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IGBT(Insulated Gate Bipolar Transistor) A power transistor that has characteristics of both MOSFET and bipolar junction transistors (BJTs). Introduced in the 1980s, the IGBT handles high current, a characteristic of BJTs, but enables fast switching with greater ease of control. IGBTs are found in home appliances, electric cars and digital stereo power amplifiers. Modules with multiple IGBTs can support very high voltage and amperage.
Non Punch-Through (NPT) and Punch-Through (PT)
When an IGBT is turned off, it exhibits a "tail current" because holes are left in the drift region. By adding an extra N+ buffer layer in what is known as a "Punch-Through" (PT) architecture, the trapped holes are quickly absorbed. Thus, the PT IGBT switches faster, but typically handles less voltage than the NPT IGBT. See power MOSFET.
|NPT and PT IGBTs|
|To make the IGBT switch faster, the extra N+ buffer layer in the PT architecture absorbs the extra holes when the transistor is turned off.|