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Module 4, Lesson 3 > ITEC 320 Exam 3 > Flashcards

ITEC 320 Exam 3 Flashcards

1
Q

Field-effect transistor

A

A transistor controlled by voltage rather than by current. The flow of current is controlled by the effects of an electric field.

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2
Q

Gate

A

An element in a FET. It is the control element of the devices. It corresponds to the base of a bipolar transistor.

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3
Q

Drain

A

The terminal of a FET that is the drain for charge carriers from the FET channel.

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4
Q

Source

A

In general, the origin of the electrical energy supplied to a device. In FET’s, it is one of the electrodes.

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5
Q

The FET is a semiconductor device in which output current is controlled by

A

An electric field or gate

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6
Q

The control element in a FET is the

A

Gate

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7
Q

The point at which an increase in voltage from source to drain no longer produces an increase in current is called

A

Saturation current

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8
Q

When the negative gate voltage (VGS) stops the current flow from source to drain, the FET has reached its

A

Cutoff voltage

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9
Q

Does the FET have a high or low input impedance

A

High

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10
Q

Common-source amplifier

A

An amplifier in which an FET is the active device. The source of the FET is common to the input and output circuits. Input is applied to the gate and the output is applied to the drain

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11
Q

Does the common-source FET amplifier require complicated bias arrangements, why or why not

A

No, because we do not need reverse bias and its self-biased.

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12
Q

Common-source FET amplifiers have a high input

A

Impedance

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13
Q

How many degrees is the phase shift between input and output signals in a common-source amplifier

A

180 degrees

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14
Q

What type of input signal does a common-source FET amplifier require to produce a large output signal

A

Powerful input signal (4/10v)

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15
Q

Source-follower

A

An amplifier where the drain is common to the input and output circuits. Input is applied to the gate. Output occurs at the source. Voltage gain is less than 1

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16
Q

Emitter-follower

A

A transistor stage in which the collector is common to the input and output circuits. Input is applied to the base. Output occurs at the emitter. Voltage gain is less than 1

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17
Q

In a source-follower circuit, how many degrees is the output inverted from the input

A

Its not, they follow one another or zero

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18
Q

Does a source-follower have a high or low output impedance

A

Low

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19
Q

The voltage gain of a source-follower is less than

A

1

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20
Q

The source-follower has a fairly poor what

A

Gain

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21
Q

Does the source-follower circuit have a high or low input impedance

A

High

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22
Q

The FET is a semiconductor device in which an electrical field within the device controls

A

Output current

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23
Q

You can increase or decrease the electric field within a FET with the amount of voltage applied to the

A

Gate

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24
Q

The electric field in a FET determines the amount of current flowing from the

A

Source to drain

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25
Q

An advantage of a FET is its

A

High input impedance

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26
Q

FET’s use what as part of their circuitry

A

Self-bias

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27
Q

FET’s need what to produce a large output at the load

A

A small amount of input power

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28
Q

A common-source amplifier accepts and amplifies a

A

Fairly wide range of frequencies

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29
Q

Voltage gain formula

A

Output voltage/input voltage

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30
Q

The output of a source-follower is take from a resistor in the

A

Source circuit

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31
Q

A source-follower is used in many

A

Impedance matching situations

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32
Q

MOSFET

A

Metal oxide semiconductor field-effect transistor. A FET with an insulated gate (IGFET.) The metal gate is insulated from the semiconductor by an oxide layer.

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33
Q

2 types of MOSFETs

A

Enhancement-types (turned off) or depletion-types (turned on)

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34
Q

Types MOSFETs can be divided into

A

N-types and P-types

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35
Q

IGFET

A

Insulated gate FET

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36
Q

Depletion mode

A

MOSFET operation in which changing the gate-to-source voltage from zero to some other value decreases the drain current. Turned on, but can be turned off when a control voltage is applied to the gate terminal

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37
Q

Enhancement mode

A

MOSFET operation in which changing the gate-to-source voltage from zero to some other value increases the drain current. Enhancement is turned off, but can be turned on when a control voltage is applied to the gate terminal

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38
Q

Majority carrier

A

The major carrier in semiconductor materials. Electrons in N-types. Holes in P-types.

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39
Q

Substrate

A

The surface, or under layer, on which electronic circuits are fabricated. It can be insulating materials, printed circuits, or photocells.

