Field Effect Transistor(FET) Symbol, Diagram, Applications


Field Effect Transistor or FET is a huge usable transistor in electronics applications. FET is a transistor that uses the electric field to control the electrical current flow through it that is why it is called a Field Effect Transistor. FET is also known as a unipolar transistor as it uses a single charge carrier for its operation. For example, either it uses electrons or holes as charge carriers but not both at the same time like a Bipolar Junction Transistor(NPN or PNP). It is a voltage-controlled device. The applied voltage to its gate terminal can control the size of the conductive channel so the flow of current through it also changed. The core characteristic of a FET is a very high input impedance at low frequency.

A field-effect transistor has main three common terminals named as - 1. Source(S) 2. Gate(G) and 3. Drain(D). The source is the terminal through which the charge carrier enters into the channel. Generally, this terminal is identified as the English letter S and the source is denoted by Is. The drain is the terminal through which the charge carrier leaves the channel. Generally, the drain terminal is denoted by the English letter D and the drain current is denoted by ID. On the other hand, the Gate terminal is that where voltage is applied to adjust or modulate the channel conductivity so the drain current can be controlled. 

Field Effect Transistor(FET) Symbol


As we know there are so many types of FET so each of them has different symbols. Here you can see the symbols,

Junction Field Effect Transistor(JFET) - P Channel


Junction Field Effect transistor or JFET is a very simple type of FET than others. There are two types of JFET - N Channel and P Channel. In the case of the P channel JFET when the voltage to the gate with respect to the source terminal is positive and gradually increasing the current conduction will be decrease. If we apply a negative voltage then the current flow will not be controlled.


Field Effect Transistor(FET) Symbol


N Channel JFET


For N channel JFET we have to apply a negative voltage to its gate terminal with respect to the source terminal to control the current flow through it. So remember that when the gate voltage is zero for the JFET it will conduct current with full capacity. The conductivity will decrease or resistivity will increase when we happy a voltage to its gate terminal. 

Junction Field Effect Transistor(FET) Symbol


P Channel enhancement Type MOSFET


MOSFET means Metal Oxide Semiconductor Field Effect Transistor. In MOSFET Silicon dioxide is used to issue to form the gate of the MOSFET that provides insulation between the gate and conductive channel to prevent the direct flow of charges. The operation of the enhancement type MOSFET is opposite to the JFET. Here we have to apply the voltage to the gate to turn on the transistor. For P channel MOSFET we have to apply positive voltage.

P Channel MOSFET Symbol(enhancement Type)

N Channel MOSFET (enhancement Type)


N channel MOSFET required a negative voltage to start its operation. Here you can see the symbolic difference between the N channel and the P channel. For the N channel, the arrow mark is towards to the gate terminal whereas in the P channel the arrow mark is backward to the gate terminal.

N Channel MOSFET Symbol(enhancement Type)


Depletion Type MOSFET(P-Type)

Depletion Type MOSFET Symbol(P Type)

Depletion Type MOSFET Symbol(N Channel)


The operation of the depletion type MOSFET is opposite to the enhancement type MOSFET and the same as the JFET. In normal conditions, when there is no voltage the depletion type MOSFET will conduct current to control the current flow or to reduce we have to apply a voltage.

Depletion Type MOSFET Symbol(N Channel)



FET Applications


1. As we know the FET is a voltage-controlled device so it is best to build the voltage amplifiers.

2. MOSFET is capable to work with high power so you will see its applications in power electronic circuits such as inverter circuits, power control circuits, etc.

3. In integrated circuits, analog circuits, and digital circuits you can see the applications of Field Effect Transistor.


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Field Effect Transistor(FET) Symbol, Diagram, Applications Field Effect Transistor(FET) Symbol, Diagram, Applications Reviewed by Author on 4/12/2022 Rating: 5

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