Novel Equivalent Circuit Model for Dual-Band Series-Unified Absorptive Common-Mode Filter

In this article, we present a novel equivalent circuit model for a dual-band unified absorptive common-mode filter (A-CMF). While existing single-band A-CMFs effectively address electromagnetic interference (EMI) issues in the 2.4–2.48 GHz frequency range, they fall short in covering the 5.17–5.33 GHz band. This study designs a dual-band A-CMF that covers both frequency bands, suppressing common-mode noise while maintaining a compact size suitable for modern electronic devices. The new design includes a wideband suppression reflective common-mode filter and a dual-band common-mode noise absorption circuit. By adjusting the electrical length of transmission lines, this method can rapidly adapt to various manufacturing processes and achieve efficient absorption within the 2.4–2.48 GHz and 5.17–5.33 GHz frequency ranges. Finally, the proposed equivalent circuit is validated using circuit-level and full-wave simulations, as well as a fabricated test sample. The experimental results show that the equivalent circuit model aligns well with both simulation and measurement results, significantly reducing the size of the matching stage and the overall structure.