# Floyd Self-test in The Operational Amplifier

(Last Updated On: December 7, 2019) 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

If you are looking for the Multiple Choice Questions in Floyd’s Electronic Devices proceed to

#### 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

Solution:

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

Solution:

3. A differential amplifier

(a) is part of an op-amp

(b) has one input and one output

(c) has two outputs

Solution:

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

Solution:

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

Solution:

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

Solution:

7. Common-mode gain is

(a) very high

(b) very low

(c) always unity

(d) unpredictable

Solution:

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

(a) 1225

(b) 10,000

(c) 80 dB

Solution:

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

Solution:

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

Solution:

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

Solution:

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

(a) 96 V/μs

(b) 0.67 V/μs

(c) 1.5 V/μs

(d) none of these

Solution:

13. The purpose of offset nulling is to

(a) reduce the gain

(b) equalize the input signals

(c) zero the output error voltage

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Solution:

19. A voltage-follower

(a) has a gain of 1

(b) is noninverting

(c) has no feedback resistor

(d) has all of these

Solution:

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

Solution:

21. Bias current compensation

(a) reduces gain

(b) reduces output error voltage

(c) increases bandwidth

(d) has no effect

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Solution:

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

(a) increases

(b) decreases

(c) stays the same

(d) fluctuates

Solution:

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

Solution:

### Complete List of Floyd Self-test in Electronic Devices

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