An Absorptive Common-Mode Suppression Filter Based on Resistor-Loaded M-Type Structure

This brief presents an absorptive common-mode filter (A-CMF) based on resistor-loaded M-type structure. The proposed structure utilizes coupled line and high-stop network to provide bandstop and high-stop filtering characteristics, respectively. Theoretical derivation and full-wave simulation are carried out to validate the design. The first-order and third-order A-CMFs are developed, while the influence of mounted resistors on the absorption is examined. A prototype of third-order A-CMF is fabricated and tested. The experimental results demonstrate that the proposed A-CMF has 95% absorption ratio in the frequency range from 4.74 GHz to 5.68 GHz. By changing the mounted resistors, an ultrawide band of absorption higher than 80% is achieved. In comparison with previous designs, the proposed A-CMF would not occupy extra area, thereby facilitating the placement and routing of electrical system.