Analog Circuits and Signal Processing Leila Safari Giuseppe Ferri Shahram Minaei Vincenzo Stornelli Current-Mode Instrumentation Amplifi ers Analog Circuits and Signal Processing Series Editors: Mohammed Ismail, Dublin, USA Mohamad Sawan, Montreal, Canada The Analog Circuits and Signal Processing book series, formerly known as the Kluwer International Series in Engineering and Computer Science, is a high level academic and professional series publishing research on the design and applications of analog integrated circuits and signal processing circuits and systems. Typically per year we publish between 5–15 research monographs, professional books, handbooks, edited volumes and textbooks with worldwide distribution to engineers, researchers, educators, and libraries. The book series promotes and expedites the dissemination of new research results and tutorial views in the analog field. There is an exciting and large volume of research activity in the field worldwide. Researchers are striving to bridge the gap between classical analog work and recent advances in very large scale integration (VLSI) technologies with improved analog capabilities. Analog VLSI has been recognized as a major technology for future information processing. Analog work is showing signs of dramatic changes with emphasis on interdisciplinary research efforts combining device/circuit/technology issues. Consequently, new design concepts, strategies and design tools are being unveiled. Topics of interest include: Analog Interface Circuits and Systems; Data converters; Active-RC, switched-capacitor and continuous-time integrated filters; Mixed analog/digital VLSI; Simulation and modeling, mixed-mode simulation; Analog nonlinear and computational circuits and signal processing; Analog Artificial Neural Networks/Artificial Intelligence; Current-mode Signal Processing; Computer-Aided Design (CAD) tools; Analog Design in emerging technologies (Scalable CMOS, BiCMOS, GaAs, heterojunction and floating gate technologies, etc.); Analog Design for Test; Integrated sensors and actuators; Analog Design Automation/Knowledge-based Systems; Analog VLSI cell libraries; Analog product development; RF Front ends, Wireless communications and Microwave Circuits; Analog behavioral modeling, Analog HDL. More information about this series at http://www.springer.com/series/7381 Leila Safari • Giuseppe Ferri • Shahram Minaei Vincenzo Stornelli Current-Mode Instrumentation Amplifiers Leila Safari Giuseppe Ferri Tehran, Iran University of L’Aquila L’aquila, Italy Shahram Minaei Doğuş University Vincenzo Stornelli Istanbul, Turkey University of L’Aquila L’aquila, Italy ISSN 1872-082X ISSN 2197-1854 (electronic) Analog Circuits and Signal Processing ISBN 978-3-030-01342-4 ISBN 978-3-030-01343-1 (eBook) https://doi.org/10.1007/978-3-030-01343-1 Library of Congress Control Number: 2018957333 © Springer Nature Switzerland AG 2019 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland Preface Instrumentation amplifiers (IAs) are among the oldest and most widely used circuits that ensure a weak differential signal amplification in the presence of strong noises and common-mode signals. In the past, IAs were implemented using Op-Amps and resistors. Their major problem is the strict matching requirement between resistors to achieve a high common-mode rejection ratio (CMRR). Another limitation associ- ated with Op-Amp-based IAs is their gain-dependent bandwidth. These weaknesses along with the rapid downscale of CMOS technology with reduced allowed supply voltages have made the Op-Amp-based IAs less attractive. Fortunately, after the emergence of current-mode signal processing, designers took the advantages of current-mode technique to mitigate the problems associated with Op-Amp-based IAs. Compared to conventional voltage-mode signal processing, the new technique showed interesting features such as wide frequency performance, simpler circuitry, low-voltage operation. This new generation of IAs based on current-mode signal processing is known as current-mode instrumentation amplifiers (CMIAs). Although signal processing is performed in current domain, the input and output signals in CMIAs can be current or voltage signals. Therefore, while benefiting from inherent advantages of current-mode signal processing such as low-voltage operation, high- frequency performance, simpler circuitry, CMIAs can cover a wide range of appli- cations. The first CMIA was reported in 1989 by C. Toumazou and F. J. Lidgey, based on supply current sensing technique. This new CMIA utilized two Op-Amps and one resistor. It showed interesting features such as high CMRR without requir- ing tightly matched resistors and wide bandwidth independent of gain. Later, the famous Wheatstone bridge was also employed and modified to take advantage of current-mode signal processing. The current-mode Wheatstone bridge (CMWB) and mixed-mode Wheatstone bridge were introduced, being capable of operating with current-mode readout circuits. These advances provided the opportunity for nearly all types of sensor readout circuits