Field-Effect Transistors (FETs): Types, Characteristics, and Applications

Question 1

Which of the following is **NOT** a type of Field-Effect Transistor (FET)?

Accepted Answer

Diac

Answer

Junction FET (JFET)

Answer

Metal-Oxide-Semiconductor FET (MOSFET)

Answer

Insulated-Gate Bipolar Transistor (IGBT)

Question 2

What is the primary function of a JFET?

Accepted Answer

Control current flow

Answer

Amplify signals

Answer

Generate oscillations

Answer

Switch signals

Question 3

What is the purpose of a FET in a switch application?

Accepted Answer

Control the flow of current

Answer

Amplify voltage signals

Answer

Filter out unwanted frequencies

Answer

Generate a square wave

Question 4

What is the significance of the transconductance parameter (gm) in a FET?

Accepted Answer

Measures the ability of the gate to control current

Answer

Indicates the maximum voltage that the FET can withstand

Answer

Determines the frequency response of the FET

Answer

Specifies the power dissipation of the FET

Question 5

What is a common application of MOSFETs in power electronics?

Accepted Answer

Power switches

Answer

Voltage regulators

Answer

Analog amplifiers

Answer

Memory devices

Question 6

Which factor **does not** affect the threshold voltage (Vth) of a FET?

Accepted Answer

Channel width

Answer

Channel type

Answer

Gate material

Answer

Gate-oxide capacitance

Question 7

Which of the following is NOT a type of Field-Effect Transistor (FET)?

Accepted Answer

Bipolar Junction Transistor (BJT)

Answer

Junction Field-Effect Transistor (JFET)

Answer

Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET)

Answer

Gallium Nitride High-Electron Mobility Transistor (GaN HEMT)

Question 8

In a depletion-mode n-channel MOSFET, what is the effect of increasing the gate-source voltage (Vgs)?

Accepted Answer

It decreases the channel resistance, increasing the drain-source current.

Answer

It increases the channel width, reducing the channel resistance.

Answer

It creates a depletion region under the gate, reducing the channel width.

Answer

It increases the threshold voltage, making the MOSFET more difficult to turn on.

Question 9

The purpose of a biasing resistor in a FET circuit is to:

Accepted Answer

Establish a stable operating point for the FET

Answer

Limit the current flowing through the FET

Answer

Provide negative feedback to improve stability

Answer

Protect the FET from damage due to overvoltage

Question 10

A cascode FET configuration is often used to achieve improved performance in amplifier circuits. What is the primary advantage of using a cascode FET configuration?

Accepted Answer

Increased voltage gain

Answer

Improved input impedance

Answer

Reduced output impedance

Answer

Increased bandwidth

Question 11

Which of the following is not a type of Field-Effect Transistor (FET)?

Accepted Answer

Bipolar Junction Transistor (BJT)

Answer

JFET

Answer

MOSFET

Answer

Insulated-Gate Field-Effect Transistor (IGFET)

Question 12

What is the primary difference between the construction of a JFET and a MOSFET?

Accepted Answer

JFETs use a semiconductor channel, while MOSFETs use an insulating layer.

Answer

JFETs are majority-carrier devices, while MOSFETs are minority-carrier devices.

Answer

JFETs have a lower input impedance than MOSFETs.

Answer

JFETs are faster switching devices than MOSFETs.

Question 13

Which of the following is a key characteristic of an enhancement-mode MOSFET?

Accepted Answer

It requires a positive gate-source voltage to turn ON.

Answer

It is normally ON.

Answer

It has a low threshold voltage.

Answer

It has a high drain current.

Question 14

What is the primary purpose of a FET bias circuit?

Accepted Answer

To provide the gate-source voltage required for proper operation.

Answer

To limit the drain current to prevent damage to the FET.

Answer

To increase the output impedance of the FET.

Answer

To protect the FET from over-voltage.

Question 15

In the output characteristics of a FET, the saturation region is the region where

Accepted Answer

the drain current is constant with increasing drain-source voltage

Answer

the drain current is linearly proportional to gate-source voltage

Answer

the FET is fully turned OFF

Answer

the FET exhibits negative resistance

Question 16

The transfer characteristic of a FET is a graph of

Accepted Answer

drain current versus gate-source voltage

Answer

drain current versus drain-source voltage

Answer

gate-source voltage versus drain current

Answer

gate-source voltage versus drain-source voltage

Question 17

In a JFET, the pinch-off voltage is the voltage at which

Accepted Answer

the drain current becomes zero

Answer

the gate-source junction becomes reverse-biased

Answer

the FET enters the saturation region

Answer

the FET is fully turned ON

Question 18

FET circuits require biasing to optimize their performance. Explain the significance of biasing in FET circuits and describe the common biasing techniques used to enhance FET operation.

Accepted Answer

Common biasing techniques for FETs include voltage divider biasing, source biasing, and current source biasing, each suited for specific applications.

Answer

Biasing is not necessary in FET circuits because they have inherent self-biasing capabilities.

Answer

The primary biasing method for FETs is self-biasing, which uses a resistor network to set the gate voltage.

Question 19

Improved: Which of the following is a key advantage of Field-Effect Transistors (FETs) over Bipolar Junction Transistors (BJTs)?

Accepted Answer

Higher input impedance

Answer

Lower output impedance

Answer

Higher current gain

Answer

Faster switching speed

Question 20

Improved: In an n-channel MOSFET, which particle is the majority carrier in the channel?

