Deck 7: DC Biasing Circuits

Question 1

Is the circuit in Figure midpoint biased?

A) Yes
B) No

Answer 1

No

Question 2

The most commonly used type of transistor biasing is

A) voltage-divider bias.
B) emitter-feedback bias.
C) collector-feedback bias.
D) emitter bias.

Answer 2

voltage-divider bias.

Question 3

The term quiescent means

A) midpoint biased.
B) at rest.
C) active.
D) Both A and B above.

Answer 3

at rest.

Question 4

What is the primary drawback to using emitter bias?

A) Emitter bias is beta dependent.
B) Emitter bias cannot provide midpoint bias.
C) Emitter bias requires the use of a dual-polarity power supply.
D) Emitter bias has no quiescent state.

Question 5

As temperature increases, the value of hFE

A) increases.
B) decreases.

Question 6

The value of VCEoff) for the circuit in Figure is

A) 20 V.
B) 10 V.
C) 5 V.
D) Cannot be determined with the information given.

Question 7

The value of ICsat) for the circuit in Figure is

A) 21.3 mA.
B) 14.1 mA.
C) 7.04 mA.
D) 0 mA.

Question 8

An emitter bias circuit has values of VCC = +8 V and VEE = -8 V. The value of VCEoff) for the circuit is

A) 4 V.
B) 8 V.
C) 16 V.
D) 0.7 V.

Question 9

Why is midpoint bias desirable for most linear amplifiers?

A) It extends the operating life of the transistor.
B) It allows optimum ac operation of the circuit.
C) It allows optimum dc operation of the circuit.
D) It keeps VCEQ at approximately half the value of VCC.

Question 10

The value of ICsat) for the circuit in Figure is

A) 1 mA.
B) 0 mA.
C) 2 mA.
D) 4 mA.

Question 11

The value of VCEoff) for the circuit in Figure is

A) 10 V.
B) 20 V.
C) 5 V.
D) 0 V.

Question 12

The change in ICQ and VCEQ that can occur when temperature changes is known as

A) midpoint bias.
B) midpoint shift.
C) output shift.
D) Q-point shift.

Question 13

Which of the following is the likely to experience significant changes in the values of ICQ and VCEQ as a result of changes in temperature?

A) Voltage-divider bias.
B) Emitter-feedback bias.
C) Base bias.
D) Collector-feedback bias.

Question 14

Which of the following is a characteristic of emitter bias ?

A) The emitter potential is very low, typically less than -1 V.
B) The base potential is very close to 0 V.
C) The collector potential is approximately equal to VCC.
D) All of the above are characteristic of emitter bias.
E) Both A and B are characteristic of emitter bias.

Question 15

The spec sheet for a given transistor contains the following table: hFE = 5 to 200 when IC = 1 mA hFE = 70 to 350 when IC = 10 mA hFE = 100 to 400 when IC = 20 mA hFE = 150 to 450 when IC = 100 mA
The transistor is being used in a circuit with the following values: VCC = 20 V, RC = 820 Ω, and RE = 180 Ω. What value of hFE should be used in the analysis of the circuit?

A) 100
B) 157
C) 200
D) None of these are correct.

Question 16

Base bias is used primarily in switching applications.

Question 17

The simplest transistor biasing circuit is called

A) voltage-divider bias.
B) emitter-feedback bias.
C) base bias.
D) collector-feedback bias.

Question 18

Is the circuit in Figure midpoint biased?

A) Yes
B) No

Question 19

A transistor has a rating of hFE = 50 to 450. What value of hFE should be used for circuit analysis purposes?

A) 50
B) 250
C) 450
D) 150

Question 20

Is the amplifier in Figure midpoint biased?

A) Yes
B) No

Question 21

Is the circuit in Figure midpoint biased?

A) Yes
B) No

Question 22

The circuit has measured values of VB = 2.2 V, VE = 1.5 V and VC = 11.5 V. Which of the following could account for these readings?

A) The 68 kΩ resistor is open.
B) The 10 kΩ resistor is open.
C) The 6.2 kΩ resistor is open.
D) The 1.1 kΩ resistor is open.
E) There is no fault. The circuit is functioning as it should.

Question 23

What type of bias requires the use of a dual-polarity power supply?

A) Base bias
B) Emitter bias
C) Voltage-divider bias
D) Collector-feedback bias
Chapter 7 DC Biasing Circuits Answer Key

Question 24

The circuit in Figure found to be in saturation. Which of the following could cause this condition?

A) A open base resistor R_B
B) An open collector resistor R_C
C) An open transistor Q₁ base-to-emitter
D) A shorted base resistor R_B

Question 25

Refer to Figure The circuit is an) .

A) base bias
B) emitter bias
C) voltage-divider bias
D) collector feedback
E) emitter-feedback

Question 26

What type of bias is shown in Figure ?

A) Base bias
B) Emitter bias
C) Voltage-divider bias
D) Emitter-feedback bias
E) Collector-feedback bias

Question 27

Refer to Figure 7-5. The circuit has measured values of VB = 1 V, VE = 0.3 V and VC = 0.4 V. Which of the following could account for these readings?

A) The 68 kΩ resistor is open.
B) The 10 kΩ resistor is open.
C) The 6.2 kΩ resistor is open.
D) The 1.1 kΩ resistor is open.
E) There is no fault. The circuit is functioning as it should.

Question 28

Refer to Figure 7-5. The circuit has measured values of VB = 0 V, VE = 0 V, and VC = 20 V. Which of the following could account for these readings?

A) The 68 kΩ resistor is open.
B) The 10 kΩ resistor is open.
C) The 6.2 kΩ resistor is open.
D) The 1.1 kΩ resistor is open.
E) There is no fault. The circuit is functioning as it should.

Question 29

The value of Rbase for the circuit is

A) 1.1 k Ω.
B) 88 k Ω.
C) 8.97 k Ω.

Question 30

What type of bias is used primarily in switching circuits?

A) Base bias
B) Emitter bias
C) Voltage-divider bias
D) Collector-feedback bias