Feedback Amplifiers


Question 1
In the circuit shown below, V_{1} and V_{2} are bias voltages. Based on input and output impedances, the circuit behaves as a

A
voltage controlled voltage source.
B
voltage controlled current source.
C
current controlled voltage source.
D
current controlled current source.
GATE EC 2023   Analog Circuits
Question 1 Explanation: 


Here from circuit,
M_{1} is common-gate amplifier and M_{2} behaves as an active load.
By using properties of common gate (CG) amplifier,
Input impedance \left(R_{i}\right) is low
Output impedance \left(R_{0}\right) is high
So, it is a current amplifier.
Current amplifier is a current controlled current source.
Question 2
A good transimpedance amplifier has
A
low input impedance and high output impedance.
B
high input impedance and high output impedance.
C
high input impedance and low output impedance.
D
low input impedance and low output impedance.
GATE EC 2018   Analog Circuits
Question 2 Explanation: 
A good transimpedance amplifier should have low input impedance and low output impedance


Question 3
A good transconductance amplifier should have
A
high input resistance and low output resistance
B
low input resistance and high output resistance
C
high input and output resistances
D
low input and output resistance
GATE EC 2017-SET-1   Analog Circuits
Question 3 Explanation: 
A good transconductance amplifier should have very high input resistance and very high output resistance.
Question 4
The desirable characteristics of a transconductance amplifier are
A
high input resistance and high output resistance
B
high input resistance and low output resistance
C
low input resistance and high output resistance
D
low input resistance and low output resistance
GATE EC 2014-SET-3   Analog Circuits
Question 5
The feedback topology in the amplifier circuit ( the base bias circuit is not shown for simplicity) in the figure is
A
Voltage shunt feedback
B
Current series feedback
C
Current shunt feedback
D
Voltage series feedback
GATE EC 2014-SET-2   Analog Circuits
Question 5 Explanation: 
The feedback topology in the amplifier circuit is
current series because
Sampling \rightarrow Current
Mixing \rightarrow Series
So current-series feedback


There are 5 questions to complete.