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Analog circuits : Electronics and Communication Engineering, THE GATE ACADEMY

Mar 16, 2016

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THE GATE ACADEMY's GATE Correspondence Materials consist of complete GATE syllabus in the form of booklets with theory, solved examples, model tests, formulae and questions in various levels of difficulty in all the topics of the syllabus. The material is designed in such a way that it has proven to be an ideal material in-terms of an accurate and efficient preparation for GATE. Quick Refresher Guide : is especially developed for the students, for their quick revision of concepts preparing for GATE examination. Also get 1 All India Mock Tests with results including Rank,Percentile,detailed performance analysis and with video solutions GATE QUESTION BANK : is a topic-wise and subject wise collection of previous year GATE questions ( 2001 – 2013). Also get 1 All India Mock Tests with results including Rank,Percentile,detailed performance analysis and with video solutions Bangalore Head Office: THE GATE ACADEMY Jayanagar 4th block E-Mail: [email protected] Landline: 080-61766222
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Page 1: Analog circuits : Electronics and Communication Engineering, THE GATE ACADEMY
Page 2: Analog circuits : Electronics and Communication Engineering, THE GATE ACADEMY

ANALOG CIRCUITS

For

ECE / EE / IN

By

www.thegateacademy.com

Page 3: Analog circuits : Electronics and Communication Engineering, THE GATE ACADEMY

Syllabus Analog Circuits

THE GATE ACADEMY PVT.LTD. H.O.: #74, Keshava Krupa (third Floor), 30th Cross, 10th Main, Jayanagar 4th Block, Bangalore-11 : 080-65700750, [email protected] © Copyright reserved. Web: www.thegateacademy.com

Syllabus for Analog Circuits

Small Signal Equivalent circuits of diodes, BJTs, MOSFETs and analog CMOS. Simple diode

circuits, clipping, clamping, rectifier. Biasing and bias stability of transistor and FET amplifiers.

Amplifiers: single-and multi-stage, differential and operational, feedback, and power. Frequency

response of amplifiers. Simple op-amp circuits. Filters. Sinusoidal oscillators; criterion for

oscillation; single-transistor and op-amp configurations. Function generators and wave-shaping

circuits, 555 Timers. Power supplies.

Analysis of GATE Papers

(Analog Circuits)

Year ECE EE IN

2013 15.00 8.00 18.00

2012 6.00 5.00 5.00

2011 10.00 5.00 15.00

2010 9.00 4.00 9.00

Over All

Percentage

10.00% 5.50% 11.75%

Page 4: Analog circuits : Electronics and Communication Engineering, THE GATE ACADEMY

Contents Analog Circuits

THE GATE ACADEMY PVT.LTD. H.O.: #74, Keshava Krupa (third Floor), 30th Cross, 10th Main, Jayanagar 4th Block, Bangalore-11 : 080-65700750, [email protected] © Copyright reserved. Web: www.thegateacademy.com Page I

CC OO NN TT EE NN TT SS

Chapters Page No. #1. Diode Circuits-Anaylsis & Application 1 – 39

Wave Shaping Circuit 1 – 12

Rectifiers and Power Supplies 13 – 17

Solved Examples 18 – 20

Assignment 1 21 – 28

Assignment 2 29 – 32

Answer Keys 33

Explanation s 33 – 39

#2. AC & DC Biasing-BJTs & FET 40 - 87 Operating Point 40 – 46

BIAS Stabilization 46 – 55

Compensation Techniques 55 – 66

Assignment 1 67 – 73

Assignment 2 74 – 78

Answer Keys 79

Explanations 79 – 87

#3. Small Signal Modeling Of BJT & FET 88 – 136 BJT Transistor Modeling 88 – 94

The Hybrid Equivalent Model 94 – 99

Characteristic of Common Base Amplifier 99 – 105

FET Small signal Model. 105 – 114

Assignment 1 115 – 121

Assignment 2 122 – 126

Answer Keys 127

Explanations 127 – 136

#4. BJT & JFET Frequency Response 137 – 169 Introduction 137 – 139

Low Frequency Response –BJT Amplifier 139 – 142

Low frequency Response –FET Amplifier 142 – 144

Miller Effect Capacitance 144 – 147

High Frequency Response –BJT Applfier 147 – 149

High Frequency Response -FET Amplifier 149 – 155

Assignment 1 156 – 160

Assignment 2 161 – 164

Answer Keys 165

Explanations 165 – 169

Page 5: Analog circuits : Electronics and Communication Engineering, THE GATE ACADEMY

