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transistors Flashcards

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1
Q

When transistors are used in digital circuits they usually operate in the:
active region
breakdown region
saturation and cutoff regions
linear region

A

saturation and cutoff regions

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2
Q

Three different Q points are shown on a dc load line. The upper Q point represents the:
minimum current gain
intermediate current gain
maximum current gain
cutoff point

A

maximum current gain

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3
Q

A transistor has a mca12_1001a1.gif of 250 and a base current, IB, of 20 mu.gif A. The collector current, IC, equals:
500 uA
5 mA
50 mA
5 A

A

5 mA

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4
Q

A current ratio of IC/IE is usually less than one and is called:
beta
theta
alpha
omega

A

alpha

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5
Q

With the positive probe on an NPN base, an ohmmeter reading between the other transistor terminals should be:
open
infinite
low resistance
high resistance

A

low resistance

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6
Q

In a C-E configuration, an emitter resistor is used for:
stabilization
ac signal bypass
collector bias
higher gain

A

stabilization

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7
Q

Voltage-divider bias provides:
an unstable Q point
a stable Q point
a Q point that easily varies with changes in the transistor’s current gain
a Q point that is stable and easily varies with changes in the transistor’s current gain

A

a stable Q point

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8
Q

To operate properly, a transistor’s base-emitter junction must be forward biased with reverse bias applied to which junction?
collector-emitter
base-collector
base-emitter
collector-base

A

collector-base

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9
Q

The ends of a load line drawn on a family of curves determine:
saturation and cutoff
the operating point
the power curve
the amplification factor

A

saturation and cutoff

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10
Q

The C-B configuration is used to provide which type of gain?
voltage
current
resistance
power

A

voltage

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11
Q

The Q point on a load line may be used to determine:
VC
VCC
VB
IC

A

VB

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12
Q

A transistor may be used as a switching device or as a:
fixed resistor
tuning device
rectifier
variable resistor

A

variable resistor

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13
Q

Which is beta’s current ratio?
IC/IB
IC/IE
IB/IE
IE/IB

A

IC/IB

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14
Q

A collector characteristic curve is a graph showing:

emitter current (IE) versus collector-emitter voltage (VCE) with (VBB) base bias voltage held constant

collector current (IC) versus collector-emitter voltage (VCE) with (VBB) base bias voltage held constant

collector current (IC) versus collector-emitter voltage (VC) with (VBB) base bias voltage held constant

collector current (IC) versus collector-emitter voltage (VCC) with (VBB) base bias voltage held constant

A

collector current (IC) versus collector-emitter voltage (VCE) with (VBB) base bias voltage held constant

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15
Q

With low-power transistor packages, the base terminal is usually the:
tab end
middle
right end
stud mount

A

middle

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16
Q

When a silicon diode is forward biased, what is VBE for a C-E configuration?
voltage-divider bias
0.4 V
0.7 V
emitter voltage

A

0.7

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17
Q

With a PNP circuit, the most positive voltage is probably:
ground
VC
VBE
VCC

A

ground

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18
Q

Most of the electrons in the base of an NPN transistor flow:
out of the base lead
into the collector
into the emitter
into the base supply

A

into the collector

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19
Q

In a transistor, collector current is controlled by:
collector voltage
base current
collector resistance
all of the above

A

base current

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20
Q

Total emitter current is:
IE – IC
IC + IE
IB + IC
IB – IC

A

IB + IC

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21
Q

Often a common-collector will be the last stage before the load; the main function(s) of this stage is to:
provide voltage gain
provide phase inversion
provide a high-frequency path to improve the frequency response
buffer the voltage amplifiers from the low-resistance load and provide impedance matching for maximum power transfer

A

buffer the voltage amplifiers from the low-resistance load and provide impedance matching for maximum power transfer

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22
Q

For a C-C configuration to operate properly, the collector-base junction should be reverse biased, while forward bias should be applied to which junction?
collector-emitter
base-emitter
collector-base
cathode-anode

A

collector-emitter

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23
Q

The input/output relationship of the common-collector and common-base amplifiers is:
270 degrees
180 degrees
90 degrees
0 degrees

A

0 degrees

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24
Q

If a transistor operates at the middle of the dc load line, a decrease in the current gain will move the Q point:
off the load line
nowhere
up
down

