Modeling and design of a compact wideband common-mode filter using internal coupling technique

Abstract

In order to suppress the common mode (CM) noise in high-speed differential signal traces, a compact CM filter is proposed in the letter, which adopts two C-shaped defected ground structure (DGS) cells and one double-headed arrow-shaped DGS cell. An equivalent circuit model is used to explain the working principle of the CM filter. The filter has a small size of 11 mm by 10 mm. It provides a CM suppression from 3.5 GHz to 12.4 GHz over 15 dB, while the differential signals still keep good signal integrity. The experimental results are in good agreement with the simulated results.