The development of the high switching frequency static converters based on Wide-Bandgap Semiconductors (GaN and SiC) requires EMI filters with high-performance for aeronautic applications. It is well known that the high frequency parasitic couplings between passive components have a negative impact on EMI filter attenuation. In this paper, the method of reduction in parasitic couplings between component-component and component-PCB is analyzed in order to increase the EMI filter attenuation at high frequency (beyond 10MHz). Because of simulation complexity of these high frequency couplings, the proposed method is based mainly on experimental approach. The obtained results put in evidence the effectiveness of the proposed method to improve EMI filter attenuation up to 100MHz.