Accepted Answer

Electrons

Answer

Holes

Answer

Protons

Answer

Neutrons

Question 21

Improved: Which type of field-effect transistor is known for its high switching speed and power handling capability?

Accepted Answer

MESFET

Answer

JFET

Answer

MOSFET

Answer

IGBT

Question 22

Improved: What is the main function of the gate terminal in a FET?

Accepted Answer

To control the flow of current through the channel

Answer

To provide power to the transistor

Answer

To set the output voltage

Answer

To amplify the input signal

Question 23

Improved: What is the relationship between the drain-source current (Ids) and the gate-source voltage (Vgs) in a MOSFET in the saturation region?

Accepted Answer

Ids is saturated at a constant value

Answer

Ids is proportional to Vgs

Answer

Ids is inversely proportional to Vgs

Answer

Ids is independent of Vgs

Question 24

Improved: What is the function of the body terminal in a JFET?

Accepted Answer

To provide a path for leakage current

Answer

To control the flow of current through the channel

Answer

To stabilize the bias point

Answer

To amplify the output signal

Question 25

Which of the following is NOT a type of Field-Effect Transistor (FET)?

Accepted Answer

Bipolar Junction Transistor (BJT)

Answer

JFET

Answer

MOSFET

Question 26

Which of the following is a primary advantage of MOSFETs over JFETs?

Accepted Answer

Higher input impedance

Answer

Reduced power dissipation

Answer

Faster switching speeds

Question 27

In an FET amplifier circuit, the gate-source resistor serves primarily to:

Accepted Answer

Stabilize the bias point

Answer

To reduce input impedance

Question 28

Which of the following is NOT a common application of FETs?

Accepted Answer

Voltage regulators

Answer

Amplifiers

Answer

Switches

Answer

Logic gates

Question 29

In a JFET, the pinch-off voltage is the:

Accepted Answer

Gate-source voltage at which the channel is fully depleted

Answer

The drain-source voltage at which the FET enters the saturation region

Question 30

The semiconductor channel in a MOSFET is typically made from:

Accepted Answer

Silicon

Answer

Gallium arsenide

Question 31

The fundamental difference between a unipolar and bipolar transistor is:

Accepted Answer

Unipolar transistors are controlled by a single type of charge carrier, while bipolar transistors are controlled by both types

Answer

Bipolar transistors are faster than unipolar transistors

Question 32

Which of the following factors does NOT influence the drain current in a MOSFET?

Accepted Answer

Collector current

Answer

Drain-source voltage

Question 33

Which of the following is NOT a characteristic of a Field-Effect Transistor (FET)?

Accepted Answer

Current flow is controlled by a magnetic field.

Answer

Voltage-controlled device.

Answer

Current flow is controlled by an electric field.

Answer

High input impedance.

Question 34

Which type of FET relies on a PN junction between the source and drain to control current flow?

Accepted Answer

Junction Field-Effect Transistor (JFET)

Answer

Depletion MOSFET

Answer

Enhancement MOSFET

Answer

Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET)

Question 35

In an n-channel JFET, what happens to the drain current as the gate-source voltage becomes more negative?

Accepted Answer

Drain current decreases.

Answer

Drain current remains constant.

Answer

Drain current increases.

Answer

Drain current becomes unpredictable.

Question 36

Which type of MOSFET is primarily used in switching applications?

Accepted Answer

Enhancement MOSFET

Answer

IGFET (Insulated Gate Field-Effect Transistor)

Answer

Depletion MOSFET

Answer

JFET

Question 37

What is the primary function of the gate oxide layer in a MOSFET?

Accepted Answer

To electrically isolate the gate from the channel.

Answer

To reduce the power consumption.

Answer

To improve the frequency response.

Answer

To enhance the conductivity of the channel.

Question 38

In which of the following applications are FET amplifiers typically used?

Accepted Answer

Low-noise preamplifiers.

Answer

Digital logic circuits.

Answer

Switching circuits.

Answer

High-power amplifiers.

Question 39

Which of the following is NOT an advantage of using FETs over bipolar junction transistors (BJTs)?

Accepted Answer

Lower input impedance.

Answer

Better high-frequency performance.

Answer

Lower power consumption.

Answer

Higher input impedance.

Question 40

What is the pinch-off voltage in a JFET?

Accepted Answer

The gate-source voltage at which the drain current becomes nearly constant.

Answer

The voltage at which the JFET breaks down.

Answer

The voltage required to turn the JFET completely on.

Question 41

In a MOSFET, what is the 'threshold voltage'?

Accepted Answer

The gate-source voltage required to create a conducting channel.

Answer

The voltage at which the MOSFET becomes fully saturated.

Answer

The voltage drop across the gate oxide layer.

Question 42

Which of the following describes the behavior of a MOSFET operating in the saturation region?

Accepted Answer

A constant drain current regardless of drain-source voltage.

Answer

A very low drain current.

Answer

A linear relationship between drain current and drain-source voltage.

Question 43

Which of the following statements about FETs is true?

Accepted Answer

FETs are voltage-controlled devices.

Answer

FETs are temperature-controlled devices.

Answer

FETs are light-controlled devices.

Answer

FETs are current-controlled devices.

Question 44

What is the main difference between a JFET and a MOSFET?

Accepted Answer

JFETs use a PN junction, while MOSFETs use a metal-insulator-semiconductor interface.

Answer

JFETs are normally-on devices, while MOSFETs are normally-off devices.

Answer

JFETs have a higher transconductance than MOSFETs.