The Impact of Mismatched Parasitic Inductances on Current Distribution in Parallel GaN HEMTs Under Transient-Overcurrent Conditions

Current imbalances occur in parallel GaN HEMTs when there are inconsistencies in circuit parasitic parameters. This imbalance is exacerbated under transient overcurrent conditions, increasing the susceptibility of GaN HEMT devices to damage. To study the effect of mismatched parasitic inductances on the current distribution in parallel GaN HEMTs, this paper conducts a simulation analysis of three scenarios of mismatched parasitic inductances under transient overcurrent conditions. The results show that the three types of parasitic inductances affect the current imbalance in parallel GaN HEMT devices differently. The gate parasitic inductance has a minimal impact on current imbalance and can be disregarded. Mismatched drain and source inductances have a significant effect on transient current imbalance in parallel GaN HEMT devices. The drain parasitic inductance is only in the power loop, while the source inductance is in both the power and gate drive loops, affecting the gate voltage during device conduction. This causes a difference in the turn-on timing of the two parallel GaN HEMT devices, leading to greater transient current differences under transient overcurrent conditions.