Comprehensive Theory

with Solved Examples and Practice Questions

Digital Electronics

Instrumentation Engineering

Publications

MADE EASY Publications

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Digital Electronics© Copyright, 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.

Publications

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

book on Digital Electronics. 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 Digital Electronics 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 ‘Boolean algebra, logic gates, combinational and sequential logic circuits,

registers, counters, logic families, converters and semiconductor memories’, are given full coverage in line with

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 1Basics of Digital Electronics .................... 1 1.1. Digital Number Systems ............................................. 2 1.2 Codes ................................................................................. 7 1.3 Arithmetic Operations ...............................................10 1.4 Signed Number Representation ............................13 1.5 Over Flow Concept .....................................................19 Student Assignments ...................................................21

Chapter 2Boolean Algebra & Minimization Techniques .............................................22 2.1 Logic Operations .........................................................22 2.2 Laws of Boolean Algebra ..........................................23 2.3 Boolean Algebric Theorems ....................................24 2.4 Minimization of Boolean Functions......................27 2.5 Representation of Boolean Functions .................27 2.6 Implicants, Prime Implicants and Essential Prime

Implicants ......................................................................37 Student Assignments ...................................................41

Chapter 3Logic Gates and Switching Circuits ......43 3.1 Basic Gates .....................................................................43 3.2 Universal Gates ............................................................49 3.3 Special Purpose Gate .................................................52 3.4 Realization of Logic Gates Using

Universal Gates ............................................................57 Student Assignments ...................................................61

Chapter 4Combinational Logic Circuits................63 4.1 Design Procedure for Combinational Circuit ....63 4.2 Arithmetic Circuits ......................................................64 4.3 Non-arithmetic Circuit ...............................................77 4.4 Hazards ........................................................................ 108 Student Assignments ................................................ 111

Chapter 5Sequential Logic Circuits ....................114 5.1 Latches and Flip-Flops ............................................ 115 5.2 Race Around Condition .......................................... 126

5.3 Conversion of Flip-Flops ........................................ 129 5.4 Applications of Flip-Flops ...................................... 131 Student Assignments ................................................ 133

Chapter 6Registers ...............................................135 6.1 Shift Register .............................................................. 135

Student Assignments ................................................ 144

Chapter 7Counters ...............................................145 7.1 Asynchronous/Ripple Counters .......................... 147

7.2 Synchronous Counters ........................................... 152

7.3 Synchronous Counter Design .............................. 159

7.4 State Diagram and State Table ............................ 162

7.5 Finite State Model/Machine ................................. 165

Student Assignments ................................................ 167

Chapter 8Logic Families ......................................170 8.1 Switching Circuits .................................................... 171

8.2 Classification of Digital Logic Family ................. 175

8.3 Characteristics of Digital Logic Family .............. 176

8.4 Logic Families ............................................................ 181

Student Assignments ................................................ 204

Chapter 9A/D and D/A Converters ......................207 9.1 Digital to Analog Converter ................................. 207

9.2 Analog to Digital Converters................................ 217

Student Assignments ................................................ 229

Chapter 10Semiconductor Memories ...................231 10.1 Memory Device, Parameters

and Specifications .................................................... 232

10.2 Memory Classification ............................................ 233

Student Assignments ................................................ 244

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