ELECTRONIC · 2018-10-01 · # Preface to the First Edition... Electronic Principles is a compulsory subject for the engineering students from all the disciplines. This book is primarily

(For B.E., B.Tech, B.Sc (Engineering), A.M.I.E., (India), A.M.I.E.E. (London),

Grad I.E.T.E. (India), GATE, UPSC., I.E.S., and Other Various Engg.

& Competitive Examinations)

ELECTRONIC

PRINCIPLES

Dr. SANJAY SHARMAB.E., M.Tech, Ph.D, MIETE

Edited By

DEEKSHA SHARMA

&

V. SHARMA

S.K. KATARIA & SONS®

Publisher of Engineering and Computer Books4885/109, Prakash Mahal, Dr. Subhash Bhargav Lane,

Opposite Delhi Medical Association, Daryaganj, New Delhi–110002

Phone: +91-11-23243489, 23269324; Telefax: +91-11-23243489

e-mail: [email protected]; [email protected]

Website: www.skkatariaandsons.com

First Edition : September, 2007; Reprint : 2009; Second Edition: June, 2010; Reprint: 2012; Third Edition: March, 2014

Price: `̀̀̀̀ 495/-

Published by:

S.K. Kataria & Sons®

4885/109, Prakash Mahal, Dr. Subhash Bhargav Lane,

Opposite Delhi Medical Association, Daryaganj, New Delhi–110002

Phone: +91-11-23243489, 23269324; Telefax: +91-11-23243489

e-mail: [email protected]; [email protected]

Head Office:Opp. Clock Tower, Ludhiana (Pb)

Ph. : 2726401

© ALL RIGHTS STRICTLY RESERVED

Laser Type Setting: Printed at:

PLUS COMPUTERS, Shahdara, Delhi New A.S. Printing Press, Delhi

STATUTORY WARNING

Information contained in this book has been obtained by author from sources believed to be reliable

and are correct to the best of his knowledge. Every effort has been made to avoid errors and

omissions and ensure accuracy. Any error or omission noted may be brought to the notice of the

publisher which shall be taken care of in forthcoming edition of this book. However, neither the

publisher nor the author guarantee the accuracy or completeness of any information published herein,

and neither the publisher nor author take any responsibility of liability for any inconvenience, expenses,

losses or damage to anyone resulting from contents of this book.

The book is meant for educational and learning purposes and there is no attempt on the part of

publisher/author to render engineering and other professional services. If such services are required,

the assistance of an appropriate professional should be sought.

The author of the book has taken all possible care to ensure that the contents of the book do not

violate any existing copyright or other intellectual property rights of any person in any manner whatsoever.

In the event, the author has been unable to track any source and if any copyright has been inadvertently

infringed, the facts may be brought to the notice of the publisher in writing for corrective action.

Send all correspondence to : M/s S.K. Kataria & Sons, New Delhi

e-mail: [email protected]

Preface to the Third Edition...

I feel happy in presenting the third revised and enlarged edition of this book to the students. In fact, the

favourable and warm reception which the first and second edition has earned has been a matter of great satisfaction

for me. The author wishes to express his deep gratitude to the large number of readers who have used it and a

particular to those of them, who sent valuable suggestions for the improvements of the book.

In this addition, the author has made sincere efforts to make the book up-to-date.

The present edition has been thoroughly revised and a lot of useful material has been added. To make it more

useful, several solved examples and problems have been added from the Examination point of view. The mistakes

and misprints, which had crept in last edition, have been eliminated in this edition. The author hopes that all

these features will make the book even more useful and attractive to the readers

Any errors, misprints and suggestions for the improvements of the book, brought to my notice would be gratefully

and thankfully acknowledged and incorporated in the next edition.

Dr. Sanjay SharmaMarch, 2014

Preface to the First Edition...

Electronic Principles is a compulsory subject for the engineering students from all the disciplines. This book is

primarily intended to serve as a textbook in accordance with the syllabus of Electronic Principles offered by various

universities in India.

The objective of the book is to provide a clear explanation of the operation of all important basic electronic

devices in general use today.

This book has been written in a very simple and lucid manner. Every effort has been made to make the treatments

simple and comprehensive. Throughout the book, the stress has been given on fundamental concepts through

illustrative examples. Neat and Clear diagrams have been used for explanation.

Summary of each chapter is provided to help the students to grasp the subject clearly. A large number of self

explanatory accurate diagrams and tables have been used to supplement the text. Exercises and problems are also

provided. These have been selected from examination papers of various Indian Universities. This will help the

students to prepare accordingly.

This book is also intended as a textbook for the use in Electronic and Communication courses in polytechnics,

IETE, AMIE and for various Engg. Electronics examinations. Thus, primarily designated as an undergraduate

textbook for students of science and technology, this study will provide balanced coverage of devices, analog and

digital circuits, with an emphasis on analog electronics. It also serves as a quick reference for practising professionals.

The whole text has been logically organized and spreaded over 28 chapters.

The author hopes that with these unique features the book will fulfill the genuine requirements of the student

community. Lastly, much originality cannot be claimed in a book of this kind. The author takes this opportunity to

place on record his indebtedness to the large number of books and journals that he has freely consulted in the

preparation of this book.

I would like to express my sincere thanks to Dr. S.N. Ahmad, Professor (ECE) JPIT, Delhi for constant inspiration

and encouragement.

Special thanks to Dr. B.P. Singh (Former Professor, Electronics & Comm. Engg., MMMEC, Gorakhpur), Dr.

R.K. Chauhan (Professor, Electronics & Comm. Engg., MMMEC, Gorakhpur), Dr. G.S. Tripathi (Electronics &

Comm. Engg., MMMEC, Gorakhpur), Dr. Arun Kumar (Former Professor, Electronics & Comm. Engg., MMMEC,

Gorakhpur) and Dr. C.B. Tripathi (Professor Electronics & Comm. Engg., MMMEC Gorakhpur), and Dr. Vipin

Kumar, for their guidance and valuable suggestions.

I am grateful to my younger brothers Rajeev and Rakesh, daughter Ritika, for inspiring me for this project.

I deeply express my heartful thanks to the publishers S.K. Kataria & Sons for publishing this book in such a

beautiful get-up and well in time.

Lastly, I am also grateful to Mr. Manoj Tyagi and his staff from Plus Computer’s for their hard work.

Dr. Sanjay SharmaSeptember, 2007

DEDICATED

TO MY LOVING SON

MRIDUL

1. BASIC ASPECTS OF ELECTRONICS ..................... 1–9

1.1 General Meaning ...................................................................... 1

1.2 Initial Developments in Electronics .................. 1

1.2.1. Recent Development in Electronics ............................. 1

1.3 Applications ............................................................................... 1

1.4 A Brief History of Electronics .................................................. 2

1.5 Voltage Dividers ........................................................................ 3

1.6 Zero Reference Level ................................................................ 3

1.7 Chassis and ground .................................................................. 4

1.8 SI System of Units .................................................................... 4

1.9 Electronic Circuits .................................................................... 5

1.10 Concept of approximations ....................................................... 5

1.10.1 An Ideal Approximation or First Approximation .... 5

1.10.2 The Second Approximation ........................................ 5

1.10.3 The Third Approximation and Beyond ..................... 5

1.11 Open and Short Circuits .......................................................... 5

1.12 Thevenin’s Theorem ................................................................. 6

1.13 Norton’s Theorem ..................................................................... 7

Summary ...................................................................................9

2. SEMICONDUCTOR MATERIALS.......................... 10–25

2.1 Introduction ............................................................................. 10

2.2 Structure of Solids .................................................................. 10

2.3 Classification of Solid Materials ............................................ 10

2.4 Structure of an Atom .............................................................. 11

2.5 Atomic Structure of Few Elements ....................................... 11

2.6 Energy Levels .......................................................................... 12

2.7 Atomic Bonds .......................................................................... 12

2.8 Energy Bands in Solid Silicon ............................................... 13

2.9 Forbidden Energy Gap ........................................................... 13

2.10 Insulators, Metals and Semiconductors on the Basis of

Band Gap ................................................................................. 13

2.10.1 Insulators .................................................................. 13

2.10.2 Metals or Conductors ............................................... 14

2.10.3 Semiconductors ......................................................... 14

2.11 Comparison of Conductors, Insulators and

Semiconductors ....................................................................... 15

2.12 Semiconductor Materials: Intrinsic and Extrinsic ............... 15

2.13 Intrinsic Semiconductor ......................................................... 15

2.13.1 Crystalline Structure of Intrinsic Semiconductors 16

2.14 Intrinsic Semiconductor at Room Temperature (300 K)

or Thermal Generation of Electron-Hole Pairs .................... 16

2.14.1 Why Intrinsic Semiconductors Behave Like

Insulators at Low Temperatures? ........................... 17

2.14.2 Recombination .......................................................... 17

2.14.3 Conduction in Intrinsic Semiconductors:

Effect of Temperature on Conductivity of ..................

