MCQs in Operational Amplifiers

This is the Multiple Choice Questions in Operational Amplifiers from the book Electronic Devices and Circuit Theory 10th Edition by Robert L. Boylestad. 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.

Online Questions and Answers Topic Outline

• MCQs in Differential Amplifier circuit
• MCQs in BiFET, BiMOS, and CMOS Differential Amplifier circuit
• MCQs in Op-Amp Basics
• MCQs in Practical Op-Amp Circuits
• MCQs in Op-Amp Specifications—DC Offset Parameters
• MCQs in Op-Amp Specifications—Frequency Parameters
• MCQs in Op-Amp Unit Specifications
• MCQs in Differential and Common-Mode Operation

Practice Exam Test Questions

Choose the letter of the best answer in each questions.

1. In which of the following are operational amplifiers (op-amps) used?

• a. Oscillators
• b. Filters
• c. Instrumentation circuits
• d. All of the above

2. This circuit is an example of a _____.

• a. single-ended input
• b. double-ended (differential) input
• c. double-ended output
• d. common-mode operation

3. This circuit is an example of a _____.

• a. single-ended input
• b. double-ended (differential) input
• c. double-ended output
• d. common-mode operation

4. This circuit is an example of a _____.

• a. single-ended input
• b. double-ended (differential) input
• c. double-ended output
• d. common-mode operation

5. This circuit is an example of a _____.

• a. single-ended input
• b. double-ended (differential) input
• c. double-ended output
• d. common-mode operation

6. In which of the following operations is the resulting output signal of the differential amplifier near zero?

• a. Single-ended
• b. Double-ended
• c. Common-mode
• d. None of the above

7. In the differential amplifier circuit, which of the following terminals are connected together?

• a. Bases
• b. Collectors
• c. One base to another collector
• d. Emitters

8. Which of the following circuits is referred to as a BiMOS circuit?

• a. Bipolar and FET
• b. Bipolar and MOSFET
• c. Opposite-type MOSFETs
• d. None of the above

9. An IC unit made using both _____ and _____ transistors is called a _____ circuit.

• a. bipolar, MOSFET, BiFET
• b. bipolar, MOSFET, BiMOS
• c. TTL, MOSFET, TailFET

10. What is the level of the voltage between the input terminals of an op-amp?

• a. Virtually zero
• b. 5 V
• c. 18 V
• d. 22 V

11. What is the level of the current through the amplifier input(s) to ground in an op-amp?

• a. Virtually zero
• b. 1.7 mA
• c. 2.8 mA
• d. 3.3 mA

12. If R_f = R_1’, the voltage gain is _____.

• a. 1
• b. –1
• c. 10
• d. very small

13. Calculate the overall voltage gain of the circuit if R₁ = 100 and R_f = 1 kΩ.

• a. –1
• b. –10
• c. 11
• d. 9

14. Calculate the overall voltage gain of the circuit if R₁ = 100 Ω and R_f = 1 kΩ.

• a. –1
• b. –10
• c. 11
• d. 9

15. What is the voltage gain of the unity follower?

• a. 0
• b. 1
• c. –1
• d. Infinity

16. Calculate the input voltage if R₁ = 100 Ω, R_f = 1 kΩ, and V_out = 550 mV.

• a. –50 mV
• b. –5 mV
• c. 550 mV
• d. 50 mV

17. Calculate the output voltage if R₁ = R₂ = R₃ = 100 Ω, Rf = 1 kΩ, and V₁ = V₂ = V₃ = 50 mV.

• a. –1.5 V
• b. 1.5 V
• c. 0.5 V
• d. –0.5 V

18. What is the scale multiplier (factor) of a basic integrator?

• a. R / C
• b. C / R
• c. –RC
• d. –1 / RC

19. The summing amplifier contains an inverting amplifier.

• a. True
• b. False

20. This circuit is referred to as a(n) _____.

• a. inverting amplifier
• b. noninverting amplifier
• c. unity follower
• d. integrator

21. This circuit is referred to as a(n) _____.

• a. inverting amplifier
• b. noninverting amplifier
• c. differentiator
• d. integrator

