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elecs- indiabix (terms) > Electronic Devices 3- FET > Flashcards

Electronic Devices 3- FET Flashcards

1
Q

For a JFET, the value of VDS at which ID becomes essentially constant is the

A

pinch-off voltage.

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2
Q

The ________ has a physical channel between the drain and source.

A

D-MOSFET

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3
Q

What type(s) of gate-to-source voltage(s) can a depletion MOSFET (D-MOSFET) operate with?

A

zero
positive
negative
any of the above

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4
Q

Midpoint bias for a D-MOSFET is ID = ________, obtained by setting VGS = 0.

A

IDSS

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5
Q

On the drain characteristic curve of a JFET for VGS = 0, the pinch-off voltage is

A

between the ohmic area and the constant current area.

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6
Q

Which of the following devices has the highest input resistance?

A

MOSFET

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7
Q

The value of VGS that makes ID approximately zero is the

A

cutoff voltage.

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8
Q

The JFET is always operated with the gate-source pn junction ________ -biased.

A

reverse

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9
Q

A dual-gated MOSFET is

A

either a depletion or an enhancement MOSFET.

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10
Q

What three areas are the drain characteristics of a JFET (VGS = 0) divided into?

A

ohmic, constant-current, breakdown

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11
Q

In a self-biased JFET circuit, if VD = VDD then ID = ________.

A

0

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12
Q

The resistance of a JFET biased in the ohmic region is controlled by

A

VGS

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13
Q

High input resistance for a JFET is due to

A

the gate-source junction being reverse-biased.

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14
Q

For a JFET, the change in drain current for a given change in gate-to-source voltage, with the drain-to-source voltage constant, is

A

forward transconductance.

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15
Q

If VD is less than expected (normal) for a self-biased JFET circuit, then it could be caused by a(n)

A

open RG.
open gate lead.
FET internally open at gate.
all of the above

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16
Q

Which of the following ratings appear(s) in the specification sheet for an FET?

A

Voltages between specific terminals
Current levels
Power dissipation
All of the above

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17
Q

What is the level of drain current ID for gate-to-source voltages VGS less than (more negative than) the pinch-off level?

A

zero amperes

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18
Q

What is the level of IG in an FET?

A

Zero amperes

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19
Q

What is the range of an FET’s input impedance?

A

1 M to several hundred M

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20
Q

Which of the following applies to a safe MOSFET handling?

A

Always pick up the transistor by the casing.
Power should always be off when network changes are made.
Always touch ground before handling the device.
All of the above

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21
Q

At which of the following condition(s) is the depletion region uniform?

A

No bias

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22
Q

Which of the following controls the level of ID?

A

VGS

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23
Q

It is the insulating layer of ________ in the MOSFET construction that accounts for the very desirable high input impedance of the device.

A

SiO2

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24
Q

The BJT is a ________ device. The FET is a ________ device.

A

bipolar, unipolar

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25
Q

The drain current will always be one-fourth of IDSS as long as the gate-to-source voltage is ________ the pinch-off value.

A

one-half

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26
Q

The transfer curve is not defined by Shockley’s equation for the ________.

A

enhancement-type MOSFET

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27
Q

The region to the left of the pinch-off locus is referred to as the ________ region.

A

ohmic

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28
Q

Which of the following transistor(s) has (have) depletion and enhancement types?

A

MOSFET

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29
Q

The three terminals of the JFET are the ________, ________, and ________.

A

gate, drain, source

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30
Q

Which of the following is (are) the terminal(s) of a field-effect transistor (FET).

A

Drain
Gate
Source
All of the above

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31
Q

A BJT is a ________-controlled device. The JFET is a ________ - controlled device.

A

current, voltage

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32
Q

How many terminals can a MOSFET have?

A

3 or 4

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33
Q

The level of VGS that results in ID = 0 mA is defined by VGS = ________.

A

VP

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34
Q

Which of the following FETs has the lowest input impedance?

A

JFET

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35
Q

Which of the following applies to MOSFETs?

A

No direct electrical connection between the gate terminal and the channel
Desirable high input impedance
Uses metal for the gate, drain, and source connections
All of the above

36
Q

At which of the following is the level of VDS equal to the pinch-off voltage?

A

When ID becomes equal to IDSS
When VGS is zero volts
IG is zero
All of the above

37
Q

Which of the following represent(s) the cutoff region for an FET?

A

ID = 0 mA
VGS = VP
IG = 0
All of the above

38
Q

Which of the following is (are) the advantage(s) of VMOS over MOSFETs?

A

Reduced channel resistance
Higher current and power ratings
Faster switching time
All of the above

39
Q

Hand-held instruments are available to measure ________ for the BJT.

A

betaDC

40
Q

Which of the following input impedances is not valid for a JFET?

A

10^8

41
Q

Which of the following is (are) not an FET?

A

p-n channel

42
Q

For the FET, the relationship between the input and output quantities is ________ due to the ________ term in Shockley’s equation.

A

nonlinear, squared

43
Q

Which of the following is (are) true of a self-bias configuration compared to a fixed-bias configuration?

