[ELECS] TRANSISTORS

MULTIPLE CHOICE QUESTIONS

1.

digital

When transistors are used in

circuits they usually operate in the:

A. active region

B. breakdown region

C. saturation and cutoff regions

D. linear region

: C

2. The input resistance of the base of an

emitter-follower is usually

A. very low

B. very high

C. shorted to ground

D. open

: B

3. The dc load line on a family of collector

characteristic curves of a transistor shows

the

A. saturation region.

B. cutoff region.

C. active region.

D. all of the above

: D

4. How many carriers participate in the

injection process of a unipolar device?

A. 1

B, 2

C. O

D. 3

: A

can

5. The input resistance of the base of a

voltage-divider biased transistor

be

neglected

A, at all times.

B. only if the base current is much smaller

than the current through R2 (the lower bias

resistor).

C. at no time.

D. only if the base current is much larger

than the current through R2 (the lower bias

resistor).

: B

6. The transconductance curve of a JFET is

a graph of:

A. Is versus Vos

B. Ic versus VCE

C. Id versus VGS

D. IDX Ros

: C

7. It is the biasing of the BJT at room

temperature with no voltage applied.

A, unbias

B. base bias

C. zero bias

D. VDB

: C

8. The flow of electron is a NPN transistor

when used in electronic circuit is from

A. Collector to emitter

B. Collector to base

C. Emitter to collector

D. Base to emitter

: C

9. Vce is ________ in cutoff

A. O V

B. Minimum

C. Equal to Vbb

D. Equal to Vec

: D

10. In a semiconductor technology, the

characteristics of a transistor in cut-off

refers to a condition when

A. Transistor is at its operating point

B. No current flows emitter to collector

C. There is no base current

D. Maximum current flows from emitter to

collector

: B

11. Three different Q points are shown on a

dc load line. The upper Q point represents

the:

A. minimum current gain

B. intermediate current gain

C. maximum current gain

D. cutoff point

: C

12. The phase difference between the input

and output ac voltage signals of a common-

emitter amplifier is

A. 0°

B. 90°

C. 180°

D. 360°

: C

13. How many layers of material does a

transistor have?

B. 2

C. 3

D. 4

: C

a

14. What are the ranges of the ac input and

output resistance for

common-base

configuration?

A. 10ohm-100 ohm, 50 Kohm -1 Mohm

B. 50 Kohm - 1 Mohm, 10 ohm-100ohm

C. 10 ohm-100 Kohm, 50ohm - 1 Kohm

D. None of the above

: A

a

15. The common-source JFET amplifier

has:

A. a very high input impedance and

relatively low voltage gain

B. a high input impedance and a very high

voltage gain

C. a high input impedance and a voltage

gain less than i

D. no voltage gain

: A

16. Which transistor bias circuit

arrangement provides good Q-point

stability, but requires both positive and

negative supply voltages?

A. base bias

B. collector-feedback bias

C. voltage-divider bias

D. emitter bias

: D

17. What separates the three regions in a

BJT?

A. N region and P region

B. Two PN junctions

C. Metal conductors

D. Space

: B

18. What is the leakage current flowing in a

common emitter configuration

A. Iceo

B. Icbo

C. Ices

D. Icbs

: A

19. In the zero signal conditions,

transistor sees

load

A. DC

B. AC

C. Both dc and AC

D. none of the choices

: A

20. The arrow in the symbol of a transistor

indicates the direction of

A. Electron current in the collector

B. Donor ion current

C. Electron current in the emitter

D. Hole current in the emitter

: D

21. A current ratio of Idle is usually less

than one and is called:

A. beta

B. theta

C. alpha

D. omega

: C

22. Base bias provides

A, a very stable Q point

B. a very unstable Q point

C. no current gain

D. zero current in the base and collector

circuits

: B

23. Which of the following equipment can

check the condition of a transistor?

A. Current tracer

B. Digital display meter (DDM)

C. Ohmmeter (VOM)

D. All of the above

: D

24. What is

the most frequently

encountered transistor configuration?

A. Common-base

B. Common-collector

C. Common-emitter

D. Emitter-collector

: C

25. Refer to this figure. In the voltage-

divider biased npn transistor circuit, if Ri

opens, the transistor is

+ vec

RI

Rc

Boc

Rz

RE

A, saturated.

