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ELECS > E-MOSFET > Flashcards

E-MOSFET Flashcards

1
Q

E-MOSFET

A

Enhancement Mode - Metal Oxide
Semiconductor Field Effect Transistor

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2
Q

A ____________ is used as the foundation on which the device is constructed.

N-Channel E-MOSFET Construction

A

p-type substrate

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3
Q

The ________ and ________ terminals are connected through metallic contacts to n-doped regions.

N-Channel E-MOSFET Construction

A

Drain (D) and Source (S)

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4
Q

The ________________ between two n-doped regions is the primary difference between depletion and enhancement type MOSFET.

N-Channel E-MOSFET Construction

A

absence of channel

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5
Q

The ________ isolate the gate from the region between the source and drain.

N-Channel E-MOSFET Construction

A

SiO2 layer

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6
Q

when VGS=0V and VDS=0, the absence of channel between drain and source will result in __________.

N-Channel E-MOSFET Construction (Basic Operation)

A

zero current

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7
Q

when VGS=0 and VDS is some positive voltage, there exist ____________ biased junction between the n-doped regions and p-substrate and absence of channel between source and drain which cause zero current to flow.

N-Channel E-MOSFET Construction (Basic Operation)

A

two reversed

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8
Q

Thus, when VGS=0 and voltage VDS is applied across drain to source terminals, the absence of channel will result in ________________ as against the ________________ where ID=IDSS when VGS=0.

N-Channel E-MOSFET Construction (Basic Operation)

A

zero drain current, depletion type MOSFET

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9
Q

When VGS and VDS are set to some positive voltages, then the positive potential get established at ________ and the ________ with respect to the ________.

N-Channel E-MOSFET Construction (Basic Operation)

A

drain, gate, source

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10
Q

The positive potential at gate will repel the holes in ____________ along the edge of the SiO2 layer however the electrons which is ____________ in p-substrate will be attracted to the ________________ and get accumulated in the region near the surface of the SiO2 layer.

N-Channel E-MOSFET Construction (Basic Operation)

A

p-type substrate, minority carrier, positive gate

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11
Q

The insulating SiO2 layer prevent the electrons being _________________________.

N-Channel E-MOSFET Construction (Basic Operation)

A

absorbed by positive gate

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12
Q

As VGS increases, the concentration of___________ increases such that a channel is induced between drain and source which allow flow of electrons from drain to source hence the flow of ____________.

N-Channel E-MOSFET Construction (Basic Operation)

A

electrons, drain current

N-Channel E-MOSFET Construction (Basic Operation)

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13
Q

The level of VGS that starts flow of current is called ____________ VGS(th) ot VT. For N-type MOSFET it is referred to _______

A

threshold voltage, VTN

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14
Q

Since the channel is not in existent with VGS=0 and enhance by the application of positive VGS, this type of MOSFET is called an __________________.

N-Channel E-MOSFET Construction (Basic Operation)

A

enhancement mode MOSFET

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15
Q

Both the depletion and enhancement type MOSFETs have ________________.

N-Channel E-MOSFET Construction (Basic Operation)

A

enhancement region

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16
Q

The depletion type MOSFETs can operate in both depletion and enhancement regions whereas enhancement type MOSFET can only operate in ___________________.

N-Channel E-MOSFET Construction (Basic Operation)

A

enhancement regions

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17
Q

With a fixed VDS drain-source voltage connected across the ________, we can plot the values of drain current, ID with varying values of VGS to obtain a graph of the MOSFET’s forward DC characteristics. These characteristics give the ____________________, gm of the transistor.

N-channel E-MOSFET I-V Characteristics

A

E-MOSFET, transconductance

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18
Q

when VGS>VTN, application of a small VDS causes a current ID to flow through an ________________ which increases with increase in _____.

N-Channel E-MOSFET Construction (Basic Operation: Applying a small VDS)

A

induced channel, VDS

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19
Q

An E-MOSFET with a small VDS is applied acts as a ____________ whose value is determined by _____.

N-Channel E-MOSFET Construction (Basic Operation: Applying a small VDS)

A

resistance, VGS

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20
Q

when VGS<VTN, ID=___, R=_______

N-Channel E-MOSFET Construction (Basic Operation: Applying a small VDS)

A

ID=0, R=infinity

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21
Q

When VGS>VTN, a ________ is induced causing flow of electrons, hence flow of ID, making R __________.

N-Channel E-MOSFET Construction (Basic Operation: Applying a small VDS)

A

channel, finite

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22
Q

as VGS increases, free electrons increases, drain current increases and ____ decreases.

