Simulation of RF Power Distribution in a Packaged GaN Power Transistor Using an Electro-Thermal Large-Signal Description

A comprehensive electro-thermal model of a packaged GaN high electron-mobility transistor (GaN-HEMT) is presented. It includes an RF large-signal description, as well as thermal coupling between the individual cells of a powerbar. Thus, it allows studying the inhomogeneous RF power distribution and other effects within the transistor. The model is verified and applied to a 50-W GaN-HEMT powerbar. The model proves to represent a versatile tool for transistor design. Important features of the new version compared to existing versions are its capability to predict internal electrical instabilities and to allow for optimization of the cell combining.