Intra-Pair Skew Metric, EIPS (Effective Intra-Pair Skew)

摘要

In the high-speed differential (HSD) interface design, the intra-pair skew becomes more critical as the link speed is ever increasing beyond 56Gbps+ signaling. The skew within a differential pair (intra-pair skew) deteriorates eye opening at the receiver and degrades the channel performance significantly in HSD signaling. However, industry lacks in an accurate and stable intra-pair skew measurement methodology, which created a significant gap in interconnect testing and qualification. In this paper, the effective intra-pair skew (EIPS) is introduced, which is directly calculated from S-parameter data as a single value without time-domain conversion. The EIPS is verified by correlating to the eye opening and the common-mode noise (CMN) in the HSD link of PCIe Gen5 32Gbps NRZ signaling. The MATLAB script for the EIPS calculation is included in the appendix.