Field Effect Transistors

Question 1

What is the full form of FET ?

Answer 1

Field Effect Transistors

Question 2

How many terminals does a FET have ?

Answer 2

3

Question 3

How do FETs control the shape and electrical conductivity of a channel ?

Answer 3

By using an electric field

Question 4

What are the two types of FETs ?

Answer 4

JFET and MOSFET

Question 5

What is the full form of JFET ?

Answer 5

Junction FET

Question 6

What is the full form of MOS FET ?

Answer 6

Metal Oxide Semiconductor FET

Question 7

What are the two types of MOS FETs ?

Answer 7

Depletion MOS FETs

Enhancement MOSFETs

Question 8

What controls a BJT ?

Answer 8

Current

Question 9

Why is a BJT a current controlled device ?

Answer 9

Output (Collector Current) depends on input current(Base current)

Question 10

What controls a FET ?

Answer 10

Voltage

Question 11

Why is a FET a voltage controlled device ?

Answer 11

The output (drain current) depends on gate-source voltage

Question 12

What are the three terminals of a BJT called ?

Answer 12

Base, Emitter and Collector

Question 13

What are the three terminals of a FET called ?

Answer 13

Gate, Source and Drain

Question 14

Which charge carrier causes current in a BJT ?

Answer 14

Both holes and electrons

Question 15

Which charge carrier causes current in a FET ?

Answer 15

Either holes or electrons

Question 16

Why are FETs called unipolar charge transistors ?

Answer 16

Either of the charge carriers causes current, but not both

Question 17

Why are FETs used in noise sensitive electronics in tuners and low noise amplifiers in satellite receivers ?

Answer 17

It produces less noise than a BJT

Question 18

What is another reason FETs are used in satellite receivers ?

Answer 18

It is relatively immune to radiation

Question 19

What makes FETs excellent signal choppers ?

Answer 19

No offset voltage at zero drain current

Question 20

Which transistor has better thermal stability, BJT or FET ?

Answer 20

Generally, FET

Question 21

What is the main advantage of a FET over a BJT ?

Answer 21

It’s high input impedance

Question 22

How high is a FET’s input impedance, generally ?

Answer 22

It is of the order of 100 M ohm

Question 23

Why do MOSFET’s need special handling during installation ?

Answer 23

They are susceptible to overload voltages

Question 24

Why is a MOSFET vulnerable to electrostatic damage during installation ?

Answer 24

It’s fragile insulating layer in between the gate and the channel

Question 25

Which transistor has a high gain-bandwidth product ?

Answer 25

BJT has higher gain-Bandwidth product

Question 26

Which transistor has better thermal stability ?

Answer 26

FETs have better thermal stability

Question 27

What are the two main configurations of JFETs ?

Answer 27

N channel and P channel JFET

Question 28

Describe the drain and source

Answer 28

Two ohmic electrical resistances at either end

Question 29

Describe the channel

Answer 29

A narrow piece of high resistivity semiconductor

Question 30

What is the purpose of the channel ?

Answer 30

A path for the majority carriers to flow form the source to drain

Question 31

What is the gate terminal in a N- channel JFET ?

Answer 31

The two embedded P type layers are connected together

Question 32

How is the drain current controlled for a given potential in between the drain and source ?

Answer 32

By externally applied potential in between source and drain V (dd)