Differential-to-common mode conversion noise suppression with unit cell EBG structure for bended differential lines

In order to reduce differential-to-common mode conversion noise in bended differential lines, we propose a unit cell electromagnetic bandgap (EBG) structure. The proposed structure compensates for mismatches of inductances and capacitances between inner and outer lines of the bended differential lines. Its performances of the common-mode noise suppression in frequency and time domains were verified by 3D full wave simulator, HFSS. Also, in order to verify the simulated results, the bended differential lines with the proposed unit cell EBG structure was fabricated and measured. As a result, suppression level of the differential-to-common mode conversion noise is below −20 dB from DC to 6 GHz, and Time-Domain-Through (TDT) common-mode noise voltage is reduced as compared with that of conventional bended differential lines.