Intrinsic Semiconductors (Silicon or Germanium) 17

2.14.4 Electron and Hole Current ...................................... 17

2.14.5 Semiconductors have a Negative Temperature

Coefficient of Resistivity .......................................... 17

2.14.6 Carrier Life Time ..................................................... 18

2.15 Conventional Current and Electron Flow ............................ 18

2.16 Extrinsic Semiconductors ...................................................... 18

2.17 N-type Semiconductor ............................................................ 19

2.17.1 Representation of N-type Semiconductor ............... 19

2.17.2 Changes in the Energy Band Diagram due to

Doping ....................................................................... 19

2.17.3 Conduction in N-type Material ................................ 19

2.18 P-type Semiconductor ............................................................. 20

2.18.1 Representation of P-type Semiconductor ............... 20

2.18.2 Changes in the Energy Band Diagram Due to

Doping ....................................................................... 20

2.18.3 Conduction in P-type Semiconductors .................... 21

2.19 Effect of Temperature on Extrinsic Semiconductors ........... 21

2.20 Intrinsic Concentration .......................................................... 21

2.21 Electrical Properties of Semiconductors ............................... 21

2.22 Comparison Between Metals (Conductors) and

Semiconductors ....................................................................... 22

2.23 Comparison of Intrinsic and Extrinsic Semiconductors ...... 22

Contents

2.24 Semiconductor Materials used for Opto Devices, Modern

Semiconductor Devices and ICs ............................................ 22

Summary .................................................................................23

Short Questions with Answers ...............................................23

Review Questions ....................................................................25

3. DIODE FUNDAMENTALS ..................................... 26–57

3.1 The Unbiased Diode : P-N Junction ...................................... 26

3.2 The Depletion Region Formation .......................................... 26

3.3 Barrier Potential or Junction Potential (Vj) ......................... 27

3.4 Energy Levels .......................................................................... 28

3.5 Atomic Bonds .......................................................................... 28

3.6 Energy-Band Diagram for Intrinsic Semiconductor ............ 29

3.7 Energy-Band Diagram for N-type Semiconductors ............. 29

3.8 Energy-Band Diagram of P-type Semiconductors ............... 30

3.9 Energy Hill: Energy Diagrams of a P-N Junction ............... 30

3.9.1 Energy Diagram of P-N Junction at Equilibrium ..30

3.10 An Open Circuited Step-Graded Junction ............................ 31

3.11 p-n Junction Diode .................................................................. 32

3.12 Biasing of a p-n junction diode .............................................. 32

3.13 Forward biasing of a p-n junction diode ............................... 33

3.13.1 Working Operation of a Forward Biased Diode ..... 33

3.13.2 Voltage Drop Across the Forward Biased

Diode (VF) .................................................................. 34

3.14 Reverse Biasing a diode ......................................................... 34

3.14.1 Working Operation of a Reverse Biased Diode ...... 34

3.14.2 Current Flow in the Reverse Biased Diode

(Reverse Saturation Current) .................................. 34

3.14.3 Resistance of Reverse Biased Diode ....................... 35

3.14.4 Voltage Across Reverse Biased Diode ..................... 35

3.15 Breakdown in the Reverse Biased Diode .............................. 35

3.15.1 Breakdown Due to the Avalanche Effect ................ 35

3.15.2 Why should we avoid Breakdown? .......................... 35

3.15.3 Breakdown due to the Zener effect ......................... 35

3.15.4 Does the Breakdown always Damage the Diode? .. 36

3.16 Barrier Potential and Temperature ...................................... 36

3.17 V-I Characteristics of P-N Junction Diode or

Practical Diode ..................................................... 37

3.17.1 Forward Characteristic ............................................ 37

3.17.2 Reverse Characteristic ............................................. 37

3.18 The Current Components in a P-N Junction Diode ............. 38

3.19 Diode Current Equation ......................................................... 39

3.20 Complete V-I Characteristics of Silicon and

Germanium Diodes ................................................................. 39

3.21 Comparison of Silicon and Germanium Diodes ................... 40

3.22 Effect of Temperature on the V-I Characteristics ................ 40

3.22.1 Germanium Diodes and Effect of Temperature ..... 41

3.22.2 Ge Diodes Produce Higher Reverse

Saturation Current ................................................... 41

3.22.3 Si Diode is More Popular than Ge Diode ................ 41

3.22.4 Dependence of I0 on Temperature .......................... 41

3.22.5 Conclusions ............................................................... 41

3.23 Basic Ideas ............................................................................... 42

3.24 The Ideal Diode: Diode Equivalent Circuit : First

Approximation of a Diode ....................................................... 44

3.25 The Second Approximation of a Diode .................................. 44

3.26 The Third Approximation of a Diode .................................... 44

3.27 Comparison of Ideal Diode and Practical Diode ................... 45

3.28 Diode Resistance ..................................................................... 45

3.28.1 DC or Static Resistance ........................................... 45

3.28.2 AC or Dynamic Resistance (rF) ............................... 46

3.28.3 Expression for the Dynamic Resistance

of a Diode ................................................................... 46

3.29 Diode as a Circuit Element and Load Line Concept ............ 48

3.29.1 Operating Point (Q Point) ........................................ 48

3.30 Bulk Resistance ...................................................................... 49

3.31 The Diode Ratings .................................................................. 49

3.32 Applications of P-N Junction Diode ...................................... 49

3.33 Diode Switching Times ........................................................... 50

3.33.1 Importance of Diode Switching Times .................... 50

Summary .................................................................................54



Numerical Problems ...............................................................57

4. RECTIFIERS AND FILTERS ................................. 58–97

4.1 Introduction ............................................................................. 58

4.2 Specifications of Rectifier Diodes .......................................... 58

4.3 The Important Terms used for a Rectifier Circuit ............... 59

4.4 Half Wave Rectifier ................................................................ 59

4.4.1 Working Operation of the Circuit ........................... 60

4.4.2 Average D.C. Load Current (IDC) ............................ 60

4.4.3 Average D.C. Load Voltage (EDC) ........................... 60

4.4.4 R.M.S. Value of Load Current (IRMS) ...................... 61

4.4.5 D.C. Power Output (PDC) ......................................... 61

4.4.6 A.C. Power Input (PAC) ............................................ 61

4.4.7 Rectifier Efficiency ( ) .............................................. 61

4.4.8 Ripple Factor ( ) ........................................................ 61

4.4.9 Load Current ............................................................ 62

4.4.10 Peak Inverse Voltage (PIV) ..................................... 62

4.4.11 Transformer Utilization Factor (T.U.F.) ................ 62

4.4.12 Voltage Regulation ................................................... 63

4.4.13 Disadvantages of Half Wave Rectifier Circuit ....... 63

4.4.14 Effect of Barrier Potential ....................................... 64

4.5 Full Wave Rectifier ................................................................. 65


4.5.2 Maximum Load Current .......................................... 67

4.5.3 Average D.C. Load Current (IDC) .......................... 67

4.5.4 Average D.C. Load Voltage (EDC) .......................... 67

4.5.5 R.M.S. Load Current (IRMS) ................................... 67

4.5.6 R.M.S. Value of the Load Voltage ........................... 68

4.5.7 D.C. Power Output (PDC) ......................................... 68

4.5.8 A.C. Power Input (PAC) ............................................ 68

4.5.9 Rectifier Efficiency ( ) .............................................. 68

4.5.10 Ripple Factor ( ) ........................................................ 68

4.5.11 Load Current (iL) ...................................................... 68

4.5.12 Peak Inverse Voltage (PIV) ..................................... 69

4.5.13 Transformer Utilization Factor (T.U.F.) ................ 69

4.5.14 Voltage Regulation ................................................... 69

4.5.15 Advantages of Full Wave Rectifier .......................... 70

4.5.16 Disadvantages of Full Wave Rectifier .................... 70

4.5.17 Comparison of Full Wave and Half Wave Circuit . 70

4.6 Bridge Rectifier ....................................................................... 72


4.6.2 Expressions for Various Parameters ...................... 73

4.6.3 PIV Rating of Diodes ................................................ 73

4.6.4 What Happens if Input and Output Terminals

are Reversed? ............................................................ 73

4.6.5 Advantages of Bridge Rectifier Circuit ................... 73

4.6.6 Disadvantages of Bridge Rectifier ........................... 73

4.6.7 Applications .............................................................. 74

4.6.8 Comparison with Two Diodes Rectifier .................. 74

4.7 Comparison of Rectifier Circuits ........................................... 75

4.8 Filter Circuits .......................................................................... 75

4.9 Capacitor Input Filter ............................................................ 76

4.9.1 Working Operation of Filter With Half Wave

Rectifier ..................................................................... 76

4.9.2 Operation with Full Wave Rectifier ........................ 77

4.9.3 Approximate Analysis of Capacitor Input Filter ... 78

4.9.4 Why Capacitor Filter is Not Suitable for

Variable Loads ? ....................................................... 79

4.9.5 How to Decrease Ripple Factor ? ............................ 79

4.9.6 D.C. Output Voltage with Capacitor Filter ............ 79

4.9.7 Expression for Ripple Voltage ................................. 80

4.9.8 Surge Current in a Capacitor Input Filter ............. 80

4.9.9 Advantages ................................................................ 80

4.9.10 Disadvantages ........................................................... 80

4.10 Inductor Filter or Choke Filter .............................................. 82

4.10.1 Operation of the Circuit ........................................... 82

4.10.2 Expression for the Ripple Factor ............................ 83

4.11 L-section Filter of LC Filter ................................................... 83

4.11.1 Derivation of Ripple Factor ..................................... 83

4.11.2 The Necessity of Bleeder Resistance RB ...................... 84

4.11.3 Comparison between Capacitor Input and LC

Filter .......................................................................... 85

