Scalable GaN-HEMT Model for X-band RF Applications

The cutoff voltage (VOFF) of a HEMT is an important parameter that affects its performance, and it can indeed change with self-heating. In this work, we study the effect of geometrical features of GaN high electron mobility transistor (HEMT) device on cutoff voltage and self-heating. ASM-HEMT framework is used and improved to account for the geometrical dependencies. The model is validated with DC-IV and RF characteristics upto 20 GHz for three SSPL developed GaN HEMT devices with distinct gate periphery ((W × NF) – 75 × 4 μm, 75 × 6 μm and 100 × 8 μm). The measured data and the modeled outcomes are in good agreement. It has been observed that the self heating and cutoff voltage shows the linear dependency on the device size (W × NF).