System-level evaluation of dynamic effects in a GaN-based class-E power amplifier

Abstract

Gallium Nitride shows huge potential in power electronics applications thanks to the superior intrinsic material properties which result in improved performance both at device level and system level. Great effort has been taken in recent years to industrialize GaN technology and to solve some of the major drawbacks like reliability issues and dynamic effects. The goal of this work is to propose a novel methodology to analyse the role of these phenomena on the end application efficiency. These insights can thus lead to a system-level driven optimization of GaN technology. We propose a method based on T-CAD mixed-mode simulation and we give an example of its implementation in the analysis of a class-E power amplifier for wireless power transfer. Efficiency curve is extracted for different load resistance values. This is carried out for the device both in relaxed and in stressed conditions to evaluate the impact of buffer traps. It is demonstrated how the main degradation resides in the increased dynamic resistance while threshold voltage shift and output capacitance variations both play a minor role. A method to calculate the dynamic resistance evolution during the switching cycles is then outlined. At the design point the resistance is expected to fully recover to the nominal value.