Suppression of Differential-to-Common-Mode Conversion on Bent Differential Lines Using Spoof Surface Plasmon Polaritons

In this paper, a method is proposed to suppress the differential-to-common-mode conversion noise in right-angle bent differential lines using spoof surface plasmon polaritons (SSPPs). Using SSPPs with asymmetric groove depths on the differential line effectively compensates for the phase delay between the inner and outer lines caused by the length difference. The method can suppress the differential-to-common-mode conversion below −20 dB from DC to 8 GHz, whereas the conventional bent differential line can only stay below −20 dB from DC to 0.5 GHz. Compared with previously proposed methods for suppressing mode conversion, our work in this paper ensures effective suppression of mode conversion without the need for additional circuit area and multilayer structure, thereby reducing the pressure for dense circuit layout in high-speed circuit boards.