4.12 Multiple L-section Filter ........................................................ 87

4.12.1 Derivation of the Ripple Factor ............................... 87

4.13 CLC Filter or Filter ............................................................. 88

4.13.1 Derivation of Ripple Factor ..................................... 88

4.13.2 Multiple -Section Filter .......................................... 89

4.13.3 Advantages ................................................................ 89

4.13.4 Disadvantages ........................................................... 89

4.14 Comparison of Filter Circuits ................................................ 90

Summary .................................................................................95



5. CLIPPERS AND CLAMPERS ............................. 98–125

5.1 Introduction ............................................................................. 98

5.2 Clipper Circuits or Limiters ................................................... 98

5.3 Steps to Analyse Clipper Circuits .......................................... 98

5.4 Series Clippers ........................................................................ 99

5.4.1 Series Negative Clipper Circuit .............................. 99

5.4.2 Series Positive Clipper Circuit .............................. 100

5.4.3 Clipping Above Reference Voltage VR ......................... 102

5.4.4 Clipping Below Reference Voltage VR ......................... 102

5.4.5 Additional D.C. Supply in Series with Diode ....... 103

5.5 Parallel Clippers ................................................................... 105

5.5.1 Basic Parallel Clipper with Positive Clipping ...... 105

5.5.2 Effect of Cut-in Voltage of Diode ........................... 106

5.5.3 Basic Parallel Clipper with Negative Limiting .... 107

5.6 Parallel Clipper Circuits with Reference Voltage VR ........... 108

5.6.1 Effect of Cut-in Voltage of Diode ........................... 109

5.7 Parallel Negative Clipper with Reference Voltage VR ......... 110

5.8 Two Way Parallel Clipper Circuit ....................................... 111

5.8.1 Working Operation ................................................. 111

5.8.2 Transfer Characteristics ........................................ 112

5.9 Clamper Circuits ................................................................... 112

5.10 Negative Clamper ................................................................. 112

5.11 Positive Clamper ................................................................... 113

5.12. Steps to Analyze Clamping Network .................................. 114

5.13 Addition of Battery in Clamper ........................................... 114

5.14 Clamper Application ............................................................. 115

5.15 Voltage Multipliers ............................................................... 115

5.16 Half Wave Voltage Doubler ................................................. 116

5.17 Full Wave Voltage Doubler .................................................. 116

5.18 Voltage Tripler ...................................................................... 117

5.18.1 Voltage Quadrupler ................................................ 118

5.19 Advantages, Applications and Limitations ......................... 118

Summary ...............................................................................123

Short Questions with Answers .............................................124

Review Questions ..................................................................125

6. SPECIAL DIODES ............................................. 126–158

6.1 Introduction ........................................................................... 126

6.2 Review of a Zener Diode. ...................................................... 126

6.3 Reverse Characteristic of a Zener Diode. ........................... 127

6.4 Specifications of Zener Diode ............................................... 127

6.5 Zener Diode Equivalent Circuit ........................................... 127

6.6 Applications of Zener Diode ................................................. 128

6.7 The Tunnel Diode ................................................................. 128

6.7.1 The Tunneling Phenomenon ................................. 128

6.7.2 Construction of Tunnel Diode ............................... 129

6.7.3 Tunnel Diode Characteristics ................................ 129

6.7.4 Detailed Characteristics of a Tunnel Diode ......... 129

6.7.5 Equivalent Circuit of a Tunnel Diode ................... 129

6.7.6 Important Specifications of Tunnel Diode ............ 130

6.7.7 Salient Features of a Tunnel Diode ...................... 130

6.7.8 Applications of Tunnel Diode as an Oscillator ..... 130

6.7.9 Other Applications ................................................. 130

6.7.10. Comparison of Tunnel Diode and p-n Junction

Diode ........................................................................ 131

6.7.11 Advantages of Tunnel Diode .................................. 131

6.7.12 Disadvantages ......................................................... 131

6.8 The Varactor (Varicap) Diode .............................................. 131

6.9 Specifications of Varactor Diode .......................................... 132

6.10 Applications of a Varactor Diode ......................................... 133

6.11 The Schottky Diode .............................................................. 133

6.11.1 Construction of Schottky Diode ............................. 134

6.11.2 Working Operation of Schottky Diode .................. 134

6.11.3 V-I Characteristics of Schottky Diode .................. 134

6.11.4 Equivalent Circuit and Circuit Symbol of

Schottky Diode ........................................................ 134

6.12 Advantages, Drawbacks and Applications .......................... 135

6.12.1 Comparison of Schottky Barrier Diode and

p-n Junction Diode ................................................. 135

6.13 The Step-Recovery Diode ..................................................... 135

6.14 A PIN Diode .......................................................................... 136

6.15 Applications of PIN Diode .................................................... 136

6.15.1 High Frequency Switching Operation .................. 137

6.15.2 PIN Diode Operation as an AM Modulator .......... 137

6.16 Light Emitting Diode (LED) ................................................ 137

6.16.1 Principle of LED Operation ................................... 138

6.17 LED Voltage Drop and Current .......................................... 139

6.17.1 Spectral Response Curves of LED ........................ 140

6.17.2 Radiation Pattern of LED ...................................... 140

6.17.3 Electrical and Optical Parameters of LED ........... 140

6.17.4 Advantages of LED ................................................. 140

6.17.5 Disadvantages of LED............................................ 140

6.18 Applications of Light Emitting Diode (LED) ...................... 140

6.19 Multicolour LED’s ................................................................. 140

6.20 The Seven-Segment Display ................................................ 141

6.21 Alpha Numeric Display ........................................................ 141

6.21.1 5 × 7 Dot Matrix Display ....................................... 141

6.22 Liquid Crystal Display (LCD) .............................................. 142

6.22.1 Types ....................................................................... 142

6.22.2 Advantages of LCDs ............................................... 142

6.22.3 Disadvantages of LCDs .......................................... 142

6.22.4 Performance Comparison of LEDs and LCDs ...... 143

6.22.5 Comparison of P-N Junction Diode and LED ...... 143

6.23 Photo Diodes ......................................................................... 143

6.23.1 Types ....................................................................... 143

6.24 p-n Photodiode ...................................................................... 143

6.24.1 Characteristics of a Photodetector ........................ 144

6.24.2 Photodiode Bandwidth ........................................... 145

6.24.3 Comparison of LED and Photodiode ..................... 146

6.25 Phototransistor ..................................................................... 146

6.25.1 Construction and Biasing ...................................... 146

6.25.2 Spectral Response .................................................. 147

6.25.3 Advantages of a Phototransistor ........................... 147

6.25.4 Drawbacks of a Phototransistor ............................ 147

6.25.5 Applications of Phototransistor ............................. 147

6.25.6 Performance Comparison of Photodiode and

Phototransistor ....................................................... 147

6.26 Photo Darlington .................................................................. 148

6.27 Photovoltaic Cell ................................................................... 148

6.28 Solar Cell: Construction and Working Operation ............. 148

6.28.1 Output Characteristics of a Solar Cell .................. 149

6.28.2 Array of Photovoltaic Cells .................................... 149

6.28.3 Spectral Response .................................................. 150

6.28.4 Equivalent Circuit .................................................. 150

6.28.5 Advantages of Solar Cells ...................................... 150

6.28.6 Drawbacks ............................................................... 150

6.28.7 Important Applications of Solar Cells .................. 150

6.29 Optocouplers / Isolators ........................................................ 150

6.29.1 Characteristics of Optocoupler .............................. 150

6.29.2 Types of Optocouplers ............................................ 151

6.29.3 Advantages of Optocouplers .................................. 151

6.29.4 Drawbacks ............................................................... 151

6.29.5 Applications of Optocouplers ................................. 151

6.29.6 The Optocoupler IC ................................................ 152

6.30 Semiconductor Lasers .......................................................... 152

6.30.1 Laser Diode: Construction ..................................... 153

6.30.2 Advantages of Laser Diode .................................... 153

6.30.3 Drawbacks of Laser Diode ..................................... 153

6.30.4 Applications of Laser Diode ................................... 153

6.30.5 Types of Lasers ....................................................... 153

6.31 Liquid Crystal Displays ........................................................ 153

6.31.1 Advantages of LCDs ............................................... 154

6.31.2 Disadvantages of LCDs .......................................... 154

6.31.3 Performance Comparison of LEDs and LCDs ...... 154

Summary ...............................................................................155


Numerical Problems .............................................................158

