A Field-Effect Transistor (FET) is a type of transistor used in electronic circuits for amplification, switching, and signal processing. Unlike its bipolar junction transistor (BJT) counterpart, which relies on the movement of charge carriers (electrons or holes) through a semiconductor material, FETs operate based on the modulation of an electric field within a semiconductor region, resulting in the control of current flow between two terminals.
The main types of Field-Effect Transistors are:
Metal-Oxide-Semiconductor FET (MOSFET):
Enhancement-Mode MOSFET (E-MOSFET): In its natural state, this type of MOSFET doesn't conduct between its source and drain terminals. When a positive voltage (gate-source voltage) is applied, it creates an electric field that attracts charge carriers and allows current flow between the source and drain. This is the most common type of MOSFET.
Depletion-Mode MOSFET (D-MOSFET): In its natural state, this MOSFET conducts between its source and drain. When a negative voltage (gate-source voltage) is applied, it depletes the charge carriers in the channel, reducing current flow.
Junction Field-Effect Transistor (JFET):
N-Channel JFET: In its natural state, this type of JFET conducts between its source and drain. When a reverse bias voltage is applied to the gate, it creates a depletion region that narrows the current path, reducing current flow.
P-Channel JFET: Similar to the N-channel JFET, but with P-type semiconductor material. It conducts in its natural state and a forward bias on the gate reduces current flow.
Insulated-Gate Bipolar Transistor (IGBT):
IGBTs are a combination of MOSFET and BJT structures. They have a MOSFET-like gate and a BJT-like current path. IGBTs are used in high-power applications, such as motor control and power inverters.
FETs offer advantages like high input impedance, low output impedance, and efficient switching capabilities. They are commonly used in various electronic devices, including integrated circuits, digital logic circuits, amplifiers, voltage regulators, and more.