High Efficiency Switched-Mode Power Amplifiers For Wireless Communications

220 Pages·2012·7.19 MB·English

High E–ciency Switched-Mode
Power Ampliflers For Wireless
Communications
David K. Choi
Department of Electrical and Computer
Engineering
University of California
Santa Barbara
submitted in partial fulfillment of
the requirements for the degree of
Doctor of Philosophy
March, 2001
Committee in charge:
Professor Stephen I. Long, Chairperson
Doctor Petteri Alinikula
Professor Mark J. Rodwell
Professor Robert A. York
c Copyright 2001 by David K. Choi. All rights reserved.
(cid:176)
This dissertation entitled, \High E–ciency Switched-Mode
Power Ampliflers for Wireless Communications," by David K.
Choi is approved.
Dated: March, 2001
Doctor Petteri Alinikula
Professor Mark J. Rodwell
Professor Robert A. York
Chairperson:
Professor Stephen I. Long
ii
This work is dedicated to my mother and father, for
their extraordinary love and constant faith.
iii
iv
Table of Contents
Table of Contents v
List of Tables ix
List of Figures x
Vita xv
Abstract xvii
Acknowledgements xix
1 Introduction 1
1.1 Historical Comments . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2.1 Evaluating Handset Performance . . . . . . . . . . . . 3
1.2.2 Limitations on Performance . . . . . . . . . . . . . . . 4
1.2.3 Future Performance Requirements . . . . . . . . . . . . 5
1.2.4 Need for New Topologies . . . . . . . . . . . . . . . . . 6
1.3 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.3.1 Origin of Switched-Mode Topologies . . . . . . . . . . 8
1.3.2 Present Applications and Limitations . . . . . . . . . . 9
1.3.3 Shortcomings of the Original Analyses . . . . . . . . . 11
1.3.4 Key Contributions of This Work . . . . . . . . . . . . . 12
1.4 On Scope and Style . . . . . . . . . . . . . . . . . . . . . . . . 14
1.5 Dissertation Outline . . . . . . . . . . . . . . . . . . . . . . . 14
v
2 Conventional Power Ampliflers 17
2.1 Important Distinctions . . . . . . . . . . . . . . . . . . . . . . 17
2.1.1 Some Deflnitions . . . . . . . . . . . . . . . . . . . . . 18
2.1.2 Small-Signal versus Large-Signal Operation . . . . . . . 20
2.1.3 Current Source Versus Switched-Mode Operation . . . 21
2.1.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.2 Conventional Power Ampliflers . . . . . . . . . . . . . . . . . . 24
2.2.1 Class A . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.2.2 Class B and Class C . . . . . . . . . . . . . . . . . . . 29
2.3 Consequences . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3 Switched-Mode Power Ampliflers 37
3.1 Voltage-Switching Class D . . . . . . . . . . . . . . . . . . . . 38
3.1.1 Basic Operation . . . . . . . . . . . . . . . . . . . . . . 38
3.1.2 Design Equations and P . . . . . . . . . . . . . . . 39
max
3.1.3 Practical Limitations of E–ciency . . . . . . . . . . . . 41
3.1.4 Other Class D Conflgurations . . . . . . . . . . . . . . 44
3.2 Shunt Capacitor Class E Conflguration . . . . . . . . . . . . . 46
3.2.1 Drain Current and Voltage . . . . . . . . . . . . . . . . 47
3.2.2 Design Equations . . . . . . . . . . . . . . . . . . . . . 50
3.2.3 P and Maximum Operating Frequency . . . . . . . 57
max
3.2.4 Qualitative Discussion and Practical Considerations . . 60
3.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
4 Charge Analysis of Nonlinear C 69
d
4.1 Charge Control Analysis . . . . . . . . . . . . . . . . . . . . . 69
4.1.1 Stored Charge . . . . . . . . . . . . . . . . . . . . . . . 73
4.1.2 m = 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
j
4.1.3 m = 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
j
6
4.2 Analytic Solutions . . . . . . . . . . . . . . . . . . . . . . . . 78
4.2.1 Solution for n = 1 . . . . . . . . . . . . . . . . . . . . . 79
4.2.2 Solutions for n=2 and n=3 . . . . . . . . . . . . . . . . 80
4.3 Arbitrary CV Proflles . . . . . . . . . . . . . . . . . . . . . . . 81
4.3.1 Efiective Capacitance . . . . . . . . . . . . . . . . . . . 81
4.3.2 Regression Analysis . . . . . . . . . . . . . . . . . . . . 82
4.4 Design Equations . . . . . . . . . . . . . . . . . . . . . . . . . 85
vi
4.5 Maximum Drain Current and Voltage . . . . . . . . . . . . . . 86
4.6 Efiect of V . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
knee
5 Modeling Packaged MOSFETs 91
5.1 Capacitance Measurements . . . . . . . . . . . . . . . . . . . . 92
