Insulated-Gate Bipolar Transistors (IGBTs)

An IGBT is a device suitable for high-current control combining a voltage-driven MOSFET in the front stage and a transistor allowing a large current to flow in the rear stage.

IGBT:Insulated Gate Bipolar Transistor

[Equivalent circuit and operation details]

  • The equivalent circuit of the IGBT is shown in Fig. 3-13 (b). The RBE value is set so that the NPN Tr does not turn on.
  • Applying ON signal to gate of an Nch MOSFET turns on conduction state.
  • As a result, current flows from the emitter to the base of PNP Tr. This base current works to lower the ON resistance of Nch MOSFET. (Conductivity modulation effect)

[Comparison with MOSFET]

  • Gate driving operation is the same as Nch MOSFETs.
  • In ON state, decrement of ON resistance of Nch MOS enables high current flow.
  • Voltage drop across the emitter and base of PNP Tr occurs in the entire current region.(Approximately 1.0 V is added up as ON voltage.)
Symbol of IGBT
Fig. 3-13(a) Symbol of IGBT
Internal equivalent circuit of IGBT
Fig. 3-13(b) Internal equivalent circuit of IGBT

Chapter III : Transistors

Types of Transistors
Bipolar Transistors (BJTs)
Bias Resistor Built-in Transistors (BRTs)
Junction Field-Effect Transistors (JFETs)
Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs)
Differences between BJT and MOSFET
Structure and Operation of MOSFET
MOSFET Performance Improvement: Decision Factors of RDS(ON)
MOSFET Performance Improvement: Approach to Low RDS(ON)
MOSFET Performance Improvement: Super-Junction MOSFETs (SJ-MOS)
Summary of MOSFET Features by Structure
Performance of MOSFETs: Drain Current and Power Dissipation
Performance of MOSFETs: Avalanche Capability
Performance of MOSFETs: Characteristic of Capacitance
Performance of MOSFETs: Safe Operating Area(or Area of Safe Operation)
Operation of Insulated-Gate Bipolar Transistors (IGBTs)
Performance Improvement of IGBTs: Evolution of Vertical Design
What are RC-IGBTs and IEGTs?
Application of IGBTs
Comparison of Forward Characteristics of IGBTs and MOSFETs
Comparison of Transistors by Structure
Datasheets of MOSFET: Maximum Ratings
Datasheets of MOSFET: Electrical Characteristics
Datasheets of MOSFET: Capacitance and Switching Characteristics
Datasheets of MOSFET: Body Diode

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