Transistor

A semiconductor device composed of 2 or more PN junctions and having 3 terminals. 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 the function of amplifying current, and field-effect transistors (FET), which have the function of amplifying voltage, and they are also widely used in switching power supply circuits.