Why do SiC JFET cascodes have lower gate-charge (Qg)?
The gate charge of SiC FET is determined by the low voltage MOSFET in Cascode architecture, so SiC FETs’ fully turn on voltage is only 10V. 12V gate drive can be used to drive SiC FETs very well. Using 12V gate drive means less gate charge compared to 15V or 18V gate drive.
Also, the Cascode structure enables decoupling of gate charge optimization of low-voltage Si MOSFET and figure of merit optimization of high-voltage SiC JFET.