Modeling the Virtual Gate Voltage in Dispersive GaN HEMTs

The main contribution of this paper is to present a direct solution to model the virtual gate voltage describing GaN HEMT dispersion. This virtual gate voltage is related to a fitting parameter, which links the traps to present and past voltages. It is shown that the complexity of this trap-controlled parameter with respect to the bias is almost impossible to capture. For simplicity, three simple functions are proposed to describe its bias-dependence, and it is found that the choice of a proper function enables a significant improvement in modeling accuracy of the transistor large-signal behavior.