Introduction of MOSFET

Introduction of MOSFET

Tags: VI Characteristics of MOSFET, Introduction of MOSFET,symbol of MOSFET,Operation of MOSFET,Output characteristics of MOSFET, Transfer characteristics of MOSFET, Model graph for MOSFET, Metal Oxide Semiconductor Field Effect Transistor (MOSFET)
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Introduction of MOSFET

The Metal Oxide Semiconductor Field Effect Transistor (MOSFET) is a device used to amplify or switch electronic signals. It is a unipolar, unidirectional, voltage controlled device. The symbol of MOSFET is shown below.

Operation of MOSFET


Case 1: Gate is kept open.

The negative voltage applied to source terminal will make Pn+ junction forward bias. The positive voltage applied to drain terminal will make Pn+ junction reverse bias. Therefore there will not be any drain current.

Case 2: Positive potential is applied to gate

Here the gate terminal will act as positive plate of capacitor and P-substrate acts as another plate of capacitor.

When gate is kept at +ve potential, automatically the other plate induces negative charges this forms a channel (path) for electrons to move from drain terminal to source terminal.

Thus the application of gate source voltage controls the flow of drain current.

Output characteristics


It shows relation between Vds & Id.

When Vds is increased, Id also increases, even if Vds increases furthermore, the Id remains constant.

Transfer characteristics


It is applicable widely in low power high frequency converter.

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