MCQs in Field Effect Transistor Amplifiers

(Last Updated On: December 8, 2017)
MCQs for Field Effect Transistor Amplifiers

This is the Multiple Choice Questions in Field Effect Transistor 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 FET Amplifiers
  • MCQs in FET Small-Signal Model
  • MCQs in JFET Fixed-Bias Configuration
  • MCQs in JFET Self-Bias Configuration
  • MCQs in JFET Voltage-Divider Configuration
  • MCQs in JFET Source-Follower (Common-Drain) Configuration
  • MCQs in JFET Common-Gate Configuration
  • MCQs in Depletion-type MOSFETs
  • MCQs in Enhancement-type MOSFETs
  • MCQs in E-MOSFET Drain-Feedback Configuration
  • MCQs in E-MOSFET Voltage-Divider Configuration
  • MCQs in Designing FET Amplifier Networks

Practice Exam Test Questions

Choose the letter of the best answer in each questions.

1. FET amplifiers provide ________.

  • A) excellent voltage gain
  • B) high input impedance
  • C) low power consumption
  • D) All of the above

2. A BJT is a ________-controlled device.

  • A) current
  • B) voltage
  • C) power
  • D) resistance

3. An FET is a ________-controlled device.

  • A) current
  • B) voltage
  • C) power
  • D) resistance

4. The E-MOSFET is quite popular in ________ applications.

  • A) digital circuitry
  • B) high-frequency
  • C) buffering
  • D) All of the above

5. What is the range of gm for JFETs?

  • A) 1 µS to 10 µS
  • B) 100 µS to 1000 µS
  • C) 1000 µS to 5000 µS
  • D) 10000 µS to 100000 µS

6. For what value of ID is gm equal to 0.5 gm0?

  • A) 0 mA
  • B) 0.25 IDSS
  • C) 0.5 IDSS
  • D) IDSS

7. What is the typical value for the input impedance Zi for JFETs?

  • A) 100 kΩ
  • B) 1 MΩ
  • C) 10 MΩ
  • D) 1000 MΩ
8. Referring to the transfer characteristics shown below, calculate gm at VGSQ = –1 V.

MCQs in FET Amplifiers Fig. 01

  • A) 2 mS
  • B) 3 mS
  • C) 4 mS
  • D) 5 mS
9. Use the following equation to calculate gm for a JFET having IDSS = 10 mA, VP = –5 V, and VGSQ = –2.5 V.

MCQs in FET Amplifiers Fig. 02

  • A) 2 mS
  • B) 3 mS
  • C) 4 mS
  • D) 5 mS

10. Referring to the following figure, calculate gm for VGSQ = –1.25 V.
MCQs in FET Amplifiers Fig. 03

  • A) 2 mS
  • B) 2.5 mS
  • C) 2.75 mS
  • D) 3.25 mS

11. Referring to this figure, obtain gm for ID = 6 mA.
MCQs in FET Amplifiers Fig. 04

  • A) 2.83 mS
  • B) 3.00 mS
  • C) 3.25 mS
  • D) 3.46 mS
12. Referring to the figure below, determine the output impedance for VGS = –3 V at VDS = 5 V.

MCQs in FET Amplifiers Fig. 05

  • A) 100 kΩ
  • B) 80 kΩ
  • C) 25 kΩ
  • D) 5 kΩ

13. Calculate gm and rd if yfs = 4 mS and yos = 15 ΩS.

  • A) 4 mS, 66.7 kΩ
  • B) 4 mS, 15 kΩ
  • C) 66.7 kΩ, 4 mS
  • D) None of the above
14. The steeper the slope of the ID versus VGS curve, the ________ the level of gm.
  • A) less
  • B) same
  • C) greater

15. When VGS = 0.5 Vp gm is ________ the maximum value.

  • A) one-fourth
  • B) one-half
  • C) three-fourths
  • D) two-thirds

16. If ID = IDSS / 2, gm = ___________ gmo.

  • A) 1
  • B) 0.707
  • C) 0.5
  • D) 1.414
17. The more horizontal the characteristic curves on the drain characteristics, the ________ the output impedance.
  • A) less
  • B) same
  • C) greater
18. What is (are) the function(s) of the coupling capacitors C1 and C2 in an FET circuit?
  • A) to create an open circuit for dc analysis
  • B) to isolate the dc biasing arrangement from the applied signal and load
  • C) to create a short-circuit equivalent for ac analysis
  • D) All of the above

