IGBT is insulated gate bipolar transistor,
is a composite fully controlled voltage-driven power semiconductor device composed of BJT
(bipolar transistor) and
MOS (insulated gate field effect transistor),
which also has MOSFET The advantages of high input impedance and low on-voltage drop of
The switching function of the IGBT is to form a channel by adding a positive gate voltage
to provide a base current to the PNP (formerly NPN) transistor to turn on the IGBT.
On the contrary, the reverse gate voltage is added to eliminate the channel,
cut off the base current, and turn off the IGBT.
The driving method of IGBT is basically the same as that of MOSFET,
only the input pole N-channel MOSFET is controlled,
so it has high input impedance characteristics.
After the channel of the MOSFET is formed,
holes (minor carriers) are injected from the P+ base to the N- layer to modulate the
conductance of the N- layer to reduce the resistance of the N- layer,
so that the IGBT has a low voltage even at a high voltage,
and the on-state voltage.