About MOSFET

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WELCOME TO MY PRESENTATION 1

Transcript of About MOSFET

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WELCOME TO MY PRESENTATION

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MD MUZAHIDUL HAQUEID# 12305145

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Metal Oxide Semiconductor FET(MOSFET)

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MOSFET

• A field effect transistor (FET) that can be operated in the enhancement-mode is called a MOSFET.

• There are 4 terminals : source (S), gate (G) and drain (D), Substrate (SS).

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MOSFET Structure

p-Sin+ L

Source Gate Drain

Field Oxide

Gate Oxide

Bulk (Substrate)

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Types of Field Effect Transistors (The Classification)

JFET

MOSFET

n-Channel JFETp-Channel JFET

n-Channel EMOSFET

p-Channel EMOSFET

Enhancement MOSFET

Depletion MOSFET

n-Channel DMOSFET

p-Channel DMOSFET

FET

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Depletion Type•Channel region is

already diffused between the Drain and Source•Deplete, or

“pinch-off” the Channe

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Depletion MOSFET

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Basic Operation

Before After

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• n-Channel MOSFET Schematic symbol

Depletion MOSFET

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• p-Channel MOSFET Schematic symbol

Depletion MOSFET

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Depletion MOSFET Bias• Gate bias• Self bias

• voltage-divider bias• Zero bias

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Self Bias

Some formula :

Self-biased configuration results in VGS=-IDRS

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Voltage-divider bias

Some formula :

2)(

)(

TonGS

onD

VVI

k

VGS>VT, ID=k(VGS-VT)2

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Enhancement MOSFET• Primary difference

between depletion-type and enhancement-type is the absence of channel between Source and Drain terminals.

N-channel enhancement-type MOSFET

Schematic symbol

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Enhancement Type

•No channel region exists between the Drain and Source• “Invert” the region

between the Drain and Source to induce a channel

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Enhancement MOSFET

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• p-Channel MOSFET• Construction is reverse of n-channel DMOSFET.

Enhancement MOSFETSchematic symbol

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Enhancement MOSFET Bias

• Gate bias• Voltage-divider bias• Drain-feedback bias

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E-MOSFET Voltage-Divider Biasing

• VGS=VG-IDRS

• Where VG=R2xVDD/(R1+R2)

• VDS=VDD-ID(RS+RD) 2)(

)(

TonGS

onD

VVI

k

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E-MOSFET Feedback Biasing

IG=0 V, VD=VG, VDS=VGS, VDS=VDD-IDRD, VGS=VDD-IDRD

When ID=0 A:VGS=VDD

When VGS=0 V:ID=VDD/RD

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Applications of MOSFET

• Digital integrated circuits such as microprocessors and memory devices contain thousands to millions of integrated MOSFET

• logic gates and data storage• Switch mode power supplies, • Variable frequency drives • Radio systems use MOSFETs as oscillators, or mixers to

convert frequencies. • Sound reinforcement and • Automobile sound systems

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Applications of MOSFET

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JEFT vs MOSFET JEFT MOSFET

1. High input impedance 1. Very high input impedance

2. It can be operated only in depletion mode.

2. It can be operated both depletion and enhancement mode.

3. High gate current 3. Low gate current

4. High drain resistance 4. Low drain resistance

5. Conductivity is controlled by the reverse biasing of the gate

5. Conductivity is controlled by the carriers induced in the channel

6. Schematic symbol 6. Schematic symbol

7.Transconductance curve 7.Transconductance curve

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THANKS TO ALL!!!???