19. Where do you get the level of gm and rd for an FET transistor?

  • A) from the dc biasing arrangement
  • B) from the specification sheet
  • C) from the characteristics
  • D) All of the above

20. Referring to this figure, find Zo if yos = 20 µS.
MCQs in FET Amplifiers Fig. 06

  • A) 1.85 kΩ
  • B) 1.92 kΩ
  • C) 2.05 kΩ
  • D) 2.15 kΩ

21. Referring to this figure, calculate Av if yos = 20 µS.
MCQs in FET Amplifiers Fig. 07

  • A) –3.48
  • B) –3.56
  • C) –3.62
  • D) –4.02
22. For the fixed-bias configuration, if rd < 10 • RD, then Zo = ________.
  • A) RD
  • B) RD || rd
  • C) RG
  • D) -gm • (RD || rd)
23. Which of the following is a required condition to simplify the equations for Zo and Av for the self-bias configuration?
  • A) rd ≤ 10RD
  • B) rd = RD
  • C) rd ≥ 10RD
  • D) None of the above

24. Referring to this figure, calculate Zo if yos = 40 µS.
MCQs in FET Amplifiers Fig. 08

  • A) 2.92 kΩ
  • B) 3.20 kΩ
  • C) 3.25 kΩ
  • D) 3.75 kΩ
25. On which of the following parameters does rd have no or little impact in a source-follower configuration?
  • A) Zi
  • B) Zo
  • C) Av
  • D) All of the above

26. Referring to this figure, calculate Zo for VGSQ = –3.2 V.
MCQs in FET Amplifiers Fig. 09

  • A) 362.52 Ω
  • B) 340.5 Ω
  • C) 420.5 Ω
  • D) 480.9 Ω
27. Referring to this figure, calculate Zi for yos = 20 µS. Assume VGSQ = −2.2V.

MCQs in FET Amplifiers Fig. 10

  • A) 300.2 Ω
  • B) 330.4 Ω
  • C) 340.5 Ω
  • D) 350.0 Ω

28. Which of the following is (are) related to depletion-type MOSFETs?

  • A) VGSQ can be negative, zero, or positive.
  • B) gm can be greater or smaller than gm0’.
  • C) ID can be larger than IDSS’.
  • D) All of the above

29. Referring to this figure, calculate Av for yos = 58 µS.
MCQs in FET Amplifiers Fig. 11

  • A) –7.29
  • B) –7.50
  • C) –8.05
  • D) –8.55

30. Referring to this figure, calculate Zi if rd = 19 kΩ.
MCQs in FET Amplifiers Fig. 12

  • A) 2.42 MΩ
  • B) 2.50 MΩ
  • C) 2.53 MΩ
  • C) 2.59 MΩ

31. Referring to this figure, calculate Zo if rd = 19 kΩ.
MCQs in FET Amplifiers Fig. 13

  • A) 1.75 kΩ
  • B) 1.81 kΩ
  • C) 1.92 kΩ
  • D) 2.00 kΩ

32. Referring to this figure, calculate Av if rd = 19 kΩ.
MCQs in FET Amplifiers Fig. 14

  • A) –2.85
  • B) –3.26
  • C) –2.95
  • D) –3.21

33. Determine the value for RD if the ac gain is 8.
MCQs in FET Amplifiers Fig. 15

  • A) 1.51 kΩ
  • B) 1.65 kΩ
  • C) 1.85 kΩ
  • D) 2.08 kΩ
34. Referring to this figure, calculate the value of RD if the ac gain is 10. Assume VGSQ = ¼Vp.

MCQs in FET Amplifiers Fig. 16

  • A) 2.2 kΩ
  • B) 2.42 kΩ
  • C) 2.62 kΩ
  • D) 2.82 kΩ
35. For an FET small-signal amplifier, one could go about troubleshooting a circuit by ________.
  • A) viewing the circuit board for poor solder joints
  • B) using a dc meter
  • C) applying a test ac signal
  • D) All of the above

Fill-in-the-blanks Questions

1. A field-effect transistor amplifier provides excellent voltage gain with the added feature of a _____ input impedance.
  • A) low
  • B) medium
  • C) high
  • D) None of the above
2. The depletion MOSFET circuit has a _____ input impedance than a similar JFET configuration.
  • A) much higher
  • B) much lower
  • C) lower
  • D) higher
3. The _____ is quite popular in digital circuits, especially in CMOS circuits that require very low power consumption.
  • A) JFET
  • B) BJT
  • C) D-type MOSFET
  • D) E-type MOSFET

4. _____ is the amplification factor in FET transistor amplifiers.

