Parasitic capacitance Eqoss loss mechanism, calculation, and measurement in hard-switching for GaN HEMTs

Gallium Nitride enhancement-mode high electron mobility transistors (GaN E-HEMTs) can achieve relatively high-efficiency and high-frequency in hard-switching mode. One particular reason is that GaN E-HEMTs obtain zero reverse-recovery loss and also a zero reverse-recovery period. For silicon (Si) MOSFETs, it has been a well-known issue that their Q
_rr
is too big to switch the transistor in hard-switching mode. Researchers have made extensive efforts to calculate the reverse-recovery loss. However, few of them pay attention to the Q
_oss
, as the Q
_rr
dominates in the turn-on switching loss for Si MOSFETs. For GaN HEMTs, the absence of the Q
_rr
makes the Q
_oss
noticeable, although the value of the Q
_oss
for GaN HEMTs is still the smallest among both Si and Silicon Carbide (SiC) MOSFETs. This paper focus on the Eqoss loss in GaN HEMTs. The Eqoss loss mechanism, detailed calculation and detailed measurement method for GaN HEMTs are provided. In addition, the theoretical results are verified by the double-pulse test at different junction temperatures and gate resistances.