Investigation of the RF performance degradation in GaN HEMTs associated with the kink effect

Abstract

This work comprehensively investigates the RF performance degradation in GaN high-electron-mobility transistors associated with the kink effect. A pulsed kink amplitude modulated method is proposed to quantitatively correlate kink amplitude with RF S-parameter degradation. Experimental results show that a 25% increase in kink amplitude corresponds to an 18.6% drop in intrinsic transconductance (gm) and a 10.9% decrease in cutoff frequency (fT) at VGS = −2 V and VDS = 10 V. Long-term large-signal measurements after 60 h RF stress reveal an 8.99% increase in kink amplitude, accompanied by 1.7 dB gain degradation and an 8% reduction in power-added efficiency. Furthermore, a pulse-aware trap occupancy large-signal model is developed, embedding a pulse-conditioned trap occupancy variable (N) to simultaneously govern kink amplitude and inflection voltage (VDSkink). The proposed model achieves good agreement with the measured data, including I–V, S-parameters, and large-signal characteristics, and successfully predicts RF metric degradation associated with kink amplitude variation.