WBUT Question Papers CS
Analog And Digital Electronics B Tech Third Sem 2011 2012
Time Allotted : 3 Hours
Full Marks : 70
The figures in the margin indicate full marks.
Candidates are required to give their answers in their own words
as far as practicable.
GROUP – A
( Multiple Choice Type Questions )
1. Choose the correct alternatives for any ten of the following :
10 x 1 = 10
i) Maximum efficiency of transformer coupled class A power amplifier is
a) 78-5% b) 50%
c) 25% ( d) 100%.
ii) A 2-transistor class B power amplifier is commonly called
a) push-pull b) dual
c) differential d) none of these.
iii) Class C amplifiers are used as
a) AF amplifiers b) detectors
c) RF amplifiers d) none of these.
iv) A bistable multivibrator circuit has
a) two unstable states b) two stable states c) quasi-stable states d) none ol these.
v) A Wien-bridge oscillator has a frequency a) 1/2tuVRC b) 1/VRC
c) 1 /2n RC d) none of these.
vi) Which of the following oscillators is used at audio frequency ?
a) Crystal Oscillators
b) Wien-bridge Oscillator
c) RC Phase-shift Oscillator
d) Colpitt’s Oscillator.
vii) The minimum no. of NAND gates required to design one full adder circuit is
a) 6 b) S
c) 10 d) 9.
viii) The race-around condition does not occur in flip-flop
a) J-K b) Master Slave
c) t d) None of these.
ix) The decimal equivalent of ( 1111100100 ) 2 is
a) 998 b) 568
c) 996 d) None of these.
x) The J-K flip-flop has
a) no stable state b) two stable states
c) one stable state d) none of these.
xi) The decimal equivalent of ( A0F9.0EB ) 16 is
a) 44297.0967 b) 67902.8796
c) 41209,0572 d) none of these.
xii) How many full adders are required to construct rrt bit parallel adder ?
m / 2 b) m – 1
c) rn d) m + 1. t
GROUP -B ( Short Answer Type Questions )
Answer any three of the following. 3×5 = 15
- Simplify the following Boolean function into
i) Sum of product form
ii) Product of sura form :
F( A, B, C, D } =’Z ( 0, 1, 2, 5, 8, 9, 10 ). + 2^
- Implement the following using
8 : 1 MUX, F ( A, B, C, D ) = I ( 0, 2S 4, 6 ).
- Explain the operation of successive approximation ADC with diagram.
- Draw and explain the operation of astable multivibrator using 555 Timer.
- Define upper threshold, lower threshold, hysteresis voltage
and centre voltage related to a Schmitt trigger circuit.
GROUP -C ( Long Answer Type Questions )
Answer any three of the following. 3 x 15 = 45
- a) Design an asynchronous 3-bit up-down counter using
J-K flip-flop which counts up when external signal M = 1 and counts down when M= 0.
b) With a neat circuit diagram, explain the operation of a 4-bit Johnson counter implemented using D flip-flop.
7 + 8
- a) Design full subtractor uisng 4 : 1 multiplexers.
) b) Describe the operation of a bidirectional universal shift register
( with parallel load ) with a neat diagram. 6 + 9
- a) Draw the circuit diagram of a transformer coupled
Class A power amplifiers and explain its operation.
b) Calculate the total efficiency of this amplifier.
c) What is cross-over distortion found in Class B power amplifiers ? How it can be eliminated ? 5 + 4 + 0
- a) What are the conditions necessary for the generation of
b) Explain the operation of a Wien Bridge oscillator using Opamp with af circuit diagram.
c) Derive an expression for its frequency of oscillation.
|4 + 6 + 5