Contents Analog Circuits

THE GATE ACADEMY PVT.LTD. H.O.: #74, Keshava Krupa (third Floor), 30th Cross, 10th Main, Jayanagar 4th Block, Bangalore-11 : 080-65700750, [email protected] © Copyright reserved. Web: www.thegateacademy.com Page II

#5. Feedback & Oscillator Circuits 170 – 210 Classification of Amplifier 170 – 173

Feedback of Connection Types. 173 – 178

FET Phase Shift Oscillator 179

Wien Bridge Oscillator 180 – 188

Solved Examples 189 – 194

Assignment 1 195 – 199

Assignment 2 200 – 204

Answer Keys 205

Explanations 205 – 210

#6. Operational Amplifiers & Its Applications 211 – 291 Differential Amplifiers 211 – 212

Analysis of Differential Amplifier 212 – 214

Common Mode Rejection Ratio (CMRR) 214

Operational Amplifier 214 – 223

Practical Op-Amp Circuits 223 – 240

Astable Multivibrator (Square Wave Generator) 241 - 243

Zero-Crossing Detector 244 - 254

The 555 Timer 255 – 260

Solved Examples 261 – 265

Assignment 1 266 – 274

Assignment 2 275 – 280

Answer Keys 281

Explanations 281 - 291

#7. Power Amplifiers 292 – 317 Introduction 292 – 294

Series –Fed Class Amplifer 294

DC Bias Operation 295

AC Operation 295 – 298

Transformer Coupled Amplifier 298 – 299

Push Pull Amplifier 299 – 301

Transformer Coupled Push Pull Circuit 301

Complementary –symmetry circuit 301 – 305

Total Hormonic distrtion. 305 – 306

Assignment 1 307 – 311

Assignment 2 311 – 312

Answer Keys 313

Explanations 313 – 317

Page 6: Analog circuits : Electronics and Communication Engineering, THE GATE ACADEMY

Contents Analog Circuits

THE GATE ACADEMY PVT.LTD. H.O.: #74, Keshava Krupa (third Floor), 30th Cross, 10th Main, Jayanagar 4th Block, Bangalore-11 : 080-65700750, [email protected] © Copyright reserved. Web: www.thegateacademy.com Page III

Module Test 318 – 345 Test Questions 318 – 335

Answer Keys 336

Explanations 336 – 345

Reference Books 346

Page 7: Analog circuits : Electronics and Communication Engineering, THE GATE ACADEMY

Chapter-1 Analog Circuits

THE GATE ACADEMY PVT.LTD. H.O.: #74, Keshava Krupa (third Floor), 30th Cross, 10th Main, Jayanagar 4th Block, Bangalore-11 : 080-65700750, [email protected] © Copyright reserved. Web: www.thegateacademy.com Page 1

CHAPTER 1

Diode Circuits - Analysis and Application

Wave Shaping Circuits

Wave shaping circuits are of two types

(A) Linear wave shaping circuits (B) Non linear wave shaping circuits

A. Linear Wave Shaping Circuits

The process by which the wave form of non sinusoidal signal is altered by passing it through the linear network is called the linear wave shaping

High Pass Circuit

Fig. 1 High Pass Circuit

This circuit is called the high pass filter because it passes the high frequency components and attenuates the low frequency components.

