EMI investigation in a GaN HEMT power module

Inhalt:
A half bridge power module using 650V/30A GaN HEMTs on PCB substrate has been fabricated and investigated with different ceramic decoupling capacitors for in-module EMI filtering. The experiments have shown that, by using small value decoupling capacitors, both differential and common mode currents’ spectra have been significantly reduced from conducted to radiate emission frequency range. Time domain modeling and simulation have been studied to revisit the experimental results. The placement of the common mode decoupling capacitor has been discussed. In-module filtering strategy has been suggested in the conclusion.