# MCQs in The Operational Amplifier

MCQs in The Operational Amplifier from the book Electronic Devices - Electron Flow Version and Conventional Current Version 8th Edition by Thomas L. Floyd.

This is the Multiple Choice Questions in The Operational Amplifier from the book Electronic Devices - Electron Flow Version and Conventional Current Version 8th Edition by Thomas L. Floyd. If you are looking for a reviewer in Electronics Engineering this will definitely help. I can assure you that this will be a great help in reviewing the book in preparation for your Board Exam. Make sure to familiarize each and every questions to increase the chance of passing the ECE Board Exam.

### Practice Exam Test Questions

Choose the letter of the best answer in each questions.

1. Refer to Figure 12-1(a). This amplifier is known as

Figure 12-1

• A. an inverting amplifier.
• B. a non-inverting amplifier.
• C. a voltage-follower.
• D. a common-source amplifier.

2. Refer to Figure 12-1(b). This amplifier is known as

• A. an inverting amplifier.
• B. a non-inverting amplifier.
• C. a voltage-follower.
• D. a common-source amplifier.

3. Refer to Figure 12-1(c). This amplifier is known as

• A. an inverting amplifier.
• B. a non-inverting amplifier.
• C. a voltage-follower.
• D. a common-source amplifier.

4. Refer to Figure 12-1(a). A dc voltage of –1.2 V is applied. VCC = ±12 V. What is the output voltage?

• A. 1.2 V
• B. –1.2 V
• C. 0 V
• D. 12 V

5. Refer to Figure 12-1(b). The voltage gain of this amplifier is

• A. 100.
• B. 5.
• C. 20.
• D. 21.

6. Refer to Figure 12-1(c). If an input signal of –0.5 V were applied, determine the output voltage.

• A. –5 V
• B. 5 V
• C. 10 V
• D. –10 V

7. Refer to Figure 12-1(c). The input impedance of this circuit is

• A. 500 kâ„¦.
• B. 10 kâ„¦.
• C. 50 kâ„¦.
• D. 5 kâ„¦.

8. Refer to Figure 12-1(c). You need an amplifier with an input impedance of 12 kâ„¦. You must not change the amplifier voltage gain. The new value of Ri would be _____ and the new value of Rf would be _____.

• A. 10 kâ„¦, 100 kâ„¦
• B. 13.3 kâ„¦, 120 kâ„¦
• C. 12 kâ„¦, 108 kâ„¦
• D. 12 kâ„¦, 120 kâ„¦

9. Refer to Figure 12-1(b). A dc input signal of –50 mV is applied. You would measure _____ from the inverting input to ground.

`

• A. 50 mV
• B. 1.05 V
• C. –1.05 V
• D. –50 mV

10. It takes an op-amp 22 Âµs to change its output from –15 V to +15 V. Determine the slew rate.

• A. 1.36 V/Âµs
• B. 0.68 V/Âµs
• C. –0.68 V/Âµs
• D. cannot determine

11. Refer to Figure 12-2. The purpose of R1 and R2 is

Figure 12-2

• A. for bias current compensation.
• B. for input offset voltage compensation.
• C. to set input impedance.
• D. to set input impedance and voltage gain.

12. Refer to Figure 12-2. The purpose of R4 is

• A. for bias current compensation.
• B. for input offset voltage compensation.
• C. to set input impedance.
• D. to set input impedance and voltage gain.

13. Refer to Figure 12-2. The purpose of R3 is

• A. for bias current compensation.
• B. for input offset voltage compensation.
• C. to set input impedance.
• D. to set input impedance and voltage gain.

14. Refer to Figure 12-2. If the value of R1 decreases, the voltage gain will _____ and the input impedance will _____.

• A. increase, increase
• B. increase, decrease
• C. decrease, decrease
• D. decrease, increase

15. A voltage-follower amplifier comes to you for service. You find the voltage gain to be 5.5 and the input impedance 22 kâ„¦. The probable fault in this amplifier, if any, is

• A. the gain is too low for this type of amplifier.
• B. the input impedance is too high for this amplifier.
• C. nothing is wrong. The trouble must be somewhere else.
• D. none of these.

16. An op-amp has an open-loop gain of 100,000 and a cutoff frequency of 40 Hz. Find the open-loop gain at a frequency of 30 Hz.

• A. 800
• B. 8,000
• C. 80,000
• D. 100,000

17. An op-amp has an open-loop gain of 75,000 and a cutoff frequency of 100 Hz. At 1 kHz the open-loop gain is down by

• A. 10 dB.
• B. 6 dB.
• C. 20 dB.
• D. 3 dB.

