WBUT Previous Years Question Papers EE Analog Electronic Circuits B Tech 2nd Sem 2011-12

WBUT Previous Years Question Papers EE

 Analog Electronic Circuits B Tech 2nd Sem 2011-12


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)               A stable multivibrator may be used as

a)             frequency to voltage converter

b)            voltage to frequency converter

c)             square wave generator

d) comparator.

ii)          Negative feedback in amplifier

a)           increases bandwidth and increases gain

b)          increases bandwidth and decreases gain

c)           decreases bandwidth and decreases gain

d)          decreases bandwidth and increases gain.

iii)        Which of the following is linear ?

a)           Current to voltage converter

b)           Logarithmic amplifier

c)           Comparator

d)          Squdre wave generator.

iv)         For a given op-amp, CMRR = 10 5 and differential gain = 10 5. What is the common mode gain of the op-amp ?

a)                                                                     10 10   – b) 10 5

c)                                                                                      2 x 10 5      d) 1.

v)           The output pulse width for a monostable multivibrator using NE 555 where external resistance and capacitance are 20 kQ and 0-1 |iiF is

a)                                      2-1 s                b) 2-5 ms

c)                                      2-2 urn            d) 2 ms.

vi)         Which of the following rectifier circuits has the lowest ripple factor ?

a)           Half-wave rectifier without filter

b)           Full-wave rectifier without filter

c)           Full-wave rectifier with inductor as filter

d)           Full-wave rectifier with capacitor as filter.

vii)       Voltage amplification can be obtained by using

a)           shunt shunt feedback

b)           series series feedback

c)           shunt series feedback

d)           series shunt feedback.

vill) The output of an integrator having square wave as input is

a)    triangular       b) ramp

c) sPlke                          d) parabolic,

ix) The all-pass filter has

a)          no pass band

b)          one stop band

c)           same gain at all frequency

d)              a first roll-off above cut-off. x) An instrumentation amplifier

a)           is a differential amplifier

b)          has a gain less than 1

c)           has a veiy high output impedance

d)          has low CMRR.

xi)        A precision diode may be used for

a)           half-wave and full-wave rectification

b)          peak value detector

c)           clipper and clamper

d)          all of these.

xii)      An all-pass filter is used when

a)           high roll-off rate is needed

b)          phase shift is important

c)           a maximally flat pass band is needed

d)          a ripple stop band is important.

GROUP -B ( Short Answer Type Questions )

Answer any three of the following. 3×5= 15

  1. Draw the circuit of a series voltage regulator and explain its operation.
  2. Define the following parameters in connection to op-amp :

. % .

2 x 2 i 2


a)           CMRR

b)          Slew rate.

  1. Explain the operation of a current mirror circuit.
  2. Define “thermal runaway” and “stability factor” of a
  1. With a neat diagram explain the concepts of “load line” and “Q point” of a transistor.


GROUP -C ( Long Answer Type Questions )

Answer any three of the following. 3 x 15 = 45

  1. a) Write down the h-parameter equations of a transistor

amplifier and define h-parameters.                            2 + 4

b)           Model a h-parameter equivalent circuit by following above equations. Hence derive the expressions of the following :i)            Voltage gain                                                   *

ii)           Input impedance.                                        2 + 4 + 3

  1. a) Draw the circuit of self biasing arrangement of a pnp

transistor. Explain physically how this arrangement provides a good stability against temperature variation. Also derive the expression for stability factor. 2 + 4 + 6

b)           Draw the circuits of fixed bias and collector to base

1 1

bias arrangements of transistor.                           1 2 + * 2

  1. Explain the operation of the following circuits using7 1 . 7 1

op-amp : •                                                                       2 2

a)           Logarithmic amplifier

b)           Schmitt trigger.

10. a) Draw the circuit diagram of an emitter follower and

explain the nature of feedback in this circuit. What type of feedback topology is used here ? Derive an expression for the voltage gain of the circuit. 3+1+3

b)           Draw the circuit diagram of a push-pull class B power amplifier and derive the expression for its power efficiency.             2 + 6

  1. a) Draw the circuit of a Wien-bridge oscillator and derive

the expression for its frequency of oscillation.      8

b) Explain the operation of a monostable multivibrator using 555 timer.              7

  1. Write short notes on any three of the following :       3×5

a)               Voltage controlled oscillator

b)               Level shifter

c)                Precision rectifier

d)               Switched Mode Power Supply ( SMPS )

e)               Voltage to current converter.

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