Deck 32: Field Effect Transistors

Question 1

A ______________ device depends on only one type of charge carrier, either electrons or holes.

Answer 1

unipolar

Question 2

The ______________ regions in a JFET are embedded on each side of the channel to help control the amount of current flow in the channel.

Answer 2

gate

Question 3

The amount of gate-source voltage required to reduce the drain current to zero is called the gate-source ______________ voltage.

Answer 3

cutoff

Question 4

For a ______________-channel JFET, the drain voltage is negative and the gate voltage is positive.

Question 5

The ______________-off voltage is the border between the ohmic region and the current-source region.

Question 6

JFETs are often referred to as normally ______________ devices.

Question 7

One of the most common ways to bias a JFET is with self-______________.

Question 8

The ______________ equals the change in drain current divided by the change in gate-source voltage for a fixed value of V_DS.

Question 9

The common-source amplifier's input and output voltages are ______________ degrees out of phase.

Question 10

A ______________ follower has high input impedance, low output impedance, and unity voltage gain.

Question 11

The biggest disadvantage of the ______________-gate amplifier is its low value of input impedance.

Question 12

In which JFET biasing method does the value of I_D for a given value of V_GS vary from one JFET to the next making it difficult to predict exact values of I_D and V_D?

A) Gate bias
B) Self-bias
C) Voltage-divider bias
D) Current-source bias

Question 13

JFETs are used more often than bipolar transistors to amplify small ac signals because JFETs

A) are less expensive
B) have a much higher voltage gain
C) have very high input impedance
D) have a very low input impedance

Question 14

Which of the following is not a JFET amplifier configuration?

A) Common-source
B) Common-gate
C) Common-drain
D) Drain follower

Question 15

What is the change in drain current divided by the change in gate-source voltage for a fixed value of V_DS?

A) Conductance
B) Ac beta
C) Ac alpha
D) Transconductance

Question 16

The unit of g_m is

A) joules
B) ohms
C) siemens
D) maxwells

Question 17

The current gain of a JFET amplifier is

A) low
B) high
C) zero
D) undefined

Question 18

For a common-source amplifier, the output is taken at the

A) drain
B) source
C) gate
D) power source

Question 19

For a common-source amplifier, the input and output voltages are

A) in phase
B) 45° out of phase
C) 90° out of phase
D) 180° out of phase

Question 20

What component places the source at ground for ac signals?

A) Source resistor
B) Coupling capacitor
C) Source bypass capacitor
D) Gate resistor

Question 21

Which JFET amplifier is similar to the emitter follower used with bipolar transistors?

A) Common-source
B) Common-drain
C) Common-gate
D) Gate follower

Question 22

Which JFET amplifier has high input impedance, low output impedance and unity voltage gain?

A) Common-source
B) Common-drain
C) Common-gate
D) Gate follower

Question 23

Which JFET amplifier has the disadvantage of very low input impedance?

A) Common-source
B) Common-drain
C) Common-gate
D) Gate follower

Question 24

For a common-gate JFET amplifier, the input is applied to the

A) gate
B) source
C) drain
D) power source

Question 25

The key difference between JFETs and MOSFETs is that the MOSFET has

A) a lower input impedance
B) three gates
C) an insulated gate
D) no source

Question 26

The MOSFET is sometimes referred to as a(n)

A) JFET
B) I JFET
C) IGFET
D) BJT

Question 27

Which semiconductor device is normally on?

A) Depletion-type MOSFET
B) Enhancement-type MOSFET
C) Bipolar junction transistor
D) Zener diode

Question 28

Which semiconductor device is frequently used as a small signal amplifier and frequency mixer?

A) JFET
B) BJT
C) Enhancement-type MOSFET
D) Depletion-type MOSFET

Question 29

An advantage of a MOSFET over a JFET is it

A) is a current-controlled device
B) is less expensive
C) has a higher input resistance
D) has a lower input resistance

Question 30

One disadvantage of MOSFET devices is their extreme sensitivity to

A) magnetic fields
B) cold
C) electrostatic discharge
D) heat

Question 31

The field effect transistor is a three-terminal device similar to the bipolar junction transistor.

Question 32

The FET is a bipolar device.

Question 33

Field effect transistors are current-controlled devices.

Question 34

In general, JFETs are more temperature stable than bipolar transistors.

Question 35

Because JFETs are much smaller than bipolar transistors, JFETs are more suitable for use in integrated circuits.

Question 36

Dual gate JFETs are most commonly used in frequency mixers, circuits that are frequently encountered in communications electronics.

Question 37

The current flow is between the drain and the gate terminals in a JFET.

Question 38

For the p-channel JFET the majority current carriers in the channel are free electrons.

Question 39

When a JFET is symmetrical, the drain and source leads may be interchanged without affecting its operation.

Question 40

Above the pinch-off voltage, it is common for the drain curves to have a slight upward slope.

Question 41

The amount of gate-source voltage to reduce the drain current to zero is called the gate-source cutoff voltage.

Question 42

The border between the ohmic region and the current-source region is called pinch-off.

Question 43

A graph of drain current versus gate-source voltage for a JFET results in a transconductance curve.

Question 44

Whatever method is used to bias a JFET, the gate-source junction is forward-biased.

Question 45

Gate bias is seldom used with JFETs because the characteristic of the individual JFETs used in mass production may vary over a wide range.