Download EC6401-EC II -CAT2 SET2

LOYOLA – ICAM
COLLEGE OF ENGINEERING ANDTECHNOLOGY (LICET)
Loyola Campus, Nungambakkam , Chennai – 34
Branch: ECE
Semester: IV
Date: 16-03-2015
Time: 8.00 – 10.00 am (2 Hrs)
CONTINIOUS ASSESMENT TEST-II
ELECTRONIC CIRCUITS II (EC6401)
Part-A (Answer all the questions)
(6x2=12)
1. What is the effect of cascading n stages of identical single tuned amplifiers (synchronously tuned)
on the overall 3 dB bandwidth?
2. Define unloaded Q factor
3. A tuned amplifier has its maximum gain at a frequency of 2 MHz and has a bandwidth of 50 kHz.
Calculate the Q- factor.
4. What are the disadvantages of using diode as shunt element in clipper circuit?
5. Draw a clipper circuit which clips all voltages above +2V.
6. Draw a circuit of a RC integrator and mention the condition under which the circuit behaves as a integrator
Part-B (Answer all the questions)
(3x16=48)
7. (a) (i) Explain, with suitable circuit diagrams, Hazeltine neutralization and coil neutralization techniques. (8)
(ii) A Class C tuned amplifier has R = 6 kΩ and the tank circuit is required to have Q = 80. Calculate the
values of L and C of the tank circuit. Assume Vcc = 20V, resonant frequency = 5 MHz and worst case
power dissipation = 20 mW.
(8)
(OR)
(b) (i) Explain Class C tuned amplifier and derive its efficiency.
(8)
(ii) Determine the critical coefficient coupling for maximum power transfer in a double tuned
amplifier with a neat circuit and equivalent circuit diagram.
(8)
8. (a) i) Define quality factor. Obtain the quality factor for a parallel resonant circuit.
ii) A parallel resonant circuit has a capacitor of 100 pF and an inductor of 100 micro H.
The inductor has a resistance of 5 Ohms. Find the value of frequency at which the
circuit resonates and the circuit impedance at resonance
(OR)
(b) i) With necessary circuit diagrams and waveforms, explain the operation of the following:
(1) Positive clipper, (2) Negative clipper, (3) Biased clipper and
(4) Combinational (Two-way) clipper.
(ii) Mention the applications of clamping circuits.
(12)
(4)
9. (a) (i) Explain astable multivibrator with neat sketch of waveforms at collector and base of transistors used in the
circuit.
(12)
(ii) Determine the value of capacitors to be used in an astable multivibrator to provide a train of pulse
2us wide at a repletion rate of 100KHz if R1=R2= 20K ohms
(4)
(OR)
(b) (i) Explain how a high pass RC circuit is used as a differentiator and low pass RC circuit can be
used as integrator?
(ii) Describe the response of high pass RC circuit for step, square wave and ramp input.
(8)
(8)