Transistor

A semiconductor device with three terminals composed of two or more PN junctions. It is an active device in which the collector current or gate voltage can be controlled by the magnitude of the base current or drain current, and it is often used in amplifier circuits. Types include bipolar transistors, which have a current amplification function, and field-effect transistors (FET), which have a voltage amplification function, and they are also widely used in switching power supply circuits.