18. An RC network has R = 47 kâ„¦ and C = 0.22 ÂµF. What is the cutoff frequency?

• A. 154 Hz
• B. 1540 Hz
• C. 1.54 Hz
• D. 15.4 Hz

19. An RC network has R = 500 kâ„¦ and C = 10 pF. Find the value of fc.

• A. 31831 Hz
• B. 31.831 kHz
• C. 0.031831 MHz
• D. all of the above

20. A certain op-amp has an open-loop voltage gain of 150,000. What is this gain expressed in dB?

• A. 51.7 dB
• B. 103.5 dB
• C. 150,000 dB
• D. 5.18 dB

21. The midrange open-loop gain of an op-amp is 135 dB. With negative feedback this gain is reduced to 72 dB. The closed-loop gain is

• A. 135 dB.
• B. 72 dB.
• C. 207 dB.
• D. 63 dB.

22. Refer to Figure 12-3(a). Find the midrange gain of this amplifier.

Figure 12-3

• A. 26.7
• B. –26.7
• C. 27.7
• D. –27.7

23. Refer to Figure 12-3(b). Find the midrange gain of this op-amp amplifier.

• A. 10
• B. 11
• C. –10
• D. –11

24. Refer to Figure 12-3(c). The midrange voltage gain of this amplifier is

• A. 0.5.
• B. 27.7.
• C. –11.
• D. 1.

25. Refer to Figure 12-3(a). The op-amp has a unity-gain bandwidth of 3 MHz. Determine the BW of the circuit.

• A. 3 MHz
• B. 30 kHz
• C. 112.4 kHz
• D. infinite in width

26. Refer to Figure 12-3(b). The op-amp has a unity-gain bandwidth of 1.7 MHz. Find the bandwidth of the circuit.

• A. 155 MHz
• B. 155 kHz
• C. 155 Hz
• D. 15.5 Hz

27. Refer to Figure 12-3(c). The unity-gain bandwidth of this op-amp is 10.4 kHz. What is the bandwidth of the circuit?

• A. 10.4 kHz
• B. 15.5 kHz
• C. 3 MHz
• D. 16.7 kHz

28. Refer to Figure 12-4(a). Determine the bandwidth.

Figure 12-4

• A. 1 MHz
• B. 1.5 MHz
• C. 1 kHz
• D. 1.5 kHz

29. Refer to Figure 12-4(b). Calculate the bandwidth.

• A. 8.33 MHz
• B. 833 kHz
• C. 83.3 kHz
• D. 8.33 kHz

30. Negative feedback added to an op-amp _____ the bandwidth and _____ the gain.

• A. increases, increases
• B. increases, decreases
• C. decreases, decreases
• D. decreases, increases

31. A practical op-amp has very _____ input impedance, very _____ output impedance, very _____ open-loop voltage gain, and a _____ bandwidth.

• A. high, low, high, wide
• B. high, high, low, narrow
• C. low, high, high, wide
• D. low, low, low, wide

32. The input offset voltage drift is a parameter directly related to VOS and _____.

• A. ID
• B. power dissipation
• C. temperature
• D. phase shift

33. The maximum rate of change of the output voltage in response to a step input voltage is the _____ of an op-amp.

• A. time constant
• B. maximum frequency
• C. slew rate
• D. static discharge

34. A(n) _____ amplifier configuration has a higher input impedance and a lower output impedance than the op-amp itself.

• A. non-inverting
• B. inverting
• C. voltage-follower
• D. none of the above

35. A(n) _____ amplifier configuration has an input impedance approximately equal to the input resistor Ri and an output impedance approximately equal to the output impedance of the op-amp itself.

• A. non-inverting
• B. inverting
• C. voltage-follower
• D. none of the above

36. The _____ amplifier configuration has the highest input impedance and the lowest output impedance of the three basic op-amp configurations.

• A. non-inverting
• B. inverting
• C. voltage-follower
• D. none of the above

37. Open-loop voltage gain of an op-amp can range up to _____.

• A. 10,000
• B. 50,000
• C. 100,000
• D. 200,000

38. The ______ is the voltage gain of an op-amp with external feedback.

• A. Aol
• B. Acl
• C. Av
• D. none of the above

39. A three-stage op-amp can have a maximum phase lag of _____°.

• A. –180
• B. –90
• C. –270
• D. none of the above

#### TRUE/FALSE

1. A good op-amp has low voltage gain, low output impedance, and high input impedance.

• A. True
• B. False

2. The common-mode rejection ratio (CMRR) is a measure of an op-amp's ability to reject common-mode input signals.

• A. True
• B. False

3. An inverting amplifier has an input impedance equal to the feedback resistor Rf.

• A. True
• B. False

4. A non-inverting amplifier has a higher input impedance and a lower output impedance than the op-amp itself (without feedback).

• A. True
• B. False

5. All practical op-amps have input bias currents and voltages that produce output error voltages.

• A. True
• B. False

6. Open-loop gain of an op-amp is the voltage gain without feedback.

• A. True
• B. False

7. Closed-loop gain is the gain with negative feedback.

• A. True
• B. False

8. Open-loop gain is always smaller than closed-loop gain.

• A. True
• B. False

9. Negative feedback decreases the bandwidth and increases the voltage gain.

• A. True
• B. False

10. When the open-loop gain of an op-amp is reduced by negative feedback, the bandwidth is increased.

• A. True
• B. False

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