Common-mode noise reduction of bended coupled lines by using time compensation technology

New schemes of right-angle bended coupled lines with axis-aligned periodic stepped-impedance lines (SILs) and non-axis-aligned periodic SILs are proposed to suppress common-mode noise and differential-to-common mode conversion in this paper. The advantages of the periodic SILs structures employed in coupled lines have lower manufacture cost and easier implemented in two-layer PCB, preserving acceptable transmission level and low reflection to maintain signal integrity (SI). The function of SILs structures is used to increase the electrical length of the shorter one, i.e., to increase its respective propagation time, thereby improves the SI when differential signals pass through the asymmetric bended coupled lines.