MCQs in FET Amplifiers and Switching Circuits

This is the Multiple Choice Questions in FET Amplifiers and Switching Circuits 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. A common-drain amplifier is similar in configuration to which BJT amplifier?

• A. common-emitter
• B. common-collector
• C. common-base
• D. common-gate

2. A common-source amplifier is similar in configuration to which BJT amplifier?

• A. common-base
• B. common-collector
• C. common-emitter
• D. emitter-follower

3. A common-gate amplifier is similar in configuration to which BJT amplifier?

• A. common-emitter
• B. common-collector
• C. common-base
• D. emitter-follower

4. In a common-source amplifier, the purpose of the bypass capacitor, C₂, is to

• A. keep the source effectively at ac ground.
• B. provide a dc path to ground.
• C. provide coupling to the input.
• D. provide coupling to the load.

5. Which FET amplifier(s) has (have) a phase inversion between input and output signals?

• A. common-gate
• B. common-drain
• C. common-source
• D. all of the above

6. Input resistance of a common-drain amplifier is

• A. R_G || R_IN(gate).
• B. RG + R_IN(gate).
• C. RG.
• D. R_IN(gate).

7. Refer to Figure 9-1. For midpoint biasing, I_D would be

Figure 9-1

• A. 10 mA.
• B. 7.5 mA.
• C. 5 mA.
• D. 2.5 mA.

8. Refer to Figure 9-1. Find the value of V_D.

• A. 20 V
• B. 11 V
• C. 10 V
• D. 9 V

9. Refer to Figure 9-1. If V_GS = –6 V, calculate the value of R_S that will provide this value.

• A. 2.2 kΩ
• B. 1.2 kΩ
• C. 600 kΩ
• D. 100 kΩ

10. Refer to Figure 9-1. The voltage gain is

• A. 1.2.
• B. 2.4.
• C. 4.4.
• D. 8.8.

11. Refer to Figure 9-1. If V_in = 20 mV p-p what is the output voltage?

• A. 176 mV p-p
• B. 88 mV p-p
• C. 48 mV p-p
• D. 24 mV p-p

12. Refer to Figure 9-1. If V_in = 1 V p-p, the output voltage V_out would be

• A. undistorted.
• B. clipped on the negative peaks.
• C. clipped on the positive peaks.
• D. 0 V p-p.

13. Refer to Figure 9-2. If I_D = 4 mA, I_DSS = 16 mA, and V_GS(off) = –8 V, find V_DS.

Figure 9-2

• A. 19.2 V
• B. –6 V
• C. 10.8 V
• D. 30 V

14. Refer to Figure 9-2. If I_D = 4 mA, find the value of V_GS.

• A. 10.8 V
• B. 6 V
• C. –0.7 V
• D. –6 V

15. Refer to Figure 9-2. If g_m = 4000 mS and a signal of 75 mV rms is applied to the gate, calculate the p-p output voltage.

• A. 990 mV
• B. 1.13 V p-p
• C. 2.8 V p-p
• D. 990 V p-p

16. Refer to Figure 9-2. The approximate value of R_in is

• A. 100 MΩ.
• B. 1.5 kΩ.
• C. 3.3 kΩ.
• D. 48 MΩ.

17. Refer to Figure 9-3. If C₄ opened, the signal voltage at the drain of Q₁ would

Figure 9-3

• A. increase.
• B. decrease.
• C. remain the same.
• D. distort.

18. Refer to Figure 9-3. If R₇ were to decrease in value, V_out would

• A. increase.
• B. decrease.
• C. remain the same.
• D. distort.

19. Refer to Figure 9-3. If C₂ shorted, V_out would

• A. increase.
• B. decrease.
• C. remain the same.
• D. distort.

20.Refer to Figure 9-3. If V_in was increased in amplitude a little, the signal voltage at the source of Q₂ would

• A. increase.
• B. decrease.
• C. remain the same.
• D. distort.

21. Refer to Figure 9-3. If R₆ opened, the signal at the drain of Q₁ would

• A. increase.
• B. decrease.
• C. remain the same.
• D. distort.