N-Channel E-MOSFET Construction (Basic Operation: Applying a small VDS)

A

R

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23
Q

The dashed line between the source and drain in enhancement type MOSFET reflects that ____________ is physically constructed between source to drain. Channel get induced when _________.

Symbol of MOSFET

A

no channel, VGS>VT

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24
Q

This transconductance relates the output current to the input voltage representing the gain of the ____________. The slope of the transconductance curve at any point along it is therefore given as: ____________ for a constant value of VDS.

N-channel E-MOSFET I-V Characteristics

A

transistor, gm = ID/VGS

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25
Q

When VGS>VTN, a ________ is induced and application of positive VDS cause ____________ to flow.

N-Channel E-MOSFET Construction (Basic Operation)

A

channel, drain current

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26
Q

Now if you keep VGS fixed and VDS is increased, the drain terminal becomes more positive than ________. The charge carriers get attracted towards drain rather getting accumulated near SiO2 surface and hence the charge density in the channel towards drain decreases. Therefore, increase in “VDS” will ____________ the induced channel towards drain but the “high potential” at drain attract increased number of charge carriers to flow through ______________.

N-Channel E-MOSFET Construction (Basic Operation)

A

gate, narrow down, narrow channel

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27
Q

with further increase in VDS, the drain current will eventually reach to a ________________ that occurs due to ________ process depicted by the narrower channel.

N-Channel E-MOSFET Construction (Basic Operation)

A

saturation level, pinch-off

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28
Q

Increase in VGS will cause the pinch-off to occur at higher value of ____ than the earlier.

N-Channel E-MOSFET Construction (Basic Operation)

A

VDS

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29
Q

Thus higher the VGS, higher is the current flow and higher is the value of VDS that cause ________________ condition.

N-Channel E-MOSFET Construction (Basic Operation)

A

pinch-off or saturation

30
Q

The saturation value of VDS is given by _____________

N-Channel E-MOSFET Construction (Basic Operation)

A

VDsat = VGS - VT

31
Q

If VGS < VT, the drain current ID = ____ and the MOSFET is said to be in __________

N-Channel E-MOSFET Construction (Basic Operation)

A

ID=0, cutoff region

32
Q

for VGS > VT and VDS <= VGS-VT, the MOSFET operate in _______________ or _______________

N-Channel E-MOSFET Construction (Basic Operation)

A

non-saturation or triode region

33
Q

for VGS >VT and VDS >= VGS-VT, the MOSFET operate in __________ or _______________

N-Channel E-MOSFET Construction (Basic Operation)

A

saturation, pinch-off region

34
Q

when VGS > VTN and for a small values of VDS, a complete ________ from ________ to ________ is __________

N-Channel E-MOSFET Construction (Drain Characteristics Curve)

A

channel, drain to source, induced

35
Q

____________ acts as a resistor whose value is determined by VGS

N-Channel E-MOSFET Construction (Drain Characteristics Curve)

A

E-MOSFET

36
Q

when VGS > VTN and VDS is larger value but VDS < _________

N-Channel E-MOSFET Construction (Drain Characteristics Curve)

A

VDS(sat)

37
Q

the _______________charge density near the drain _____________ and hence the incremental conductance of the channel at the drain ____________,

N-Channel E-MOSFET Construction (Drain Characteristics Curve)

A

induced inversion, decreases, decreases

38
Q

when VGS > VTN and VDS = VDS(sat) , the ____________charge density at the drain terminal is _______ hence the incremental channel conductance at the drain is zero

N-Channel E-MOSFET Construction (Drain Characteristics), po

A

induced inversion, zero

39
Q

_____________ is at drain

N-Channel E-MOSFET Construction (Drain Characteristics)

A

Pinch-off point

40
Q

when VGS >VTN and VDS > VDS(sat), the ________ in the channel at which the inversion charge is zero moves toward the ____________

N-Channel E-MOSFET Construction (Drain Characteristics)

A

point, source terminal

41
Q

The ________________________ is similar to the n-channel except that the voltage polarities and current directions are reversed.

p-channel Enhancement-type MOSFET

A

p-channel Enhancement-type MOSFET

42
Q

The ___________ operate in pinch-off/saturation region

N-Channel E-MOSFET Construction (Drain Characteristics)

A

MOSFET

43
Q

An essential step in the design of a MOSFET amplifier circuit is the establishment of an appropriate __________________.

Biasing Circuits used for MOSFET

A

dc operating point

44
Q

Biasing circuit ensures operation of MOSFET in the ______________ for all expected input-signal levels.

