A Multifunctional Double Pulse Tester for Cascode GaN Devices

Gallium Nitride (GaN) power devices with low switching and conduction losses can lead to superior power density in numerous power conversion applications. Their fast switching speeds, however, pose challenges in dynamic device characterization. The large parasitic inductances and contact impedances in conventional double pulse testers (DPTs) meant for Si devices, make them unsuitable for GaN characterization. GaN devices are directly soldered on to testers for minimizing parasitic effects. Furthermore, currently different testers are used for different types of device characterization, requiring the device under test to be repeatedly soldered to different boards. This paper proposes a multifunctional tester well suited for GaN devices and capable of completing all the dynamic characterization on the same board. The proposed tester is able to characterize: device turn on and off transition under hard and soft switching, dynamic Rdson, diode reverse recovery, and device reverse conduction voltage drop. The proposed tester has been implemented in hardware and the functions are validated with tests on a cascode GaN device. Some special properties of the cascode GaN device seen from these tests are highlighted. Detailed design procedures for selecting the critical components of the DPT are presented.