B.E. (Third semester) EXAMINATION, JUNE. 2009
(Common for EC/EE/EX Engg.)
Note: (i) Attempt any five questions.
(ii) All question carry equal marks.
(iii) Assume any missing data.
1. (a) Explain the working of a Zener diode with its V-1 characteristics .
(b) Explain the working of a JEFT and give its characteristics curves.
(a) List different method of biasing a transistor . Explain emitter bias in detail.
(b) Find the Transistor currents in the circuit of ahead fig.1. A silicon transistor with ß=150 and ICQ. =20
nA is under consideration . Determine wheatear or not transistor is operating in the active region.
2. (a) What is feedback amplifier? Classify the feedback techniques and enlist the advantages of
(b) Explain the effect of coupling and bypass capacitors on low frequency response of the amplifier .
(a) Explain Hartley and colitis oscillator in short.
(b) Explain the working of a class A amplifier.
3. (a) Draw and explain the working of bistable multavibrator .
(b) Draw a Darlington emitter follower . Explain why the input impedance is higher than that of a single
stage emitter follower.
(a) What is comparator circuits ? How does such a circuit differ from a clipping circuits ?
(b) How FET is used as a voltage variable resistor (VVR) ? Explain
4. (a) What is main difference between square wave generator and Schmitt trigger ? Explain Schmitt
trigger in brief.
(b) Discuss logarithmic amplifier with proper analysis.
For the amplifier of the given fig.2. determine the maximum possible output offset voltage due to :
(i) Input offset
(ii) Input bias current IB
Parameters : Vio(max) = 6 mV d.c.
IB (max) =500 nA d.c.
VS = ± 15 V at t = 25oc
5. (a) Draw the block diagram of SMPS and explain each block in detail.
(b) Write short note on current limiting circuits.
Write short notes on any two of the following :
(ii) Cascade amplifier