Modeling the turn-off characteristics of the bipolar-MOS transistor

Since the turn-off speed of the new bipolar-MOS power transistor is slow compared to that of a MOSFET, it is important to understand the limiting mechanism and the prospect for future improvement. In this letter, it is demonstrated that the turnoff waveform can be explained by a model based on a simple equivalent circuit and the transistor open-base turn-off process. The model is applied to explore the impact of some process modifications on speed improvement and to study the tradeoff between speed and on-resistance.