Analog Electronics - MCQ on FEEDBACK AMPLIFIER

 Multiple Choice Questions and Answers on Feedback Amplifiers - Analog Electronics


1. To obtain very high input and output impedance in a feedback amplifier, the topology mostly used is

       a)  voltage-series
   b)  current-series
   c)  voltage-shunt
   d)  current-shunt

Answer: b


2. In a feedback amplifier, sensitivity D is equal to

a      a)  
    b)  1-Aβ
    c)  1+Aβ
    d) 1/(Aβ+1)

Answer: c


3. In a negative feedback amplifier, voltage sampling

a     a)  tends to decrease the output resistance
   b)  tends to increase the output resistance7
   c)  does not alter output resistance
   d)  produces same effect on output resistance as current sampling

Answer: a


4. In a negative feedback amplifier, current sampling

       a)  tends to decrease the output resistance
   b)  tends to increase the output resistance
   c)  does not alter output resistance
   d)  produces same effect on output resistance as voltage sampling

Answer: b


5. Open loop gain of a amplifier is given by

         a)  A
     b) 
     c)   β
     d)  None of the above

Answer: a


6.  Loop gain is given by

         a)  A
     b) 
     c)  β
     d)  None of the above

Answer: b


7. In a negative feedback amplifier, series mixing

         a)  tends to decrease the input resistance
     b)  tends to increase the input resistance
     c)  does not alter input resistance
     d)  produces same effect on input resistance as shunt mixing

Answer: b


8. For a shunt-shunt negative feedback amplifier

         a)  input impedance decrease but output impedance increases
     b)  both input impedance and output impedance increases
     c)  both input impedance and output impedance decreases
     d)  none of the above

Answer: c


9. An amplifier with negative feedback

         a)  controls the gain
     b)  reduces the noise
     c)  reduces phase distortion
     d)  all of the above

Answer: d


10. In a negative feedback amplifier, shunt mixing

         a)  tends to decrease the input resistance
     b)  tends to increase the input resistance
     c)  does not alter input resistance
     d)  produces same effect on input resistance as series mixing

Answer: a


11. Negative feedback in an amplifier improves

         a)  signal to noise ratio at the output
     b)  reduces distortion
     c)  both (a) and (b)
     d)  none of the above

Answer: c


12. Barkhausen criterion is:

      a)  positive feedback, Aβ=1, θ=0 or multiple 360
      b)  negative feedback, Aβ=1, θ=0 or multiple 360
      c)  positive feedback, Aβ=0, θ=0 or multiple 360
      d)  negative feedback, Aβ=1, θ= 360

Answer: a


13. Negative feedback in an amplifier

         a)  increases voltage gain
     b)  decreases voltage gain
     c)  stabilizes voltage gain
     d)  both b and c are correct

Answer: d


14. Input impedance of an amplifier can be increased from 2Kohms to 250Kohms by introducing

         a)  shunt current negative feedback
     b)  shunt voltage negative feedback
     c)  series current negative feedback
     d)  none of these

Answer: c


15. The voltage between the input terminals of an ideal OPAMP is

         a)  zero
     b)  very small
     c)  very large
     c)  equal to te input voltage

Answer: a


16. One of the effects of negative feedback in amplifier is to

         a)  increase the noise
     b)  decrease the harmonic distortion
     c)  increase the voltage gain
     d)  decrease the bandwidth

Answer: b


17. An emitter follower circuit is widely used in electric instruments because

         a)  its voltage gain is very high
     b)  its voltage gain is less than 1
     c)  input impedance is high and output impedance is low
     d)  it employees no bypass capacitor

Answer: c


18. When OPAMP is not saturated, the voltages at the non invertiong and inverting inputs are

        a)  almost equal
        b)  much different
        c)  equal to the output voltage
        d)  equal to -15V

Answer: a


19. Open loop voltage gain equals the

         a)  gain with negative feedback
     b)  differential voltage gain of OPAMP
     c)  Gain when B is 1
     d)  gain at unity

Answer: b


20. The voltage between the input terminals of a real OPAMP is

         a)  0
     b)  very small
     c)  very large
     d)  equal to input voltage

Answer: b


21. Transresistance of an amplifier is the ratio of its

         a)  o/p current ti i/p voltage
     b)  i/p voltage to o/p current
     c)  o/p voltage to i/p voltage
     d)  o/p voltage to i/p current

Answer: d


22. The input impedance of a current – to – voltage converter is

         a)  small
     b)  large
     c)  ideally zero
     d)  ideally infinitre

Answer: c


23. Negative feedback reduces the

         a)  feedback fraction
     b)  distortion
     c)  input offset voltage
     d)  loop gain

Answer: b


24. Voltage follower has a loop gain of

         a)  much less than 1
     b)  1
     c)  more than 1
     d)  A

Answer: b


25. Negative feedback does not improve

         a)  stability of voltage gain
     b)  non linear distortion in later stages
     c)  output offset voltage
     d)  power bandwidth

Answer: d



Hope this post on "Analog Electronics - MCQ on FEEDBACK AMPLIFIERwill help Electronics Engineering and Electrical Engineering students in preparation of technical interviews, GATE, IES etc.

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