What is FET (Field Effect Transistor) & it’s Types?

In this tutorial, we are going to learn about FET (Field Effect Transistor).

FET (Field Effect Transistor)

  • It is a semiconductor device, which can be used as amplifier or switch.
  • It is three terminal device such as drain (D), source (S) and gate (G).In which gate terminal act as terminal acts.

Classifications of FET (Field Effect Transistor)

  • Junction Field Effect Transistor (JFET)
  • Metal Oxide Semiconductor FET (MOSFET)  

Features of JFET

  • It is voltage controlled device. In FET, the voltage is applied between gate and source (VSS) control the drain current (ID) so FET is voltage controlled device.
  • FET is unipolar device, In FET current is carried by only one type of charge particles either electrons or holes so that FET is called unipolar device.
  • FET is temperature dependant device.
  • FET has very high input impedance.
  •  FET requires less space than BJT.

Junction Field Effect Transistor (JFET)        

The Junction Field Effect Transistor (JFET) It is a voltage controlled three-terminal unipolar semiconductor device available in N-channel and P-channel. The N-channel J channel is doped with donor impurities its means the flow of current through the channel is negative in the form of electrons and the P-channel channel is doped with acceptor impurities meaning that the flow of current through the channel is positive in the form of holes. N-channel is greater channel conductivity (lower resistance) than their equivalent P-channel types, while electrons have higher mobility through a conductor compared to holes. This makes the N-channel JFET’s a more efficient conductor compared to their P-channel counterparts.

Metal Oxide Semiconductor FET (MOSFET)  

It is a semiconductor field-effect transistor which is a combination of field-effect transistors (FET with an insulated gate) which is the voltage that determines the conductivity of the device. MOSFET is generally used for switching or amplifying signals. MOSFET has the ability to change conductivity with the amount of applied voltage that can be used for amplifying or switching electronic signals. MOSFETs are now even more common than BJTs in digital and analogue circuits. The silicon dioxide forms the gate of the MOSFET which is used to provide isolation by preventing the direct flow of charges on the gate to the conducting channel.

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