Insulated gate bipolar transistor (IGBT)

Insulated gate bipolar transistor (IGBT) is one of the extensively used fully controlled switching devices. The three terminals of this device are gate, emitter and collector. IGBT is behavior is similar to that of a power MOSFET from gate-emitter side and is similar to a BJT from collector-emitter side. Thus IGBT carries combination of MOSFET and BJT features. The voltage applied between gate and emitter terminals controls collector to emitter current flow and acts as a voltage controlled device. Normal rating of an IGBT is around 2000A, 3500V. Its switching frequency is around 20 kHz. Reverse voltage blocking capability is another feature of IGBT. IGBTs are extensively used nowadays in DC and AC motor drives, power supplies, contactors and solid-state relays. Input impedance is high for IGBT. It can be used to block negative voltages, if they are manufactured without a hybrid reverse diode integral. I-V characteristics of an IGBT are very much similar to that of a BJT but without a second breakdown. Use of trench-gate technology reduces the ON-state power loss in IGBT. Positive temperature co-efficient of IGBT provides a thermally insulated square SOA which allows design of IGBT converter with or without a snubber.