Impact of GaN HEMT dynamic on-state resistance on converter performance

Abstract

A single-shot switching test circuit and a continuously operating converter are used to investigate dynamic on-state resistance in three 600 V GaN devices under representative converter operating conditions. The increase in dynamic on-state resistance following an off-state stress of a few micro-seconds was measured and demonstrated to be in the range of 6%–35% depending on the individual device. The dynamic on-state resistance effect is seen to be insensitive to temperature over the range 25–125T. A more severe increase in dynamic on-state resistance is observed when the device is exposed to a stress voltage for an extended stress time, in particular the e-mode devices exhibited two to three times the DC resistance. The dynamic on-state resistance has a more pronounced effect in continuously operating converters at higher switching frequencies; an increased on-state loss of 35.9% compared with the DC value is estimated for a converter operating at 300 V, 10 A, 400 kHz and 0.5 duty ratio.