Disclosed is a method for deadtime optimization in a half-bridge switch or full-bridge switch wherein high-side and low-side switches comprise GaN transistors; a circuit for implementing the method; and a power switching system comprising a GaN half-bridge or a GaN full-bridge and a deadtime optimization system. The circuit comprises a drain current bump filter for generating a current charge output; and circuit elements for comparing the current charge output to a reference current charge Coss and generating a deadtime adjust signal. The deadtime adjust signal may be used to adjust deadtime to reduce or minimize deadtime, and deadtime losses, while avoiding cross-conduction.