WBUT Question Papers CS Analog And Digital Electronics B Tech Third Sem 2011 2012

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%.

t*

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

1

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 ?

a)

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

  1. 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^

  1. Implement the following using

8 : 1 MUX, F ( A, B, C, D ) = I ( 0, 2S 4, 6 ).

  1. Explain the operation of successive approximation ADC with diagram.
  2. Draw and explain the operation of astable multivibrator using 555 Timer.
  3. 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

  1. 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

  1. 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

  1. 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

  1. a) What are the conditions necessary for the generation of

oscillation ?

■ %

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

  1. Write short notes on any three of the following :        3×5
a) Ring Counter
b) Odd Parity Generator and Checker
c) BCD adder
d) R-2R ladder DAC.
e) CMOS Logic family
f) Data lock-out in a counter.

 

152-(N)

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