5.2 NWA Measurements . . . . . . . . . . . . . . . . . . . . . . . 96
5.2.1 Calibration . . . . . . . . . . . . . . . . . . . . . . . . 97
5.2.2 S-Parameter Measurements . . . . . . . . . . . . . . . 98
5.3 DC IV Measurements . . . . . . . . . . . . . . . . . . . . . . . 108
5.4 The Complete Device Model . . . . . . . . . . . . . . . . . . . 111
6 Practical Implementation 119
6.1 Finite Inductor DC Feed Approaches . . . . . . . . . . . . . . 120
6.1.1 Laplace Transforms . . . . . . . . . . . . . . . . . . . . 120
6.1.2 Resonant DC Feed . . . . . . . . . . . . . . . . . . . . 121
6.1.3 Even Harmonic Class E . . . . . . . . . . . . . . . . . 122
6.2 A Simple DC Feed Approach . . . . . . . . . . . . . . . . . . . 124
6.2.1 Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . 125
6.2.2 Design Equations . . . . . . . . . . . . . . . . . . . . . 128
6.3 Output Network Design . . . . . . . . . . . . . . . . . . . . . 131
6.3.1 Design with Nonlinear Capacitance . . . . . . . . . . . 131
6.3.2 Implementation with Finite DC Feed . . . . . . . . . . 133
6.4 Input Matching . . . . . . . . . . . . . . . . . . . . . . . . . . 135
6.4.1 Tapped Inductor Matching Network . . . . . . . . . . . 138
7 Measured and Simulated Results 143
7.1 Class E Output Network . . . . . . . . . . . . . . . . . . . . . 143
7.2 Input Matching . . . . . . . . . . . . . . . . . . . . . . . . . . 146
7.3 Power Measurements . . . . . . . . . . . . . . . . . . . . . . . 148
7.3.1 Swept Input Power . . . . . . . . . . . . . . . . . . . . 150
7.3.2 Frequency and Time Domain Measurements . . . . . . 153
7.3.3 Swept Gate Bias . . . . . . . . . . . . . . . . . . . . . 155
7.3.4 Swept Frequency . . . . . . . . . . . . . . . . . . . . . 161
7.3.5 Swept Supply Voltage . . . . . . . . . . . . . . . . . . 162
vii
8 Conclusion 167
8.1 Achievements . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
8.2 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
8.2.1 Input Drive . . . . . . . . . . . . . . . . . . . . . . . . 169
8.2.2 Linearization and Power Control . . . . . . . . . . . . 170
8.3 Final Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
A Explicit Class E Equations 173
A.1 The Phase Factor, ` . . . . . . . . . . . . . . . . . . . . . . . 173
A.2 Drain Current and Voltage . . . . . . . . . . . . . . . . . . . . 174
A.3 Design Equations . . . . . . . . . . . . . . . . . . . . . . . . . 174
A.4 Final Expressions . . . . . . . . . . . . . . . . . . . . . . . . . 176
A.4.1 Final Expressions for `, I ((cid:181)), and V ((cid:181)) . . . . . . . 176
D DS
A.4.2 Final Expressions for C , R , and X . . . . . . . . . . 177
d L
B Mathematica Notebook 179
C Even Harmonic Class E with Finite L 181
b
C.1 Currents and Voltages . . . . . . . . . . . . . . . . . . . . . . 181
C.1.1 Non-Conduction Interval (0 < (cid:181) …) . . . . . . . . . . 183
•
C.1.2 Conduction Interval (… < (cid:181) 2…): . . . . . . . . . . . . 186
•
C.1.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . 188
C.2 Design Equations . . . . . . . . . . . . . . . . . . . . . . . . . 189
D Mathematica Notebook 191
Bibliography 193
viii
List of Tables
1.1 Present US Wireless Communications Systems . . . . . . . . . 4
2.1 Categorizing Ampliflers by Application . . . . . . . . . . . . . 18
2.2 Comparison of Switched versus Pulsed-Current Operation . . . 24
3.1 Maximum E–ciency and Normalized Output Power Capability 68
5.1 Extracted Values for Extrinsic and Package Parasitic Elements 108
5.2 Extracted Values of Intrinsic Transconductance, K . . . . . . 112
0
5.3 Gate Capacitance Component Values . . . . . . . . . . . . . . 113
5.4 Drain Capacitance Parameters for C . . . . . . . . . . . . . . 114
d
7.1 Values for Circuit Elements in flg. 7.1 . . . . . . . . . . . . . . 146
7.2 Values for Circuit Elements in flg. 7.4 . . . . . . . . . . . . . . 147
7.3 Simulated versus Measured Values at 200MHz, V = 12V,
dq
V = 3:12V, and V = 15:17V . . . . . . . . . . . . . . . 155
gq gs;mag
7.4 DesignValuesforP ,R ,andX asaFunctionofV (200MHz,
out L dq
45% Duty-Cycle, and (cid:190) = 0) . . . . . . . . . . . . . . . . . . . 165
7.5 Highest Measured E–ciency and PAE (V = 12V, V = 3:12V)165
dq gq
8.1 Bluetooth Classes and Power Levels . . . . . . . . . . . . . . . 171
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