Research Advances in the Design of Absorptive Common-mode Suppression Filters

A systematic review of the recent advances in absorptive common-mode suppression filters is provided, which effectively suppress electromagnetic interference in high-speed digital circuits by converting common-mode noise energy into thermal energy, with performance superior to that of traditional reflective filters demonstrated. Two mainstream types of common-mode suppression filter structures based on dielectric loss materials and chip resistors are focused on, and their working principles, typical architectures, as well as common challenges (such as performance trade-offs, large area occupancy, and limited bandwidth) are discussed respectively. In response to these challenges, multiple innovative solutions have been proposed: a "transmission space separation structure" is adopted to synergistically enhance the common-mode absorption and differential-mode transmission performance of dielectric-based filters; "narrow-edge coupled resonators" are utilized to optimize multi-stage structures, with performance improved while layout area is reduced; and a "sandwich" matching component is implemented to significantly expand the absorption bandwidth and enhance design flexibility of single-stage structures. Finally, the application prospects of such filters in advanced packaging and other cutting-edge fields are prospected.