7. BIPOLAR JUNCTION TRANSISTOR ................ 159–202

7.1 Introduction ........................................................................... 159

7.2 Junction Transistor Construction ....................................... 160

7.3 Transistor Symbols ............................................................... 160

7.4 Unbiased Transistor ............................................................. 160

7.5 Biasing of a Transistor ......................................................... 161

7.6 The Working of a Transistor ................................................ 161

7.7 Simplified Transistor Working Diagram to Show

Different Currents ................................................................ 162

7.8 Transistor as a Two Port Network ...................................... 162

7.9 Transistor Configurations .................................................... 162

7.10 Transistor as an Amplifier ................................................... 163

7.11 Standard Notation for Symbols ........................................... 164

7.12. Current Gain of a Transistor in Common-Base

Configuration ........................................................................ 164

7.13 Current Gain of a Transistor in Common-Emitter

Configuration ........................................................................ 165

7.14 Relation Between Current Gain and 165

7.15 Leakage Current in a Common-Base Transistor ............... 166

7.16 Leakage Current in Common-Emitter Configuration ....... 166

7.17 Transistor Characteristics ................................................... 167

7.17.1 Transistor Characteristics in Common-Base .............

Configuration .......................................................... 167

7.17.2 Transistor Characteristics in Common-Emitter

Configuration .......................................................... 169

7.18 Common Collector (CC) Configuration .............................. 170

7.18.1 Current Gain or Current Amplification Factor .........

in CC Configuration ............................................... 170

7.18.2 Calculation of Collector Current ........................... 170

7.19 Comparison between Three Transistor Configurations .... 170

7.20 CE Configuration is Most Widely Used in Amplifier

Circuits ................................................................................. 171

7.21 Basic Common Emitter Amplifier and D.C. Load Line ..... 171

7.21.1 D.C. Load Line ........................................................ 171

7.21.2 Importance of d.c. Load Line ................................. 172

7.21.3 Operating Point ...................................................... 172

7.21.4 Analysis of Amplifier Using d.c. Load Line .......... 173

7.22 Numbering System Used for Naming the Semiconductor

Devices ................................................................................. 174

7.23 Transistor Biasing ................................................................ 175

7.24 Selection of Operating Point ................................................ 175

7.25 Bias Stabilization .................................................................. 175

7.26 Stability Factor ..................................................................... 176

7.27 Requirement of Biasing Circuits ......................................... 177

7.28 Methods of Transistor Biasing ............................................. 177

7.29 Fixed Bias Circuit ................................................................. 177

7.30 Collector to Base Bias Circuit .............................................. 179

7.31 Self-Bias or Voltage Divider Bias ........................................ 180

7.32 Emitter Bias Circuit ............................................................. 182

Summary ...............................................................................198



Numerical Problems .............................................................201

8. SMALL SIGNAL LOW FREQUENCY

TRANSISTOR .................................................... 203–245

8.1 Introduction ........................................................................... 203

8.1.1 Linear Amplifier ..................................................... 203

8.1.2 Amplifier Analysis .................................................. 203

8.1.3 The Bipolar Linear Amplifier ................................ 203

8.1.4 Block Diagram of an Amplifier .............................. 204

8.1.5 Amplifier Characteristics ....................................... 204

8.2 Types of BJT Amplifiers ....................................................... 204

8.2.1 Common Emitter (CE) Amplifier .......................... 204

8.2.2 Working of the Amplifier with the Help of

DC Load Line .......................................................... 206

8.2.3 Common Collector or Emitter Follower

Amplifier Circuit ..................................................... 207

8.2.4 Common Base Amplifier ........................................ 207

8.2.5 Small Signal Operation .......................................... 208

8.3 Concept of Frequency Response .......................................... 208

8.4 Typical Frequency Response ................................................ 208

8.4.1 Different Regions in Frequency Response ........... 208

8.4.2 Bandwidth of an Amplifier .................................... 209

8.4.3 Definitions of Upper and Lower Cutoff

Frequencies ............................................................. 209

8.4.4 Procedure to Calculate the Bandwidth ................. 209

8.4.5 Voltage Gain in Different Frequency Regions ..... 209

8.4.6 Factors Affecting the Bandwidth of the RC ...............

Coupled Amplifier ................................................... 210

8.4.7 Effect of Coupling Capacitors ................................ 210

8.4.8 Effect of Bypass Capacitor ..................................... 210

8.4.9 Effect of Internal Transistor Capacitances .......... 210

8.5 Small Signal Analysis ........................................................... 212

8.5.1 Analysis of Transistor Amplifiers ......................... 213

8.6 AC Equivalent Circuit .......................................................... 213

8.6.1 Various Models used for AC Analysis ................... 213

8.7 Two Port Devices and the Hybrid Equivalent Model ........ 213

8.7.1 Description of Hybrid Equivalent Model .............. 214

8.7.2 Hybrid Equivalent Circuit ..................................... 214

8.7.3 Hybrid Model for a Transistor ............................... 215

8.7.4 h-parameter Equivalent Circuit for CE

Configuration .......................................................... 215

8.7.5 Approximate (Simplified) h-parameter

Equivalent Circuit .................................................. 215

8.7.6 Hybrid Equivalent Models for the other

Transistor Configurations ..................................... 216

8.7.7 h-parameter Values for Various Configurations .216

8.7.8 Conversion Formulae for the Parameters of the .......

Three Transistor Configurations

(Parameter Conversion) ......................................... 216

8.8 Analysis of a Transistor Amplifier Circuit Using

h-parameters ......................................................................... 217

8.8.1 Meaning of Analysis ............................................... 217

8.8.2 Steps to follow for Analysis of a Transistor ................

Amplifier Circuit ..................................................... 220

8.9 CE Amplifier (Bypassed RE) ................................................ 220

8.9.1 Approximate Analysis ............................................ 220

8.9.2 Examples of CE Amplifier with Voltage Divider

Biasing and Bypassed RE .................................................... 222

8.10 Analysis of a CE Amplifier with Unbypassed RE .................... 226

8.11 Small Signal Analysis of a CE Amplifier with

Fixed Bias Circuit ................................................................. 230

8.12 Analysis of the Common Collector or Emitter

Follower Amplifier ................................................................ 231

8.12.1 AC Equivalent Circuit ............................................ 231

8.12.2 Why is this Circuit Called Common Collector

Circuit? .................................................................... 231

8.12.3 Analysis ................................................................... 231

8.12.4 Analysis of Common Base Circuit ......................... 236

8.13 Miller’s Theorem ................................................................... 240

8.13.1 Dual of Miller’s Theorem ....................................... 241

8.14 Comparison of Transistor Amplifier Configurations ......... 242

Summary ...............................................................................244



9. TRANSISTOR AT HIGH FREQUENCY ............. 246–262

9.1 Introduction to Hybrid- Model ........................................... 246

9.2 The High Frequency Model or Hybrid- Model for a

Bipolar Junction Transistor ................................................ 246

9.3 Explanation of Parameters .................................................. 247

9.3.1 Hybrid- Parameter Values ................................... 247

9.4 Hybrid- Conductances ........................................................ 247

9.4.1 Transistor Transconductance gm ................................... 247

9.4.2 The Input Conductance gb e ............................................... 248

9.4.3 The Feedback Conductance gb c ...................................... 248

9.4.4 The Base-spreading Resistance rbb 248

9.4.5 The Output Conductance gce ............................................. 249

9.5 The Hybrid- Capacitances .................................................. 249

9.6 Conversion Equations .......................................................... 249

9.7 The Variation of Hybrid- Parameters ............................... 250

9.8 Frequency Response of Common Emitter (CE) Amplifier .250

9.9 The CE Short-Circuit Current Gain .................................... 250

9.9.1 The Cut-off Frequency ........................................ 251

9.9.2 The Cut-Off Frequency ....................................... 251

9.9.3 The Parameter fT or Gain-Bandwidth Product .... 252

9.9.4 High Frequency Current Gain with Resistive ...........

Load ......................................................................... 253

9.9.5 Effect of Source Resistance on Frequency

Response .................................................................. 253

9.10 Basic Single-Stage BJT Amplifier Configurations Using

High-Frequency Hybrid- Model ......................................... 255

9.11 The Common-Emitter (CE) Amplifier ................................. 255

9.12 Common-Emitter (CE) Amplifier with a Resistance

in the Emitter ....................................................................... 256

9.13 The Common-Base (CB) Amplifier ...................................... 257

9.14 The Common-Collector (CC) Amplifier or

Emitter-Follower .................................................................. 258

9.15 Internal Capacitances of the BJT ........................................ 259

Summary ...............................................................................261



10. FIELD EFFECT DEVICES : JFET ..................... 263–300

10.1 Introduction ........................................................................... 263

10.2 Junction Field-Effect Transistor (JFET) ............................ 263

10.3 Basic Ideas ............................................................................. 264

10.3.1 Symbol for JFET..................................................... 264

10.3.2 Voltage Controlled or Current Controlled? .......... 264

10.3.3 Unipolar or Bipolar? ............................................... 264

10.3.4 Advantages of JFET Over BJT ............................. 264

10.3.5 Disadvantage of JFET............................................ 264

10.4 Formation of Depletion Region in JFET ............................. 265

10.5 Operation of JFET ................................................................ 265

10.6 Characteristics of JFET ....................................................... 266

10.7 Drain Curves: Drain Characteristics .................................. 266

10.8 Effect of Gate-to-Source Voltage on

Drain Characteristics ........................................................... 267

