LECTURE 24

IGBT

Topics to be coveredTopics to be covered Electrorestriction

IGBT: InsulatedIGBT: Insulated--Gate Bipolar Gate Bipolar TransistorTransistor Combination BJT and MOSFET◦ High Input Impedance (MOSFET)◦ Low On-state Conduction Losses (BJT)

High Voltage and Current Ratings Symbol

3

CrossCross--Sectional View of an IGBTSectional View of an IGBT

Metal

Silicon Dioxide

Metal

IGBT Equivalent Circuit for VIGBT Equivalent Circuit for VGEGE<V<VTT

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+

VCCIEPNP

ICPNP

IBPNP

ICNPN

IENPN

IBNPN

Leakage Current

IRBE

Both transistors are OFF

IGBT Equivalent Circuit for VIGBT Equivalent Circuit for VGEGE>V>VTT

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+

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.

Channel is Induced When VChannel is Induced When VGEGE>V>VTT

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Induced Channel

electrons

RMOD PNP

RBE

NPN

IGBT Output CharacteristicsIGBT Output Characteristics

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Follows an SCR characteristic

IGBT Transfer CharacteristicIGBT Transfer Characteristic

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IGBT Used as a SwitchIGBT Used as a Switch

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Fairchild FGA25N120AND IGBTFairchild FGA25N120AND IGBT

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