Chapter III : Transistors : Operation of Insulated-Gate Bipolar Transistors (IGBTs)

Operation of the IGBT connected as in Fig. 3-14(a) is shown below.
(1) Inversion layer is made in P layer under gate by applying positive voltage to gate. The Nch MOSFET in Fig. 3-14(b) turns on like a normal Nch MOSFET.
(2) When the Nch MOSFET is ON status, collector’s potential is positive. So, holes are injected from P+ through N+ to N-, and this injection accelerates injection of electrons from emitter.
(3) As a result, increment of carriers (electrons and holes) decreases resistance of N- layer that normally has high resistance (conductivity modulation effect).

Thus, ON resistance of the Nch MOSFET varies to lower as shown in Fig. 3-14(b).

Operation of IGBT/Equivalent circuit of IGBT and image of actual operation

Fig. 3-14(a) Operation of IGBT

Fig. 3-14(b) Equivalent circuit of IGBT and image of actual operation

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)
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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