Nanosecond switching of ohmic loads using SiC MOSFETs in ultra-low inductive PCB-packages

Abstract

In pulsed power systems, nanosecond switching transients are required to meet the demanding pulse specifications of voltage rise and fall times. To achieve these fast transients, SiC MOSFETs are promising semiconductor devices due to their high intrinsic switching speed. However, the parasitics of the semiconductor chip, the package and the board layout limit the achievable switching times. So far, no low inductive designs have been used to investigate the switching speed limits of SiC MOSFETs in pulsed power applications. Therefore, this paper focuses on the limits of the output voltage switching speed of a chopper type half bridge with an ohmic load, which is the fundamental switching cell of many solid-state pulse generators. The modelling of the half bridge is described and a linearized analytical model is presented for calculating the output voltage switching speed. For verification of the theoretical analysis, a sandwiched power module is built using a SiC MOSFET in a low inductive PCB-package.