Electronics Engineering Electronic Devices and Circuits Comprehensive Theory with Solved Examples and Practice Questions MADE EASY Publications Corporate Office: 44-A/4, Kalu Sarai (Near Hauz Khas Metro Station), New Delhi-110016 E-mail: infomep@madeeasy.in Contact: 011-45124612, 0-9958995830, 8860378007 Visit us at: www.madeeasypublications.org Electronic Devices and Circuits Copyright © 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: 2015 Second 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. Preface 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 Contents Electronic Devices and Circuits Chapter 1 2.8 Some Special Diodes..................................................85 Semiconductor Physics............................ 1 2.9 Metal-Semiconductor Junctions............................91 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 Student Assignments....................................................94 Chapter 3 Bipolar Junction Transistors..................96 3.1 Device Structure...........................................................96 3.2 Transistor Action...........................................................99 3.3 Base Width Modulation........................................... 103 Semiconductor.............................................................10 3.4 BJT Configuration...................................................... 105 1.8 Conductivity of a Semiconductor..........................12 3.5 The Common Base Configuration....................... 105 1.9 Extrinsic Semiconductor: Donor and 3.6 The Common-Emitter Configuration................. 109 Acceptor Impurities.....................................................14 3.7 The Common-Collector Configuration............. 113 1.10 The Mass-Action Law..................................................16 1.11 Carrier Concentrations...............................................18 1.12 Charge Neutrality.........................................................25 1.13 Drift of Carriers in Electric Student Assignments................................................. 114 Chapter 4 Field Effect Transistor (FET)��������������������� 116 and Magnetic Fields....................................................29 4.1 Construction of JFETs.............................................. 117 1.14 Diffusion of Carriers.....................................................36 4.2 Symbols........................................................................ 117 1.15 The Continuity Equation............................................39 4.3 FET Operation............................................................. 118 1.16 Hall Effect........................................................................41 4.4 The Pinch-off Voltage Vp....................................... 118 Student Assignments....................................................44 4.5 The JFET Volt-Ampere Characteristics............... 119 4.6 The Transfer Characteristic..................................... 121 4.7 Interpretation and Sketching of Transfer Chapter 2 P-N Junction and Diodes........................46 Characteristics Curve............................................... 121 2.1 Basic Structure of the p-n Junction.......................46 4.8 FET Parameters........................................................... 123 2.2 Equilibrium Conditions..............................................47 4.9 MOSFET......................................................................... 126 2.3 Forward and Reverse Biased 4.10 Enhancement Type MOSFET................................. 130 Junctions-Steady State Conditions........................58 4.11 Derivation of the ID – VDS Relationship........... 133 2.4 Capacitive Effects in the p-n Junction..................71 4.12 Functional Analysis of Enhancement MOSFET......138 2.5 Different Types of Junctions.....................................77 4.13 Depletion Type MOSFET......................................... 142 2.6 Charge Storage and Diode Transients..................79 2.7 Reverse Bias-Breakdown...........................................81 Student Assignments................................................. 147 nnnn (iv)