Distortion_In_RF_Power_Amplifiers

onestab

Contents
Acknowledgments ix
Chapter 1 Introduction 1
1.1 Motivation .................................................................... 1
1.2 Historical Perspective ................................................... 2
1.3 Linearization and Memory Effects ............................... 3
1.4 Main Contents of the Book.........................................4..
1.5 Outline of the Book....................................................6..
References ...................................................................................8
Chapter 2 Some Circuit Theory and Terminology 9
2.1 Classification of Electrical Systems ........................... 10
2.1.1 Linear Systems and Memory ............................ 10
2.1.2 Nonlinear Systems ........................................... 13
2.1.3 Common Measures of Nonlinearity.................. 15
2.2 Calculating Spectrums in Nonlinear Systems ............. 18
2.3 Memoryless Spectral Regrowth .................................. 21
2.4 Signal Bandwidth Dependent Nonlinear Effects ......... 25
2.5 Analysis of Nonlinear Systems ................................... 27
2.5.1 Volterra Series Analysis................................... 28
2.5.2 Direct Calculation of Nonlinear Responses ...... 30
2.5.3 Two Volterra Modeling Approaches ................ 34
vi Distortion in RF Power Amplifiers
2.6 Summary .................................................................... 39
2.7 Key Points to Remember ............................................ 41
References .................................................................................41
Chapter 3 Memory Effects in RF Power Amplifiers 43
3.1 Efficiency ................................................................... 43
3.2 Linearization .............................................................. 45
3.2.1 Linearization and Efficiency ............................ 45
3.2.2 Linearization Techniques ................................. 46
3.2.3 Linearization and Memory Effects ................... 48
3.3 Electrical Memory Effects .......................................... 51
3.4 Electrothermal Memory Effects .................................. 56
3.5 Amplitude Domain Effects ......................................... 59
3.5.1 Fifth-Order Analysis Without Memory Effects 60
3.5.2 Fifth-Order Analysis with Memory Effects ...... 62
3.6 Summary .................................................................... 66
3.7 Key Points to Remember ............................................ 67
References .................................................................................68
Chapter 4 The Volterra Model 71
4.1 Nonlinear Modeling ................................................... 71
4.1.1 Nonlinear Simulation Models........................... 72
4.1.2 The Properties of the Volterra Models ............. 75
4.2 Nonlinear I-V and Q-V Characteristics ...................... 77
4.2.1 IC-VBE-VCE Characteristic................................ 78
4.2.2 gpi and rbb ........................................................ 82
4.2.3 Capacitance Models ......................................... 82
4.3 Model of a Common-Emitter BJT/HBT Amplifier ..... 84
4.3.1 Linear Analysis ................................................ 84
4.3.2 Nonlinear Analysis........................................... 87
4.4 IM3 in a BJT CE Amplifier ........................................ 95
4.4.1 BJT as a Cascade of Two Nonlinear Blocks ..... 95
4.4.2 Detailed BJT Analysis.................................... 102
4.5 MESFET Model and Analysis .................................. 109
4.6 Summary .................................................................. 115
4.7 Key Points to Remember .......................................... 117
References ...............................................................................118
Contents vii
Chapter 5 Characterization of Volterra Models 123
5.1 Fitting Polynomial Models ....................................... 124
5.1.1 Exact and LMSE Fitting................................. 124
5.1.2 Effects of Fitting Range ................................. 126
5.2 Self-Heating Effects ................................................. 127
5.2.1 Pulsed Measurements..................................... 129
5.2.2 Thermal Operating Point ................................ 131
5.3 DC I-V Characterization .......................................... 133
5.3.1 Pulsed DC Measurement Setup ...................... 133
5.3.2 Fitting I-V Measurements .............................. 134
5.4 AC Characterization Flow ........................................ 136
5.5 Pulsed S-Parameter Measurements ........................... 137
5.5.1 Test Setup ...................................................... 137
5.5.2 Calibration ..................................................... 139
5.6 De-embedding the Effects of the Package ................ 140
5.6.1 Full 4-Port De-embedding.............................. 141
5.6.2 De-embedding Plain Bonding Wires .............. 143
5.7 Calculation of Small-Signal Parameters ................... 145
5.8 Fitting the AC Measurements ................................... 147
5.8.1 Fitting of Nonlinear Capacitances .................. 147
5.8.2 Fitting of Drain Current Nonlinearities .......... 149
5.9 Nonlinear Model of a 1-W BJT ................................ 152
5.10 Nonlinear Model of a 1-W MESFET ........................ 155
5.11 Nonlinear Model of a 30-W LDMOS ....................... 160
5.12 Summary .................................................................. 165
5.13 Key Points to Remember .......................................... 166
References ...............................................................................167
Chapter 6 Simulating and Measuring Memory Effects 171
6.1 Simulating Memory Effects ...................................... 172
6.1.1 Normalization of IM3 Components ................ 172
6.1.2 Simulation of Normalized IM3 Components .. 175
6.2 Measuring the Memory Effects ................................ 180
6.2.1 Test Setup and Calibration ............................. 181
6.2.2 Measurement Accuracy.................................. 184
6.2.3 Memory Effects in a BJT PA ......................... 185
6.2.4 Memory Effects in an MESFET PA ............... 187
6.3 Memory Effects and Linearization ........................... 187
6.4 Summary .................................................................. 190
viii Distortion in RF Power Amplifiers
6.5 Key Points to Remember .......................................... 191
References ...............................................................................192
Chapter 7 Cancellation of Memory Effects 193
7.1 Envelope Filtering .................................................... 194
7.2 Impedance Optimization .......................................... 198
7.2.1 Active Load Principle .................................... 199
7.2.2 Test Setup and Its Calibration ........................ 202
7.2.3 Optimum ZBB at the Envelope Frequency
Without Predistortion .................................. 203
7.2.4 Optimum ZBB at the Envelope Frequency
with Predistortion ........................................ 204
7.3 Envelope Injection ................................................... 207
7.3.1 Cancellation of Memory Effects in a
CE BJT Amplifier ........................................ 209
7.3.2 Cancellation of Memory Effects in a
CS MESFET Amplifier ............................... 211
7.4 Summary .................................................................. 217
7.5 Key Points to Remember .......................................... 219
References ...............................................................................220
Appendix A: Basics of Volterra Analysis 221
Reference ................................................................................225
Appendix B: Truncation Error 227
Appendix C: IM3 Equations for Cascaded Second-Degree
Nonlinearities 231
Appendix D: About the Measurement Setups 245
Reference ................................................................................247
Glossary 249
About the Authors 253
Index 255
Distortion_In_RF_Power_Amplifiers