22. This circuit is referred to as a(n) _____.

• a. inverting amplifier
• b. noninverting amplifier
• c. differentiator
• d.integrator

23. Which of the following circuit conditions affect(s) the output offset voltage of an op-amp?

• a. An input offset voltage, V_IO
• b. An input offset current, I_IO
• c. Both an input offset voltage, V_IO and an input offset current, I_IO
• d. None of the above

24. What is the level of the roll-off in most op-amps?

• a. –6 dB / decade
• b. –20 dB / octave
• c. –6 dB / decade or –20 dB / octave
• d. –20 dB / decade or –6 dB / octave

25. Which of the following is (are) the result of gain reduction by a feedback?

• a. The amplifier voltage gain is a more stable and precise value.
• b. The input impedance of the circuit is increased over that of the op-amp alone.
• c. The output impedance is reduced over that of the op-amp alone.
• d. All of the above

26. What is the open-loop gain of an op-amp at the gain-bandwidth product of the op-amp?

• a. 200,000
• b. 50,000
• c. 200
• d. 1

27. What is the cutoff frequency of an op-amp if the unity-gain frequency is 1.5 MHz and the open-loop gain is 100,000?

• a. 5 Hz
• b. 10 Hz
• c. 15 Hz
• d. 20 Hz

28. What is the slew rate of an op-amp if the output voltages change from 2 V to 3 V in 0.2 ms?

• a. 5 V/ms
• b. 3 V/ms
• c. 2 V/ms
• d. 1 V/ms

29. For an op-amp having a slew rate SR = 5 V/ms, what is the maximum closed-loop voltage gain that can be used when the input signal varies by 0.2 V in 10 ms?

• a. 150
• b. 200
• c. 250
• d. 300

30. Calculate the output impedance of an inverting op-amp using the 741 op-amp (r_o = 75 Ω, A_OL = 200 V/mV) if R₁ = 100 Ω and Rf = 1 kΩ.

• a. 0.011
• b. 0.00375
• c. 0.0375
• d. 0.375

31. What is the difference output voltage of any signals applied to the input terminals?

• a. The differential gain times the difference input voltage.
• b. The common-mode gain times the common input voltage.
• c. The sum of the differential gain times the difference input voltage and the common-mode gain times the common input voltage.
• d. The difference of the differential gain times the difference input voltage and the common-mode gain times the common input voltage.

32. What is the difference voltage if the inputs are an ideal opposite signal?

• a. The differential gain times twice the input signal.
• b. The differential gain times the input signal.
• c. The common-mode gain times twice the input signal.
• d. The common-mode gain times the input signal.

33. What is the difference voltage if the inputs are an ideal in-phase signal?

• a. The differential gain times twice the input signal.
• b. The differential gain times the input signal.
• c. The common-mode gain times twice the input signal.
• d. The common-mode gain times the input signal.

34. At what input voltage level does the output voltage level become numerically equal to the value of the differential gain of the amplifier?

• a. Vi₁ = –Vi₂ = 0.25 V
• b. V i₁ = –V i₂ = 0.50 V
• c. V i₁ = –V i₂ = 0.75 V
• d. V i₁ = –Vi₂ = 1.00 V

35. At what input voltage level does the output voltage level become numerically equal to the value of the common-mode gain of the amplifier?

• a. Vi₁ = –Vi₂ = 0.25 V
• b. Vi₁ = –Vi₂ = 0.50 V
• c. Vi₁ = –Vi₂ = 0.75 V
• d.Vi₁ = –Vi₂ = 1.00 V

FILL-IN-THE-BLANKS

1. An operational amplifier is a _____ gain and _____ bandwidth differential amplifier.

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

2. An operational amplifier has a _____ input impedance and a _____ output impedance.

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

3. The output signal of an op-amp is _____ out of phase with its input signal connected to the inverting input terminal.

• A. 0º
• B. 90º
• C. 180º
• D. 270º

4. In double-ended (differential) input operation, _____.

• A. an input is applied between the two input terminals
• B. two separate signals are applied to the input terminals
• C. either an input is applied between the two input terminals or two separate signals are applied to the input terminals
• D. None of the above

5. An input applied to either input terminal will result in _____.

• A. outputs from both output terminals, which have opposite polarities
• B. outputs from both output terminals, which have the same polarities
• C. a single output from one of the output terminals
• D. None of the above

6. In a differential connection, the signals that are opposite at the inputs are _____ amplified, and those that are common to the two inputs are _____ amplified.

