Progress Review of Wide-Band Common-Mode Filter in High Speed Interconnect System

In high data-rate differential transmission, even small asymmetries can significantly impact signal integrity and electromagnetic compatibility performance. To address this issue, wideband common-mode filters have been developed. This paper presents the concept and calculation of the mixed-mode scatter parameter of differential signals. It discusses the features of wideband common-mode filters, including their operational mechanisms, analytical methods, and performance, with the aid of an illustrative example. Furthermore, this paper introduces three typical common-mode filters based on various structures, such as defected ground, electromagnetic band-gap, and metamaterials. The basic principles, typical characteristics, and latest research progress of each filter type are thoroughly explained. Ultimately, this paper aims to provide useful references for scholars studying the topic of high-speed differential transmission.