Real-time channel temperature monitoring of p-GaN HEMTs based on gate leakage current

The thermal response of Lateral GaN-based High Electron Mobility Transistor (HEMT) is much faster than that of Si-based power devices, owing to its higher power density. This makes temperature-related effects even more critical for GaN HEMTs, highlighting the necessity of monitoring their operating temperature to improve the efficiency and reliability of power circuits. In this article, a real-time monitoring method for channel temperature of p-GaN HEMTs using gate leakage current as a medium is proposed. The dependence of gate current on temperature is demonstrated by 2D electro-thermal TCAD simulation on the reference p-GaN HEMT structure. A novel simple and low-cost gate driver circuit is proposed that integrates a monitoring circuit utilizing the current amplification capability of bipolar transistors and an RC integrator network. The proposed solution is confirmed through SPICE electrothermal simulations and experimental validation on commercially available devices. In conclusion, the online monitoring circuit has been proved effective, higher sensitivity and with minimal impact on the normal switching behavior, offering a promising pathway to improve the reliability of p-GaN HEMTs.