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. RG || RIN(gate).
- B. RG + RIN(gate).
- C. RG.
- D. RIN(gate).
7. Refer to Figure 9-1. For midpoint biasing, ID 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 VD.
- A. 20 V
- B. 11 V
- C. 10 V
- D. 9 V
9. Refer to Figure 9-1. If VGS = –6 V, calculate the value of RS 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 Vin = 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 Vin = 1 V p-p, the output voltage Vout 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 ID = 4 mA, IDSS = 16 mA, and VGS(off) = –8 V, find VDS.

Figure 9-2
- A. 19.2 V
- B. –6 V
- C. 10.8 V
- D. 30 V
14. Refer to Figure 9-2. If ID = 4 mA, find the value of VGS.
- A. 10.8 V
- B. 6 V
- C. –0.7 V
- D. –6 V
15. Refer to Figure 9-2. If gm = 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 Rin 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, Vout would
- A. increase.
- B. decrease.
- C. remain the same.
- D. distort.
19. Refer to Figure 9-3. If C2 shorted, Vout would
- A. increase.
- B. decrease.
- C. remain the same.
- D. distort.
20.Refer to Figure 9-3. If Vin 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 (Rin(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 (VGS(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. VGS(th)
- C. the switch's power handling
- D. VDS
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 gm and Rd.
- 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
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