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GATE : Previous questions on Feedback Amplifier

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GATE 1993
1) Negative feedback in Amplifiers

a) Improves the Signal to Noise ratio at I/p
b) Improves the Signal to Noise ratio at O/p
c) Does not improvee signal to noise ratio at I/o
d) Reduces distortion

Ans : d

GATE 1995
2) To obtain very high input impedance and output impedances in a feedback Amplifier , which is the suitable configuration

a) Voltage – Series
b) Current – Series
c) Voltage – Shunt
d) Current – Shunt

Ans : b

Note: Explanation is given after 3rd question.

GATE 1998
3) In a shunt-shunt negative feedback Amplifier, as compared to the basic Amplifer.

a) Both input and output impedance increases
b) Input impedance decreases, but output impedance increases
c) Input impedance increases, but output impedance decreases
d) both input and output impedance increases

Hint : Feedback topology naming convention goes this way

Shunt(I/P) – Shunt(O/P). Remember Shunt-Shunt is also called as Voltage – Shunt. You can read that HERE
Impedance at input or output side depends on the word Series/Shunt. If Series then impedance increases
and if Shunt, then impedance decrease. In this question, the feedback topology is shunt-shunt, hence the correct answer is option d.

Ans : d

GATE 1991

4) Two non-inverting amplifiers, one having a unity gain and other having a gain of twenty, are made using identical operational amplifiers. As compared to the unity gain amplifier, the amplifier with gain twenty has

a) less negative feedback
b) More input impedance
c) Less Bandwidth
d) None of the above

Ans : c

Try to dissolve the above question.

More questions will be added..

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