The short circuit capability of gallium nitride high electron mobility transistor (GaN HEMT) exhibits great differences under different drain-source voltages, thus its short circuit protection is critical for practical applications. This paper presents a new short circuit protection method developed for p-GaN HEMTs, which is based on the detection of gate voltage during on-state of the devices. The short circuit capability and the unique gate characteristics for p-GaN during short circuit fault are illustrated, and the principle of the proposed short circuit protection method is analyzed in detail. The experimental results show that the proposed method can detect the short circuit within 620ns and turn off the GaN devices within 140ns. Compared with conventional desaturation protection, the scheme in this paper offers benefits in terms of low costs, temperature advantage, flexibility in threshold selection and minimal impact on the normal switching behavior.

Enhancement mode, GaN HEMT, gate voltage, short circuit protection, short circuit capability.