to benefit from current-mode signal pro- cessing. Then, the CMIAs emerged as a rapidly advancing subject, so numerous topologies are found in literature, and new current-mode building blocks were intro- duced intended for CMIA applications. However, a book entirely and exclusively dedicated to the design of CMIAs is lacking. We decided to write this book to v vi Preface address the need for a guide on CMIA design and applications. It grew out employ- ing the content of published journal and conference papers in the CMIA subject written by researchers all around the world. Our aim is to give an overall knowledge on CMIA design and make the comparison between various structures easier. The operation principle, advantages, and disadvantages of each topology are high- lighted. Also, we have classified the reported CMIAs in four categories depending on their input and output signals. This classification simplifies selecting a specific topology for the desired application. This book is written in nine chapters. In the first chapter, the general definitions of the common-mode rejection ratio concept in single-ended, fully differential, and cascaded structures are studied. Then, we discuss about the limitations of the conventional Op-Amp-based IAs. The general classification of CMIAs is also developed in this chapter. In Chap. 2, we cover supply current sensing technique which is the oldest and powerful method used in the design of CMIA. The basic concept and performance analysis of circuits based on this technique are discussed. The first and second gen- erations of CMIAs developed using this technique are reviewed. Then, performance analysis of each generation as well as their limitations is studied. This chapter ends with an interesting comparison between the two generations. In Chap. 3, we discuss about the Wheatstone bridges. First the fundamentals of conventional voltage-mode Wheatstone bridge (VMWB) and its readout circuits are studied. Then current-mode Wheatstone bridge (CMWB) principle, its readout cir- cuit, and linearization technique are discussed. At the end of this chapter, the mixed- mode Wheatstone bridge principle and readout circuits which are aimed to take the benefits of both voltage-mode and current-mode signal processing are covered. In Chap. 4, we consider the CMIA topologies designed with current conveyors. As the second-generation current conveyor (CCII) is considered the most famous and widely used current-mode building block, a chapter is solely dedicated to the CCII-based CMIA topologies. These CMIAs include topologies proposed by Wilson, Gift, Khan et al., Galanis and Haritantis, Su and Lidgey, Gkotsis et al., Koli and Halonen, etc. The principles and the effect of CCII’s non-idealities on the over- all CMRR of each topology are also studied. In Chap. 5, all CMIA topologies based on various current-mode building blocks are described. These building blocks include operational floating current conveyor (OFCC), current differencing buffered amplifier (CDBA), current feedback opera- tional amplifier (CFOA), operational transresistance amplifier (OTRA), differential difference current conveyor (DDCC), and differential voltage current conveyor (DVCC). The CMIAs studied in this chapter are classified according to their input and output signals. In Chap. 6, we study CMIA structures with electronically tunable gain feature. Different methods used to achieve electronically tunable gain are discussed. The electronically tunable CMIAs are divided into two groups. In first group, gain is varied by the active building block, while, in second group, electronically variable resistors are used for this purpose. Preface vii In Chap. 7, we briefly discuss about the implications (and limitations) caused by mismatches in the CMIAs. Helpful techniques used to reduce the occurrence of mismatches are also reviewed. The chapter is finished by studying a CMIA topol- ogy with robust performance against mismatches. In Chap. 8, we focus on the CMIAs designed for biomedical and low-voltage low-power applications. In particular, design considerations and challenges for bio- medical applications are discussed. We study the realization of well-known boot- strapping technique in current-mode domain. Techniques used to improve noise performance of CMIAs are also reviewed. Then, various methods and implementa- tions used to design low-voltage low-power CMIAs are studied. In the final chapter, the CMIAs intended for sensor applications are reviewed. These include piezo-resistive, differential capacitive, ISFET, pH, and temperature sensors. For each application, background knowledge on the related sensor is given, and then the topology of the used CMIA is studied. The intended audience for this book includes design engineers, researchers, and students. We tried our best to present each chapter in the simplest form as possible and independent of other chapters, so the readers are able to select and read a single chapter separately, based on their requirement. We hope that this book will be helpful in inspiring new ideas in CMIA design and applications. Tehran, Iran Leila Safari L’aquila, Italy Giuseppe Ferri Istanbul, Turkey Shahram Minaei L’aquila, Italy Vincenzo Stornelli Contents 1 Principles of Instrumentation Amplifiers . