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IGBT Insulated Gate Bipolar Transistor Characteristics

IGBT Insulated Gate Bipolar Transistor

IGBT stands for an insulated gate bipolar transistor. It is having the advantage of both power MOSFET and BJT. In IGBT, layer P is used as a substrate. One side is deposited with a metal layer to form a collector and on another side of the P substrate, the N layer is epitaxially grown. The other layer is the same as power MOSFET. The three-terminal of IGBT are Emitter E, Gate G, and collector C.

The IGBT is a four-layer N-P-N-P device with a MOS gated channel connecting two N-type regions. It is a new high conductance MOS gate-controlled power switch. In the operation of IGBT, the epitaxial region is conductivity modulated and thereby eliminating a major component of the on-resistance. 

V-I Characteristics of IGBT

V-I Characteristics of IGBT V-I Characteristics of IGBT

IGBT maintains gate control over a wide range of anode currents and voltage. The basic structure of the IGBT is shown in the figure.

In many respects, it is similar to a power MOSFET. The main difference is the presence of P as the injecting layer. Next is the N layer. There is a P-N  junction between this layer and more junctions as shown in the figure.

IGBT Application Examples

IGBT is widely used in medium power applications such as Dc and AC motor drive UPS systems, power supplies for solenoids, relays, and contractors. Though IGBTs are more expensive than BJTs, they have lower gate drive requirements and lower switch losses. 

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