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.