Accurate GaN HEMT nonquasi-static large-signal model including dispersive effects

The purpose of this study is to present an advanced technique for accurately modeling the behavior of a GaN HEMT under realistic working conditions. Since this semiconductor transistor technology has demonstrated to be very well suited for high-frequency (HF) high-power applications, an equivalent circuit model is developed to account for the device nonlinearities at microwave frequencies. In particular, the proposed model includes bias dependence of both low-frequency (LF) dispersive effects affecting GaN devices and HF nonquasi-static effects, since these two types of frequency dependent phenomena play a crucial role under microwave large-signal condition. The extraction procedure consists of two main steps. First, an accurate multibias small-signal nonquasi-static equivalent circuit is analytically extracted from scattering parameters measured under a wide range of bias points. Thereafter, this linear model is used as a cornerstone for building a nonlinear nonquasi-static equivalent circuit, which is expanded to account for the LF dispersive phenomena by using an empirical formulation directly identified from the HF large-signal measurements. The accuracy of the proposed modeling approach is completely and successfully verified by comparing model simulations with LF and HF large-signal measurements.