Temperature measurements of GaN FETs by means of average gate current sensing

Gallium Nitride is a promising technology to increase power density in future DC-DC converter. However, the size and volume of heat sinks and cooling equipment needed will limit the maximum achievable power density. Reducing the cooling effort for volume reduction of the heat sink is an option to increase the power density but requires good knowledge of the junction temperature to avoid overheating. The temperature dependent gate leakage of GaN FETs can be used to estimate the junction temperature during operation. This can be measured by observing the current supplied to the gate drive. The methodology shows how the average current supplied to the gate drive unit follows the device temperature.