analysis, and Simulation 62

2.3.3 Variations 69

2.3.4 Chireix: Conclusions 71

References 72

3 Some Topics in PA Nonlinearity 73

3.1 Introduction 73

3.2 A Problem, a Solution, and Problems with the

Solution 74

3.3 Power Series, Volterra Series, and Polynomials 77

3.4 Two-Carrier Characterization 89

3.5 Memory and IM Asymmetry in RFPAs 94

3.6 PAs and Peak-to-Average Ratios 105

3.7 Conclusions 109

References 110

4 Feedback Techniques 111

4.1 Introduction 111

4.2 Feedback Techniques 114

4.3 Amplitude Envelope Feedback: Configuration and

Analysis 121

4.4 Vector Envelope Feedback 137

vi Advanced Techniques in RF Power Amplifier Design

4.5 Low Latency PA Design 140

4.6 Variations 146

4.7 Conclusions 150

References 151

5 Predistortion Techniques 153

5.1 Introduction 153

5.2 Third-Degree PA: Predistortion Analysis 156

5.3 PD Characteristic for General PA Model 163

5.4 Practical Realization of the Predistorter Function:

Introduction 177

5.5 Analog Predistorters 179

5.6 DSP Predistortion 187

5.7 Conclusions 194

References 195

6 Feedforward Power Amplifiers 197

6.1 Introduction 197

6.2 The Feedforward Loop 198

6.3 AM-PM Correction in the Feedforward Loop 204

6.4 Error Insertion Coupling 208

6.5 Third-Degree Analysis of the Generalized

Feedforward (FFW) Loop 216

6.5.1 Formulation and Analysis 216

6.5.2 Tracking Errors 222

6.5.3 Compression Adjustment 224

6.5.4 Third-Degree Analysis: Conclusions 228

6.6 Feedforward Loop Simulation 229

6.6.1 Effect of AM-PM in Main PA 231

6.6.2 Gain Compression Adjustment 233

Contents vii

6.6.3 EPR Change 233

6.6.4 Gain and Phase Tracking 235

6.6.5 Multicarrier Simulation 235

6.7 Feedforward Loop Efficiency Considerations 236

6.8 Adaption and Correction: Closing the Loop 241

6.9 Variations 249

6.9.1 The Double Feedforward Loop 249

6.9.2 A Feedforward-Enhanced Power Combiner 252

6.9.3 “Budget” FFW Systems 253

6.10 Conclusions 255

References 256

7 Microwave Power Amplifiers 257

7.1 Introduction 257

7.2 Broadband Microwave Power Amplifier Design 259

7.2.1 Introduction 259

7.2.2 Broadband Matching Using Network Synthesis 259

7.2.3 Balanced Amplifiers 270

7.2.4 Broadband Power Amplifier Design Issues 273

7.3 Microwave Circuits and MIC Techniques 280

7.3.1 Introduction 280

7.3.2 Substrate and Heatsink Materials 281

7.3.3 MIC Components and Structures 283

7.4 PA Design Using Prematched Modules 287

7.4.1 Introduction 287

7.4.2 Matching Issues for IMTs 287

7.4.3 Biasing Issues for IMTs 290

7.4.4 Power Combining of IMTs 291

7.5 Distributed Amplifiers 293

7.6 Conclusions 296

References 297

viii Advanced Techniques in RF Power Amplifier Design

Appendix 299

Notes 299

Selected Bibliography 300

Glossary 301

About the Author 305

Index 307

RF.Power.Amplifier.Design