# Floyd Self-test in The Operational Amplifier

(Last Updated On: December 8, 2017)

This is the Self-test in Chapter 12: The Operational Amplifier from the book Electronic Devices Conventional Current Version, 9th edition by Thomas L. Floyd. If you are looking for a reviewer in Electronics Engineering this will definitely help you before taking the Board Exam.

### Floyd Self-test Chapter 12 Topic Outline

• Floyd Self-test in Introduction to Operational Amplifiers
• Floyd Self-test in Op-Amp Input Modes and Parameters
• Floyd Self-test in Negative Feedback
• Floyd Self-test in Op-Amps with Negative Feedback
• Floyd Self-test in Effects of Negative Feedback on Op-Amp Impedances
• Floyd Self-test in Bias Current and Offset Voltage
• Floyd Self-test in Open-Loop Frequency and Phase Responses
• Floyd Self-test in Closed-Loop Frequency Response

### Start Practice Exam Test Questions

Choose the letter of the best answer in each questions.

1. An integrated circuit (IC) op-amp has

• (a) two inputs and two outputs
• (b) one input and one output
• (c) two inputs and one output

2. Which of the following characteristics does not necessarily apply to an op-amp?

• (a) High gain
• (b) Low power
• (c) High input impedance
• (d) Low output impedance

3. A differential amplifier

• (a) is part of an op-amp
• (b) has one input and one output
• (c) has two outputs
• (d) answers (a) and (c)

4. When an op-amp is operated in the single-ended differential mode,

• (a) the output is grounded
• (b) one input is grounded and a signal is applied to the other
• (c) both inputs are connected together
• (d) the output is not inverted

5. In the double-ended differential mode,

• (a) a signal is applied between the two inputs
• (b) the gain is 1
• (c) the outputs are different amplitudes
• (d) only one supply voltage is used

6. In the common mode,

• (a) both inputs are grounded
• (b) the outputs are connected together
• (c) an identical signal appears on both inputs
• (d) the output signals are in-phase

7. Common-mode gain is

• (a) very high
• (b) very low
• (c) always unity
• (d) unpredictable

8. If Aol = 3500 and Acm = 0.35, the CMRR is

• (a) 1225
• (b) 10,000
• (c) 80 dB
• (d) answers (b) and (c)

9. With zero volts on both inputs, an op-amp ideally should have an output equal to

• (a) the positive supply voltage
• (b) the negative supply voltage
• (c) zero
• (d) the CMRR

10. Of the values listed, the most realistic value for open-loop gain of an op-amp is

• (a) 1
• (b) 2000
• (c) 80 dB
• (d) 100,000

11. A certain op-amp has bias currents of 50μA and 49.3μA. The input offset current is

• (a) 700 nA
• (b)99.3μA
• (c)49.7μA
• (d) none of these

12. The output of a particular op-amp increases 8 V in 12μs. The slew rate is

• (a) 96V/ μs
• (b)0.67V/ μs
• (c) 1.5V/ μs
• (d) none of these

13. The purpose of offset nulling is to

• (a) reduce the gain
• (b) equalize the input signals
• (c) zero the output error voltage
• (d) answers (b) and (c)

14. 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 (a) and (c)

15. 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) fed back to the noninverting input

16. A certain noninverting amplifier has an Ri of and an Rf of The closed-loop gain is

• (a) 100,000
• (b) 1000
• (c) 101
• (d) 100

17. If the feedback resistor in Question 16 is open, the voltage gain

• (a) increases
• (b) decreases
• (c) is not affected
• (d) depends on Ri

18. A certain inverting amplifier has a closed-loop gain of 25. The op-amp has an open-loop gain of 100,000. If another op-amp with an open-loop gain of 200,000 is substituted in the configuration, the closed-loop gain

• (a) doubles
• (b) drops to 12.5
• (c) remains at 25
• (d) increases slightly

19. A voltage-follower

• (a) has a gain of 1
• (b) is noninverting
• (c) has no feedback resistor
• (d) has all of these

20. Negative feedback

• (a) increases the input and output impedances
• (b) increases the input impedance and the bandwidth
• (c) decreases the output impedance and the bandwidth
• (d) does not affect impedances or bandwidth

21. Bias current compensation

• (a) reduces gain
• (b) reduces output error voltage
• (c) increases bandwidth
• (d) has no effect

22. The midrange open-loop gain of an op-amp

• (a) extends from the lower critical frequency to the upper critical frequency
• (b) extends from 0 Hz to the upper critical frequency
• (c) rolls off at 20 dB/decade beginning at 0 Hz
• (d) answers (b) and (c)

23. The frequency at which the open-loop gain is equal to 1 is called

• (a) the upper critical frequency
• (b) the cutoff frequency
• (c) the notch frequency
• (d) the unity-gain frequency

24. Phase shift through an op-amp is caused by

• (a) the internal RC circuits
• (b) the external RC circuits
• (c) the gain roll-off
• (d) negative feedback

25. Each RC circuit in an op-amp

• (a) causes the gain to roll off at
• (b) causes the gain to roll off at
• (c) reduces the midrange gain by 3 dB
• (d) answers (a) and (b)

26. If a certain op-amp has a midrange open-loop gain of 200,000 and a unity-gain frequency of 5 MHz, the gain-bandwidth product is

• (a) 200,000 Hz
• (b) 5,000,000 Hz
• (c) 1 x 1012 Hz
• (d) not determinable from the information

27. The bandwidth of an ac amplifier having a lower critical frequency of 1 kHz and an upper critical frequency of 10 kHz is

• (a) 1 kHz
• (b) 9 kHz
• (c) 10 kHz
• (d) 11 kHz

28. The bandwidth of a dc amplifier having an upper critical frequency of 100 kHz is

• (a) 100 kHz
• (b) unknown
• (c) infinity
• (d) 0 kHz

29. When negative feedback is used, the gain-bandwidth product of an op-amp

• (a) increases
• (b) decreases
• (c) stays the same
• (d) fluctuates

30. If a certain op-amp has a closed-loop gain of 20 and an upper critical frequency of 10 MHz, the gain-bandwidth product is

• (a) 200 MHz
• (b) 10 MHz
• (c) the unity-gain frequency
• (d) answers (a) and (c)