250+ TOP MCQs on Effect of Finite Open-Loop gain and Bandwidth on Circuit Performance and Answers

Electronic Devices and Circuits Multiple Choice Questions on “Effect of Finite Open-Loop gain and Bandwidth on Circuit Performance”.

1. An internally compensated op amp is specified to have an open-loop dc gain of 106 dB and a unity gain bandwidth of 3 MHz. Find fb and the open-loop gain at fb.
A. 15Hz and 103 db
B. 30Hz and 103 db
C. 15 Hz and 51.5 db
D. 30 Hz and 51.5 db

Answer: A

2. A single-pole model has __________ db/decade roll-off of the gain.
A. -3 db/decade
B. -6 db/decade
C. -10 db/decade
D. -20 db/decade

Answer: D
Clarification: It is a standard characteristic of a single-pole model.

3. Single-pole model is also known as
A. Frequent pole
B. Stable pole
C. Dominant pole
D. Responsive pole

Answer: C
Clarification: Single-pole model is also called dominant pole.

4. An op amp having a 106-dB gain at dc and a single-pole frequency response with ft = 2 MHz is used to design a non-inverting amplifier with nominal dc gain of 100. The 3-dB frequency of the closed-loop gain is
A. 10 kHz
B. 20 kHz
C. 30 kHz
D. 40 kHz

Answer: B
5. An internally compensated op amp has a dc open-loop gain of 106 V/V and an AC open-loop gain of 40 dB at 10 kHz. Estimate its gain–bandwidth product and its expected gain at 1 kHz.
A. 0.1 MHz and -60 db
B. 10 MHz and -60 db
C. 10 MHz and 60 db
D. 1 MHz and 60 db
Answer: D

6. An inverting amplifier with nominal gain of −20 V/V employs an op amp having a dc gain of 104 and a unity-gain frequency of 106 Hz. What is the 3-dB frequency f3dB of the closed-loop amplifier?
A. 2π 23.8 kHz
B. 2π 47.6 kHz
C. 2π 71.4 kHz
D. 2π 95.2 kHz

Answer: B

7. cascading two identical amplifier stages, each having a low-pass STC frequency response with a 3dB frequency f1, results in an overall amplifier with a 3dB frequency given by
A. √(√2+1) f1
B. √(√3-1) f1
C. √(√2-1) f1
D. √(√3+1) f1

Answer: C

8. Find the ft required for internally compensated op amps to be used in the implementation of the closed loop amplifiers with dc gain of +100 V/V and 3db bandwidth of 100kHz?
A. 1 kHz
B. 10 kHz
C. 100 kHz
D. 1 MHz

Answer: B
Clarification: None

9. A particular op amp, characterized by a gain–bandwidth product of 20 MHz, is operated with a closed-loop gain of +100 V/V. What 3-dB bandwidth results? At what frequency does the closed-loop amplifier exhibit a −6° phase shift?
A. 21 kHz
B. 31.5 kHz
C. 42 kHz
D. 52.5 kHz

Answer: A

10. Find the ft required for internally compensated op amps to be used in the implementation of the closed loop amplifiers with dc gain of -2 V/V and 3db bandwidth of 10 MHz?
A. 7.5 MHz
B. 15 MHz
C. 22.5 MHz
D. 30 MHz

Answer: D
Clarification: -R2R1 = -2VV
f3db = 10 MHZ ft = 10 MHZ(2 + 1) = 30 MHZ.