Novel Single-Stage Absorptive Common-Mode Filters (A-CMFs) Unit With Sandwiched Matching Components

In this article, a novel single-stage absorptive common-mode filter (A-CMF) unit with sandwiched matching components is proposed. Compared with traditional single-stage A-CMFs whose absorption band is usually single and narrow, high-performance bidirectional A-CMFs can be achieved by using the proposed single-stage unit. For the first time, dual-band and second-order single-stage A-CMFs are developed. In the design of dual-band A-CMF, a prototype is fabricated and tested, and the experimental results demonstrate that the developed dual-band A-CMF achieves two absorption bands (1.32–1.66 GHz and 2.88–3.10 GHz). To further increase the absorption band, a band-enhanced A-CMF is developed by cascading the designed dual-band single-stage A-CMF with extra absorption stages. In the design of second-order single-stage A-CMF, a double-layer vias connected asymmetrical coplanar strip is proposed to realize a low characteristic impedance transmission line. The fabricated prototype achieves a 95% absorption ratio from 2.20 to 2.82 GHz.