Rajiv Gandhi Proudyogiki Vishwavidyalaya 2010 B.E Computer Science Electronic devices and circuits (cs/it-304(n)) - Question Paper

Total No. of Questions:10

CS/IT-304(N)
B.E(Third Semester)EXAMINATION,FEB.,2010
(New Scheme)
(Common for CS & IT Engg.Branch)
ELECTRONIC DEVICES AND CIRCUITS
Time:Three Hours
Maximum Marks:100
Minimum Pass Marks:35

Note:(i) There are 5 Units.Attempt 1 ques. from every Unit.
(ii) All ques. carry equal marks.
(iii) presume and Mention suitable missing data if any.


Unit-1

1(a) discuss with reference to the Zener diode characteristic,Zener voltage, breakdown current and dynamic impedance.How does the dynamic impedence vary with Zener current?[10 marks]

1(b)What is PIN diode? Why is it so called? What is swept out voltage?Why is it suitable as a microwave switch? Is it operated in Forward bias or in a reverse bias mode?[10 marks]

OR

2(a) discuss the working of transistor as an amplifier? [10 marks]

2(b) provided hie=2.4kohm, hfe=100, hre= 4*10^-4 and hoe=25us.Sketch the common emmiter equivalent model.[10 marks]

Unit-2

3(a) Differentiate ranging from positive and negative feedback.How does negative feedback replace the gain of an amplifier? [10 marks]

3(b) Derive the expression for the gain of an amplifier using negative feedback. [10 marks]

OR

4(a) Draw the circuit of a Wien bridge oscillator. explain its working.Will oscillation takes place if bridge is balanced? [10 marks]

4(b) A class B push-pull amplifier is supllied with Vcc=50V.The signal swings the collector voltage down to Vmin=10V.The dissipation in both transistors total 40W.Find the total power and coversion effiency. [10 marks]

Unit-3

5(a) For a monostable multivibrator compute the input pulse width for the design values of Rc=2k ohm, C=0.1 uF, Vcc=10V, VBE(sat)=0.8V. [10 marks]

5(b)Draw the circuit diagram of an astable multivibrator.Justify that it is a 2 stage R-C coupled amplifier Using feedback.How does it provide a square wave? [10 marks]

OR

6(a) How is transistor used as a clipper? Draw the cicuit diagram and output waveform for sinusoidal input signal. [10 marks]

6(b) Draw the circuit diagram of Darlington amplifier. provide its characteristics, merits and applications. [10 marks]

Unit-4

7(a) Why current source is used in conjunction with differential amplifier? Draw the circuit diagram. [10 marks]

7(b) Draw the circuit diagram of a log and antilog amplifier circuit using OP-Amp and write the expression for output voltage. [10 marks]

OR

8(a) Using 555 timer draw the circuit of monostable multivibrator and obtain the expression for pulse width. [10 marks]

8(b) Determine the voltage gain of an Op-Amp. instrumentation amplifier. [10 marks]

Unit-5

9(a) discuss the working principle of a regulated power instrumentation amplifier. [10 marks]

9(b) Explain, with a neat block diagram of the internal blocks, the working of an I.C. voltage regulator. [10 marks]

OR

10(a) For a transformer output of 24V and a filter capacitor of 200pF, determine the minimum input voltage when connected to a load drawing 300mA. [10 marks]

10(b) Write the principle of voltage regulator. What do you understand by SMPS? [10 marks]

Earning:   Approval pending.