B. cutoff.

C. nonconducting.

D. shorted

: B

26. The overall input capacitance of a dual-

gate

D-MOSFET is lower because the

devices are usually connected:

A. in parallel

B. with separate insulation

C. with separate inputs

D. in series

: D

27. With proper bias applied to a transistor,

what should be the relative resistance of (a)

the emitter - base junction and (b) the base

collector junction?

A. (a) High (b) low

B. (a) High (b) high

C. (a) Low (b) low

D. (a) Low (b) high

: D

28. In

power transistors, the metal

mounting tab or case is connected to which

transistor region?

A, Base

B. Emitter

C. Collector

D. None of the above

: C

29. The purpose of emitter capacitor (i.e.

capacitor across RE) is to

A. forward bias the emitter

B. reduce noise the amplifier

C. avoid voltage drop in gain

D. none of the choices

: C

30. If a sinusoidal voltage is connected to

the base of a biased non transistor and the

resulting collector voltage is clipped near

zero volts, the transistor is

A. Being driven to saturation

B. Being driven to cut off

C. Operating nonlinearity

D. A and C

: D

31.

With the positive probe on an NPN

base, an ohmmeter reading between the

other transistor terminals should be:

А. open

B. infinite

C. low resistance

D. high resistance

: C

32. VCE approximately equals

when a transistor switch is cut off.

A. Vcc

B. VB

C. 0.2 V

D. 0,7 V

: A

33. For what kind of amplifications can the

active region of the common-emitter

configuration be used?

A. Voltage

B. Current

C. Power

D. All of the above

: D

34. Which of the following regions is (are)

part of the output characteristics of a

transistor?

A. Active

B. Cutoff

C, Saturation

D. All of the above

: D

35. Junction Field Effect Transistors

(JFET) contain how many diodes?

A. 4

B. 3

C. 2

D. 1

: D

36. Which component is considered to be

an "OFF" device?

A. transistor

B. JFET

C. D-MOSFET

D. E-MOSFET

: D

protects

37.

What is the layer

which

junctions in transistors called?

A. Insulating

B. Conducting

C. Tendon

D. Passivating

: D

38. The main reason for the variation of

amplifier gain with frequency is

A. Due to interstage transformer

B. the presence of capacitance both

external and internal

C. The logarithmic increase in its output

D. The miller effect

: B

39. If a transistor amplifier feeds a load of

low resistance, then voltage gain will be

A. low

B. high

C. very high

D. moderate

: A

40. The type of bias used where only

moderate changes in ambient temperature

are expected?

B. Self bias

C. Fixed bias

D. Limited bias

: C

an

emitter

41. In a C-E configuration,

resistor is used for:

A. stabilization

B. ac signal bypass

C. collector bias

D. higher gain

: A

42. The input resistance, Rin of a common-

collector amplifier, consists

of

Vin

link

.

A. Rin Re X AC Current Gain

B. Rin

C. Ri Re X a

D. none of the above

: A

.

3

43. In the active region, while the collector-

base junction is

-biased, the base-

emitter is

-biased.

A. forward, forward

B. forward, reverse

C. reverse, forward

D. reverse, reverse

: C

44. How many individual pnp silicon

transistors can be housed in a 14-pin plastic

dual-in-line package?

A, 4

B, 7

C. 10

D. 14

: A

45. When not in use, MOSFET pins are

kept at the same potential through the use

of:

A. shipping foil

B. nonconductive foam

C. conductive foam

D, a wrist strap

: C

46. In an n-channel JFET, what will happen

at the pinch-off voltage?

A. the value of Vos at which further

increases in Vos will cause no further

increase in ID

B. the value of Vas at which further

decreases in VGS will

cause no further

increases in ID

C.

the

value of VDG at which further

decreases in VDG will cause no further

increases in ID

D. the value of Vos

at which further

increases in

Vos will cause no

further

increases in ID

: A

47. The configuration noted for its stability

in radio-frequency power amplifiers is the:

A. common-emitter circuit

B. common-base circuit

C. common-collector circuit

D. emitter-follower circuit

: B

48. Bipolar junction transistor is considered

as a bipolar device due to the fact that both

holes and electrons flow during its

operation. For FET, only one carrier is

involved and is therefore called a unipolar

device. The carrier used in FET is

A. Either holes and electrons

B. Majority carriers

C. Minority carriers

D. None of these

: A

49. The DC load of a transistor amplifier is

generally

that of AC load.

