Sustained Oscillation Characterization of GaN HEMT at Cryogenic Temperature

Cryogenic power electronics has emerged as a transformative technique to achieve ultra-high efficiency and power density. Many projects have been conducted to investigate the application of cryogenic power electronics. Compared with other types of semiconductors, gallium nitride (GaN) high electron mobility transistor (HEMT) is proved to be the best candidate for cryogenic application with large reduction of on-state resistance and switching loss. However, the unique stability issue of the GaN HEMT is not explored under cryogenic. Therefore, in this paper, the unique sustained oscillation characteristic of GaN HEMT at cryogenic temperature is investigated and analyzed. After simplifying the equivalent circuit, the small-signal model is established to conduct the stability analysis. A cryogenic clamped inductive switching test platform, operating at [133 K-298 K], is built to evaluate the sustained oscillation performance. Experimental results reveal a 75% increase in sustained oscillation voltage range span at 133 K compared to ambient conditions. which indicates that GaN HMET is more prone to sustained oscillation at cryogenic temperature.