finals-JFET Flashcards

1
Q

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

A

JFET

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2
Q

4 main Parts of JFET Device

A

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

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3
Q

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

A

Source, S

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4
Q

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

A

Drain, D

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5
Q

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

A

Gate, G

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6
Q

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

A

Channel

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7
Q

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

A

resistance to current flow

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8
Q

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

A

gate terminal VG

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9
Q

FET has 3 terminals:

Basic Operation of JFET

A

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

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10
Q

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

Basic Operation of JFET

A

Drain and Source, Gate

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11
Q

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

Basic Operation of JFET

A

Source and Drain

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12
Q

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

A

FET

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13
Q

varies in different types of FETs

Basic Operation of JFET

A

mechanism of gate control

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14
Q

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

Basic Operation of JFET

A

Gate and Forward voltage between Drain and Source

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15
Q

2 Basic Operation of JFET:

A

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

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16
Q

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

Basic Operation of JFET

A

depletion region

17
Q

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

Basic Operation of JFET

A

equal thickness and symmetrical

18
Q

is zero as VD is 0V wrt source

Basic Operation of JFET

A

Drain current ID

19
Q

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

Basic Operation of JFET

A

positive voltage

20
Q

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

21
Q

increasing the depletion region;

Basic Operation of JFET

A

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

22
Q

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

A

current ID

23
Q

being larger at the drain end than at the source end

Basic Operation of JFET

A

wedge shaped depletion regions

24
Q

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

JFET

A

IV Characteristic Curve

25
after pinch off voltage the drain current become constant, this constant level is known as ___________ ## Footnote JFET
Saturation Level
26
The region behind the pinch off voltage where the drain current increase rapidly is known as ____________ ## Footnote JFET
Ohmic Region
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
Breakdown Region
28
The gate-source voltage, when the drain current become zero is called cut-off voltage. Denoted as VGS(off)
Cutoff Region
29
a linear region, JFET behaves like an ordinary resistor ## Footnote REGIONS OF JFET ACTION
Ohmic Region
30
the Saturation Region, JFET operates as a constant current device. The JFET is used as an amplifier in this region ## Footnote REGIONS OF JFET ACTION
Pinch Off Region
31
If VDS is increased beyond its avalanche breakdown voltage. Id increases to an excessive value. ## Footnote REGIONS OF JFET ACTION
Breakdown Region
32
Two depletion regions touch each other, channel width is zero, ID is zero. VGS (off) = -Vp ## Footnote REGIONS OF JFET ACTION
Cut Off Region
33
3 JFET Modes of Operation
1) Common Source (CS) Configuration 2) Common Gate (CG) Configuration 3) Common Drain (CD) Configuration
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 ## Footnote JFET Modes of Operation
Common Source (CS) Configuration
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 ## Footnote JFET Modes of Operation
Common Gate (CG) Configuration
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
Common Drain (CD) Configuration
37
3 Biasing Circuits used for JFET
1) Fixed Bias Circuit 2) Self Bias Circuit 3) Potential Divider Bias Circuit