For low frequency, the reactance of the capacitance is large

(a) Sinusoidal input:

( )

|

|

√ (

⁄ )

( ) ( )

Vo R

Vi

C

+ +

- -

Page 8: Analog circuits : Electronics and Communication Engineering, THE GATE ACADEMY

Chapter-1 Analog Circuits

THE GATE ACADEMY PVT.LTD. H.O.: #74, Keshava Krupa (third Floor), 30th Cross, 10th Main, Jayanagar 4th Block, Bangalore-11 : 080-65700750, [email protected] © Copyright reserved. Web: www.thegateacademy.com Page 2

Fig. 2 Gain-frequency plot of high pass circuit

(b) Step Input:

Fig. 3 Output voltage of high pass circuit when input is a step voltage

(t) = ( ) ( ) ( ) ( )

( ) = 1/C ( )

iR,

So ( ) 1/RC (t) dt + ( ) ( )

It is a single time constant circuit and a first order equation is obtained. The general solution of any single time constant circuit can be written as,

( ) ( ) , here Vf = 0, Vi = V, Vo(t) = Ve- τwhere τ

(c) Pulse Input: ( ) [ ( ) ( )]

1)

2) ( )

τ

τ

( )

0

V

| |

1 0.707

Page 9: Analog circuits : Electronics and Communication Engineering, THE GATE ACADEMY

Chapter-1 Analog Circuits

THE GATE ACADEMY PVT.LTD. H.O.: #74, Keshava Krupa (third Floor), 30th Cross, 10th Main, Jayanagar 4th Block, Bangalore-11 : 080-65700750, [email protected] © Copyright reserved. Web: www.thegateacademy.com Page 3

Fig. 4 Output of high pass filter, when input is a pulse

For a low time constant the peak – to – peak amplitudes will be double. The process of converting pulses into spikes by means of a low time constant is called peaking.

In high pass RC circuit, the average level of the output is always zero. The area above the zero axis should be equal to the area below the zero axis, A1 = A2

(d) Square Wave Input

For a non-symmetrical square wave , + = T = 1/f. The extreme cases are

Case 1: τ τ The input and output are shown below,

(a)

(b)

Fig: 5 (a) Square wave input; (b) Output voltage if the time constant is very large (compared with T). The dc component V d –c of the output is always zero. Area A1 equals area A2.

V0

V 0

T1 T2

t

Zero voltage

T

T1

A2

A1

Zero voltage

Average voltage

( )

0

V

1

2

Page 10: Analog circuits : Electronics and Communication Engineering, THE GATE ACADEMY

Chapter-1 Analog Circuits

THE GATE ACADEMY PVT.LTD. H.O.: #74, Keshava Krupa (third Floor), 30th Cross, 10th Main, Jayanagar 4th Block, Bangalore-11 : 080-65700750, [email protected] © Copyright reserved. Web: www.thegateacademy.com Page 4

Case 2: τ τ The response is shown below;Note: 5(a) Square wave input

Fig: 6 Peaking of a square wave resulting from a time constant small compared with T.

More generally the response to a square wave must have the appearance shown below:

The four levels V1, V1’ 2,V2’ can be determined from (refer figure 7)

For symmetrical square wave:

T1 = T2 = T/2

’ and the response is shown below in Fig. 7(b)

P c ‘P’ by

P =

100

100 %

=

100 %

Where f1 =

and

V0

T1 T2

T

V

V

0

Input

t

Page 11: Analog circuits : Electronics and Communication Engineering, THE GATE ACADEMY

Chapter-1 Analog Circuits

THE GATE ACADEMY PVT.LTD. H.O.: #74, Keshava Krupa (third Floor), 30th Cross, 10th Main, Jayanagar 4th Block, Bangalore-11 : 080-65700750, [email protected] © Copyright reserved. Web: www.thegateacademy.com Page 5

Fig. 7 Linear tilt of a square wave when RC/T >> 1.

(e) Ramp Input:

Vi(t) = t u (t) and Vo(t) = τ (1 ), are shown below,

Fig. 8 (a) Response of a high pass RC circuit to a ramp voltage for RC / T >> 1;

(b)Response to a ramp voltage for RC / T << 1.

For t <<τ as a measure of departure from linearity, transmission error, et is defined as

Deviation from Linearity

Output

Input = Signal

0 T t

Fig (a)

t

Output

0 T

Fig (b)

t

( )

t

( )

Output

Input

(b)

Page 12: Analog circuits : Electronics and Communication Engineering, THE GATE ACADEMY