D R3940 Pages: 2

frequency.
b) With neat diagram derive the expression for frequency of oscillation of RC phase (7)

shift oscillator.
6 a) Derive the expression for upper cut off frequency of a common base amplifier (8)

using high frequency hybrid ‏ع‎ equivalent model. 9) Draw the circuit of Colpitts oscillator and outline
its working principle. (7)

PARTC
Answer any two full questions, each carries 20 marks.
7 ಖ With neat diagram explain the working of astable multivibrator. Derive the (10) expression for
time period of the astable multivibrator.
b) With neat diagram explain how voltage regulation is achieved in series voltage
(10) regulator.
8 a) Explain class A power amplifier. Show that the maximum conversion efficiency (10) of the
transformer coupled class A power amplifier is 50%.
b) Determine drain to source voltage of a MOSFET common source circuit using (7)
voltage divider bias and source is directly grounded. Given that Vpp=10V, Ri=l0MQ,
R2=10MQ, Rp=2KQ, Vt= 29, and Ip= 2 mA. State which region, the MOSFET is
working in the circuit with supportive computations.
©) Determine gm for enhancement type MOSFET if Vascn=3V and it is biased at
(3)
7050-87. Assume 10.35.10 3 mA/ V?.
9 a) With neat diagram explain Schmitt trigger. (7) b) What is meant by cross over
distortion. How it is eliminated. (3)
c) Derive expression for voltage gain, input impedance and output impedance of (10)

Enhancement MOSFET drain feedback configuration.

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