Modeling of the Dynamic On-State Resistance of GaN-HEMTs

Abstract:
Unfortunately, in real switching operation, GaN-HEMTs often do not achieve the promising datasheet values in terms of on-state resistance, as charge trapping effects lead to so-called dynamic on-state resistance. Several dependencies of the on-state resistance, such as the blocking voltage, switched current, switching frequency, duty cycle, and device temperature, as well as type of switching transition (hard or soft switching), make reliable loss predictions difficult. In order to accurately predict conduction losses of GaN-HEMTs in real applications, this paper proposes a modeling approach based on measured data. The study incorporates the blocking voltage, switched current, temperature, switching frequency, and duty cycle. The final model exemplarily derived for hard switching operation is based on the resistance values gained by steady-state operation of the converter and consists simply of linear dependencies on the operating point. It incorporates a positive temperature coefficient and a negative coefficient regarding the switched current.