This paper is concerned with a detailed device and mixed-mode circuit numerical analysis of SiC-based switches. Two structures have been chosen, a SiC trench MOSFET and SiC JFET coupled with a Si MOSFET in a Cascode configuration. The paper provides for the first time an insight into the physics of switching of the two structures and proves that the Cascode configuration is a superior alternative to the classical SiC trench MOSFET owing to higher switching frequency, lower on-state resistance and reduced overall transient losses. In addition the high voltage SiC trench MOSFET suffers from low channel mobility and may encounter oxide breakdown during both on-state operation and blocking mode.