# Floyd Self-test in FET Amplifiers and Switching Circuits

(Last Updated On: December 8, 2017)

This is the Self-test in Chapter 9: FET Amplifiers and Switching Circuits 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 9 Topic Outline

• Floyd Self-test in The Common-Source Amplifier
• Floyd Self-test in The Common-Drain Amplifier
• Floyd Self-test in The Common-Gate Amplifier
• Floyd Self-test in The Class D Amplifier
• Floyd Self-test in MOSFET Analog Switching
• Floyd Self-test in MOSFET Digital Switching

### Start Practice Exam Test Questions

Choose the letter of the best answer in each questions.

1. In a common-source amplifier, the output voltage is

• (a) 180ᵒ out of phase with the input
• (b) in phase with the input
• (c) taken at the source
• d) taken at the drain
• (e) answers (a) and (c)
• (f ) answers (a) and (d)

2. In a certain common-source (CS) amplifier, Vds= 3.2 V rms and Vgs =280 mV rms. The voltage gain is

• (a) 1
• (b) 11.4
• (c) 8.75
• (d) 3.2

3. In a certain CS amplifier, RD= 1.0kΩ,RS= 560Ω, VDD= 10 V, AND gm= 4500 μS If the source resistor is completely bypassed, the voltage gain is

• (a) 450
• (b) 45
• (c) 4.5
• (d) 2.52

4. Ideally, the equivalent circuit of a FET contains

• (a) a current source in series with a resistance
• (b) a resistance between drain and source terminals
• (c) a current source between gate and source terminals
• (d) a current source between drain and source terminals

5. The value of the current source in Question 4 is dependent on the

• (a) transconductance and gate-to-source voltage
• (b) dc supply voltage
• (c) external drain resistance
• (d) answers (b) and (c)

6. A certain common-source amplifier has a voltage gain of 10. If the source bypass capacitor is removed,

• (a) the voltage gain will increase
• (b) the transconductance will increase
• (c) the voltage gain will decrease
• (d) the Q-point will shift

7. A CS amplifier has a load resistance of 10 k Ω and RD = 820Ω. If gm = 5 mS and Vin= 500 mV, the output signal voltage is

• (a) 1.89 V
• (b) 2.05 V
• (c) 25 V
• (d) 0.5 V

8. If the load resistance in Question 7 is removed, the output voltage will

• (a) stay the same
• (b) decrease
• (c) increase
• (d) be zero

9. A certain common-drain (CD) amplifier with RS= 1.0 kΩ has a transconductance of 6000 μS .The voltage gain is

• (a) 1
• (b) 0.86
• c) 0.98
• (d) 6

10. The datasheet for the transistor used in a CD amplifier specifies IGSS = 5 nA at VGS = 10 V. If the resistor from gate to ground, RG, is 50MΩ, the total input resistance is approximately

• (a) 50MΩ
• (b) 200MΩ
• (c) 40MΩ
• (d) 20.5MΩ

11. The common-gate (CG) amplifier differs from both the CS and CD configurations in that it has a

• (a) much higher voltage gain
• (b) much lower voltage gain
• (c) much higher input resistance
• (d) much lower input resistance

12. If you are looking for both good voltage gain and high input resistance, you must use a

• (a) CS amplifier
• (b) CD amplifier
• (c) CG amplifier

13. A cascode amplifier consists of

• (a) a CD and a CS amplifier
• (b) a CS and a CG amplifier
• (c) a CG and a CD amplifier
• (d) two CG amplifiers

14. The class D amplifier is similar to

• (a) class C
• (b) class B
• (c) class A
• (d) none of these

15. The class D amplifier uses

• (a) frequency modulation
• (b) amplitude modulation
• (c) pulse-width modulation
• (d) duty cycle modulation

16. E-MOSFETs are generally used for switching applications because of their

• (a) threshold characteristic
• (b) high input resistance
• (c) linearity
• (d) high gain

17. A sampling circuit must sample a signal at a minimum of

• (a) one time per cycle
• (b) the signal frequency
• (c) twice the signal frequency
• (d) alternate cycles

18. The value of resistance emulated by a switched-capacitor circuit is a function of

• (a) voltage and capacitance
• (b) frequency and capacitance
• (c) gain and transconductance
• (d) frequency and transconductance

19. A basic CMOS circuit uses a combination of

• (a) n-channel MOSFETs
• (b) p-channel MOSFETs
• (c) pnp and npn BJTs
• (d) an n-channel and a p-channel MOSFET

20. CMOS is commonly used in

• (a) digital circuits
• (b) linear circuits
• (c) RF circuits
• (d) power circuits

21. If there is an internal open between the drain and source in a CS amplifier, the drain voltage is equal to

• (a) 0 V
• (b) VDD
• (c) VGS
• (d) VGD