22. A JFET cascade amplifier employs

• A. 2 common-gate amplifiers.
• B. 2 common-source amplifiers.
• C. 1 common-gate and 1 common-source amplifier.
• D. 1 common-gate and 1 common-drain amplifier.

23. The theoretical efficiency of a class D amplifier is

• A. 75%.
• B. 85%.
• C. 90%.
• D. 100%.

24. The input resistance at the gate of a FET is extremely

• A. high.
• B. low.

25. There is a _____º phase inversion between gate and source in a source follower.

• A. 0
• B. 90
• C. 180
• D. none of the above

26. What is the input resistance (R_in(source)) of a common-gate amplifier?

• A. Rs
• B. (1 /gm) ||Rs
• C. 1 / gm
• D. none of the above

27. Which type of FETs can operate with a gate-to-source Q-point value of 0 V?

• A. JFET
• B. E-MOSFET
• C. D-MOSFET
• D. none of the above

28. What common factor determines the voltage gain and input resistance of a common-gate amplifier?

• A. RD
• B. RL
• C. gm
• D. none of the above

29. The class D amplifier uses what type of transistors?

• A. JFETs
• B. BJTs
• C. MOSFETs
• D. any of the above

30. Class D amplifiers differ from all other classes of amplifiers because

• A. the output transistors are operated as switches.
• B. of their very low input capacitance.
• C. of their high-frequency response capabilities.
• D. they employ dual MOSFETs.

31. E-MOSFETs are generally used in switching applications because

• A. of their very low input capacitance.
• B. of their threshold characteristic (V_GS(th)).
• C. of their high-frequency response capabilities.
• D. of their power handling.

32. What limits the signal amplitude in an analog MOSFET switch?

• A. the switch input capacitance
• B. V_GS(th)
• C. the switch's power handling
• D. V_DS

33. MOSFET digital switching is used to produce which digital gates?

• A. inverters
• B. NOR gates
• C. NAND gates
• D. all of the above

34. CMOS digital switches use

• A. n-channel and p-channel D-MOSFETs in series.
• B. n-channel and p-channel D-MOSFETs in parallel.
• C. n-channel and p-channel E-MOSFETs in series.
• D. n-channel and p-channel E-MOSFETs in parallel.

35. MOSFETs make better power switches than BJTs because they have

• A. lower turn-off times.
• B. lower on-state resistance.
• C. a positive temperature coefficient.
• D. all of the above

TRUE/FALSE:

1. The voltage gain of a common-source amplifier is found by the product of g_m and R_d.

• A. True
• B. False

2. There is no phase inversion between the gate and the drain voltages.

• A. True
• B. False

3. There is a 180º phase inversion between the gate and source voltages.

• A. True
• B. False

4. A load resistance connected to the output of an amplifier reduces the voltage gain.

• A. True
• B. False

5. Bypassing a source resistor reduces the voltage gain.

• A. True
• B. False

6. Generally, higher voltage gains can be achieved with bipolar amplifiers than with FET amplifiers.

• A. True
• B False

7. The common-drain amplifier is also called a source-follower.

• A. True
• B. False

8. The common-gate configuration has extremely high input resistance.

• A. True
• B. False

9. The common-source configuration has extremely high input resistance.

• A. True
• B. False

10. The common-drain configuration has extremely high input resistance.

• A. True
• B. False

11. In a class D amplifier, the output transistors are operated in a nonlinear mode.

• A. True
• B. False

12. Class D amplifier efficiencies can reach practical levels of more than 90%.

• A. True
• B. False

13. In a class D amplifier, the low-pass filter comes directly after the pulse-width modulator.

• A. True
• B. False

14. In an analog MOSFET switch, the input is applied to the gate and the output is taken from the source.

• A. True
• B. False

15. Digital MOSFET switches are used in the sample-and-hold circuit of an analog-to-digital converter.

• A. True
• B. False

Check your work.

Answer in FET Amplifiers and Switching Circuits

Complete List of Chapter MCQs in Floyd's Electronic Devices

Multiple Choice Questions in Floyd's Electronic Devices

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