Design of very low distortion dense routings for skew compensation in high speed interconnects

Line skew compensation is required in the design of high speed buses in state of the art server platforms in both printed circuit boards (PCB) and packaging layout. Generally, serpentine or trombone-like routing geometries are used to achieve the skew compensation target that ranges several hundreds of mils. In order to avoid distortion due to crosstalk, wide self-spacing distance is used. However, the design layout can be challenging and consume real estate. In this paper, it is shown that self-coupled routings carefully designed can achieve very small distortion for the slew rate or frequency range of interest. Simulations were performed in a full wave electromagnetic solver and a trombone-like structure was built and measured to confirm the effectiveness of the proposal.