What is JFET (junction field effect transistor)?

The junction field effect transistor (JFET) is a type of field effect transistor (FET). It is three terminal uni-polar solid state devices that can be used as voltage controlled resistors or electronically controlled switch.

An N type JFET consists of a channel of semiconductor material holding a large amount of negative charge carriers or holes. Whereas a P type JFET consists of a channel of semiconductor material holding a large amount of positive charge carriers or holes, at each end of the JFET, ohmic contacts form the source and drain.

Electric charge flows through the channel between the source and drain. Electric current can be impeded or switched off by applying a reverse bias voltage to a gate.

The junction field effect transistor (JFET) is classified into two categories are follows:

• N channel junction field effect transistor (JFET).
• P channel junction field effect transistor (JFET).