B.E/B.Tech DEGREE EXAMINATION, MAY/JUNE 2009.
Electronics and Communication Engineering
EC 1251 - ELECTRONIC CIRCUITS - II
(Common to B.E.(Part time)Third Semester - Regulation 2005)
Time: Three Hours Maximum: 100 marks
Answer all questions
PART - A (10 * 2 = 20 marks)
1. What happens to the input resistance based on type of feedback in an amplifier?
2. What are the steps to be carried out for complete analysis of a feedback amplifier?
3. How is amplitude stabilization performed in Wienbridge oscillator?
4. What is frequency stability of an oscillator?
5. Draw the ideal response and actual response of tuned amplifier.
6. Define gain bandwidth product of a tuned amplifier.
7. What are the disadvantages of using diode as shunt element in clipper circuit?
8. Why is monostable multivibrator also called as delay circuit?
9. What is displacement error?
10. What are the applications of blocking oscillators?
PART - B (5 * 16 = 80 marks)
11 (a) Discuss quantitatively on the effect of topology of a feedback amplifier upon output resistance. Also obtain the expression for output resistance for all four topologies. (16)
(b) Draw the circuit diagram of voltage series feedback amplifier using BJT and analyze the circuit to determine the input and output resistance (16)
12 (a) Explain the working of RC phase shift oscillator using BJT with small signal equivalent circuit and derive the expression for frequency of oscillation. (16)
(b) Draw the circuit diagram and explain the working of Hartley oscillator. Also derive the expression for frequency of oscillation and condition for sustained oscillation. (16)
13 (a) With neat circuit diagram and equivalent circuit derive the expression for impedance and admittance and plot the frequency response. (16)
(i) Hazeltine neutralization. (8)
(ii) Coil neutralization (8)
14 (a) Explain the operation of collector-coupled monostable circuit with circuit diagram, waveform and equivalent circuit during each state. (16)
(b) explain the operation of Schmitt Trigger with neat circuit diagram and response of Schmitt trigger circuit for different loop gains. Also explain how hysteresis is eliminated in Schmitt Trigger. (16)
15 (a) (i) Explain with circuit diagram. How UJT acts as sawtooth generator. (8)
(ii) How frequency control is established using core saturation? (8)
(b) Explain the operation of bootstrap time base generator with circuit diagram and waveforms.(16)