Characterization of a 25V GaN d-HEMT Device through Large Signal Gate Charge Measurements and In-Converter Testing

To achieve high density power conversion, the switching frequency must be increased to reduce the sizes of passive filtering components. Gallium Nitride (GaN) is a material capable of providing the improved switching characteristics, necessary for higher frequencies. Non fine-geometry or non-monolithic integration of the driver and power switches results in higher parasitic inductance within the gate driver loop. This parasitic inductance creates difficulties in gate current measurement and in achieving optimum gate driving performance. This paper describes different methods to characterize a gate driving IC and GaN d-HEMT switching bridge system. The devices used in this work include a new research level 130 nm BiCMOS gate driver IC and a 25 V monolithic asymmetrical depletion mode GaN d-HEMT switching bridge. These are evaluated stand-alone and in a 12 V Point of Load (POL) 2 MHz buck converter circuit and achieve 95 % switching bridge efficiency.