  • A) Zi
  • B) gm
  • C) ID
  • D) IG

5. _____ is an undefined quantity in a JFET.

  • A) Ai
  • B) Av
  • C) Zi
  • D) Zo

6. The _____ controls the _____ of an FET.

  • A) ID’, VGS
  • B) VGS’, ID
  • C) IG’, VDS
  • D) IG’, ID

7. Transconductance is the ratio of changes in _____.

  • A) ID to VGS
  • B) ID to VDS
  • C) VGS to IG
  • D) VGS to VDS

8. The transconductance gm _____ as the Q-point moves from Vp to IDSS

  • A) decreases
  • B) remains the same
  • C) increases
  • D) None of the above

9. gm has its maximum value for a JFET at _____.

  • A) Vp
  • B) 0.5 Vp
  • C) 0.3 Vp
  • D) IDSS
10. The value of gm is at its maximum gm0 at VGS equal to _____ and zero at VGS equal to _____.
  • A) 0 V, Vp
  • B) Vp, 0 V
  • C) 0.5Vp, 0.3Vp
  • D) 0.3Vp , 0.5Vp

11. The range of input impedance Zi for MOSFETs is _____.

  • A) 1 kΩ –10 kΩ
  • B) 100 kΩ –1 MΩ
  • C) 10 MΩ –100 MΩ
  • D) 1012 Ω to 1015 Ω

12. The range of output admittance yos for FETs is _____.

  • A) 5 µS –10 µS
  • B) 10 µS –50 µS
  • C) 50 µS –100 µS
  • D) 200 µS –500 µS
13. The _____ configuration has the distinct disadvantage of requiring two dc voltage sources.
  • A) self-bias
  • B) voltage-divider
  • C) fixed-bias
  • D) All of the above
14. _____ is the network-input impedance for a JFET fixed-bias configuration.
  • A) RG
  • B) RD
  • C) Zero
  • D) None of the above

15. _____ is a required step in order to calculate Zo.

  • A) Setting IG equal to zero
  • B) Setting Vi equal to zero
  • C) Setting ID equal to IDSS
  • D) None of the above

16. _____ configuration(s) has (have) Zo ≈ RD.

  • A) Fixed-bias
  • B) Self-bias
  • C) Voltage-divider
  • D) All of the above
17. _____ is the only parameter that is different between voltage-divider and fixed-bias configurations.
  • A) Zi
  • B) Av
  • C) Zo
  • D) None of the above
18. The input and output signals are in phase in a _____ configuration.
  • A) fixed-bias
  • B) source-follower
  • C) voltage-divider
  • D) self-bias

19. A _____ configuration has a voltage gain less than 1.

  • A) fixed-bias
  • B) self-bias
  • C) source-follower
  • D) voltage-divider
20. The input and output signals are 180º out of phase in a _____ configuration.
  • A) source-follower
  • B) common-gate
  • C) common-drain
  • D) voltage-divider
21. The isolation between input and output circuits in the ac equivalent circuit is lost in a _____ configuration.
  • A) common-gate
  • B) common-source
  • C) common-drain
  • D) None of the above
22. The _____ configuration has an input impedance, which is other than RG.
  • A) common-source
  • B) common-gate
  • C) common-drain
  • D) None of the above
23. The gate-to-source voltage VGS of a(n) _____ must be larger than the threshold VGS(Th) for the transistor to conduct.
  • A) JFET
  • B) D-type MOSFET
  • C) E-type MOSFET
  • D) None of the above
24. rd changes from one operation region to another with _____ values typically occurring at _____ levels of VGS (closer to zero).
  • A) lower, lower
  • B) lower, higher
  • C) higher, lower
  • D) None of the above

25. The _____ does not support Shockley’s equation.

  • A) JFET
  • B) D-type MOSFET
  • C) E-type MOSFET
  • D) None of the above

Check your work.

Complete List of Chapter Quiz in Electronic Devices and Circuit Theory

credit: Robert L. Boylestad© 2014 www.PinoyBIX.org
MCQs in Field Effect Transistor Amplifiers
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