COSS hysteresis in advanced superjunction MOSFETs

Abstract

In this work, a Sawyer-Tower circuit is employed to characterize the output capacitance (COSS) of advanced superjunction MOSFETs. It is shown that some of the most advanced superjunction MOSFETs exhibit significant hysteresis in their output capacitance which leads to unrecoverable power loss. This work shows that the conventional impedance analyzer method can only measure COSS accurately when hysteresis is not present while measurement of COSS with a Sawyer-Tower circuit gives accurate results regardless of whether hysteresis is present or not. Accurate measurement of COSS with a Sawyer-Tower circuit not only enables designers to more accurately calculate and predict power loss but even more importantly allows the power semiconductor industry to more effectively advance future generations of superjunction MOSFETs for optimum efficiency, especially for use in resonant converter applications.