A Broadband and Transient-Accurate AlGaN/GaN HEMT SPICE Model for X-Band RF Applications

Abstract

Dispersive effects such as trapping play a vital role in determining the performance of AlGaN/gallium nitride (GaN) high-electron mobility transistors (HEMTs) for RF and power applications—necessitating accurate modeling for robust circuit designs. This work presents a rigorous SPICE model to capture the transient and large-signal impact of traps in AlGaN/GaN HEMTs. The model has been implemented in the industry-standard ASM-HEMT compact-model framework. The model accurately accounts for the variation in threshold voltage and change in 2DEG charge carrier concentration in the source- and drain-side access regions under various drain-lag and gate-lag quiescent conditions. Threshold voltage and 2DEG charge carrier concentration at the source- and drain-side access regions show a linear dependence on drain-lag and gate-lag quiescent conditions, respectively. The results obtained using the developed model are in good agreement with the measured data. This model is valid for transient current simulations at different quiescent conditions and accurately captures the large-signal behavior at the optimal load impedance. Finally, pulsed IV characteristics at different temperatures have been validated against device measurements.