3-17. 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

3-1. Types of Transistors
3-2. Bipolar Transistors (BJTs)
3-3. Bias Resistor Built-in Transistors (BRTs)
3-4. Junction Field-Effect Transistors (JFETs)
3-5. Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs)
3-6. Differences between BJT and MOSFET
3-7. Structure and Operation of MOSFET
3-8. MOSFET Performance Improvement: Decision Factors of RDS(ON)
3-9. MOSFET Performance Improvement: Approach to Low RDS(ON)
3-10. MOSFET Performance Improvement: Super-Junction MOSFETs (SJ-MOS)
3-11. Summary of MOSFET Features by Structure
3-12. Performance of MOSFETs: Drain Current and Power Dissipation
3-13. Performance of MOSFETs: Avalanche Capability
3-14. Performance of MOSFETs: Characteristic of Capacitance
3-15. Performance of MOSFETs: Safe Operating Area(or Area of Safe Operation)
3-16. Insulated-Gate Bipolar Transistors (IGBTs)
3-18. Performance Improvement of IGBTs: Evolution of Vertical Design
3-19. What are RC-IGBTs and IEGTs?
3-20. Application of IGBTs
3-21. Comparison of Forward Characteristics of IGBTs and MOSFETs
3-22. Comparison of Transistors by Structure
3-23. Datasheets of MOSFET: Maximum Ratings
3-24. Datasheets of MOSFET: Electrical Characteristics
3-25. Datasheets of MOSFET: Capacitance and Switching Characteristics
3-26. Datasheets of MOSFET: Body Diode

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