B.E / B.TECH. DEGREE EXAMINATIONS : MAY/JUNE 2010
REGULATION : 2008
FOURTH SEMESTER -ELECTRONICS AND COMMUNICATION ENGG.
ELECTRONIC CIRCUITS II
TIME :3Hours Max.Mark:100
1. What are the merits of negative feedback?
2. Classify negative feedback amplifiers.
3. Define feedback factors.
4. State Nyquist stability factor.
5. Mention the essential conditions satisfied by
an oscillator circuit.
6. Draw the equivalent circuit of a quqrtz crystal.
7. Define piezo-electric effect.
8. Find the frequency oscillation of a wein bridge
oscillator with R1=R2=220kOHMS,C1=C2=250pF.
9. If the practical lower limit on C is 47pF in a Wein-Bridge
oscilltor ,what should be the fixed value of R to
produce an upper frequency limit of 200KHz?
10. Define resonant frequency?
11. Write down the expression for the bandwidth of a
tuned circiut in terms of quality factor and
12. a series resonant circuit has the following
13. What is a positive clamper?
14. Draw the circuit of biased clipper with input
and output waveforms.
15. Define quality factor.
16. What are the limitations of single tuned
17. What do you mean by free running blocking
18. How is linearization achieved in current
time base circuit.
19. Mention some applications of pulse transformer.
20. What is the effect of output resistance of the
amplifier with series feedback connection and
shunt feedback connection?
(5*12 = 60 MARKS)
21.(a) Draw the block diagram of current sampling
-Series Mixing feedback configuration and
derive an expression for transfer gain,input
resistance and output resistance. (8 Marks)
(b) How the negative feedback amplifier improves
stability,reduces noise and increases the input
impedance? (4 Marks)
22. i) Identify the four possible topologies of a
ii) Identify the o/p signal & f/b signal for each
topology(Whether current or voltage).
iii) Identify the transfer gain & feedback factor for
each topology. (12 Marks)
23.(a) Explain RC phase shift oscillator with neat
circuit diagram. derive its frequency of
oscillation . (6 Marks)
(b) A 3 section RC Phase oscilltor has R=10KO and
C=0.01mF . (6 Marks)
(a) What is the frequency of oscillation?
(b) If the oscillator is to be made variable,
using the same values of R,what should be
the tuning range of the capacitor to
obtain a frequency range of 2KHz to 200KHz.
24.(a) Explain the working of a Colpitt's (6 Marks)
oscillator in detail and derive the frequency
(b) What is crossover distortion? How it can be
eliminated ? (6 Marks)
25.(a) Derive the equation for the 'gain-bandwidth'
product of a single tuned amplifier circuit.
(b) A tank circuit has a capacitor of 100pF
and an inductor of 150mH.The series resistance
is 15ohm.Find the impedance and bandwidth
of resonant circuit. (6 Marks)
26.(a) With a neat circuit diagram, explain the working
of an Astable multivibrator. (8 marks)
(b) Describe the parallel biased clipper operation
with necessary diagrams. (4 Marks)
27.(a) With a neat circuit diagram,explain the working
of bistable moltivibrator, derive necessary
equations and plot its waveforms. (6 Marks)
(b) With neat circuit explain the operation
of a Schmitt trigger. (6 Marks)
28.(a) Draw the circuit diagram and explain the
operation of a Push-pull Astable blocking
oscillator with emitter timing. (6 Marks)
(b) Descibe briefly about UJT saw tooth generator.