Deck 10: Other BJT Amplifiers

Question 1

Which biasing circuits are commonly used in common-base amplifiers?

A) Voltage-divider bias and base bias
B) Base bias and emitter bias
C) Emitter bias and voltage-divider bias
D) Collector feedback and emitter follower bias

Answer 1

Emitter bias and voltage-divider bias

Question 2

A Darlington pair has values of hfcl = hfc2 = 150. What is the overall value of Ai for the pair?

A) 300
B) 150
C) 22,500
D) None of these are correct.

Answer 2

22,500

Question 3

An emitter follower has the following values: hic = 3 kΩ, hfc = 150, and RE = 1.5 kΩ. What is the approximate value of Av for the circuit?

A) 0.5
B) 0.993
C) 0.987
D) Cannot be determined with the information given

Answer 3

0.987

Question 4

C₃ in Figure is used to

A) increase the voltage gain of the circuit.
B) increase the current gain of the circuit.
C) couple VCC to ground.
D) prevent unwanted variations in VCC.

Question 5

Which of the following statements about emitter followers is true?

A) The value of Av is greater than the value of Ai.
B) The value of Ai is greater than the value of Ap.
C) The value of Av is greater than the value of Ap.
D) The values for Av and Ap are approximately equal under normal circumstances.

Question 6

What is the approximate value of Ai for the circuit in Figure ?

A) 150
B) 20
C) 17.9
D) 22.5

Question 7

The value of Av for the circuit in Figure is

A) 0.988.
B) 0.990.
C) 0.998.
D) None of these are correct.

Question 8

Replacing a standard transistor with a Darlington pair in an emitter follower will cause the value of Ap for the circuit to

A) increase.
B) decrease.
C) remain the same.

Question 9

Which of the following statements is true for a midpoint-biased emitter follower?

A) The values of VE and VCC are approximately equal.
B) The values of VCE and VE are approximately equal.
C) The value of VCE is approximately twice the value of VE.
D) None of the above statements are true.

Question 10

What is the value of ICsat) for the circuit in Figure?

A) 1.14 mA
B) 3.41 mA
C) 2.27 mA
D) Cannot be determined with the information given.

Question 11

A common-base amplifier has values of rʹe = 15 Ω and RE = 3 kΩ. What is the approximate input impedance of the circuit?

A) 3 kΩ
B) 3015 Ω
C) 15 Ω
D) 200 Ω

Question 12

Which of the following statements about the common-base amplifier is true?

A) The value of Av is greater than the value of Ai.
B) The value of Ai is greater than the value of Ap.
C) The value of Ap is greater than the value of Av.
D) The values of Ai and Ap are approximately equal under normal circumstances.

Question 13

The circuit values of ICsat) and VCEoff) are .

A) 2.5 mA and 20 V
B) 2.5 mA and 10 V
C) 5 mA and 20 V
D) 10 mA and 20 V

Question 14

The source and load in Figure exhibit:

A) matched impedance.
B) saturated source impedance.
C) mismatched impedance.
D) over loaded current gain.

Question 15

Is the circuit in Figure midpoint biased?

A) Yes
B) No

Question 16

A common-base amplifier can be used to match a resistance source to a resistance load.

A) high; high
B) low; high
C) high; low
D) low; low

Question 17

A common-base amplifier does not provide gain.

A) voltage
B) current
C) power
D) current and power

Question 18

Emitter followers can be used to match a resistance source to a resistance load.

A) high; high
B) low; high
C) high; low
D) low; low

Question 19

Which of the following statements is true?

A) Darlington emitter-followers provide extremely high values of Av.
B) An emitter follower containing a single transistor has lower output impedance than an identical circuit containing a Darlington pair.
C) The Darlington emitter follower has extremely low input impedance.
D) Darlington emitter followers have high input impedance and low output impedance.

Question 20

Refer to Figure 10-1. The circuit values of ICsat) and VCEoff) are .

A) 2.273 and 5 V
B) 2.273 mA and 5 V
C) 2.73 mA and 2.5 V
D) cannot be determined since RC is a short.

Question 21

The circuit in Figure has the following values: R1 = 60 kΩ, R2 = 20 kΩ, RC = 3.3 kΩ, RL = 10 kΩ, RE = 1.5 kΩ and VCC = 9 V.
The values for ICsat) and VCEoff) for the circuit are

A) 1.1 mA and 9 V.
B) 1.9 mA and 9 V.
C) 1.9 mA and 4.5 V.
D) 1.1 mA and 4.5 V.

Question 22

The circuit in Figure is a amplifier.

A) CE
B) CC
C) CB
D) VBB

Question 23

The circuit in Figure is

A) voltage divider biased.
B) emitter biased.
C) common collector biased.
D) drawn incorrectly. The input should be applied to the base.

Question 24

Which best describes an emitter follower?

A) The emitter follower is a voltage amplifier with a voltage gain that equals 1.
B) The emitter follower is a current amplifier with a voltage gain that equals 1.
C) The emitter follower is a power amplifier with a power gain that equals 1.
D) The emitter follower is a current amplifier with a voltage gain that is less than 1.

Question 25

The circuit in Figure has the following values: R1 = 60 kΩ, R2 = 20 kΩ, RE = 1.5 kΩ,RC = 3.3 kΩ, and RL = 10 kΩ, and VCC = 9 V.
What is the circuit value of Av?

A) About 1
B) 0.984
C) 102
D) 132

Question 26

Which amplifier configurations produce no voltage phase shift from input to output?

A) CC and CE
B) CB and CE
C) CB, CC, and CE
D) CC and CB

Question 27

An engineer is designing a P.A. system. He intends to use a 300 Ω microphone and 8 Ω speakers. What values of Zin and Zout should this P.A. system amplifier have?

A) Zin = 8 Ω, Zout = 300 Ω
B) Zin = 300 Ω, Zout = 8 Ω
C) Zin much greater than 8 Ω and Zout much lower that 300 Ω
D) Zin much lower than 300 Ω and Zout much greater than 8 Ω

Question 28

Which of the following would be used to properly couple the source to the load?

A) A common base amplifier with Zin = 150 kΩ and Zout = 20 Ω
B) A common base amplifier with Zin = 20 Ω and Zout = 150 kΩ
C) A common collector amplifier with Zin = 150 kΩ and Zout = 20 Ω
D) A common collector amplifier with Zin = 20 Ω and Zout = 150 Ω
E) A direct connection between the source and load

Question 29

Which of the following would be used to properly couple the source to the load?

A) A common base amplifier with Zin = 30 Ω and Zout = 6 kΩ
B) A common base amplifier with Zin = 6 kΩ and Zout = 30 Ω
C) A common collector amplifier with Zin = 30 Ω and Zout = 6 kΩ
D) A common collector amplifier with Zin = 6 kΩ and Zout = 30 Ω
E) A direct connection between the source and load