Amplifier MCQs | Amplifier Multiple Choice Questions and Answers

Questions
1 A differential amplifier ……………..
A is a part of an Op-amp
B has one input and one output
C has two outputs
D answers (1) and (2)

Answer: answers (1) and (2)
2 When a differential amplifier is operated single-ended, …………
A the output is grounded
B one input is grounded and signal is applied to the other
C both inputs are connected together
D the output is not inverted

Answer: one input is grounded and signal is applied to the other
3 If ADM = 3500 and ACM = 0.35, the CMRR is ……….
A 1225
B 10,000
C 80 dB
D answers (1) and (3)

Answer: answers (1) and (3)
4 With zero volts on both inputs, an OP-amp ideally should have an output ………..
A equal to the positive supply voltage
B equal to the negative supply voltage
C equal to zero
D None of the above

Answer: equal to zero
5 A certain OP-amp has bias currents of 50 μA. The input offset current is ……..
A 700 nA
B 99.3 μA
C 49.7 μA
D none of these

Answer: 700 nA
6 The output of a particular Op-amp increases 8V in 12μs. The slew rate is …….
A 90 V/μs
B 0.67 V/μs
C 1.5 V/μs
D none of these

Answer: 0.67 V/μs
7 For an Op-amp with negative feedback, the output is …….
A equal to the input
B increased
C fed back to the inverting input
D None Of The Above

Answer: fed back to the inverting input
8 The use of negative feedback ………
A reduces the voltage gain of an Op-amp
B makes the Op-amp oscillate
C makes linear operation possible
D answers (1) and (2)

Answer: answers (1) and (2)
9 The gain of an amplifier without feedback is 100 db. If a negative feedback of 3 db is applied, the gain of the amplifier will become …………..
A 5 db
B 300 db
C 97 db
D None of the Above

Answer: 97 db
10 The value of negative feedback fraction is always …………….
A Less than 1
B More than 1
C Equal to 1
D None Of The Above

Answer: Less than 1
11 When negative voltage feedback is applied to an amplifier, its voltage gain ……………….
A Is increased
B Is reduced
C Remains the same
D None of the above

Answer: Is reduced
12 Current cannot flow to ground through …….
A a mechanical ground
B an a.c. ground
C a virtual ground
D None of the above

Answer: a virtual ground
13 The input stage of an Op-amp is usually a ……….
A differential amplifier
B class B push-pull amplifier
C CE amplifier
D swamped amplifier

Answer: differential amplifier
14 The common-mode voltage gain is ………
A smaller than differentail voltage gain
B equal to differential voltage gain
C greater than differential voltage gain
D none of the above

Answer: smaller than differentail voltage gain
15 A common-mode signal is applied to ……….
A the noninverting input
B the inverting input
C both iputs
D top of the tail resistor

Answer: both iputs
16 The tail current in a differential amplifier equals …….
A difference between two emitter currents
B sum of two emitter currents
C collector current divided by current gain
D None of the above

Answer: sum of two emitter currents
17 The tail current of a differential amplifier is …….
A half of either collector current
B equal to either collector current
C two times either collector current
D equal to the difference in base currents

Answer: two times either collector current
18 The input offset current equals the ……….
A difference between two base currents
B average of two base currents
C collector current divided by current gain
D None of the above

Answer: difference between two base currents
19 Negative feedback ………..
A increases the input and output impedances
B increases the input impedance and bandwidth
C decreases the output impedance and bandwidth
D None of the above

Answer: increases the input impedance and bandwidth
20 In the common mode, ……………
A both inputs are grounded
B the outputs are connected together
C an identical signal appears on both the inputs
D the output signal are in-phase

Answer: an identical signal appears on both the inputs
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