CMOS-compatible 100 V / 650 V enhancement-mode high electron mobility transistors (E-HEMTs) and 650 V depletion-mode MISFET (D-MISFET) are fabricated on 6-inch GaN-on-Si wafers. These devices show excellent power converter switching performances. Both 100 V and 650 V E-HEMTs had passed industrial reliability qualifications. The importance of bulk leakage, interface quality and gate trapping in dynamic on-resistance is figured out. The device with optimized processes shows a significant reduction of the dynamic on-resistance degradation.