A

down

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25
Which is the higher gain provided by a C-E configuration? voltage current resistance power
power
26
Junction Field Effect Transistors (JFET) contain how many diodes? 4 3 2 1
2
27
When not in use, MOSFET pins are kept at the same potential through the use of: shipping foil nonconductive foam conductive foam a wrist strap
conductive foam
28
D-MOSFETs are sometimes used in series to construct a cascode high-frequency amplifier to overcome the loss of: low output impedance capacitive reactance high input impedance inductive reactance
high input impedance
29
A "U" shaped, opposite-polarity material built near a JFET-channel center is called the: gate block drain heat sink
gate
30
When testing an n-channel D-MOSFET, resistance G to D = , resistance G to S = , resistance D to SS = and 500 , depending on the polarity of the ohmmeter, and resistance D to S = 500 . What is wrong? short D to S open G to D open D to SS nothing
nothing
31
In the constant-current region, how will the IDS change in an n-channel JFET? As VGS decreases ID decreases. As VGS increases ID increases. As VGS decreases ID remains constant. As VGS increases ID remains constant.
As VGS decreases ID decreases.
32
A MOSFET has how many terminals? 2 or 3 3 4 3 or 4
3 or 4
33
IDSS can be defined as: the minimum possible drain current the maximum possible current with VGS held at –4 V the maximum possible current with VGS held at 0 V the maximum drain current with the source shorted
the maximum possible current with VGS held at 0 V
34
What is the input impedance of a common-gate configured JFET? very low low high very high
very low
35
JFET terminal "legs" are connections to the drain, the gate, and the: channel source substrate cathode
source
36
A very simple bias for a D-MOSFET is called: self biasing gate biasing zero biasing voltage-divider biasing
zero biasing
37
With the E-MOSFET, when gate input voltage is zero, drain current is: at saturation zero IDSS widening the channel
zero
38
With a 30-volt VDD, and an 8-kilohm drain resistor, what is the E-MOSFET Q point voltage, with ID = 3 mA? 6 V 10 V 24 V 30 V
6 V
39
When an input signal reduces the channel size, the process is called: enhancement substrate connecting gate charge depletion
depletion
40
Which JFET configuration would connect a high-resistance signal source to a low-resistance load? source follower common-source common-drain common-gate
source follower
41
How will electrons flow through a p-channel JFET? from source to drain from source to gate from drain to gate from drain to source
from drain to source
42
When VGS = 0 V, a JFET is: saturated an analog device an open switch cut off
saturated
43
When applied input voltage varies the resistance of a channel, the result is called: saturization polarization cutoff field effect
field effect
44
When is a vertical channel E-MOSFET used? for high frequencies for high voltages for high currents for high resistances
for high currents
45
When the JFET is no longer able to control the current, this point is called the: breakdown region depletion region saturation point pinch-off region
breakdown region
46
With a JFET, a ratio of output current change against an input voltage change is called: transconductance siemens resistivity gain
transconductance
47
Which type of JFET bias requires a negative supply voltage? feedback source gate voltage divider
gate
48
How will a D-MOSFET input impedance change with signal frequency? As frequency increases input impedance increases. As frequency increases input impedance is constant. As frequency decreases input impedance increases. As frequency decreases input impedance is constant.
As frequency decreases input impedance increases.
49
The type of bias most often used with E-MOSFET circuits is: constant current drain-feedback voltage-divider zero biasing
drain-feedback
50
The transconductance curve of a JFET is a graph of: IS versus VDS IC versus VCE ID versus VGS ID × RDS
ID versus VGS
51
The common-source JFET amplifier has: a very high input impedance and a relatively low voltage gain a high input impedance and a very high voltage gain a high input impedance and a voltage gain less than 1 no voltage gain
a very high input impedance and a relatively low voltage gain
52
The overall input capacitance of a dual-gate D-MOSFET is lower because the devices are usually connected: in parallel with separate insulation with separate inputs in series
in series
53
What is the transconductance of an FET when ID = 1 mA and VGS = 1 V? 1 kS 1 mS 1 k 1 m
1 mS
54
Which component is considered to be an "OFF" device? transistor JFET D-MOSFET E-MOSFET
E- MOSFET
55
In an n-channel JFET, what will happen at the pinch-off voltage? the value of VDS at which further increases in VDS will cause no further increase in ID the value of VGS at which further decreases in VGS will cause no further increases in ID the value of VDG at which further decreases in VDG will cause no further increases in ID the value of VDS at which further increases in VGS will cause no further increases in ID
the value of VDS at which further increases in VDS will cause no further increase in ID
56
The primary function of the bias circuit is to hold the circuit stable at VCC hold the circuit stable at vin ensure proper gain is achieved hold the circuit stable at the designed Q-point
hold the circuit stable at the designed Q-point
57
A JFET is a current-controlled device has a low input resistance is a voltage-controlled device is always forward-biased
is a voltage-controlled device
58
A source follower has a voltage gain (Av) of
Av= gmRs/(1+gmRs)
59
The capacitor that produces an ac ground is called a(n) coupling capacitor dc open bypass capacitor ac open
bypass capacitor
60
The formula used to calculate the approximate ac resistance of the base-emitter diode (re) is
re=25mV/IE
61
The signal voltage gain of an amplifier, Av, is defined as:
Av=RC/RE
62
In a class B push-pull amplifier, the transistors are biased slightly above cutoff to avoid crossover distortion unusually high efficiency negative feedback a low input impedance
crossover distortion
63
The depletion-mode MOSFET can operate with only positive gate voltages can operate with only negative gate voltages cannot operate in the ohmic region can operate with positive as well as negative gate voltages
can operate with positive as well as negative gate voltages
64
Three different points are shown on a dc load line. The upper point represents the minimum current gain quiescent point saturation point cutoff point
saturation point
65
Which of the following conditions are needed to properly bias an npn transistor amplifier? Forward bias the base/emitter junction and reverse bias the base/collector junction. Forward bias the collector/base junction and reverse bias the emitter/base junction. Apply a positive voltage on the n-type material and a negative voltage on the p-type material. Apply a large voltage on the base.
Forward bias the base/emitter junction and reverse bias the base/collector junction.
66
Often a common-collector will be the last stage before the load; the main function of this stage is to provide voltage gain buffer the voltage amplifiers from the low-resistance load provide phase inversion provide a high-frequency path to improve the frequency response
buffer the voltage amplifiers from the low-resistance load
67
In order for feedback oscillators to have any practical value, the gain has to be < 1 self-adjusting stabilized nonlinear
self-adjusting
68
To get a negative gate-source voltage in a self-biased JFET circuit, you must use a voltage divider source resistor ground negative gate supply voltage
source resistor
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