A

One of the dc supplies is eliminated.
A resistor RS is added.
VGS is a function of the output current ID.
All of the above

44
Q

The input controlling variable for a(n) ________ is a current level and a voltage level for a(n) ________.

A

BJT, FET

45
Q

Through proper design, a ________ can be introduced that will affect the biasing level of a voltage-controlled JFET resistor.

A

thermistor

46
Q

On the universal JFET bias curve, the vertical scale labeled ________ can, in itself, be used to find the solution to ________ configurations.

A

m, fixed-bias

47
Q

Which of the following current equations is true?

A

ID = IS

48
Q

Which of the following represents the voltage level of VGS in a self-bias configuration?

A

VS

49
Q

Which of the following is a false statement regarding the dc load line when comparing self-bias and voltage-divider configurations?

A

Both cross the origin.

50
Q

For the noninverting amplifier, one of the most important advantages associated with using a JFET for control is the fact that it is ________ rather than ________ control.

A

ac, dc

51
Q

What is the approximate current level in the gate of an FET in dc analysis?

A

0A

52
Q

Which of the following describe(s) the difference(s) between JFETs and depletion-type MOSFETs?

A

VGS can be positive or negative for the depletion-type.
ID can exceed IDSS for the depletion-type.
The depletion-type can operate in the enhancement mode.
All of the above

53
Q

A common-gate amplifier is similar in configuration to which BJT amplifier?

A

common-base

54
Q

The theoretical efficiency of a class D amplifier is

A

100%.

55
Q

A common-source amplifier is similar in configuration to which BJT amplifier?

A

common-emitter

56
Q

A common-drain amplifier is similar in configuration to which BJT amplifier?

A

common-collector

57
Q

Where do you get the level of gm and rd for an FET transistor?

A

from the dc biasing arrangement
from the specification sheet
from the characteristics
All of the above

58
Q

The class D amplifier uses what type of transistors?

A

MOSFETs

59
Q

What is (are) the function(s) of the coupling capacitors C1 and C2 in an FET circuit?

A

to create an open circuit for dc analysis
to isolate the dc biasing arrangement from the applied signal and load
to create a short-circuit equivalent for ac analysis
All of the above

60
Q

What is the input resistance (Rin(source)) of a common-gate amplifier?

A

1 / gm

61
Q

There is a ________º phase inversion between gate and source in a source follower.

A

0

62
Q

Which of the following is a required condition to simplify the equations for Zo and Av for the self-bias configuration?

A

rd >_10RD

63
Q

The steeper the slope of the ID versus VGS curve, the ________ the level of gm.

A

greater

64
Q

What is the typical value for the input impedance Zi for JFETs?

A

1000 Mohms

65
Q

MOSFETs make better power switches than BJTs because they have

A

lower turn-off times.
lower on-state resistance.
a positive temperature coefficient.
all of the above

66
Q

When VGS = 0.5 Vp gm is ________ the maximum value.

A

one-half

67
Q

MOSFET digital switching is used to produce which digital gates?

A

inverters
NOR gates
NAND gates
all of the above

68
Q

Which type of FETs can operate with a gate-to-source Q-point value of 0 V?

A

D-MOSFET

69
Q

On which of the following parameters does rd have no or little impact in a source-follower configuration?

A

Zi
Zo
Av
All of the above

70
Q

Class D amplifiers differ from all other classes of amplifiers because

A

the output transistors are operated as switches.

71
Q

Which FET amplifier(s) has (have) a phase inversion between input and output signals?

A

common-source

72
Q

What common factor determines the voltage gain and input resistance of a common-gate amplifier?

A

gm

73
Q

The more horizontal the characteristic curves on the drain characteristics, the ________ the output impedance.

A

greater

74
Q

Which of the following is (are) related to depletion-type MOSFETs?

A

Vgs(q)can be negative, zero, or positive.
gm can be greater or smaller than gm0.
ID can be larger than IDSS.
All of the above

75
Q

The input resistance at the gate of a FET is extremely

A

high

76
Q

FET amplifiers provide ________.

A

excellent voltage gain
high input impedance
low power consumption
All of the above

77
Q

CMOS digital switches use

A

n-channel and p-channel E-MOSFETs in series.

78
Q

What is the range of gm for JFETs?

A

1000uS to 5000uS

79
Q

What limits the signal amplitude in an analog MOSFET switch?

A

VGS(th)

80
Q

Input resistance of a common-drain amplifier is

A

RG || RIN(gate).

81
Q

A JFET cascade amplifier employs

A

1 common-gate and 1 common-source amplifier.

82
Q

E-MOSFETs are generally used in switching applications because

A

of their threshold characteristic (VGS(th)).

83
Q

For an FET small-signal amplifier, one could go about troubleshooting a circuit by ________.

A

viewing the circuit board for poor solder joints
using a dc meter
applying a test ac signal
All of the above

84
Q

The E-MOSFET is quite popular in ________ applications.

A

digital circuitry
high-frequency
buffering
All of the above

85
Q

In a common-source amplifier, the purpose of the bypass capacitor, C2, is to

A

keep the source effectively at ac ground.

86
Q

If ID = IDSS / 2, gm = ________ gmo.

A

0.707

elecs- indiabix (terms) (6 decks)

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