Thermal modeling of high frequency GaN power HEMT´s using analytic approach

Accurate electrical modeling of high power GaN HEMT´s needs to accurate calculation of the channel temperature, by using proper thermal model. Such model must be used in conjunction with the electrical model in circuit simulators, and hence it´s computational load is crucial. FDTD and FEM numerical techniques have been widely used for this purpose, but they are computationally inefficient. In this paper we propose a new thermal model that is obtained by analytic solution of heat equation. The proposed analytic solution has been obtained using Green´s function approach, in conjunction with the proper application of image theory. The proposed analytic approach is very fast, since it calculates the channel temperature directly at the channel points, without need to solve the heat equation at all points inside the devices, as in the case of numerical methods. The accuracy and efficiency of the obtained solution has been proved by comparing with FEM results.