A. the same as

B. less than

C. more than

D. none of the choices

: C

50. FET's are more temperature stable than

BJTs and are usually

BJT's

A. Bigger than

B. Smaller than

C. Same as

D. None of the above

: B

51. Voltage-divider bias provides:

A. an unstable Q point

B. a stable Q point

C. a Q point that easily varies with changes

in the transistor's current gain

D. a Q point that is stable and easily varies

with changes in the transistor's current gain

: B

52. The signal voltage gain of an amplifier,

AV, is defined as

AVout

A. Av =

Vin

B. Av = Ic x RC

RL

C. Av

D. Av =

: A

RC

RL

53. What range of resistor values would

you get when checking a transistor for

forward- and reverse-biased conditions by

an ohmmeter?

A. 1002 to a few ks2, exceeding 100 ks2

B. Exceeding 100 k92, 100 to a few k12

C. Exceeding 100 ks2, exceeding 100 k92

D. 100Ω to a few kΩ, 1ooΩ to a few kΩ

: A

are broken

54. Most specification sheets

down into

A. maximum ratings

B. thermal characteristics

C. electrical characteristics

D. All of the above

: D

55. D-MOSFETS are sometimes used in

series to construct a cascode high-

frequency amplifier to overcome the loss

of;

A. low output impedance

B. capacitive reactance

C. high input impedance

D. inductive reactance

: C

56. To get a negative gate-source voltage in

a self-biased JFET circuit, you must use a

A. negative gate supply voltage

B. ground

C. voltage divider

D. source resistor

: D

57. A common-emitter amplifier circuit

always contains

A. a diode

B. a JFET

C. a bipolar transistor

D. a transformer

: C

58. A BJT is a current-controlled current

source device while a JFET is a

A. voltage-controlled current source

B. current-controlled voltage source

C. voltage-controlled voltage source

D. transconductance-controlled

: A

59. Ideally, a dc load line is a straight line

drawn on the collector characteristic curves

between

A. The Q point and the cutoff

B. The Q point and the saturation

C.

Cutoff

V ce

and saturated collector

current

D. At zero base current and ratio of

collector current and beta

: C

region

60. What JFET operating

corresponds to saturation of BJT?

A, cut-off

B. saturation

C. ohmic

D. breakdown

: C

61. To operate properly, a transistor's base-

emitter junction must be forward biased

with reverse bias applied to which

junction?

A. collector-emitter

B. base-collector

C. base-emitter

D. collector-base

: D

62. VCE approximately equals

when a transistor switch is in saturation.

A. Vc

B. VB

C. 0.3 V

D. 0.7 V

: C

63. What is (are) the component(s) of

electrical characteristics

on

the

specification sheets?

A. On

B. Off

C. Small-signal characteristics

D. All of the above

: D

64. What is the ratio of the total width to

that of the center layer for a transistor?

A. 1:15

B. 1:150

C. 15:1

D. 150:1

: D

65.

"U" shaped, opposite-polarity

material built near a JFET-channel center is

called the:

A. gate

B. block

C. drain

D. heat sink

: A

66. One advantage of voltage-divider bias

is that the dependency of drain current, ID,

on the range of Q points is

A, reduced

B. increased

C. not affected

D. none of the above

: A

67. What type of bias keeps the base bias

constant and improves thermal stability?

A. Self bias

B. Fixed bias

C. Combination bias

D. Each of the above

: C

can

as

an

68. An FET

act

excellent

amplifier because

A. It has a low input impedance and a high

output impedance

B. It has a high input impedance and a low

output impedance

C. It has a very high voltage gain and a low

noise level

D. Smaller size, longer life, and lower

efficiency

: B

69. When the electron transit time through

the base region is very short, this

A, creates a higher potential barrier

B. makes the transistor unable to amplify

C. provides higher cut-off frequency

D. provides a Zener effect

: C

70. Since it is a voltage-controlled much

like a vacuum tube, it is sometimes called

the "solid-state vacuum tube"

A. UJT

B. phototransistor

C. FET

D. bipolar transistor

: C

a

71. The ends of a load line drawn on

family of curves determine:

A, saturation and cutoff

B. the operating point

C. the power curve

D. the amplification factor

: A

72. An emitter-follower has a voltage gain

that is

A, much less than one

B. approximately equal to one

C. greater than one

D. zero

: B

73. In which region are both the collector-

base and base-emitter junctions forward-

biased?

