Modelling of SiC and GaN transistors based on pulsed S-parameter measurements

For the design of fast-switching inverters a precise model of power semiconductors is required. Based on pulsed S-parameter measurements in the frequency range of 2 MHz to 500 MHz a SiC MOSFET and a GaN HEMT have been characterized. As basis for precise modelling, measurements under varying load conditions have been taken for many operating points covering the pinch-off, ohmic, and active regions. The employed model to describe the transistor uses a circuit comprising 12 circuit elements. Thereby, the elements of the intrinsic transistor vary with the transistor’s operating point and parameters describing the influence of the package are considered to be constant. The model parameters have been adjusted iteratively. A comparison of the obtained model with the original S-parameter measurements exhibits an excellent match.