Andhra University 2007 B.E ELECTRONICS-II - Question Paper

II Year B.E./B.Tech Degree exams

ELECTRONICS-II

(Common to EEE & ECE Branches)

Time : 3 hours Maximum : 75 Marks

ques. one is compulsory

ans any 4 from ques. two to 8

All ques. carry equal marks

1. a) What do you understand by feedback in amplifiers? discuss

the terms feedback factor and open loop gain.

b) elaborate the characteristics of an ideal operational amplier?

c) In class A power amplifier circuit, Vcc=20v, the load

resistance is 12W . obtain out power, input power and

efficiency.

d) discuss lower and upper triggering voltages in a Schmitt

trigger.

e) provide the simple Miller Sweep circuit using NPN transister

and discuss.

2. a) Draw the circuit of Wien Bridge oscillator and discuss the

principle of operation.

b) Derive the expression for its frequence of oscillations. What

is the condition on b for getting sustained oscillations.

c) State Barkansen Criterion for oscillation.

3. a) find the response of an RC high-pass filter to a step input.

b) find the condition of RC high-pass filter to behave as a

good differentitatior.

c) find the response of an RC high-pass filter and to a pulse

Input for Rc/tp>>1 and Rc/tp<<1.

9

4. a) Draw the circuit of class B Power amplifier using BJT and

discuss its working principle. Derive the expression for its

efficiency.

b) elaborate the advantages of push pull amplifiers

5. a) Draw the circuit diagram of a single tuned FET Amplifier

and discuss its operation.

b) elaborate the advantages of doubled tuned amplifiers over

single tuned amplifiers.

6. a) Draw the circuit diagram of an emittercoupled binary and

discuss its operation. State its advantages over collectorcoupled

binary circuit.

b) Design an astable Multivator to produce the squate wave at

10KHZ. With 30% duty cycle. Use transistors having

( hfe )min=60, VBE (sat)=0.7V. VBE (cut off)=0V and

VCE (sat)=0.2V. presume Ic(sat)=1mA and VCC=10V. Show

the circuit diagram with all-------------------------------

7. a) Draw the circuit diagram of a linear current time base

generator and discuss its operation with waveforms.

b) discuss the subsequent with relevant sketches

i) Diode clipper at 2 independent levels

ii) Diode Clamping circuits

8. a) discuss the concepts of Miller and Bootstrap time base

generators with neat circuits.

b) Write short notes on the subsequent

i) Simple current sweep generator

ii) Transistor as a switch


iii) Comprator Circuit.

Earning:   Approval pending.