electronic · 2018-10-01 · # preface to the first edition... electronic principles is a...
TRANSCRIPT
(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
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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.
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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
Short Questions with Answers ...............................................54
Review Questions ....................................................................56
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
4.5.1 Working Operation of the Circuit ........................... 66
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
4.6.1 Working Operation of the Circuit ........................... 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
Short Questions with Answers ...............................................95
Review Questions ....................................................................96
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
Short Questions with Answers .............................................156
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
Short Questions with Answers .............................................199
Review Questions ..................................................................201
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
Short Questions with Answers .............................................244
Review Questions ..................................................................245
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
Short Questions with Answers .............................................262
Review Questions ..................................................................262
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
Short Questions with Answers ............................................337
Review Questions .................................................................338
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
Short Questions with Answers ............................................354
Review Questions .................................................................355
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
Short Questions with Answers ............................................379
Review Questions .................................................................379
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
Short Questions with Answers ............................................415
Review Questions .................................................................416
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
Class A Amplifier ................................................ 423
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
Class A Amplifier ................................................ 427
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
Short Questions with Answers ............................................436
Review Questions .................................................................437
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
Short Questions with Answers ............................................448
Review Questions .................................................................448
Numerical Problems ............................................................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
Short Questions with Answers ............................................476
Review Questions .................................................................477
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
Short Questions with Answers ............................................517
Review Questions .................................................................518
Numerical Problems ............................................................519
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
19.9.3 Working Operation .............................................. 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
Short Questions with Answers ............................................536
Review Questions .................................................................538
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
20.11.1 Working Operation .............................................. 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
20.14.2 Spectral Response ............................................... 555
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
20.17.3 Spectral Response ............................................... 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
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