IGBT

The insulated gate bipolar transistor IGBT is a semiconductor device with three terminals and is used mainly as an electronic switch. It is characterized by fast switching and high efficiency, which makes it a necessary component in modern appliances such as lamp ballasts, electric cars and variable frequency drives VFDs.


Its ability to turn on and off, rapidly, makes it applicable in amplifiers to process complex wave-patterns with pulse width modulation. IGBT combines the characteristics of MOSFETs and BJTs to attain high current and low saturation voltage capacity respectively. It integrates an isolated gate using FET Field effect transistor to obtain a control input.


IGBT has a very low value of ON state resistance RON than a MOSFET. This implies that the voltage drop (I2R) across the bipolar for a particular switching operation is very low. The forward blocking action of the IGBT is similar to that of a MOSFET.

When an IGBT is used as controlled switch in a static state, its current and voltage ratings equal to that of BJT. On the contrary, the isolated gate in IGBT makes it easier to drive BJT charges and hence less power is required.
IGBT is switched ON or OFF based on whether its gate terminal has been activated or deactivated. A constant positive potential difference across the gate and the emitter maintains the IGBT in the ON state. When the input signal is removed, the IGBT is turned OFF.


Application of IGBT:
The insulated gate bipolar transistor (IGBT) is used Ac and DC motor drivers.
The IGBT is used in unregulated power supply (UPS) system.
The IGBT is used to combines the simple gate-drive characteristics of MOSFET with the high-current and low-saturation-voltage of bipolar transistors.
The IGBT is used in switched-mode power supplies (SMPS).
It is used in traction motor control and induction heating.
It is used in inverters.