Wideband common-mode suppression filter using defected corrugated reference plane structures

This article describes a broadband common-mode filter for suppressing common-mode (CM) noise in high-speed differential signals. The filter used a novel defected corrugated reference plane (DCRP) structure. It used structure changes to impact the characteristic impedances in the CM current return path, which caused many approach transmission zeros. The main purpose generated a larger CM noise stopband effect. The experimental results showed that the frequency domain can reduce the CM noise over 9.29 dB from 3.67 to 17.03 GHz. The fractional bandwidth was 129%. The CM noise can be improved by 68.2%. The insertion loss in differential mode (DM) was kept at less than -1.611 dB from DC to 20 GHz with good signal integrity. The eye diagram can support a 16 Gb/s transmission rate in the time domain. The DCRP structure filter supports high-speed computer buses up to PCI Express 4.0, SATA Express, HDMI 1.4, and USB 3.2, which meet current computer products' needs.