研究目的

Investigating the stability of GaN-on-Si HEMTs with substrate-to-source termination in a high-voltage half-bridge and the impact of parasitic substrate loop on switching behavior.

研究成果

The substrate-loop and resulting parasitic inductance LBS was introduced as a new effect hindering fast switching. It was shown that the external substrate-to-source termination results in a third parasitic loop, which might result in instabilities of half-bridge circuits after hard-switching turn-on events, even in the case of otherwise zero gate-loop and power-loop parasitic inductances. The trade-off between gate-resistance and substrate-loop inductance was analyzed. Measurements using a PCB-embedded GaN half-bridge verified the results.

研究不足

The proposed substrate damping does not avoid the initial fault turn-on event, but only avoids an instability after this event. The solution to damp the substrate oscillation with an additional damping resistor RBS will add additional switching losses to the circuit.