Adaptive RF Front-Ends for Hand-held Applications

by Andre van Bezooijen, Reza Mahmoudi, Arthur H.M. van Roermund

Overview

The RF front-end – antenna combination is a vital part of a mobile phone because its performance is very relevant to the link quality between hand-set and cellular network base-stations. The RF front-end performance suffers from changes in operating environment, like hand-effects, that are often unpredictable.

Adaptive RF Front-Ends for Hand-Held Applications presents an analysis on the impact of fluctuating environmental parameters. In order to overcome undesired behavior two different adaptive control methods are treated that make RF frond-ends more resilient: adaptive impedance control, and adaptive power control.

Several adaptive impedance control techniques are discussed, using a priori knowledge on matching network properties, in order to simplify robust 2-dimensional control. A generic protection concept is presented, based on adaptive power control, which improves the ruggedness of a power amplifier or preserves its linearity under extremes. It comprises over-voltage, over-temperature, and under-voltage protection.

Product Details

ISBN-13:	9789048199341
Publisher:	Springer Netherlands
Publication date:	11/05/2010
Series:	Analog Circuits and Signal Processing
Edition description:	2011
Pages:	153
Product dimensions:	6.10(w) x 9.25(h) x 0.36(d)

Table of Contents

1 Introduction 1

1.1 Context and Trends in Wireless Communication 1

1.2 Resilience to Unpredictably Changing Environments 2

1.3 Improvements by Adaptively Controlled RF Front-Ends 4

1.4 Aim and Scope of This Book 5

1.5 Book Outline 7

2 Adaptive RF Front-Ends 9

2.1 Introduction 9

2.2 RF Front-End Functionality 10

2.2.1 Antenna Switch 10

2.2.2 Power Amplifier 11

2.2.3 Duplexer 13

2.2.4 Blocking Filter 14

2.3 Fluctuations in Operating Conditions 14

2.4 Impact of Variables 16

2.4.1 Current Fluctuation 16

2.4.2 Voltage Fluctuation 18

2.4.3 Die Temperature Fluctuation 21

2.4.4 Efficiency Fluctuation 22

2.4.5 Discussion on the Impact of Variables 24

2.5 Adaptive Control Theory 25

2.6 Identification of Variables for Detection and Correction 27

2.6.1 Independent Variables 28

2.6.2 Dependent Variables 29

2.7 Conclusions on Adaptive RF Front-Ends 32

3 Adaptive Impedance Control 35

3.1 Introduction 35

3.1.1 Dimensionality 37

3.1.2 Non-linearity 39

3.1.3 Robust Control 41

3.1.4 Impedance Tuning Region 45

3.1.5 Insertion Loss 47

3.1.6 System Gain 48

3.2 Mismatch Detection Method 49

3.2.1 Sensing 49

3.2.2 Detector Concept 50

3.2.3 Simulation Results 51

3.2.4 Conclusions on Mismatch Detection 52

3.3 Adaptively Controlled PI-Networks Using Differentially Controlled Capacitors 52

3.3.1 Concept 53

3.3.2 Differentially Controlled Single-Section PI-Network 55

3.3.3 Differentially Controlled Dual-Section PI-Network 58

3.3.4 Simulations 59

3.3.5 Conclusions on Adaptively Controlled PI-Networks 64

3.4 Adaptively Controlled L-Network Using Cascaded Loops 65

3.4.1 Concept 65

3.4.2 Actuation 66

3.4.3 Convergence 70

3.4.4 Simulations 72

3.4.5 Capacitance Tuning Range Requirement 75

3.4.6 Insertion Loss 78

3.4.7 Tuning Range Requirement 79

3.4.8 Conclusions on Adaptively Controlled L-Network 81

3.5 Adaptive Series-LC Matching Network Using RF-MEMS 82

3.5.1 Adaptive Tuning System 83

3.5.2 Adaptive RF-MEMS System Design 87

3.5.3 Experimental Verification 95

3.5.4 Conclusions on Adaptive Series-LC Matching Module 99

3.6 Load Line Adaptation 99

3.6.1 Introduction 99

3.6.2 Concept 100

3.6.3 Implementation of Load Line Adaptation 102

3.6.4 Simulation Results 103

3.6.5 Conclusions on Load Line Adaptation 105

3.7 Conclusions on Adaptive Impedance Control 106

4 Adaptive Power Control 107

4.1 Introduction 107

4.1.1 Over-Voltage Protection for Improved Ruggedness 108

4.1.2 Over-Temperature Protection for Improved Ruggedness 108

4.1.3 Under-Voltage Protection for Improved Linearity 109

4.2 Safe Operating Conditions 109

4.3 Power Adaptation for Ruggedness 112

4.3.1 Concept 112

4.3.2 Simulations 114

4.3.3 Over-Voltage Protection Circuit 115

4.3.4 Over-Temperature Protection Circuit 116

4.3.5 Technology 117

4.3.6 Experimental Verification 117

4.4 Power Adaptation for Linearity 121

4.4.1 Concept 121

4.4.2 Simulations 122

4.4.3 Circuit Design 123

4.4.4 Experimental Verification 125

4.5 Conclusions on Adaptive Power Control 127

5 Conclusions 129

Appendix A Overview of Adaptively Controlled Matching Networks 131

Appendix B A Dual-Banding Technique 137

Appendix C Transistor Breakdown Voltages 139

Summary 147

References 148