Reduction of cross-talk in high speed digital circuits using novel structured microstrips

A new method is presented to suppress the cross-talk of high speed digital circuits, when the rise time and fall time of transmitted signal are shorter than 500 ps. The proposed method is to use alternative smoothly changing phase-velocity microstrip lines (Alter-β lines) on printed circuit board. A pair of Alter-β lines are composed of a homogeneous line and a period structured slow-wave line, which makes the phase velocity difference between neighboring tracks. Preliminary theoretical analysis, with. the quasi-TEM and no loss approximation, proves the cross-talk between tracks can be controlled by the phase constant difference of the tracks. Simulation and experiment have shown that the cross-talk is lower than conventional parallel microstrip lines.