10.9 The Transconductance Curves : ................................................

Transfer Characteristics ...................................................... 268

10.10 The JFET Parameters .......................................................... 269

10.10.1 Transconductance (gm) ........................................... 269

10.10.2 D.C. drain resistance (RDS) .................................... 269

10.10.3 A.C. drain resistance (rd) ....................................... 269

10.10.4 Amplification factor (µ) .......................................... 270

10.10.5 Input resistance (Ri) ............................................... 270

10.11 The Mathematical Expression for Transconductance ....... 270

10.12 FET as Voltage Variable Resistance (VVR) ........................ 272

10.13 Comparison between FET and BJT .................................... 272

10.13.1 Applications of VVR ............................................... 272

10.14 Summary of Various Features of JFET .............................. 273

10.14.1 Peculiarities ............................................................ 273

10.14.2 Advantages of FET ................................................. 273

10.14.3 Disadvantages of JFET .......................................... 273

10.14.4 Applications of JFET .............................................. 273

10.15 JFET Biasing ....................................................................... 273

10.16. JFET Biasing in the Ohmic Region .................................... 273

10.16.1 Gate Bias or Fixed-Bias Circuit ......................... 273

10.17 Biasing in the Active Region ............................................... 274

10.17.1 Self-Bias Circuit .................................................. 274

10.17.2 Setting of a Q-Point ............................................. 275

10.17.3 Setting of a Q-Point Using D.C. Load Line ....... 277

10.17.4 Biasing Against Device Parameter Variation ... 278

10.17.5 Voltage Divider Bias ........................................... 278

10.17.6 Two Supply Source Bias or Source Bias ............ 280

10.17.7 Current Source Bias ............................................ 280

10.18 Small-Signal FET Model ..................................................... 280

10.19 Small-Signal Low-Frequency FET Model .......................... 280

10.20 Small-Signal High-Frequency FET Model ........................ 281

10.21 JFET Amplifiers .................................................................. 281

10.22 Common Source (CS) Amplifier .......................................... 281

10.23 Analysis of Common Source Amplifier ............................. 282

10.24 Effect of A.C. Load on Amplifier Parameters .................... 283

10.25 Effect of External Source Resistance on Voltage Gain ..... 284

10.26 The Common Drain Amplifier ............................................ 285

10.27 Analysis of a Common Drain Amplifier ............................. 285

10.28 Common Gate Amplifier ..................................................... 287

10.29 Analysis of a Common Gate Amplifier ............................... 287

10.30 Applications of FETs ........................................................... 293

10.30.1 As an Analog Switch ........................................... 293

10.30.2 Low Noise Amplifier ............................................ 294

10.30.3 Buffer Amplifier ................................................... 294

10.30.4 Cascode Amplifier ................................................ 295

10.30.5 Chopper Amplifier ............................................... 295

10.30.6 Multiplexer ........................................................... 296

10.30.7 Current Limiter ................................................... 296

10.30.8 Phase Shift Oscillators ........................................ 296

Summary ..............................................................................296

Short Questions with Answers ............................................297

Review Questions .................................................................298

Numerical Problems ............................................................299

11. MOSFETS .......................................................... 301–338

11.1 Introduction .......................................................................... 301

11.1.1 Voltage Controlled or Current Controlled? ....... 301

11.1.2 Unipolar or Bipolar ............................................. 301

11.1.3 Advantages of JFET over BJT ........................... 301

11.1.4 Drawback of JFET .............................................. 301

11.1.5 Classification of Field Effect Transistors .......... 302

11.2 MOSFET .............................................................................. 302

11.3 Depletion-type MOSFET ..................................................... 302

11.3.1 Construction of n-channel D-MOSFET ............. 302

11.3.2 Working Operation of n-channel Depletion

MOSFET .............................................................. 302

11.3.3 Drain Characteristics of n-channel Depletion

MOSFET .............................................................. 303

11.3.4 Construction of p-channel Depletion-Type

MOSFET .............................................................. 303

11.3.5 Symbols of n and p-type Depletion MOSFETs ..304

11.3.6 Effects of Silicon Dioxide Layer ......................... 304

11.4 Enhancement MOSFET ...................................................... 304

11.4.1 Construction of n-Channel EMOSFET .............. 304

11.4.2 Working Operation of n-channel Enhancement

MOSFET .............................................................. 305

11.4.3 Characteristics of n-channel Enhancement

Type MOSFET ..................................................... 305

11.4.4 Construction of p-channel Enhancement-Type

MOSFETs ............................................................. 306

11.4.5 Characteristics of p-channel Enhancement

Type MOSFET ..................................................... 306

11.4.6 Symbols of Enhancement MOSFET .................. 307

11.5 Parameters of FETs ............................................................. 307

11.5.1 Dynamic Drain Resistance (ro) ........................... 307

11.5.2 Transconductance (gm) ........................................ 307

11.5.3 Conduction Parameter (k) .................................. 307

11.6 Complementary MOSFETs (CMOS) Devices .................... 308

11.7 Non-ideal Current Voltage Characteristics ....................... 308

11.7.1 Finite Output Resistance .................................... 308

11.7.2 Channel Length Modulation .............................. 309

11.7.3 Body Effect ........................................................... 309

11.7.4 Subthreshold Conduction ................................... 310

11.7.5 Breakdown Effects .............................................. 310

11.7.6 Temperature Effects in MOSFETs .................... 310

11.7.7 Peculiarities of an Enhancement type

MOSFET .............................................................. 311

11.7.8 Applications of E-MOSFET ................................ 311

11.7.9 Peculiarities of Depletion Type MOSFET ......... 311

11.7.10 Applications of D-MOSFET ................................ 311

11.8 Input Protection in MOSFET ............................................. 311

11.8.1 Working Operation of the Protection Circuit .... 312

11.9 Handling Precautions for the MOS Devices ...................... 312

11.10 Performance comparison ..................................................... 312

11.10.1 Performance Comparison of JFET and

MOSFET .............................................................. 312

11.10.2 Performance Comparison of JFET and

D-MOSFET .......................................................... 313

11.10.3 Performance Comparison of DMOSFET and

EMOSFET ............................................................ 313

11.10.4 Performance Comparison of BJT and JFET ..... 314

11.11 MOSFETs at DC: Biasing of MOSFETs ............................ 314

11.12 Common Source (CS) Circuit .............................................. 314

11.12.1 CS Circuit using p-Channel MOSFET ............... 315

11.12.2 Regions of MOSFET Operation .......................... 315

11.12.3 Biasing Circuits ................................................... 315

11.12.4 Analysis and Design of Biasing Circuits ........... 316

11.12.5 Biasing of Enhancement Type MOSFET .......... 316

11.13 Load line and Modes of Operations .................................... 316

11.14 Biasing Circuits for Enhancement MOSFET .................... 317

11.14.1 Feedback Biasing Arrangement for

Enhancement MOSFET ...................................... 317

11.14.2 Voltage Divider Biasing for Enhancement

Type MOSFET ..................................................... 318

11.14.3 CS Circuit using p-Channel MOSFET ............... 320

11.15 Biasing Circuits for Depletion Type MOSFETs ................ 321

11.15.1 DC Analysis ......................................................... 321

11.16 DC Analysis of Common MOSFET Configurations ......... 322

11.16.1 NMOS Common Source Circuit with Source

Resistor ................................................................. 322

11.16.2 MOSFET Circuit Biased with a Constant

Current Source .................................................... 324

11.16.3 NMOS as Enhancement Load Device ................ 324

11.16.4 NMOS Driver with Enhancement Load ............ 325

11.16.5 Depletion MOSFET as Load Device .................. 326

11.16.6 NMOS Driver with Depletion Load ................... 327

11.16.7 CMOS (Complementary MOS) Inverter ............ 327

11.17 Constant Current Source Biasing ...................................... 328

Summary ..............................................................................336



12. MOSFET AS AMPLIFIER AND SWITCH ......... 339–355

12.1 Introduction .......................................................................... 339

12.2 The MOSFET Amplifier ...................................................... 339

12.2.1 Working Operation of MOSFET as Amplifier ... 340

12.2.2 Graphical Analysis, Load Line and Small

Signal Parameters ............................................... 341

12.2.3 Load Line and Small Signal Parameters .......... 341

12.2.4 Graphical Representation ................................... 341

12.2.5 AC Equivalent Circuit ......................................... 341

12.2.6 Expanded Small Signal Equivalent Circuit ...... 342

12.2.7 Problem Solving Technique for a MOSFET

Amplifier .............................................................. 343

12.2.8 MOSFET Amplifier Using P-channel

Enhancement MOSFET ...................................... 343

12.2.9 Modelling the Body Effect ................................... 343

12.2.10 Basic Configuration of a MOSFET Amplifier ... 344

12.3 The Common Source (CS) Amplifier .................................. 344

12.3.1 Common Source Circuit with Source Bypass

Capacitor .............................................................. 345

12.3.2 CS Amplifier with Source Resistance ................ 347

12.4 The Source Follower Amplifier ........................................... 348

12.5 The Common Gate Configuration using NMOS ............... 350

12.5.1 Comparison of the Three Basic Amplifier

Configurations ..................................................... 352

12.6 MOSFET Internal Capacitances ........................................ 352

12.7 High Frequency Model of a MOSFET ................................ 353

12.7.1 Various Components in Equivalent Circuit ...... 353

12.7.2 Effect of rs ................................................................................. 353

12.7.3 Equivalent Circuit of P-channel MOSFET ........ 353

12.8 MOSFET as Switch ............................................................. 354

Summary ..............................................................................354



