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 kΩ.
- B. 10 kΩ.
- C. 50 kΩ.
- D. 5 kΩ.
8. Refer to Figure 12-1(c). You need an amplifier with an input impedance of 12 kΩ. 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 kΩ, 100 kΩ
- B. 13.3 kΩ, 120 kΩ
- C. 12 kΩ, 108 kΩ
- D. 12 kΩ, 120 kΩ
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 µs to change its output from –15 V to +15 V. Determine the slew rate.
- A. 1.36 V/µs
- B. 0.68 V/µs
- C. –0.68 V/µs
- 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 kΩ. 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 kΩ and C = 0.22 µF. 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 kΩ 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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