Capacitively-Coupled Chopper Amplifiers

184 Pages·2014·86.28 MB·English

CWMITIVILY-COUPLID
AMPUrif
CHOPPIR M
QlNWEN rAN

Capacitively- Coupled
Chopper Amplifiers
Qinwen Fan

Capacitively-Coupled
Chopper Amplifiers
TU Delft Libra'7
Prometheusplein 1
2628 ZC Delft
ter verkrijging van de graad van doctor
aan de Technische Universiteit Delft,
op gezag van de Rector Magnificus prof ir. K.C.A.M. Luyben,
voorzitter van het College voor Promoties,
in het openbaar te verdedigen op 6 december 2013 om 12:30 uur
door
Qinwen FAN,
Master of Science in Electncal Engineering
geboren te Huhhot, China.
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Dit proefschrift is goedgekeurd door de promotor:
Prof. dr. ir. K.A.A. Makinwa
Samenstelling promotiecommissie:
Rector Magnificus, voorzitter
Prof. dr. ir. K.A.A. Makinwa, Technische Universiteit Delft, promotor
Prof. dr. ir. J.H. Huijsing, Technische Universiteit Delft
Prof. dr. W.M.C Sausen, Katholieke Universiteit Leuven
Prof. ir. A.J.M, van Tuijl, Universiteit Twente
Prof. dr. C.C. Enz, École Polytechnique Federale
Prof. R.B. Staszewski, Technische Universiteit Delft
Dr, R.G.H, Eschauzier, Maxim Integrated Delft
Prof. dr. ir. G.C.M. Meijer, Technische Universiteit Delft, reservelid
Published and distributed by: Ipskamp Drukkers B.V.
ISBN 978-94^6191-999-1
Copyright © 2013 by Q. Fan
All rights reserved. No part of the material protected by this copyright notice may be reproduced or
utilized in any form or by any means, electronic or mechanical, including photocopying, recording or
by any information storage and retrieval system, without written permission of the author.
Printed in The Netherlands
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Contents
Chapter 1 Introduction 9
1.1 Problem 9
1.2 Traditional solutions 10
1.3 A promising solution: Capacitively-coupled chopper amplifier 13
1.4 Challenging issues 16
1.5 Organization 17
1.6 References 19
Chapter 2 The Chopping Technique 21
2.1 Basic working principle 22
2.2 Basic chopper amplifier topologies 22
2.2.1 Basic chopper opamp and instrumentation amplifier topologies 22
2.2.2 Chopper stabiUzation 26
2.3 Ripple reduction techniques 26
2.3.1 The SC notch filter 27
2.3.2 AC-coupled ripple reduction loop 28
2.3.3 Auto-correction feedback loop 30
2.3.4 Digitally-assisted trimming 31
2.3.5 Chopping-I- auto-zeroing 32
2.4 Chopping non-idealities 37
2.5 Chopping pros and cons 38
2.6 Conclusions 39
2.7 References 40
Chapters Capacitively-coupled Chopper Amplifiers 43
3.1 Capacitively-coupled chopper opamps (CCOPA) 44
3.1.1 Offset and 1/f noise 44
3.1.2 Noise and power efficiency 45
3.1.3 CMRR and CMVR 46
3.1.4. Input impedance 46
3.1.5 Settiing and transient issues 46
3.2 Capacitively-coupled chopper lAs (CCIA) 48
3.2.1 Offset and 1/f noise 48
3.2.2 Noise and power efficiency 48
3.2.3 CMRR and CMVR 49
3.2.4 Gain accuracy 49
3.2.5 Input impedance 50
3.2.6 Output spikes 50
3.2.7 Settling and transient issues 50
3.3 Conclusions 51
3.4 References 52
Chapter 4 Choppers for High Input Common-mode Voltages 53
4.1 Choice of transistors 54
4.2. HV chopper topologies 56
4.2.1 HV chopper with HV amplifier level-shifter 56
4.2.2 Capacitively-coupled HV choppers 57
4.3 Transient Protection 61
4.4 Conclusions 62
4.5 References 63
Chapter 5 Capacitively-Coupled Chopper Operational Amplifiers 65
5.1 Introduction 65
5.2 Conventional techniques to expand the CMVR 66
5.3 The single-path CCOPA 67
5.3.1 Design of the single-path CCOPA 67
5.3.2 Implementation of the basic CCOPA 71
5.3.3 Experimental Results 78
5.4 Multi-Path CCOPA 79
5.4.1 Design of the multi-path CCOPA (MCCOPA) 80
5.4.2 Implementation of the multi-path CCOPA 82
5.4.3 Experimental results of the MCCOPA 84
5.5 Conclusions 86
5.6 References 88
Chapter 6 Capacitively-Coupled Chopper Instrumentation Amplifiers for High-Side Current Sensing
91
6.1 Introduction 91
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6.2 Overview of the state-of-the-art 92
6.2.1 HV chopper-stabilized current-feedback instrumentation amplifier 92
6.2.2 HV current-mode three-opamp instrumentation amphfier 94
6.2.3 HV lA with isolated transformer 95
6.2.4 Conclusions 95
6.3 Design of the CCIA for current-sensing applications 95
6.3.1 Input chopper 97
6.3.2 Ripple Reduction Loop (RRL) 97
6.3.3 CCIA opamp 99
6.3.4 Output spikes 99
6.4 Realization 100
6.4.1 Global parameters (chopping frequency and capacitor bridge) 100
6.4.2 Implementation of the input chopper 101
6.4.3 Implementation of the CM biasing circuit 102
6.4.4 Implementation of the CCIA opamp 105
6.4.5 Implementation of the output S&H switch 108
6.4.6 Implementation of the RRL 108
6.5 Experimental Results 112
6.6 Conclusions 114
6.7 References 115
Chapter 7 Capacitively-Coupled Chopper Instrumentation Amplifiers for Low-Voltage Applications
117
7.1 Introduction 118
7.2 Overview of the state-of-the-art 120
7.2.1 State-of-the-art precision lAs for DC sensing 120
7.2.2 State-of-the-art lAs for AC biomedical sensing 122
7.2.3 Conclusions 126
7.3 Design of a CCIA for wireless sensor nodes 126
7.3.1 Input impedance boosdng loop 128
7.3.2 SC Ripple reduction loop (SC RRL) 129
7.3.3 DC servo loop (DSL) 130
7.4 Realization 136
7.4.1 Global parameters (chopping frequency, capacitive bridge and transistor type) 136
7.4.2 Opamp of the CCIA 138
7.4.3 Biasing resistor Rb 138
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7.4.4 Impedance boosting loop or positive feed back loop (PFL) 139
7.4.5 SCRRL 141
7.4.6 DC servo loop (DSL) 143
7.5 Experimental Results 144
7.6 Conclusion 148
7.7 References 149
Chapter 8 Conclusions 151
8.1 Conclusions 151
8.2 Future work 153
8.3 Original Contributions 154
8.4 References 155
Summary 157
Samenvatting 163
List of Publications 169
About the author 171
Acknowledgements 172