Enhancement mode (e-mode) GaN high electron mobility transistors (HEMTs) generally behave like n-channel power MOSFETs. Common curve tracers, parametric analyzers, and automatic discrete device parametric testers used for an n-channel power MOSFET can be applicable for the characterization of e-mode GaN transistors, but the implementation details differ for GaN. Typical e-mode GaN HEMTs have very low parasitic components. They switch very fast at high frequencies with short delays. Without proper consideration, the equipment used to perform the tests can introduce parasitics that contaminate the results and lead to incorrect measurements. In addition, possible shortcomings have been identified with the conventional double pulse testing (DPT) results related to the dynamic on-resistance of GaN devices.