A, Active

B. Cutoff

C. Saturation

D. All of the above

: C

74. Which component of the collector

current IC is called the leakage current?

A. Majority

B. Independent

C. Minority

D. None of the above

: C

75. In the constant-current region, how will

the IDS change in an n-channel JFET?

A. As Vos decreases Ip decreases.

B. As Vos increases Ip increases.

C. As Vos decreases Ip remains constant.

D. As Vos increases Ip remains constant.

: A

A

will

76.

produce a

change in Vps

change in I».

A. small, large

B. large, small

C. large, large

D. small, small

: B

77. The disadvantage of a base bias is that

A. It is very complex

B. Provides a stable bias point

C. It produces low gain

D. It produces high leakage current

: C

78. A JFET is similar in operation to what

other device?

A. Diode

B. Triode

C. Triac

D. UJT

: B

79. The value of collector load RC in a

transistor amplifier is

the output

impedance of the transistor.

A. the same as

B. less than

C. more than

D. none of the choices

: B

80. The current through the channel of a

JFET is directly affected by all of the

following except:

A. Drain voltage

B. Transconductance

C. Gate voltage

D. Gate Bias

: B

is

used

to

81. The C-B configuration

provide which type of gain?

A. voltage

B. current

C. resistance

D. power

: A

82. The primary function of the bias circuit

is to

A. hold the circuit stable at Voc

B. hold the circuit stable at Vin

C. ensure proper gain is achieved

D. hold the circuit stable at the designed Q-

point

: D

83. Which of the following is (are) the

terminal(s) of a transistor?

A. Emitter

B. Base

C. Collector

D. All of the above

: D

base-

84. For the BJT to operate in the active

(linear) region, the base-emitter junction

must be

-biased and the

collector junction must be

biased.

A. forward, forward

B. forward, reverse

C. reverse, reverse

D. reverse, forward

: B

85. A MOSFET has how many terminals?

A. 2 or 3

B. 3

C. 4

D. 3 or 4

: D

86. A

JFET amplifier

provides a voltage gain of less than one.

A. common-source

B. common-gate

C. common-drain

D. cascode amplifier

: C

87. The leakage current in CE arrangement

is

that in CB arrangement.

A. more than

B. less

C. the same as

D. none of the above

: A

88. The transconductance curve is

A. Linear

B. Similar to the graph of a resistor

C. Nonlinear

D. Like a single drain curve

: C

89. Equivalent circuit commonly used in

transistors small signal analysis.

A. Hybrid parameter model

B. Ebers-Moll model

C. Hybrid-pi model

D. T-equivalent model

: A

90. The minimum value of VGS that will

cause the drain current to drop to zero.

A. O V

B. thermal voltage

C. 26 mV

D. gate-source cutoff voltage

: D

91. The Q point on a load line may be used

to determine:

A. Vc

B. Vcc

C. VB

D. Ic

: C

92. A JFET

A, is a current-controlled device

B. has a low input resistance

C. is a voltage-controlled device

D. is always forward-biased

: C

93. In a JFET

A. drain current is very nearly equal to

source current

B. drain current is much less than source

current

C. drain current may be equal to or less than

source current

D. drain current may be even more than

source current

: A

94. The cutoff region is defined by IB ___OA.

A. >

B. <

C. <

D.

: C

95. Ipss can be defined as:

A. the minimum possible drain current

B. the maximum possible current with Vos

held at -4 V

C. the maximum possible current with VGS

held at O V

D. the maximum drain current with the

source shorted

: C

96. Which of the following configurations

has the lowest output impedance?

A. Fixed-bias

B. Voltage-divider

C. Emitter-follower

D. None of the above

: C

97. The CE stage with a feedback resistor

in the emitter circuit.

A. Swamped amplifier

B. CE amplifier

C. Differential amplifier

D. Class B push pull amplifier

: A

98. In а source follower, which of the

electrodes of the JFET receives the input

signal?

A. none of them

B. the source

C. the gate

D, the drain

: C

99. T-equivalent circuit is considered as a

representation

A. Physical

B. Black box

C. Four-terminal network

D. General

: A

100. What is/are the function(s) of the

coupling capacitors in an FET circuits?

A. To create an open circuit for de analysis

B. To isolate the de biasing arrangement

from the applied signal and load

C. To create a short circuit equivalent for ac

analysis

: D