FET is based on the concept that charging on a nearby object can attract charges within a semiconductor channel.
FET is made up of a semiconductor channel with electrodes at each end called leakage and source. A control electrode called a gate is placed in the immediate vicinity of the channel so that its electrical charge can affect the channel
In this way, the FET gate controls the flow of bearers (electrons or holes) flowing from the source to drain. This is done by controlling the size and shape of the conductive channel.
The semiconductor channel in which the current flow occurs may be either P or N type. This gives rise to two types or categories of FET known as P-Channel and N-Channel FET.
The electric field for current control is applied to a third electrode known as a gate. Because only the electric field controls the current flowing in the channel, it is said that the device is voltage-driven and has a large input impedance, usually many megohms. This can be a distinct advantage over the currently running bipolar transistor and has a much lower input impedance.
The outer field on the gate may serve to deplete the conveyor channel, in which case the FET is known as a FET exhaustion mode or may serve to improve the bearers in the channel when known as a FET enhancement mode.
FET circuits
The efficiency of field effect transistors is widely used in all circuit types than those used in discrete circuit circuits, to those used in integrated circuits.
Transistor type effects
There are several ways to define the different types of available FETs. These can be classified in several ways, but some of the major types of FET can be covered in the tree scheme below.
There are many different types of FETs on the market for which there are many names. Some of the major categories are delayed below.
Junction FET (JFET): As the name suggests, this form of FET uses a biased reverse diode junction to provide isolation from the channel. This is the most basic type of FET, and the one that was developed for the first time. However, it still provides excellent services in many areas of electronics. Read more about Junction FET
FET Insulated FET / Metal Oxides Silicon FET MOSFET: This type of FET uses a later insulation between gate and channel. Usually it is formed from a layer of semiconductor oxide. The most common type of IGFET. MOSFET – FET metallic silicon oxide. Here the gate is made of a layer of metal on silicon oxide which in turn is on the silicon channel. Read more about MOSFET
Dual Gate MOSFET: This is a specialized form of MOSFET that has two gates in series along the channel. This allows considerable performance improvements, especially at RF, compared to single gate devices. Read more about MOSFET Gate Dual
MESFET: Siltal FET Metals are normally manufactured using gallium arsenide and are often called GaAs FET. It offers very high performance, but given the gate structure, it is very sensitive to ESD. Read more about MESFET / GaAsFET
HEMT / PHEMT: the high electron mobility transducer and the pseudomorphic electron high-velocity transistor are developments in the basic FET concept but developed to allow very high frequency operation. Read more about HEMT / PHEMT
FinFET: FinFET technology is now used in integrated circuits to allow for higher levels of integration by allowing smaller dimensions of features. Read more about FinFET
VMOS: Vertical MOS VMOS standard. It is a type of FET that uses a vertical current flow to improve the switching and transport performance of the current. VMOS FETs are widely used for power applications.