13. CASCADED AMPLIFIERS :

MULTISTAGE AMPLIFIERS ............................. 356–379

13.1 Introduction .......................................................................... 356

13.2 Need of Cascading ............................................................... 356

13.2.1 Requirements of Multistage Amplifier .............. 356

13.2.2 Gain of the Cascaded Configuration .................. 356

13.2.3 n-stage Cascaded Amplifier ................................ 357

13.2.4 Gain in Decibles ................................................... 357

13.2.5 Why to Express Gain in dB ................................ 357

13.3 How to Select Amplifier Configurations for Cascade

Connection? .......................................................................... 357

13.3.1 Selection of Configuration for the Input Stage .358

13.3.2 Selection of Configuration for the Output

Stage ..................................................................... 358

13.3.3 Selection of Configuration for the Middle

Stages ................................................................... 358

13.4 Methods of Coupling Multistage Amplifiers ...................... 358

13.4.1 R-C Coupled Amplifiers ...................................... 358

13.4.2 Transformer Coupled Amplifiers ....................... 359

13.4.3 Direct Coupled Amplifiers .................................. 360

13.4.4 Performance Comparison of Different

Coupling Techniques ........................................... 361

13.5 Procedure to Analyze the Multistage Amplifiers .............. 362

13.5.1 Formulae to be used for Analysis of Each

Stage ..................................................................... 362

13.5.2 Types of Two Stage Cascaded Amplifiers: ......... 362

13.6 A CE-CE Cascade Amplifier ............................................... 362

13.6.1 AC Analysis of CE-CE Cascade Configuration .362

13.6.2 Features of CE-CE Cascade ............................... 365

13.7 CE-CB (Cascode) Amplifier ................................................. 365

13.7.1 Analysis of the Cascode Amplifier ..................... 365

13.7.2 Features of Cascode Amplifier ........................... 366

13.7.3 Applications of Cascode Amplifier ..................... 366

13.7.4 AV, Ri, AI, Ro for Cascode Amplifier ................... 366

13.8 Effect of Cascading on Bandwidth...................................... 367

13.8.1 Lower 3 dB Frequency of a Cascaded

Multistage Amplifier ........................................... 368

13.8.2 Upper 3 dB Frequency of a Cascaded

Multistage Amplifier ........................................... 368

13.8.3 Frequency Response and Bandwidth of

Cascaded Amplifier ............................................. 368

13.9 Techniques to Improve the Input Impedance of Emitter

Follower .............................................................................. 369

13.10 Bootstrap Emitter Follower ................................................ 369

13.10.1 Analysis of Bootstrapped Emitter Follower ...... 370

13.11 Darlington Connection ........................................................ 372

13.11.1 Current Gain of the Darlington Pair ................. 373

13.11.2 Emitter Follower Using Darlington Pair .......... 373

13.11.3 Analysis of Darlington Emitter Follower .......... 373

13.11.4 Features of Darlington Emitter Follower ......... 376

13.11.5 Effect of Biasing Resistors on the Input ..................

Resistance ............................................................ 376

Summary ..............................................................................378



14. FREQUENCY RESPONSE ............................... 380–416

14.1 Introduction .......................................................................... 380

14.2 Frequency Response ............................................................ 380

14.2.1 Basic Concept ....................................................... 380

14.2.2. Significance of Frequency Response .................. 380

14.2.3 A Typical Frequency Response .......................... 380

14.2.4 Various Regions in Frequency Response ........... 381

14.2.5 Steps to Plot the Frequency Response .............. 381

14.2.6 Bandwidth of an Amplifier ................................. 381

14.2.7 Concept of Upper and Lower Cut off

Frequencies .......................................................... 381

14.2.8 Bandwidth Calculation ....................................... 381

14.2.9 Voltage Gains in Different Frequency Regions 382

14.2.10 Factors Affecting the Bandwidth of the RC

Coupled Amplifier ............................................... 382

14.2.11 Effect of Coupling Capacitors ............................. 382

14.2.12 Effect of Bypass Capacitor .................................. 382

14.2.13 Effect of Internal Transistor Capacitances ....... 383

14.3 Introduction to Miller’s Theorem ....................................... 384

14.3.1 Application of Miller’s Theorem to BJT and

FET Amplifiers .................................................... 385

14.4 Decibel .............................................................................. 385

14.5 Analysis of Frequency Response Using Equivalent

Circuits. .............................................................................. 385

14.6 Frequency Response Analysis ............................................ 386

14.6.1 System Transfer Functions ................................ 386

14.6.2 s-Domain Analysis ............................................... 386

14.6.3 Two Standard forms of Transfer Functions ...... 386

14.7 Two Standard RC Circuits .................................................. 386

14.7.1 Series Coupling Capacitor Circuit ..................... 386

14.7.2 Parallel Load Capacitor Circuit ......................... 387

14.7.3 First Order Functions ......................................... 388

14.8 Bode Plots ............................................................................. 388

14.8.1 Bode Plot of Series Coupling Capacitor Circuit 388

14.8.2 Bode Plot of Phase Function .............................. 390

14.8.3 Bode Plot for Parallel Load Capacitor Circuit .. 391

14.8.4 Phase Transfer Function .................................... 391

14.9 Short Circuit and Open Circuit Time Constants .............. 392

14.9.1 Open Circuit Time Constant (ts) ........................ 392

14.9.2 Short Circuit Time Constant tp ................................... 393

14.9.3 Corner Frequencies of Bode Plot ....................... 393

14.10 Lower Frequency Response of a BJT Amplifier

(Using h-Parameters) .......................................................... 394

14.10.1 R.C. Networks Deciding the Low Frequency

Response ............................................................... 394

14.10.2 The Input R.C. Network ..................................... 395

14.10.3 Voltage Roll off at Low Frequencies .................. 395

14.10.4 dB/Decade ............................................................ 395

14.10.5 dB/Octave ............................................................. 395

14.10.6 The Output RC Circuit ........................................ 396

14.10.7 The Bypass RC Circuit ........................................ 396

14.10.8 Dominant Network .............................................. 396

14.11 Low Frequency Response of Transistor Amplifier ............ 397

(Using Hybrid- Model) ....................................................... 397

14.11.1 Effect of Input Coupling Capacitor .................... 397

14.11.2 Analysis of CE Amplifier (Effect of C1) .............. 398

14.11.3 Effect of the Other Capacitors ............................ 399

14.11.4 RC Network Consisting of the Bypass .....................

Capacitor CE ........................................................................... 399

14.11.5 Combined Effect of Coupling and Bypass

Capacitors ............................................................ 400

14.11.6 Effect of Load Capacitor ..................................... 400

14.11.7 Combined Effect of Coupling and Load

Capacitance .......................................................... 401

14.11.8 Midband Gain |AV| ........................................... 402

14.11.9 Low Frequency Response of an Emitter

Follower ................................................................ 403

14.12 Analysis of an FET Amplifier at Low Frequency .............. 404

14.12.1 The Input RC Circuit .......................................... 405

14.12.2 The Output RC Network ..................................... 405

14.13 High Frequency Response ................................................... 405

14.14 Frequency Response: Bipolar Transistor ........................... 406

14.14.1 Extended Hybrid- Equivalent Circuit .............. 406

14.14.2 Simplified Extended Hybrid- Model ................ 406

14.15 Short-Circuit Current Gain ................................................ 406

14.15.1 Cut-off Frequency f 407

14.15.2 Cut-off Frequency f 407

14.15.3 Relation Between f and f 408

14.15.4 The Cut off Frequency fT ................................................. 408

14.16 Miller Effect and Miller Capacitance ................................. 409

14.17 High Frequency Response of the FET ............................... 410

14.17.1 Various Components in the Equivalent Circuit 410

14.17.2 Effect of rs ............................................................ 410

14.17.3 Equivalent Circuit of P-Channel MOSFET ....... 410

14.17.4 Unity Gain Bandwidth ........................................ 411

14.17.5 Miller Effect and Miller Capacitance ................. 411

14.17.6 Cut off Frequency of MOSFET (fT) .................... 412

14.18 High Frequency Response of Transistor and FET

Circuits .............................................................................. 412

14.18.1 High Frequency Response of CE and CS

Circuits ................................................................. 412

14.18.2 High Frequency Response of a CS Circuit ........ 413

Summary ..............................................................................414



15. LARGE SIGNAL AMPLIFIERS:

POWER AMPLIFIERS ...................................... 417–437

15.1 Introduction .......................................................................... 417

15.2 Comparison of Small Signal and Large Signal

Amplifiers ............................................................................. 417

