Comprehensive Theory

with Solved Examples and Practice Questions

Electronic Devicesand Circuits

ElectronicsEngineering

MADE EASY Publications

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Electronic Devices and CircuitsCopyright © 2016, by MADE EASY Publications.All rights are reserved. No part of this publication may be reproduced, stored in or introduced into a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photo-copying, recording or otherwise), without the prior written permission of the above mentioned publisher of this book.

First Edition: 2015Second Edition: 2016 (Revised and Updated)

© All rights reserved by MADE EASY PUBLICATIONS. No part of this book may be reproduced or utilized in any form without the written permission from the publisher.

This book was motivated by the desire to further the evolution of a concise

book on Electronic Devices and Circuits. Keeping in focus the importance

of this subject in GATE and ESE, we have done a proper study and

thereafter developed the content of the book accordingly. This edition has

an expanded discussion of all relevant topics in the subject.

Initially, we compiled the perceptions of our students on their problems

in GATE and ESE while dealing with the questions from this subject. We

identified their various problems like- lack of fundamentals of the subject,

difficulty in solving simple questions, shortage of a complete study package, etc. These strengthened

our determination to present a complete edition of Electronic Devices and Circuits textbook.

The book addresses all the requirements of the students, i.e. comprehensive coverage of theory, fundamental

concepts, objective type problems and conventional problems, articulated in a lucid language. The concise

presentation will help the readers grasp the concepts with clarity and apply them with ease to solve problems

quickly. The book not only covers the entire syllabus of GATE and ESE, but also addresses the need of many

other competitive examinations. Topics like ‘Intrinsic and Extrinsic Semiconductors, Conductivity and Mobility

of Semiconductors, Mass-action Law, Drift and Diffusion of Carriers, Hall-effect, P-N Junction Diodes, BJT, and

FET’ etc. are given full coverage in line with of our research on their importance in competitive examinations.

We have put in our sincere efforts to present elaborate solutions for various problems, different problem solving

methodology, some useful quick techniques to save time while attempting MCQs without compromising the accuracy

of answers. A summary of important points to remember is added at the end of each topic. For the convenience of

the readers, points to remember are specifically highlighted in the form of a note- both in theory as well as solved

examples. At the end of each chapter, sets of practice question are given with their keys, that will allow the readers

to evaluate their understanding of the topics and sharpen their problem solving skills.

Our team has made their best efforts to remove all possible errors of any kind. Nonetheless, we would highly

appreciate and acknowledge if you find and share with us any printing, calculation and conceptual error.

It is impossible to thank all the individuals who helped us, but we would like to sincerely thank all the authors, editors

and reviewers for putting in their efforts to publish this book.

With Best Wishes

B. Singh

CMD, MADE EASY

Preface

Chapter 1Semiconductor Physics ........................... 1 1.1 The Nature of The Atom .............................................. 1

1.2 Atomic Energy Levels................................................... 3

1.3 Electronic Structure of the Elements ..................... 4

1.4 The Energy-Band Theory of Crystals ...................... 5

1.5 Insulators, Semiconductors and Metals ................ 6

1.6 Direct and Indirect Semiconductors ...................... 8

1.7 Electrons and Holes in an Intrinsic

Semiconductor.............................................................10

1.8 Conductivity of a Semiconductor .........................12

1.9 Extrinsic Semiconductor: Donor and

Acceptor Impurities ....................................................14

1.10 The Mass-Action Law .................................................16

1.11 Carrier Concentrations ..............................................18

1.12 Charge Neutrality ........................................................25

1.13 Drift of Carriers in Electric

and Magnetic Fields ...................................................29

1.14 Diffusion of Carriers ....................................................36

1.15 The Continuity Equation ...........................................39

1.16 Hall Effect .......................................................................41

Student Assignments ...................................................44

Chapter 2P-N Junction and Diodes .......................46 2.1 Basic Structure of the p-n Junction ......................46

2.2 Equilibrium Conditions .............................................47

2.3 Forward and Reverse Biased

Junctions-Steady State Conditions .......................58

2.4 Capacitive Effects in the p-n Junction .................71

2.5 Different Types of Junctions ....................................77

2.6 Charge Storage and Diode Transients .................79

2.7 Reverse Bias-Breakdown...........................................81

2.8 Some Special Diodes .................................................85

2.9 Metal-Semiconductor Junctions ...........................91

Student Assignments ...................................................94

Chapter 3Bipolar Junction Transistors .................96 3.1 Device Structure ..........................................................96

3.2 Transistor Action ..........................................................99

3.3 Base Width Modulation .......................................... 103

3.4 BJT Configuration ..................................................... 105

3.5 The Common Base Configuration ...................... 105

3.6 The Common-Emitter Configuration ................ 109

3.7 The Common-Collector Configuration............. 113

Student Assignments ................................................ 114

Chapter 4Field Effect Transistor (FET) ..................... 116 4.1 Construction of JFETs.............................................. 117

4.2 Symbols ....................................................................... 117

4.3 FET Operation ............................................................ 118

4.4 The Pinch-off Voltage Vp ...................................... 118

4.5 The JFET Volt-Ampere Characteristics .............. 119

4.6 The Transfer Characteristic .................................... 121

4.7 Interpretation and Sketching of Transfer

Characteristics Curve .............................................. 121

4.8 FET Parameters .......................................................... 123

4.9 MOSFET ........................................................................ 126

4.10 Enhancement Type MOSFET ................................ 130

4.11 Derivation of the ID – VDS Relationship .......... 133

4.12 Functional Analysis of Enhancement MOSFET .....138

4.13 Depletion Type MOSFET ........................................ 142

Student Assignments ................................................ 147

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Electronic Devices and CircuitsContents