C_oss related energy loss in power MOSFETs used in zero-voltage-switched applications

Abstract

This paper presents a general method to measure the output capacitance (C <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oss</inf> ) related energy loss per switching cycle in power MOSFETs used in zero-voltage-switched (ZVS) applications. It is shown that a simple model using C <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oss</inf> in series with a resistance R <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oss</inf> is inadequate for describing the observed energy loss and a different model is needed. This work also shows that the traditional hard-switched test methods for measuring the dynamic performance of power MOSFETs are inadequate for describing the dynamic performance of power MOSFETs used in ZVS applications. Finally, this study proposes a new power MOSFET figure of merit suitable for differentiating the performance of MOSFETs for use in ZVS applications.