B.E. (Third semester) EXAMINATION, JUNE. 2008
(Common for EC/EE/EX Engg.)
Note: Attempt any five questions. All question carry equal marks.
1. (a) What is a varactor diode ? Write its application.
(b) How does the diode voltage vary with temperature ?
(c ) Explain with the help of diagram the working of N-channel FET and draw its volt-ampere
2. (a) Draw the complete output and input characteristics of CE amplifier and explain them.
(b) A transistor used in CE connection has the following set of h-parameters.
Hie = 1k, hfe= 100, hre = 5 × 10-4 ,and hoe 2 × 10-5 with RL = 5 K,
Determine Ri and Ai.
3. (a) What is feedback amplifier ? Discuss the advantages and disadvantages of negative feedback.
(b) Prove how input resistance is increased in volyage-series feedback topology ?
4. (a) Write the difference between an enhancement and depletion type MOSFET.
(b) Determine the quiescent and the collector to emitter voltage for a silicon transistor with ß=50 I
the self – biasing arrangement of fig.
5. (a) What do you mean by class-A , class –B and class-C amplifiers?
(b) Discuss the merits of push pull power amplifier over single ended power amplifier .
(c ) Define CMRR for an operational amplifier .
6. (a) What is a multavibrator circuit ? Draw the circuit diagram of biastable multavibrator and explain
its working .
(b) What do you mean by clamping circuits ? Explain.
7. (a) Draw the circuit diagram of a Wien’s bridge oscillator and explain its operation .
(b) What is an operational amplifier ? How it works as a
(i) Differentiator ?
(ii) Comparator ?
8. Write short notes on any four of the following :
(i) Thermal stability
(ii) Clipping circuits
(iii) Tunnel diode
(v) Effect of feedback on output resistance
(vi) Boot strapping technique.