A Reconfigurable AC Power Cycling Test Setup for Comprehensive Reliability Evaluation of GaN HEMTs

To address the challenges in long-term reliability testing of GaN power devices, this paper proposes a reconfigurable AC power cycling test setup. While addressing the limitations of existing aging tests, the proposed setup enables accelerated aging of GaN devices under a wide range of realistic stress conditions. Specifically, various hard and soft switching modes can be tested to realistically emulate different application scenarios. In addition to the ability to control test temperature, the setup also features adjustable power loop inductance that enables precise control over voltage overshoot during hard switching transients. Further, an on-state resistance based junction temperature estimation technique is used for closed loop junction temperature control. For this, a fast drain-source voltage measurement circuit along with an algorithm for closed-loop control of the mean junction temperature is presented in detail. Furthermore, the magnitudes of the temperature swing under different operation conditions are discussed in depth which provides a good insight to control temperature swings. Finally, a prototype is built to validate the proposed test design.