15.3 Block Schematic of AF Amplifiers ...................................... 418

15.3.1 Important Features of a Power Amplifier ......... 418

15.3.2 Class B Power Amplifiers ................................... 418

15.3.3 Class AB Amplifier .............................................. 419

15.3.4 Class C Amplifier ................................................ 420

15.3.5 Comparison of Different Types of Power

Amplifiers ............................................................. 420

15.4 Importance of Impedance Matching ................................... 421

15.5 Single Stage Class a Power Amplifier ............................... 421

15.5.1 Series Fed, Directly Coupled Class A

Amplifier .............................................................. 421

15.5.2 Analysis of the Series Fed, Directly Coupled

Class A Amplifier ................................................ 421

15.5.3 Advantages of Directly Coupled Class A

Amplifier .............................................................. 423

15.5.4 Disadvantages of Directly Coupled


15.6 Distortions in Amplifiers ..................................................... 423

15.6.1 Amplitude Distortion or Non-linear Distortion 423

15.6.2 Frequency Distortion .......................................... 423

15.6.3 Phase Shift Distortion ......................................... 423

15.6.4 Harmonic Distortion ........................................... 424

15.6.5 Second Harmonic Distortion .............................. 424

15.7 Transformer Coupled Class A Power Amplifier ................ 424

15.7.1 Analysis of Transformer Coupled Class

A Amplifier ........................................................... 425

15.7.2 Advantages of Transformer Coupled Class

A Amplifier ........................................................... 427

15.7.3 Disadvantages of Transformer Coupled


15.8 Class A Push-Pull Amplifier ............................................... 427

15.8.1 Harmonic Analysis .............................................. 428

15.8.2 Advantages of Push-pull Amplifiers .................. 428

15.8.3 Disadvantages of Push-pull Amplifiers ............ 428

15.9 Class B Power Amplifiers ................................................... 428

15.9.1 Class B-Push Pull Amplifier ............................... 428

15.9.2 Analysis of Class B Push Pull Amplifier ........... 430

15.9.3 Advantages of Class B Amplifiers ...................... 431

15.9.4 Applications of Class B Amplifiers ..................... 431

15.9.5 Complementary Symmetry Class B Amplifiers 431

15.9.6 Advantages of Complementary Symmetry ..............

Amplifier .............................................................. 432

15.9.7 Disadvantages of Complementary Symmetry ........

Amplifier .............................................................. 432

15.10 Cross-over Distortion........................................................... 432

15.10.1 Complementary Push Pull and Crossover ..............

Distortion ............................................................. 432

15.11 Class AB Push Pull Amplifier ............................................. 433

15.11.1 Complementary Symmetry Class AB

Amplifier .............................................................. 433

15.11.2 Complementary Symmetry Class AB

Amplifier using Diodes for Biasing .................... 434

15.11.3 The Complementary Symmetry Circuit using a

Single Supply ....................................................... 434

15.12 Class C Amplifiers ............................................................... 434

Summary ..............................................................................435



16. TUNED VOLTAGE AMPLIFIERS ...................... 438–448

16.1 Introduction .......................................................................... 438

16.2 Resonance ............................................................................. 438

16.3 A Series Resonance Circuit ................................................. 439

16.4 Characteristics of a Series Resonant Circuit ..................... 439

16.5 A Parallel Resonance Circuit or Tuned Circuit ................. 441

16.6 Characteristics of Parallel Resonant or Tuned Circuit .... 442

16.7 Performance Comparison of Series and Parallel

Resonant Circuits ................................................................ 443

16.8 Merits of Tuned Amplifiers ................................................. 444

16.9 Reasons for not Using the Tuned Amplifiers for

Amplification of Low Frequency Signals ........................... 444

16.10 The Single-Tuned Voltage Amplifier. ................................ 445

16.11 The Frequency Response of a Single-tuned Voltage

Amplifier .............................................................................. 445

16.12 Limitation of a Single-tuned Voltage Amplifier ................ 446

16.13 Double-Tuned Voltage Amplifier ........................................ 446

16.14. The Frequency Response of Double-tuned Voltage

Amplifier .............................................................................. 447

16.15 Stagger-Tuned Voltage Amplifier. ...................................... 447

Summary ..............................................................................448




17. FEEDBACK AMPLIFIERS ................................ 449–477

17.1 Introduction .......................................................................... 449

17.2 Classification of Amplifiers Based on Feedback Topology 449

17.2.1 Voltage Amplifiers ............................................... 449

17.2.2 Current Amplifier ................................................ 450

17.2.3 Transconductance Amplifier .............................. 450

17.2.4 Transresistance Amplifier .................................. 450

17.3 Concept of Feedback ............................................................ 451

17.3.1 Amplifier Without Feedback .............................. 451

17.3.2 Amplifier With Feedback .................................... 451

17.3.3 Amplifier with a Negative Feedback ................. 451

17.3.4 Sampling Network .............................................. 452

17.3.5 Comparator or Mixer Network ........................... 452

17.3.6 Feedback Network .............................................. 452

17.3.7 Positive or Negative Feedback ........................... 452

17.3.8 Transfer Ratio or Gain of Different Types

of Amplifiers ......................................................... 453

17.3.9 Transfer Gain with Feedback (Af) of

Different Types of Amplifiers ............................. 453

17.4 Feedback Topologies ............................................................ 453

17.4.1 Voltage Series Feedback ..................................... 454

17.4.2 Voltage Shunt Feedback ..................................... 454

17.4.3 Current Series Feedback .................................... 454

17.4.4 Current Shunt Feedback .................................... 454

17.4.5 Loop Gain ............................................................. 454

17.4.6 Basic Assumptions .............................................. 454

17.4.7 Advantags of using Negative Feedback ............. 454

17.4.8 Disadvantages of Negative Feedback ................ 455

17.4.9 Applications of Negative Feedback .................... 455

17.5 General Characteristics of Negative Feedback

Amplifiers ............................................................................. 455

17.5.1 Expression for Transfer Gain with

Feeback (Af) ......................................................... 455

17.5.2 Stabilization of Gain ........................................... 455

17.5.3 Effect of Negative Feedback on the Input

Resistance ............................................................ 456

17.5.4 Effect on the Output Resistance ........................ 457

17.5.5 Effect on Bandwidth ............................................ 457

17.5.6 Effect on the Non-linear Distortion ................... 458

17.5.7. Effect on Noise ........................................................ 458

17.5.8. Effect on Frequency Distortion ............................. 458

17.6 Effect of Negative Feedback on Ri and Ro .................................. 458

17.7 Procedure for the Analysis of a Feedback Amplifier ........ 463

17.7.1 Separation of Basic Amplifier from the

Feedback Network (Step 2) ................................ 463

17.8 Voltage Series Feedback ..................................................... 464

17.8.1 Emitter Follower Using Transistor ................... 464

17.8.2 A Voltage Series Feedback Pair ......................... 466

17.8.3 Analysis of Multistage Amplifier with

Voltage Series Feedback ..................................... 467

17.9 Current Series Feedback .................................................... 469

17.9.1 CE Transistor Amplifier with Unbypassed Re ... 469

17.10 Current Shunt Feedback ..................................................... 471

17.11 Voltage Shunt Feedback ..................................................... 474

Summary ..............................................................................476