Biasing Circuits used for MOSFET

A

saturation region

45
Q

The operating point of the MOSFET is located at the coordinate (VDS, ID) on the ___________________.

Biasing Circuits used for MOSFET

A

characteristic graph

46
Q

A popular biasing arrangement for enhancement-type MOSFETS

A

Feedback Biasing

47
Q

Here the large feedback resistance ___ forces the _________ at the gate to be equal to that at the drain (because IG = 0 ). Since IG = 0mA and VRG=0 V, the dc equivalent network appears as shown

Feedback Biasing

A

RG, dc voltage

48
Q

A direct connection now exists between _______ and ______

Feedback Biasing

A

drain and gate

49
Q

Another popular biasing arrangement for enhancement-type MOSFETS

A

Voltage Divider Biasing

50
Q

It is the ratio of change in the drain source voltage (Δ VDS ) to the change in drain current (ΔlD) at constant gate-source voltage.

Parameters of E-MOSFET

A

AC drain resistance (rd)

51
Q

It is the ratio of change in drain current (ΔlD) to the change in gate source voltage (ΔVGS).

Parameters of E-MOSFET

A

Transconductance parameter (gm)

52
Q

It is the ratio of change in drain-source voltage (ΔVDS) to the change in gate-source voltage (ΔVGS) .

Parameters of E-MOSFET

A

Amplification Factor (µ)

53
Q

The __________ behaves as a voltage- controlled current source.

AC equivalent circuit of n channel E-MOSFET

A

MOSFET

54
Q

It provides a drain current proportional to vgs.

AC equivalent circuit of n channel E-MOSFET

A

E MOSFET

55
Q

The input resistance is very high ideally infinite.

AC equivalent circuit of n channel E-MOSFET

A

E-MOSFET

56
Q

The output resistance is also high

AC equivalent circuit of n channel E-MOSFET

A

E-MOSFET

57
Q

Since rd is __________, it can be neglected from the ckt

AC equivalent circuit of n channel E-MOSFET

A

very high

58
Q

In the ______________, the MOSFET acts as a voltage-controlled current source: Changes in the ___________ voltage VGS causes changes in the _______ current ID.

E-MOSFET as an Amplifier

A

saturation region, gate-to-source, drain

59
Q

Thus the saturated MOSFET behaves as ________________ amplifier

E-MOSFET as an Amplifier

A

trans-conductance

60
Q

changes in vi causes changes in ID which in turn changes ____.

E-MOSFET as an Amplifier

A

Vo

61
Q

Thus, the trans-conductance amplifier is converted into a __________ amplifier.

E-MOSFET as an Amplifier

A

voltage

62
Q

Load line equation:

Large signal Transfer Characteristic of MOSFET Circuit

A

Vo = VDS = VDD - (RD)(ID)

63
Q

for vi < VTH the ____________ will be cut off, ID will be ______, and VO = VDS = VDD (point A).

Large signal Transfer Characteristic of MOSFET Circuit

A

transistor, zero

64
Q

As Vi exceeds VTH the transistor turns ____, ID ________, and VO __________. This corresponds to points along the segment of the load line from A to В.

Large signal Transfer Characteristic of MOSFET Circuit

A

on, increases, decreases

65
Q

_________________ operation continues until VO decreases below VDSsat

Large signal Transfer Characteristic of MOSFET Circuit

A

Saturation-region

66
Q

When VDS < VDSsat the MOSFET enters its ______________

Large signal Transfer Characteristic of MOSFET Circuit

A

triode region

67
Q

For Vi > VIB, the transistor is driven deeper into the triode region and voltage decreases slowly towards ______.

Large signal Transfer Characteristic of MOSFET Circuit

A

zero

68
Q

When the MOSFET is used as a _________, it is operated at the extreme points of the _____________.

MOSFET as a Switch

A

switch, transfer curve

69
Q

The device is ____________ by keeping, V < VTH which provide VO = VDD

MOSFET as a Switch

A

turned off

70
Q

The switch is turned on by applying a voltage close to _____. Here, vo is ____________.

MOSFET as a Switch

A

VDD, very small

71
Q

For the FET to operate as a ______________, the transistor must be biased in the ___________ region, and the instantaneous drain current ID and drain-to-source voltage VDS must be confined to the ___________ region.

E-MOSFET Common Source Amplifier

A

linear amplifier, saturation, saturation

72
Q

The device is biased at a somewhere near to the middle of the curve. The voltage signal to be amplified vi is then ________________ on the dc bias voltage.

E-MOSFET Common Source Amplifier

A

superimposed

ELECS (10 decks)

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