A 600V quick punch through (QPT) IGBT design concept for reducing EMI

Punch Through IGBTs inherently generate more EMI than their MOSFET counter part. This results from the nature of the IGBT being a two carrier device and the switching characteristics being controlled by the gain of the p-n-p bipolar. The EMI is a direct result of the abrupt turn-off di/dt. In this paper, a novel IGBT, the QPT, that enables the PT IGBT to switch similar to a MOSFET is presented and analyzed. This is achieved by designing the PT IGBT with a thinner lower concentration drift region. This allows the depletion layer to punch through to the buffer at a lower voltage. The capacitances of the QPT are optimized so that the channel remains open until the collector voltage reaches the bus voltage. This provides the ability to control and thereby minimize the turn-off di/dt.