In-Situ Extraction of Time-Resolved $E_{\text{OSS}}$ on GaN Power Device Based on a Modified Hard Switching Platform

$C_{\text{OSS}}$
loss (
$E_{\text{OSS}}$
) and Dynamic
$R_{\text{ON}}$
, which combine switching loss and conduction loss in currently available GaN HEMTs, severely limit their performance in hard switching topologies. The effect of dynamic
$R_{\text{ON}}$
under various stress conditions have been extensively explored. However, Coss discharge process remains elusive, as the current flowing through Coss cannot be detected directly. This work proposes an easy-to-implement method to extract the dynamic
$E_{\text{OSS}}$
under long-term OFF-state drain stress and hard-switching stress. The dynamic FOM
$R_{\text{ON}}\times E_{\text{OSS}}$
dependence on the continuous hard-switching stress is investigated, which is critical for the insights into the physical origin of
$C_{\text{OSS}}$
loss and practical application.