Linear circuit design handbook

Linear Circuit Design Handbook

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Linear Circuit Design Handbook

Hank Zumbahlen

with the engineering staff of Analog Devices

AMSTERDAM • BOSTON • HEIDELBERG • LONDON • NEW YORK • OXFORD

PARIS • SAN DIEGO • SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO

Newnes is an imprint of Elsevier

Cover images courtesy of Analog Devices

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Copyright © 2008 by Analog Devices. All rights reserved.

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Recognizing the importance of preserving what has been written, Elsevier prints its books on acid-free paper

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Library of Congress Cataloging-in-Publication Data

Linear circuit design handbook / edited by Hank Zumbahlen ; with the engineering staff of Analog Devices.

p. cm.

ISBN 978-0-7506-8703-4

1. Electronic circuits. 2. Analog electronic systems. 3. Operational amplifi ers. I. Zumbahlen, Hank.

II. Analog Devices, inc.

TK7867.L57 2008

627.39 5--dc22 2007053012

British Library Cataloguing-in-Publication Data

A catalogue record for this book is available from the British Library.

ISBN: 978-0-7506-8703-4

For information on all Newnes publications

visit our Web site at www.books.elsevier.com

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08 09 10 11 10 9 8 7 6 5 4 3 2 1

Printed in the United States of America

v

Contents

Preface ....................................................................................................................ix

Chapter 1: The Op Amp ............................................................................................ 1

Section 1-1: Op Amp Operation .....................................................................................3

Section 1-2: Op Amp Specifi cations ..............................................................................25

Section 1-3: How to Read a Data Sheet ........................................................................69

Section 1-4: Choosing an Op Amp ...............................................................................81

Chapter 2: Other Linear Circuits .............................................................................. 83

Section 2-1: Buffer Amplifi ers .......................................................................................85

Section 2-2: Gain Blocks ..............................................................................................89

Section 2-3: Instrumentation Amplifi ers ........................................................................91

Section 2-4: Differential Amplifi ers ............................................................................. 107

Section 2-5: Isolation Amplifi ers ................................................................................. 109

Section 2-6: Digital Isolation Techniques .................................................................... 113

Section 2-7: Active Feedback Amplifi ers ...................................................................... 123

Section 2-8: Logarithmic Amplifi ers ............................................................................ 125

Section 2-9: High Speed Clamping Amplifi ers ............................................................. 131

Section 2-10: Comparators ........................................................................................ 137

Section 2-11: Analog Multipliers ................................................................................ 147

Section 2-12: RMS to DC Converters .......................................................................... 153

Section 2-13: Programmable Gain Amplifi ers .............................................................. 157

Section 2-14: Audio Amplifi ers ................................................................................... 165

Section 2-15: Auto-Zero Amplifi ers ............................................................................. 185

Chapter 3: Sensors ............................................................................................... 193

Section 3-1: Positional Sensors ................................................................................... 195

Section 3-2: Temperature Sensors ............................................................................... 215

Section 3-3: Charge Coupled Devices .......................................................................... 241

Chapter 4: RF/IF Circuits ...................................................................................... 245

Section 4-1: Mixers .................................................................................................... 248

Section 4-2: Modulators ............................................................................................ 255

vi

Contents

Section 4-3: Analog Multipliers .................................................................................. 257

Section 4-4: Logarithmic Amplifi ers ............................................................................ 265

Section 4-5: Tru-Power Detectors ............................................................................... 271

Section 4-6: VGAs ...................................................................................................... 275

Section 4-7: Direct Digital Synthesis ............................................................................ 281

Section 4-8: PLLs ....................................................................................................... 289

Chapter 5: Fundamentals of Sampled Data Systems ................................................. 307

Section 5-1: Coding and Quantizing ........................................................................... 309

Section 5-2: Sampling Theory ..................................................................................... 327

Chapter 6: Converters ........................................................................................... 337

Section 6-1: DAC Architectures .................................................................................. 340

Section 6-2: ADC Architectures .................................................................................. 371

Section 6-3: Sigma–Delta Converters .......................................................................... 407

Section 6-4: Defi ning the Specifi cations ...................................................................... 431

Section 6-5: DAC and ADC Static Transfer Functions and DC Errors ............................ 433

Section 6-6: Data Converter AC Errors ........................................................................ 443

Section 6-7: Timing Specifi cations .............................................................................. 483

Section 6-8: How to Read a Data Sheet ...................................................................... 487

Section 6-9: Choosing a Data Converter ..................................................................... 509

Chapter 7: Data Converter Support Circuits ............................................................ 513

Section 7-1: Voltage References .................................................................................. 515

Section 7-2: Analog Switches and Multiplexers ............................................................ 531

Section 7-3: Sample-and-Hold Circuits ....................................................................... 555

Section 7-4: Clock Generation and Distribution Circuits .............................................. 565

Chapter 8: Analog Filters ...................................................................................... 581

Section 8-1: Introduction ........................................................................................... 583

Section 8-2: The Transfer Function ............................................................................. 587

Section 8-3: Time Domain Response .......................................................................... 597

Section 8-4: Standard Responses ................................................................................ 599

Section 8-5: Frequency Transformations ..................................................................... 623

Section 8-6: Filter Realizations .................................................................................... 629

Section 8-7: Practical Problems in Filter Implementation ............................................. 653

Section 8-8: Design Examples ..................................................................................... 663

Chapter 9: Power Management .............................................................................. 681