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Principles and Applications of Instrumentation Amplifiers . . . . . . . . 1 1.2 Common-Mode Rejection Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2.1 Definitions of Common-Mode Rejection Ratio . . . . . . . . . . . 3 1.2.2 Common-Mode Rejection Ratio for Cascaded Stages. . . . . . 5 1.3 Conventional 3-Op-Amp Based Voltage-Mode Instrumentation Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.3.1 CMRR Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.3.2 Differential Gain Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.3.3 Gain Bandwidth Conflict . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 1.4 Current-Mode Instrumentation Amplifiers (CMIAs) . . . . . . . . . . . . . 11 1.4.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 1.4.2 Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2 CMIA Based on Op-Amp Power Supply Current Sensing Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.1 Op-Amp Power Supply Current Sensing Technique . . . . . . . . . . . . . 15 2.1.1 Basic Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.1.2 Analysis of Op-Amp Power Supply Current Sensing Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 2.1.3 Limitation and Design Challenges . . . . . . . . . . . . . . . . . . . . . 18 2.2 CMIA Based on Op-Amp Power Supply Current Sensing . . . . . . . . 19 2.2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.2.2 First Generation with Single-Output Structure . . . . . . . . . . . 20 2.2.3 Second Generation with Balanced Structure . . . . . . . . . . . . . 23 2.2.4 Performance Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2.2.5 Comparison Between Different Generations of CMIA Based on Op-Amp Power Supply Sensing Technique . . . . . . 27 2.3 C onclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 ix x Contents 3 Current-Mode Wheatstone Bridge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 3.1 Traditional Voltage-Mode Wheatstone Bridge . . . . . . . . . . . . . . . . . . 29 3.1.1 Introduction to Traditional Voltage-Mode Wheatstone Bridge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 3.1.2 Read-Out Circuits for Voltage-Mode Wheatstone Bridge . . . 32 3.1.3 Linearization of Voltage-Mode Wheatstone Bridge . . . . . . . . 35 3.2 C urrent-Mode Wheatstone Bridge . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 3.2.1 Introduction to Current-Mode Wheatstone Bridge . . . . . . . . 36 3.2.2 Linearization of Current-Mode Wheatstone Bridge . . . . . . . 39 3.2.3 Read-Out Circuits for Current-Mode Wheatstone Bridge . . . 40 3.3 Mixed-Mode Wheatstone Bridge and Read-Out Circuits . . . . . . . . . 54 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 4 Current-Mode Instrumentation Amplifiers Using Current Conveyors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 4.1 CCII-Based Basic CMIAs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 4.1.1 Wilson Current-Mode Instrumentation Amplifier . . . . . . . . . 59 4.1.2 Gift Current-Mode Instrumentation Amplifier. . . . . . . . . . . . 62 4.2 Current Conveyor-Based Enhanced CMIAs with Double Common- Mode Cancellation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 4.2.1 Khan et al. Current-Mode Instrumentation Amplifier . . . . . . 63 4.2.2 Su and Lidgey Current-Mode Instrumentation Amplifier . . . 64 4.2.3 Galanis Current-Mode Instrumentation Amplifier . . . . . . . . . 65 4.2.4 Gkotsis Current-Mode Instrumentation Amplifier . . . . . . . . . 66 4.2.5 Koli Current-Mode Instrumentation Amplifier . . . . . . . . . . . 66 4.2.6 Azhari and Fazlalipour Current-Mode Instrumentation Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 4.2.7 Gift et al. Enhanced Current-Mode Instrumentation Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 5 Current-Mode Instrumentation Amplifiers Based on Various Current- Mode Building Blocks . . . . . . . . . . . . . . . . . . . . . . 71 5.1 Current Input-Current Output (I-I) CMIAs . . . . . . . . . . . . . . . . . . . . 71 5.1.1 CDBA-Based I-I CMIA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 5.1.2 CFOA Based I-I CMIA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 5.1.3 OFCC-Based I-I CMIA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 5.2 Current Input-Voltage Output (I-V) CMIAs . . . . . . . . . . . . . . . . . . . 77 5.2.1 OFCC-Based I-V CMIA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 5.2.2 OTRA-Based I-V CMIA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 5.3 Voltage Input-Current Output (V-I) CMIAs . . . . . . . . . . . . . . . . . . . 82 5.3.1 OFCC-Based CMIA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 5.4 Voltage Input-Voltage Output (V-V) CMIAs . . . . . . . . . . . . . . . . . . . 83 5.4.1 OFCC Based V-V CMIAs . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 5.4.2 DDCC-Based V-V CMIAs . . . . . . . . . . . . . . . . . . . . . . . . . . . 86