Vertical eye margin measurement using channel receiver equalizer

Abstract

Embodiments include systems and methods for determining link margins of data communications channels in a communications system. For example, an integrated circuit includes a large number of input/output (I/O) channels, each with a respective receiver system. The receiver system can include equalizer subsystems, that attempt to adapt to their respective channels (e.g., to eliminate inter-symbol interference). Embodiments manipulate filter tap weights in the equalizer subsystems to controllably close its respective data eye until a failure region is detected, indicating that a threshold I/O error rate has been exceeded. Thus, for each channel, the filter tap weights can be allowed to fully adjust to identify fully adapted values, and they can be forced into a failure region to identify failure region values. A link margin for each channel can be derived for each channel according to the difference between the fully adapted and failure region values of the filter tap weights.