A new gate drive technique for superjunction MOSFETs to compensate the effects of common source inductance

Abstract

It is well known that in fast-and hard-switching power systems the switching transients are essentially influenced by a common source inductance LSc, i.e. any inductance common to gate and power loop. Particularly for Superjunction (SJ) MOSFETs without Kelvin source connection significantly increased switching losses and a strong oscillation tendency may result. In this paper two different LSc-related effects associated with “on” and “off” switching are identified, and their dependence on transistor parameters (transconductance, nonlinear capacitances) is analyzed. A new technique based on an inductive rather than resistive gate drive impedance is proposed to mitigate or even completely compensate the effects of LSc; experimental results are given that clearly verify simulations.