B.E. (Third semester) EXAMINATION, JUNE. 2011
(Common for EC/EE/EX Engg.)
Note. Attempt one question from each unit. All question carry equal marks.
1. (a) Explain transition capacitance and diffusion capacitance in semiconductor diodes .
(b) Explain the reason why one cannot build a transistor by connecting two diodes back to back.
2. (A)The emitter bias configuration of fig.1, has the following specifications: 1CQ=1/2 Isat,IC sat=8mA, Vc=18Vand b=110.
Determine Rc ,RE ,RB.
(b) Explain the principle of working of MOSFET.
3. (a) Calculate the gain with feedback for the FET amplifier circuit of fig.2, with the following circuit values:
R1=80k?, R2=20k?, R0=10k?, RD=10k? and gm=4000µs.
(b) dertermine the efficiency of class B power amplifier.
4. (a) Explain the principle of working of Wein’s bridge oscillator.
(b) Explain gain, input impedance and out put impedance of current shunt feedback amplifier.
5. (a) Explain the switching characteristics of transistor.
(b) With the help of timing diagram explain the working principle of monostable multivibrator.
6. (a) Obtain the output wavefrom of the following circuit in fig.3.
(b) Explain the working principle of Darlington pair.
7. Explain the following application of Op-amp:
(a) Averager (b) Differentiator (c) Antilog amplifier (d) Current to voltage converter
8. (a) Explain the working principle of Schmitt trigger.
(b) Explain the working of Bi-stable multivibrator using 555 timer.
9. (a) Explain the working of shunt regulrtor.
(b) Explain in brief the principle of IC voltage regulator.
10. Write short notes on the following :
(a) Adjustable switching regulator