Thermal influence on S 22 kink behavior of a 0.15 μm gate length AlGaN/GaN/SiC HEMT for microwave applications

Thermal influence on S-22 kink behavior has been carried out on a 0.15 mu m gate length AlGaN/ GaN/SiC high electron mobility transistor over a wide range of temperature. The size and the shape of the S-22 kink effect (KE) in terms of biasing and temperature have been evaluated. The main finding is that S-22 of the studied device is affected by two kinks the first one appears at approximately 19 GHz and then the second one appears at about 43 GHz. The impact of the intrinsic circuit parameters on the S-22 kink phenomena is inspected to assess their contribution. In addition, a new procedure is proposed to quantify this type of phenomenon by defining the kink area as the area between the two curves corresponding to S-22 with and without the KE. The relevance of this study emerges from the fact that an exhaustive characterization of these anomalous phenomena can empower RF engineers to effectively take them into account for both modeling and design purposes.