• A. slightly, slightly
• B. slightly, highly
• C. highly, highly
• D. highly, slightly

7. In a differential amplifier circuit, if an input signal is applied to either input with the other input connected to ground, the operation is referred to as _____.

• A. double-ended
• B. single-ended
• C. common-mode
• D. All of the above

8. If two opposite-polarity input signals are applied, the operation is referred to as _____.

• A. double-ended
• B. single-ended
• C. common-mode
• D. All of the above

9. If the same input is applied to both inputs, the operation is called _____.

• A. double-ended
• B. single-ended
• C. common-mode
• D. All of the above

10. The main feature of the differential amplifier is the _____ gain when opposite signals are applied to the inputs as compared to the _____ gain resulting from common inputs.

• A. very large, large
• B. very small, large
• C. very small, very large
• D. very large, very small

11. An IC unit containing a differential amplifier built using both bipolar and FET transistors is referred to as a _____ circuit.

• A. CMOS
• B. BiFET
• C. BiMOS
• D. None of the above

12. An IC unit containing a differential amplifier built using opposite-type MOSFET transistors is referred to as a _____ circuit.

• A. CMOS
• B. BiFET
• C. BiMOS
• D. None of the above

13. A _____ differential amplifier is particularly well suited for battery operation due to its low power consumption.

• A. BiFET
• B. BiMOS
• C. CMOS
• D. BJT

14. An ideal op-amp circuit has _____input impedance, _____ output impedance, and _____ voltage gain.

• A. zero, infinite, infinite
• B. infinite, zero, zero
• C. zero, zero, infinite
• D. infinite, zero, infinite

15. The _____ amplifier is the most widely used constant-gain amplifier circuit.

• A. inverting
• B. noninverting
• C. differential
• D. None of the above

16. The feedback component of an integrator is a(n) _____.

• A. resistor
• B. capacitor
• C. inductor
• D. diode

17. _____ is the unit for the slew rate, SR.

• A. V/ms
• B. ms/V
• C. V
• D. V/s

18. The maximum frequency at which an op-amp may operate depends on the _____.

• A. bandwidth (BW)
• B. slew rate (SR)
• C. unity-gain bandwidth
• D. All of the above

19. As the supply voltage increases, the voltage gain of the circuit _____ and the power consumption _____.

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

20. As the frequency increases, the input impedance of an op-amp _____ and the output impedance _____.

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

21. Inverting amplifier connection is more widely used because it has _____.

• A. higher gain
• B. better frequency stability
• C. unit gain
• D. None of the above

22. The output offset voltage is determined by _____.

• A. the input offset voltage and input offset current
• B. the closed-loop gain
• C. both the input offset voltage and the closed-loop gain
• D. None of the above

23. The ratio of the unity-gain frequency to the cutoff frequency is numerically equal to the level of _____.

• A. CMRR
• B. common-mode gain
• C. closed-loop gain
• D. open-loop gain

24. When both input signals are the same, a common signal element due to the two inputs can be defined as the _____ of the two signals.

• A. difference
• B. sum
• C. average of the sum
• D. product

25. The common-mode rejection ratio (CMRR) is defined by _____.

• A. A_d / A_c
• B. A_c / A_d
• C. A_d × A_c
• D. A_d + A_c

26. Ideally, the value of the CMRR is _____. Practically, the _____ the value of CMRR, the better the circuit operation.

• A. zero, smaller
• B. infinite, larger
• C. zero, larger
• D. infinite, smaller

Complete List of Chapter Quiz in Electronic Devices and Circuit Theory

Multiple Choice Questions in Electronic Devices and Circuit Theory

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