Channel Operating Margin (COM): Evolution of Channel Specifications for 25 Gbps and Beyond

摘要

Channel Operating Margin (COM) is a fast and efficient means to assign a single figure of merit (FOM) to interconnect channels composed of PCB, backplane, connectors, and components. Loss and crosstalk graphs anchored many past interconnect specifications. Their effectiveness was more limited at higher Gbps data rates. Specifications such as IEEE Std 802.3ba-2010 were augmented and improved with integrated power sum based metrics. Combining time-domain and statistical analysis, COM is a further evolution and refinement of the single FOM for channel design and specification. This is remarkably meaningful for multiple engineering disciplines. Mathematical representation and computer code implementation is straight forward providing a frame work for integration into commercial PCB design and signal integrity tools.