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40
Q

Dual-gate MOSFET

A

Also called a tetrode MOSFET. A MOSFET having two independent gates. Circuit action is controlled by either gate. Provides flexibility

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41
Q

Is there a PN junction between the gate and source in a MOSFET

A

No

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42
Q

A MOSFET has a (higher, lower) input resistance than a JFET

A

Higher

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43
Q

Is a depletion-mode MOSFET a normally off device

A

No

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44
Q

The enhancement-mode MOSFET has a (diffused, induced) conducting channel

A

Induced

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45
Q

In an enhancement-mode MOSFET with 0V bias, an AC signal operates the device on the

A

Positive AC alternations

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46
Q

VHF

A

The very high frequency range. It extends from 30 to 300 megahertz

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47
Q

UHF

A

The ultra high frequency range. It extends from 300 to 3000 megahertz

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48
Q

What are three basic circuit arrangements for a MOSFET

A

Common-source, common-gate, and common-drain

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49
Q

In what configuration is the source-follower circuit connected

A

Common-gate

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50
Q

The common-gate amplifier has a (higher, lower) voltage gain than the common-source amplifier

A

Lower

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51
Q

The common-gate circuit matches what to what impedance

A

Low source resistance impedance to a high source resistance impedance

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52
Q

The common what circuit inverts the signal 180 degrees

A

Source

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53
Q

Mixers

A

A circuit that accepts two or more input signals and combines them in some specific manner

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54
Q

Modulator

A

A circuit that varies the amplitude or frequency of sine-wave voltage according to variations of another voltage or current.

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55
Q

Automatic gain control (AGC)

A

A circuit or system that maintains the output signal level of an electronic device constant, compensating fro changes of input signal level.

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56
Q

Automatic volume control (AVC)

A

A circuit or system that maintains the output volume of a sound-producing system constant, compensating for changes of input signal level

57
Q

Why are MOSFETs useful in communications circuits

A

High input resistance and low input capacitance

58
Q

You can operate the gates in a dual-gate MOSFET

A

Independently

59
Q

A gain control voltage appearing at one of the gates acts as an added

A

Additional bias voltage

60
Q

For an N-channel MOSFET, a more (negative, positive) voltage is needed to reduce the gain of the device

A

Negative

61
Q

The gate of a MOSFET is

A

Insulated from the channel by an oxide layer

62
Q

An insulated gate of a MOSFET provides

A

An even higher input resistance than the JFET

63
Q

A MOSFET can operate with either what appearing at its gate

A

Polarity

64
Q

In an N-channel MOSFET, a (negative, positive gate voltage) increases drain current

A

Positive gate voltage

65
Q

In an N-channel depletion-mode MOSFET, the drain-to-source voltage is always applied with

A

The drain more positive than the source

66
Q

The depletion-mode MOSFET conducts a substantial amount of current

A

With a gate voltage of zero

67
Q

The enhancement-mode MOSFET conducts almost no drain current

A

When the gate is zero

68
Q

In the common-gate circuit, the gate is common to

A

Both the input and the output

69
Q

The common-gate circuit is a

A

Voltage amplifier

70
Q

The two gates of a dual-gate MOSFET can be operated

A

Independently

71
Q

Photoelectric effect

A

The effect produced by some materials when they are subjected to light.

72
Q

Light sensitive

A

When a device is sensitive to various amounts of light and converts the changes of light intensity into changes of some electrical characteristic

73
Q

Photoconductive cell

A

A type of photocell which acts as a variable resistor

74
Q

Photovoltaic cell

A

A type of photocell which builds up a charge depending on the amount of light hitting it

75
Q

Photocells

A

Also called photoelectric cell (PEC). A light-sensitive cell that converts variations of light intensity into variations of some electrical characteristic

76
Q

Photoresistive cells

A

A photoelectric cell where the electrical resistance varies inversely with the intensity of light which strikes it

77
Q

Bulk photoconductor

A

A term used to describe large photoconductive cells because of their bulk construction

78
Q

Wavelength

A

The distance between two corresponding points of two consecutive waves.

79
Q

What is a photoelectric device

A

A device used to detect distance, absence, or presence of an object by using a light transmitter.

80
Q

What is a photoconductive cell

A

A light variable resistor

81
Q

Can a photoconductive cell be improperly biased

A

No

82
Q

Does the resistance of a photoconductive cell increase or decrease with an increase in light

A

Decrease

83
Q

In a photocell, is the increase in resistance exactly proportional to the decrease in light

A

No

84
Q

Thyristor

A

A term used to describe a group of 4-layer semiconductor devices that can be pulsed into conduction, but can be turned off only by interrupting the applied voltage. SCRs and traics are thyristors

85
Q

Silicon controlled rectifier (SCR)

A

A solid-state switching device that does not require any control current after it has been turned on. An SCR acts as an open circuit until a positive potential is applied to its gate terminal. The other two electrodes are the anode and cathode.

