In　this　work,　we　develop　a　dynamic　RONtest　bench　for　GaN　HEMT　based　on　two　half-bridge　pulse　generating　circuits,　enabling　versatile　selection　of　soft　switching　(SSW)　and　hard　switching　(HSW)　test,　allowing　long-duration　test,　and　supporting　both　packaged　large-area　devices　and　on-wafer　small-size　devices.　For　packaged　devices,　under　SSW　test,　Schottky-gate　p-GaN　HEMT　(SG-HEMT)　exhibit　a　bell-shaped　dynamic　RONand　VDScurve,　while　the　ohmic-gate　p-GaN　HEMT　(GIT)　and　Si　superjunction　(SJ-)　MOSFET　exhibit　stable　dynamic　RON.　Under　HSW　test,　the　dynamic　RONof　SG-HEMT　and　GIT　are　both　slightly　higher　than　SSW　test.　The　hard-switching　energy　(EHSW)　is　controlled　by　a　capacitor　CHSW.　During　1-hour　continuous　SSW　and　HSW　test,　the　dynamic　RONof　GaN　HEMT　increases　gradually　and　saturates.　The　on-wafer　device　in　this　work　is　an　active-passivation　HEMT　(AP-HEMT)　with　W　G=10　μ　m.　The　SSW　dynamic　RON　of　AP-HEMT,　extracted　with　a　delay　time　of　∼　20　μ　s,　is　comparable　to　that　of　the-state-of-the-art　commercial　GaN　transistor　using　the　same　testing　condition.　　©　2024　IEEE.