For the first time, a novel mixed insulated gate bipolar transistor (MIGBT) is proposed and verified by two-dimensional (2D) mixed device-circuit simulations. The structure of the proposed device is almost identical with that of the conventional IGBT, except for the buffer layer which is formed by employing the n+/n- structure, so that the trade-off relation between the conduction and switching losses is greatly improved and efficiently decoupled. Furthermore, the proposed device exhibits larger forward blocking voltage and positive temperature coefficient of the forward voltage drop, facilitating parallel integration.