# Floyd Self-test in BJT Amplifiers

(Last Updated On: December 8, 2017) This is the Self-test in Chapter 6: Bipolar Junction Transistor Amplifiers 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 6 Topic Outline

• Floyd Self-test in Bipolar Junction Transistors Amplifiers
• Floyd Self-test in Amplifier Operation
• Floyd Self-test in Transistor AC Models
• Floyd Self-test in The Common-Emitter Amplifier
• Floyd Self-test in The Common-Collector Amplifier
• Floyd Self-test in The Common-Base Amplifier
• Floyd Self-test in Multistage Amplifiers
• Floyd Self-test in The Differential Amplifier

### Start Practice Exam Test Questions

Choose the letter of the best answer in each questions.

1. A small-signal amplifier

• (a) uses only a small portion of its load line
• (b) always has an output signal in the mV range
• (c) goes into saturation once on each input cycle
• (d) is always a common-emitter amplifier

2. The parameter hfe corresponds to

• (a) βdc
• (b) βac
• (c) r’e
• (d) r’c

3. If the dc emitter current in a certain transistor amplifier is 3 mA, the approximate value of is

• (a) 3kΩ
• (b) 3Ω
• (c) 8.33Ω
• (d) 0.33Ω

4. A certain common-emitter amplifier has a voltage gain of 100. If the emitter bypass capacitor is removed,

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

5. For a common-emitter amplifier, RC = 1.0 kΩ, RE = 390Ω, r e = 15 Ω, and = 75.

Assuming that RE is completely bypassed at the operating frequency, the voltage gain is

• (a) 66.7
• (b) 2.56
• (c) 2.47
• (d) 75

6. In the circuit of Question 5, if the frequency is reduced to the point where XC (bypass)= RE, the voltage gain

• (a)remains the same
• (b) is less
• (c) is greater

7. In a common-emitter amplifier with voltage-divider bias, RIN(BASE)=68kΩ, R1= 33kΩ, and R2= 15kΩ. The total ac input resistance is

• (a) 68kΩ
• (b) 8.95kΩ
• (c) 22.2kΩ
• (d) 12.3kΩ

8. A CE amplifier is driving a load. If the voltage gain is approximately

• (a) 220
• (b) 1000
• (c) 10
• (d) 180

9. For a common-collector amplifier, RE= 100Ω, r’e =10Ω, and = 150. The ac input

resistance at the base is

• (a) 1500 Ω
• (b) 15k Ω
• (c) 110 Ω
• (d) 16.5k Ω

10. If a 10 mV signal is applied to the base of the emitter-follower circuit in Question 9, the output signal is approximately

• (a) 100 mV
• (b) 150 mV
• (c) 1.5 V
• (d) 10 mV

11. In a certain emitter-follower circuit, the current gain is 50. The power gain is approximately

• (a) 50AV
• (b) 50
• (c) 1
• (d) answers (a) and (b)

12. In a Darlington pair configuration, each transistor has an ac beta of 125. If RE is the

input resistance is

• (a) 560Ω
• (b) 70kΩ
• (c) 8.75M Ω
• (d) 140kΩ

13. The input resistance of a common-base amplifier is

• (a) very low
• (b) very high
• (c) the same as a CE
• (d) the same as a CC

14. Each stage of a four-stage amplifier has a voltage gain of 15. The overall voltage gain is

• (a) 60
• (b) 15
• (c) 50,625
• (d) 3078

15. The overall gain found in Question 14 can be expressed in decibels as

• (a) 94.1 dB
• (b) 47.0 dB
• (c) 35.6 dB
• (d) 69.8 dB

16. A differential amplifier

• (a) is used in op-amps
• (b) has one input and one output
• (c) has two outputs
• (d) answers (a) and (c)

17. When a differential amplifier is operated single-ended,

• (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

18. In the double-ended differential mode,

• (a) opposite polarity signals are applied to the inputs
• (b) the gain is 1
• (c) the outputs are different amplitudes
• (d) only one supply voltage is used

19. 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

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