# RGPV Previous Questions Papers 3rd Semester Electronics Dec 2003

RGTU B.E. (Third semester) EXAMINATION, DEC, 2003

(Common for EC/EE/IP Engg.)

(ELECTRONICS – EE/EC/EX-404)

Note:      Attempt any five questions.  Assume  missing data suitably.

1. (a) Define the following :

(i)   Cut-in (knee) voltage (ii) depletion layer (iii) reserve saturation current (ICBO)

(b)   For the circuit show in fig. 1, draw the load line. Determine the operating point and show it on the

load line. Assume VBE =0.7 volts.

2. (a) Draw the circuit diagram of L-C oscillator and explain its working.

(b)  Give classification of power amplifiers . What is PDmax  rating ? Explain.

3. (a) Define the following :

(i) CMRR  (ii) Offset voltage   (iii) Slew rate

(b) Draw circuit diagram of a difference amplifier using OP-AMP and derive an expression for its gain.

4. (a) Explain V-1 characterics of an SCR.

(b)  Discuss the working of a simple inverter .

5.(a) Explain the working of a clamper circuit with input and output wave forms.

(b) Draw the circuit diagram of a monostable multivibrator using 555 IC and explain its working.

6. (a) Show that the maximum conversion efficiency of a class –B amplifier system is 78.5 % .

(b) Draw circuit diagram of an emitter follower. Give its low frequency h-parameter model. Analysis

Its feedback mechanism (no diversion desired).

7. (a) Derive an expression for resonant frequency of a tank. (tuning) circuit of BJT amplifiers.

(b) Work out the following quantities for the circuit show in ahead fig.2

(i) a.c. emitter current

(ii) a.c. voltage at emitter base and collector

(iii) a.c. voltage gain

Assume hie = 250 , hfe  =50

8. Attempt any two of the following :

(i) Explain the working of a bridge rectifier . Also calculate PIV (peak inverse voltage) for the same.

(ii) Discuss the Boot stamping Techniques I brief. (need not to derive expressions)

(iii) Give the working of a Schmitt trigger circuit.

(iv) Give the working of a chopper circuit.

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(b)  Explain the working of enhancement model in a MOSFET with circuit symbol and characteristics .

3.  (a) Draw a self-bias circuit . Explain qualitatively  why such a circuit is an improvement on the fixed

bias as far  as stability is concerned . How is load line drawn for a self bias circuit ?

(b) Define h-parameter of a transmission . Find the input and output resistance in CE  configuration.

4. (a) Draw I circuit voltage series feedback amplifier. Derive the expression for the following :

(i)  Voltage gain with feedback AVF

(ii) Output resistance with feedback Rof

(b) Sketch the circuit of Wien bridge oscillator . Explain its working Determine the frequency of

operation.

5. (a) Draw the circuit of bitable  multavibrator . Explain its working with the help of wave forms.

(b)  Draw bootstrapped Darlington circuit and explain how this increase the input the input resistance.

6.    Explain the following with the aid of diagram :

(I) Integrator using OP-AMP

(ii) Instrumentation amplifier using OP-AMP

(iii) 555 timer in monostable mode

7. (a) Explain series and parallel connection  of SCR .

(b) Explain VI characteristics of SCR in detail.

8. Write short notes on any two of the following :

(i) Varactor

(ii) UJT

(iii) Power amplifier

(iv) Schmitt trigger