Distributed-Model-Based Approach for Electrical and Thermal Analysis of High-Frequency GaN HEMTs

A fully distributed modeling approach is proposed in this paper that incorporates the wave propagation effects in developing the equivalent circuit and works as a simulation tool for analyzing high-frequency transistors such as GaN high electron mobility devices. The details regarding the device arrangement are discussed and it is explained how the parameter extraction in the proposed modeling approach is developed merely based on the physical structure of the device along with the electrode dimensions and geometry. The governing equations for obtaining the currents and voltages at each time interval and spatial distance are analyzed based on a finite difference time domain method, where an implicit scheme is developed to ensure the unconditional stability of the technique along with reducing the computation time of the developed solution. The obtained results for the current gain and maximum available gain are verified by the measurement results from a 0.1-μm nitrogen-polar oriented GaN HEMT at 0.25-67 GHz frequency range. The results are also generated for wider cases and over higher frequency ranges to show the importance of using a fully distributed modeling technique and demonstrate the convergence of the results. An experiment is also developed regarding the thermal analysis of the high-frequency HEMT device and to discuss the heat transfer phenomenon over the device width and its effects on the distributed modeling approach are analyzed.