Junction temperature prediction method of GaN HEMT power devices based on accurate on-voltage testing

Abstract

Compared with Si devices, GaN HEMT has lower on-resistance, lower junction capacitance, higher switching frequency, higher switching speed and higher junction temperature capability. It is widely used in automotive, aerospace and other fields. Severe environments may cause the junction temperature of GaN-HEMT to be too high, and excessive temperature is the main reason for power device failure. In order to ensure stable operation of GaN devices under harsh conditions, it is important to extract junction temperature information of semiconductor devices simply and effectively. However, most of the existing junction temperature prediction methods are not applicable to GaN HEMT devices due to its high switching speed and high requirement of prediction accuracy. Thus, we proposed a new method based on an accurate on-voltage clamp circuit to predict the junction temperature of GaN HEMT devices. The interrelation between the on-resistance and the junction temperature is analyzed, and the temperature coefficient is calibrated to obtain the corresponding relationship between the characterization quantity and the junction temperature. The on-resistance testing circuit suitable for GaN device is given and analyzed in detail. Finally, the conduction resistance testing circuit is used to predict the junction temperature of GaN devices, achieving extremely high accuracy. Experiments have verified under 100 ℃, the predicted junction temperature and the actual junction temperature have achieved more than 90% coincidence.