GaN-HEMTs Cascode Switch: Fabrication and Demonstration on Power Conditioning Applications

A novel metal TO-257 4-pin package is proposed for the packaging of a D-mode GaN MIS-HEMTs cascoded with an integrated power MOSFET and a Schottky diode device, and demonstrated in power conversion applications. The normally-off hybrid cascode circuit provides a maximum drain current of 14.6 A and a blocking capability of 600 V. The cascode configuration has a +3.9 V gate threshold, sufficient voltage swing, good controllability of commonly available gate drivers. Analysis of 48 V/ 2 A power conversion characteristics are discussed and show the excellent switching performance in inductive load circuits. Switching characteristics of the integral SiC SBD are also demonstrated. Finally, a 48-to-96 V boost converter is used to evaluate the benefit of GaN cascode switches. Experimental results show an output power of 94.8 W and a power efficiency of 95.37 % under a switching frequency of 100 kHz, which is higher than the 92.03% power efficiency provided by the conventional Si MOSFET with the same switching operation.