86
Q

Forward breakover voltage

A

The value of forward bias voltage applied to the gate of a thyristor that causes it to become highly conductive

87
Q

What is the control electrode in the SCR

A

Gate

88
Q

The SCR does not turn on until the forward bias from the anode to cathode reaches a certain value. What is the value

A

Forward breakover voltage

89
Q

In an AC circuit, what does an increase in an SCR’s gate current cause

A

Forward breakover voltage may decrease

90
Q

Does the gate of an SCR lose control once the SCR is turned on

A

No

91
Q

During the negative half cycle of the waveform, the SCR is

A

Reverse biased

92
Q

What must you increase to lower breakover voltage

A

Gate current

93
Q

Will the amount of power received increase or decrease if the gate triggering pulses are delayed more

A

Decrease

94
Q

Can you trigger a thyristor with a manually-operated circuit

A

Yes

95
Q

Do you use SCRs to control electrical power

A

Yes

96
Q

List three uses of SCRs

A

Relays, lamps, and dimmers

97
Q

What is the main advantage of an SCR

A

Small current triggering a larger current or voltage

98
Q

Two thyristors are the

A

Triac and diac

99
Q

SCRs use

A

3 electrodes

100
Q

The gate of an SCR

A

Is the control point

101
Q

An SCR is off when it is

A

Reverse biased

102
Q

An SCR does not turn on until the forward bias reaches

A

The forward breakover voltage

103
Q

Once an SCR is turned on

A

THe gate loses control of the cathode-to-anode current

104
Q

In a manually-operated SCR, the SCR and load are

A

In series with an AC supply voltage

105
Q

In a manually-operated SCR, you can ignore the negative half of the cycle since it will

A

Reverse bias the thyristor during that half cycle

106
Q

The main use of an SCR is to

A

Control electrical power and convert electrical power

107
Q

SCRs are used in alarm circuits because they can be triggered with

A

Very small currents

108
Q

A component that allows signal to remain electrically independent of the following circuit is called a

A

Isolater

109
Q

Between what circuits is an isolator useful in coupling a signal

A

Control circuits and power circuits

110
Q

A circuit that uses an isolator converts what energy to what energy

A

electrical energy to light energy

111
Q

The signal output from a photoconductor used as an isolator is an amplified replica of the input. T or F

A

True

112
Q

The signal output from a photoconductor used as an isolator is 180 degrees out of phase with the input. T or F

A

False

113
Q

The resistance of a photoconductive cell decreases with

A

An increase in light intensity

114
Q

The light-sensitive material in a photoconductive cell is formed in a thin layer on a

A

glass and ceramic substrate

115
Q

Large photoconductive cells are able to withstand

A

Relatively high operating voltages (300 VDC)

116
Q

In a schematic of a photoconductive cell, an arrow pointing toward the device indicates

A

The device is light sensitive

117
Q

In an intrusion detector circuit, when an intruder interrupts the light beam

A

The resistance of the photocell suddenly increases

118
Q

In an intrusion detector circuit

A

A photocell is placed in series with a relay coil and a power

119
Q

In an intrusion detector circuit, focusing a narrow beam of light from a distant light source on the light-sensitive element of the photocell

A

Keeps the resistance of the series circuit low

120
Q

An isolator is a device that

A

Couples a signal voltage between two isolated circuits

121
Q

In a basic isolator circuit, a signal voltage causes the lamp to

A

Vary in intensity

122
Q

In a basic isolator circuit, light from the lamp causes the resistance of the photoconductor to

A

Vary

123
Q

Voltage regulator circuits are used to

A

Filter circuits and refine the filtering process

124
Q

Voltage regulator circuits provide voltage regulation for

A

Power supplies

125
Q

In a power source, each component adds up to

A

An internal resistance in series with the output current

126
Q

A what is an effective shunt regulator

A

Zener diode

127
Q

Voltage output changes can occur because of a variation in

A

Line voltage input

128
Q

The smaller the percentage of regulation

A

The better the regulator

129
Q

In a shunt voltage regulator, the regulator acts as an

A

Zener diode in parallel with the load

130
Q

In a series voltage regulator, the regulator acts as an

A

Transistor in series with the load

131
Q

One use of a series voltage regulator is as a

A

Ripple filter

132
Q

An increase in current will cause the series voltage regulator to

A

Decrease in resistance

133
Q

An amplifier is a circuit that increases the amplitude of a

A

Alternating waveform

134
Q

To determine how much an amplifier can increase a signal, you determine

A

Gain

135
Q

Amplifiers may amplify either

A

Current or voltage

136
Q

When you need large gains, you can connect

A

Cascaded amplifiers

137
Q

The total gain of two amplifiers connected in cascade is

A

The product of their individual gains

138
Q

An enhancement mode MOSFET acts as a push button switch

A

Turned off

139
Q

An depletion mode MOSFET acts as a push button switch

A

Turned on

Module 4, Lesson 3 (18 decks)

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