Section 9-1: Linear Voltage Regulators ........................................................................ 684

vii

Contents

Section 9-2: Switch Mode Regulators ......................................................................... 701

Section 9-3: Switched Capacitor Voltage Converters .................................................... 741

Chapter 10: Passive Components ........................................................................... 753

Section 10-1: Capacitors ............................................................................................ 755

Section 10-2: Resistors and Potentiometers ................................................................ 767

Section 10-3: Inductors .............................................................................................. 775

Chapter 11: Overvoltage Effects on Analog Integrated Circuits .................................. 779

Section 11-1: Overvoltage Effects ............................................................................... 781

Section 11-2: Electrostatic Discharge .......................................................................... 789

Section 11-3: EMI/RFI Considerations ........................................................................ 799

Chapter 12: Printed Circuit-Board Design Issues ...................................................... 821

Section 12-1: Partitioning .......................................................................................... 824

Section 12-2: Traces .................................................................................................. 827

Section 12-3: Grounding ............................................................................................ 863

Section 12-4: Decoupling ........................................................................................... 881

Section 12-5: Thermal Management ........................................................................... 885

Index ................................................................................................................... 897

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ix

This work is based on the work of many other individuals who have been involved with applications and

Analog Devices since the company started in 1965. Much of the material that appears in this work is based

on work that has appeared in other forms. My major job function in this case was one of editor. The list of

people I would like to credit for doing the pioneering work include: Walt Kester, Walt Jung, Paul Brokaw,

James Bryant, Chuck Kitchen, and many other members of Analog Devices technical community.

In addition many others contributed to the production of this edition by helping out with the production of

this book by providing invaluable assistance by proofreading and providing commentary. I especially want

to thank Walt Kester, Bob Marwin, and Judith Douville, who also did the indexing.

Again, many thanks to those involved in this project.

Hank Zumbahlen

Senior Staff Applications Engineer

Preface

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CHAPTER 1

The Op Amp

■ Section 1-1: Op Amp Operation

■ Section 1-2: Op Amp Specifi cations

■ Section 1-3: How to Read a Data Sheet

■ Section 1-4: Choosing an Op Amp

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3

Chapter Introduction

In this chapter we will discuss the basic operation of the op amp, one of the most common linear design

building blocks.

In Section 1-1 the basic operation of the op amp will be discussed. We will concentrate on the op amp from

the black box point of view. There are a good many texts that describe the internal workings of an op amp,

so in this work a more macro view will be taken. There are a couple of times, however, that we will talk

about the insides of the op amp. It is unavoidable.

In Section 1-2 the basic specifi cations will be discussed. Some techniques to compensate for some of the op

amps limitations will also be given.

Section 1-3 will discuss how to read a data sheet. The various sections of the data sheet and how to interpret

what is written will be discussed.

Section 1-4 will discuss how to select an op amp for a given application.

Introduction

The op amp is one of the basic building blocks of linear design. In its classic form it consists of two

input terminals—one of which inverts the phase of the signal, the other preserves the phase—and an

output terminal. The standard symbol for the op amp is given in Figure 1-1 . This ignores the power supply

terminals, which are obviously required for operation.

Inputs

()

()



Figure 1-1 : Standard op amp symbol

SECTION 1-1

Op Amp Operation

4

Chapter One: The Op Amp

The name “ op amp ” is the standard abbreviation for operational amplifi er. This name comes from the early

days of amplifi er design, when the op amp was used in analog computers. (Yes, the fi rst computers were

analog in nature, rather than digital.) When the basic amplifi er was used with a few external components,

various mathematical “ operations ” could be performed. One of the primary uses of analog computers was

during World War II, when they were used for plotting ordinance trajectories.

Voltage Feedback Model

The classic model of the voltage feedback (VFB) op amp incorporates the following characteristics:

1. Infi nite input impedance

2. Infi nite bandwidth

3. Infi nite gain

4. Zero output impedance

5. Zero power consumption

None of these can be actually realized, of course. How close we come to these ideals determines the quality

of the op amp.

This is referred to as the VFB model. This type of op amp comprises nearly all op amps below 10 MHz

bandwidth and on the order of 90% of those with higher bandwidths ( Figure 1-2 ).

Positive supply

• Ideal op amp attributes

– Infinite differential gain

– Zero common mode gain

– Zero offset voltage

– Zero bias current

– Infinite bandwidth

• Op amp input attributes

– Infinite impedance

– Zero bias current

– Respond to differential voltages

– Do not respond to common mode voltages

• Op amp output attributes

– Zero impedance

Negative supply

Inputs Output

()

()



Op amp

Figure 1-2 : The attributes of an ideal op amp

Basic Operation

The basic operation of the op amp can be easily summarized. First we assume that there is a portion of the

output that is feedback to the inverting terminal to establish the fi xed gain for the amplifi er. This is negative

feedback. Any differential voltage across the input terminals of the op amp is multiplied by the amplifi er ’ s

open-loop gain. If the magnitude of this differential voltage is more positive on the inverting (  ) terminal

than on the non-inverting ( ) terminal, the output will go more negative. If the magnitude of the

differential voltage is more positive on the non-inverting ( ) terminal than on the inverting (  ) terminal,

the output voltage will become more positive. The open-loop gain of the amplifi er will attempt to force the

differential voltage to zero. As long as the inouts and output stays in the operational range of the amplifi er,

it will keep the differential voltage at zero and the output will be the input voltage multiplied by the gain