IGBT: Insulated-Gate Bipolar Transistor

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IGBT: Insulated-Gate Bipolar Transistor

• Combination BJT and MOSFET– High Input Impedance (MOSFET)– Low On-state Conduction Losses (BJT)

• High Voltage and Current Ratings

• Symbol

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Cross-Sectional View of an IGBT

Metal

Silicon Dioxide

Metal

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IGBT Equivalent Circuit for VGE<VT

+

VCCIEPNP

ICPNP

IBPNP

ICNPN

IENPN

IBNPN

Leakage Current

IRBE

Both transistors are OFF

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IGBT Equivalent Circuit for VGE>VT

+

VCC

NPN Transistor becomes forward biased at the BE, drawing current from the Base of the PNP transistor.

MOS transistor conducts, drawing current from the Base of the PNP transistor.

PNP transistor turns ON,

RMOD decreases due to carrier injection from the PNP Emitter.

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Channel is Induced When VGE>VT

Induced Channel

electrons

RMOD PNP

RBE

NPN

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IGBT Output Characteristics

Follows an SCR characteristic

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IGBT Transfer Characteristic

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IGBT Used as a Switch

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Fairchild FGA25N120AND IGBT

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