H-Bridge-based Experimental Setup for GaN HEMTs' Thermal Cycling Testing

Long-term reliability testing of E-mode Gallium Nitride (GaN) High Electron Mobility Transistors (HEMTs) under accelerated thermal cycling can take several months to a few years, depending on the testing profile, including the device's junction temperature cycling window. This paper presents an H-bridge-based experimental setup for GaN HEMTs' thermal cycling testing, which aims for a significant reduction in the energy consumption (about 90%) compared to the load power and allows the implementation of two thermal cycling windows per the H-bridge GaN FETs as well as operating the devices with voltage/current patterns mimicking real field applications. A single inductive load stores the energy used for thermally cycling the devices while the H-bridge is actively controlled as a DC-DC power converter. For the proof of concept and operation of the proposed method, GaN HEMTs rated 650 V, 7.5 A with integrated gate driver are thermally cycled between room temperature (i.e., 25 °C) and a maximum junction temperature (here, 200 °C) or other temperatures predefined in the control algorithm. During thermal cycling, the voltage, current, and junction temperature of the four GaN FETs are monitored. Consequently, the RDS
on
is consistently monitored as it serves as the devices under test (DUT) junction temperature indicator.