An Improved Compact Large-Signal GaN HEMT Model for Switch Application

The accurate current model near knee voltage is critical to precisely simulate the power compression characteristics for power high-electron-mobility transistor (HEMT), especially for high-power-switch applications. An improved compact large-signal gallium nitride (GaN) HEMT model for high-power-switch applications is proposed in this article. The proposed model employs an additional slope factor in terms of hyperbolic tangent function to improve the model accuracy and flexibility of the knee current in both positive and negative regions. Besides, the improved GaN HEMT model counting in intrinsic capacitance variation of drain–source capacitance ${C}_{\text{ds}}$ and gate–source capacitance ${C}_{\text{gs}}$ can characterize the nonlinear voltage-dependent performance of HEMT even when the HEMT is biased below pinchoff voltage. The modeling of intrinsic nonlinear capacitance below the pinchoff voltage achieves improved accuracy of isolation simulation for GaN HEMT switches under large-signal excitation. The proposed model is verified by measurements, including dc ${I}{-}{V}$ characteristics, small-signal ${S}$ -parameters, as well as large-signal power compression and harmonic characteristics. The proposed model will be useful for the design of RF switches.