18. OSCILLATORS ................................................. 478–519

18.1 Introduction to an Oscillator .............................................. 478

18.2 Comparison between an Amplifier and an Oscillator ...... 478

18.3 Classification of Oscillators ................................................. 479

18.4 The Applications of Sinusoidal Oscillators ........................ 479

18.5 Nature of Sinusoidal Oscillations ....................................... 479

18.6 The Oscillatory Circuit ........................................................ 479

18.7 Frequency of Oscillatory Circuit ........................................ 480

18.8 The Frequency Stability of an Oscillator .......................... 481

18.9 Positive Feedback Amplifier as an Oscillator ................... 481

18.9.1 Barkhausen Criterion ......................................... 481

18.9.2 Effect of the Value of |A | on the Nature of

Oscillations .......................................................... 482

18.9.3 Block Diagram of an Oscillator .......................... 482

18.9.4 Introduction to LC Oscillators ............................ 483

18.10 The Transistor Oscillator .................................................... 483

18.11 The Essentials of a Transistor Oscillator .......................... 483

18.12 The Tuned Collector Oscillator ........................................... 483

18.13 The Tuned-Base Oscillator ................................................. 486

18.14 The Colpitt’s Oscillator ........................................................ 486

18.14.1 Colpitt’s Oscillator using FET ............................ 488

18.14.2 Colpitt’s Oscillator Using OP-AMP .................... 489

18.14.3 Frequency Stability ............................................. 489

18.15 The Clapp Oscillator ............................................................ 490

18.15.1 Clapp Oscillator Using FET ............................... 491

18.16 The Hartley Oscillator ......................................................... 491

18.16.1 Hartley Oscillator using FET ............................. 492

18.16.2 Hartley Oscillator using Op-Amp ...................... 492

18.17 Crystal Oscillators ............................................................... 494

18.17.1 Equivalent Circuit of a Crystal ...................... 494

18.17.2 Resonant Frequencies ....................................... 494

18.17.3 Crystal Impedance ............................................ 494

18.17.4 Types of Crystal Oscillators ............................ 495

18.17.5 Pierce Crystal Oscillator .................................. 495

18.17. Modified Pierce Crystal Oscillator ................. 495

18.17.7 Miller Crystal Oscillator .................................. 495

18.17.8 Modes of Operation in the Crystal ................ 495

18.17.9 Advantages of Crystal Oscillator .................... 496

18.17.10 Drawbacks .......................................................... 496

18.17.11 Applications of Crystal Oscillators ................. 496

18.17.12 Performance Comparison of Various LC

Oscillators ........................................................... 498

18.17.13 Performance Comparison between LC

Oscillators and Crystal Oscillators ................ 498

18.18 Audio Oscillators .................................................................. 498

18.18.1 Basic Working Principles of R-C Oscillators ..... 499

18.19 FET Phase Shift Oscillator ................................................. 499

18.20 Transistor Phase Shift Oscillator ....................................... 500

18.21 OP-AMP RC Phase Shift Oscillator ................................... 502

18.22 JFET R-C Phase Shift Oscillator (Analytic View) ............ 503

18.23 Introduction to Wien Bridge Circuit .................................. 505

18.23.1 Expressions for Feedback Factor ( ) and

Frequency ( ) ....................................................... 505

18.23.2 Wien Bridge Oscillator using a Transistor ........ 507

18.23.3 Wien Bridge Oscillator Using OP-AMP ............. 507

18.23.4. Wien Bridge Oscillator using FET ....................... 508

18.23.5. Performance Comparison of RC Oscillators ........ 509

18.24 Frequency Stability of Oscillator. ....................................... 510

18.25 Negative-Resistance Oscillators ......................................... 510

18.25.1 Tunnel Diode Oscillator ...................................... 510

18.26 General Applications of Oscillators .................................... 516

Summary ..............................................................................516




19. MULTIVIBRATORS ........................................... 520–538

19.1 Introduction .......................................................................... 520

19.2 Diode Switching Times ........................................................ 520

19.2.1 Forward and Reverse Recovery Times .............. 520

19.2.2 Forward Recovery Time Trf ........................................... 520

19.2.3 Diode Reverse Recovery Time (Trr) .................... 520

19.2.4 Storage and Transition Times ............................ 521

19.2.5 Reverse Recovery Time (Trr) .............................. 522

19.2.6 Importance of Diode Switching Times ............... 522

19.3 Transistor as a Switch ......................................................... 522

19.3.1 Switching Waveforms of an Ideal Transistor

Switch ................................................................... 523

19.4 Transistor Switching Times ................................................ 523

19.4.1 Typical values of Various Time Delays ............. 524

19.4.2 Importance of Turn ON and Turn OFF Time ... 524

19.5 Standard Tests for Saturation ............................................ 524

19.6 Applications of Transistor as a Switch .............................. 524

19.7 Multivibrators using Transistors ....................................... 525

19.7.1 Classification of Multivibrators .......................... 525

19.7.2 Astable Multivibrator .......................................... 525

19.7.3 Monostable Multivibrator ................................... 525

19.7.4 Bistable Multivibrator ........................................ 526

19.8 Monostable Multivibrator ................................................... 526

19.8.1 Basic Concept ....................................................... 526

19.8.2 Circuit Diagram ................................................... 526

19.8.3 Working Operation .............................................. 527

19.8.4 On Time (T) .......................................................... 527

19.8.5 Drawbacks ............................................................ 528

19.8.6 Applications of Monostable Multivibrator ......... 528

19.8.7 Other Names of Monostable Multivibrator ....... 528

19.8.8 Triggering Methods of Monostable

Multivibrator ....................................................... 528

19.9 Astable Multivibrator .......................................................... 529

19.9.1 Circuit Diagram ................................................... 529

19.9.2 Waveforms ........................................................... 529


19.9.4 Timing Considerations ........................................ 530

19.9.5 Frequency of Oscillations ................................... 530

19.9.6 Duty Cycle ............................................................ 530

19.9.7 Applications of Astable Multivibrator ............... 530

19.9.8 Derivation for T1, T2 and T ................................. 530

19.10 Bistable Multivibrator using a Transistor ......................... 530

19.10.1 Performance Comparison of Astable,

Monostable and Bistable Multivibrator ............. 531

19.11 Schmitt Trigger Circuit ....................................................... 532

19.11.1 Applications of Schmitt Trigger ......................... 533

19.11.2 Performance Comparison of Multivibrator .............

and Oscillator ....................................................... 533

19.11.3 Set up to Measure UTP and LTP ....................... 533

19.12 Blocking Oscillator .............................................................. 533

Summary ..............................................................................536



20. OPTOELECTRONIC DEVICES ........................ 539–565

20.1 Introduction .......................................................................... 539

20.2 Classification of Optoelectronic Devices ............................ 539

20.3 Photoemissivity .................................................................... 539

20.3.1 Retarding Potential ............................................. 540

20.3.2 Plot of Photocurrent Versus Applied Voltage ... 540

20.3.3 Graph of I Versus V at Constant Intensity,

but Variable Frequency ...................................... 540

20.3.4 Relation between f and Vr .............................................. 541

20.3.5 Characteristics of Photoemissivity .................... 541

20.3.6 Photoelectric Yield or Quantum Yield ............... 541

20.4 Introduction to Photoelectric Theory ................................. 541

20.4.1 Einstein’s Equation ............................................. 541

20.4.2 Threshold Wavelength ( c) ................................. 542

20.4.3 Spectral Response ............................................... 542

20.5 Few Important Definitions of Some Radiation Terms ..... 542

20.5.1 Electromagnetic Spectrum ................................. 543

20.6 Light Emitting Diodes (LEDs) ............................................ 543

20.6.1 Construction of LED ........................................... 543

20.6.2 Principle of LED Operation ................................ 544

20.6.3 Spectral Response Curves of LED ..................... 545

20.6.4 Radiation Pattern of LED ................................... 545

20.6.5 Output Characteristics of LED .......................... 545

20.6.6 Advantages of LEDs ............................................ 545

20.6.7 Drawbacks of LED .............................................. 546

20.6.8 Important Applications of LEDs ........................ 546

20.6.9 Performance Comparison of PN Junction

Diode and LED .................................................... 546

20.7 Seven Segment Display ....................................................... 546

20.8 Photoconductivity ................................................................ 546

20.9 Photoconductive Cell ........................................................... 546

20.9.1 Construction of LDR ........................................... 547

20.9.2 Principle of Operation ......................................... 548

20.9.3 Variation of Resistance with Intensity of Light 548

20.9.4 Applications of LDR ............................................ 548

20.9.5 Few Advantages of LDR ..................................... 549

20.9.6 Drawbacks of LDR .............................................. 549

20.10. Photodiode ............................................................................ 549

20.10.1 Construction and Working Operation ............... 549

20.10.2 Photodiode Characteristics ................................. 549

20.10.3 Advantages of Photodiode ................................... 549

20.10.4 Drawbacks of Photodiode .................................... 549

20.10.5 An Important Application of Photodiode ........... 550

20.10.6 Some Other Applications .................................... 550

20.10.7 Performance Comparison of LDR and

Photodiode ............................................................ 550

20.10.8 Performance Comparison of LED and

Photodiode ............................................................ 551

20.11 Pin Diodes ............................................................................ 551


20.11.2 PIN Diode as a Switch ........................................ 552

20.11.3 Equivalent Circuit ............................................... 552

20.11.4 Important Applications ....................................... 552

20.11.5 Peculiarities of a PIN Diode ............................... 552

20.12 Pin Photodiode ..................................................................... 553

20.13 Light Emitting Materials .................................................... 553

20.14 Phototransistor .................................................................... 554

20.14.1 Construction and Biasing ................................... 554


20.14.3 Advantages of a Phototransistor ........................ 555

20.14.4 Drawbacks of a Phototransistor ......................... 555

20.14.5 Applications of Phototransistor .......................... 555

20.14.6 Performance Comparison of Photodiode

and Phototransistor ............................................. 556

20.15 Photodarlington ................................................................... 556

20.16 Photovoltaic Cell .................................................................. 556

20.17 Solar Cell: Construction and Working Operation ............. 557

20.17.1 Output Characteristics of a Solar Cell .............. 557

20.17.2 Array of Photovoltaic Cells ................................. 558


20.17.4 Equivalent Circuit ............................................... 558

20.17.5 Advantages of Solar Cells ................................... 558

Electronics Principles

Publisher : S K Kataria and Sons( KATSON ) ISBN : 9788189757885 Author : Dr. Sajay Sharma

Type the URL : http://www.kopykitab.com/product/3671

Get this eBook

http://www.kopykitab.com/Electronics-Principles-by-Dr-Sajay-Sharma

Documents

ELECTRONIC · 2018-10-01 · # Preface to the First Edition... Electronic Principles is a compulsory subject for the engineering students from all the disciplines. This book is primarily