Q.Expand IGBT.

The insulated gate bipolar transistor (IGBT) combines the best features of the MOSFET and the BJT. From the MOSFET it inherits a high input impedance — it is voltage-controlled through an insulated gate that draws almost no steady current — and from the BJT it inherits a low on-state resistance, so it can carry a large current with a small conduction drop. This makes the IGBT the preferred switch for medium- and high-power inverters and motor drives.

Its three terminals are the collector (C), the gate (G) and the emitter (E). Its circuit symbol is a hybrid: a MOSFET-style insulated-gate input drawn together with a BJT-style emitter arrow.

The output characteristics of an n-channel IGBT look qualitatively like those of a BJT, except that the controlling quantity is the gate-emitter voltage $V_{GE}$ rather than a base current. Three regions are defined: …