finals-JFET

Question 1

is a 3 terminal semiconductor device in which current conducted by one type of carrier i.e. by electron or hole.

Answer 1

JFET

Question 2

4 main Parts of JFET Device

Answer 2

1) Source
2) Drain
3) Gate
4) Channel

Question 3

terminal which majority carriers enter into the channel is called ________ terminal __

Answer 3

Source, S

Question 4

terminal which majority carriers leave from the channel is called ________ terminal __

Answer 4

Drain, D

Question 5

There are two internally connected heavily-doped impurity regions to create two P-N junctions. These impurity regions are called the _______ terminal __

Answer 5

Gate, G

Question 6

The region between the source and drain, sandwiched between the two gates is called the ________

Answer 6

Channel

Question 7

in JFET, n-type region between the p regions offers a _________________

Answer 7

resistance to current flow

Question 8

in JFET, the resistance varies with the voltage applied to ___________

Answer 8

gate terminal VG

Question 9

FET has 3 terminals:

Basic Operation of JFET

Answer 9

Gate (G), Drain (D) and Source (S)

Question 10

in n-channel FET, ____ and ____ are connected to n-channel and ____ is connected to the p-type material

Basic Operation of JFET

Answer 10

Drain and Source, Gate

Question 11

The voltage applied at gate terminal controls the current flow between the other two terminals;

Basic Operation of JFET

Answer 11

Source and Drain

Question 12

it can be thought of as a resistance connected between Source and Drain, which is a function of the gate voltage VG

Basic Operation of JFET

Answer 12

FET

Question 13

varies in different types of FETs

Basic Operation of JFET

Answer 13

mechanism of gate control

Question 14

in operation of JFET, a reverse voltage is applied to the:

Basic Operation of JFET

Answer 14

Gate and Forward voltage between Drain and Source

Question 15

2 Basic Operation of JFET:

Answer 15

1) VG=0V and VDS=0V
2) VG=0V and VDS is +ve

Question 16

There occurs a ________ at the p-n junction as the electrons from n-channel combine with holes from p-gate

Basic Operation of JFET

Answer 16

depletion region

Question 17

since no voltages are applied, the depletion regions are of:

Basic Operation of JFET

Answer 17

equal thickness and symmetrical

Question 18

is zero as VD is 0V wrt source

Basic Operation of JFET

Answer 18

Drain current ID

Question 19

VG=0V and VDS is increased from 0 to a more:

Basic Operation of JFET

Answer 19

positive voltage

Question 20

the depletion region between p-gate and n-channel ____ as more electrons from n-channel combine with holes from p-gate

Basic Operation of JFET

Answer 20

increases

Question 21

increasing the depletion region;

Basic Operation of JFET

Answer 21

1) decreases - size of n-channel which;
2) increases - resistance of the n-channel

Question 22

Though the resistance of the channel increases with increasing VDS, the ____ doesn’t decrease, rather it increases because drain voltage wet source increases

Basic Operation of JFET

Answer 22

current ID

Question 23

being larger at the drain end than at the source end

Basic Operation of JFET

Answer 23

wedge shaped depletion regions

Question 24

it is the curve between drain current (ID) and drain-source voltage (VDS) for different gate-source voltage (VGS)

JFET

Answer 24

IV Characteristic Curve

Question 25

after pinch off voltage the drain current become constant, this constant level is known as ___________

JFET

Answer 25

Saturation Level

Question 26

The region behind the pinch off voltage where the drain current increase rapidly is known as ____________

JFET

Answer 26

Ohmic Region

Question 27

it is the region, when the drain-source voltage (VDS) is high enough to cause the JFET’s resistive channel to breakdown and pass uncontrolled maximum current

Answer 27

Breakdown Region

Question 28

The gate-source voltage, when the drain current become zero is called cut-off voltage. Denoted as VGS(off)

Answer 28

Cutoff Region

Question 29

a linear region, JFET behaves like an ordinary resistor

REGIONS OF JFET ACTION

Answer 29

Ohmic Region

Question 30

the Saturation Region, JFET operates as a constant current device. The JFET is used as an amplifier in this region

REGIONS OF JFET ACTION

Answer 30

Pinch Off Region

Question 31

If VDS is increased beyond its avalanche breakdown voltage. Id increases to an excessive value.

REGIONS OF JFET ACTION

Answer 31

Breakdown Region

Question 32

Two depletion regions touch each other, channel width is zero, ID is zero.
VGS (off) = -Vp

REGIONS OF JFET ACTION

Answer 32

Cut Off Region

Question 33

3 JFET Modes of Operation

Answer 33

1) Common Source (CS) Configuration
2) Common Gate (CG) Configuration
3) Common Drain (CD) Configuration

Question 34

• Most common modes of operation
• High input impedance
• High voltage gain
• Used in audio frequency amplifier
• Output signal 180o “out-of-phase” with the input

JFET Modes of Operation

Answer 34

Common Source (CS) Configuration

Question 35

• Input terminal: Source
• Output terminal: Drain
• Low input impedance
• High output impedance
• Used in high frequency and in impedance matching circuits
• Output signal 0 degrees “In-phase” with the input

JFET Modes of Operation

Answer 35

Common Gate (CG) Configuration

Question 36

• Input terminal: Gate
• Output terminal: Source
• High input impedance
• Low output impedance
• Near-unity voltage gain
• Used in buffer amplifiers, also called source follower
• Output signal 0 degrees “In-phase” with the input

Answer 36

Common Drain (CD) Configuration

Question 37

3 Biasing Circuits used for JFET

Answer 37

1) Fixed Bias Circuit
2) Self Bias Circuit
3) Potential Divider Bias Circuit