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DS125BR820: Eye pattern analysis

Part Number: DS125BR820

Hello team,

Could you advise how I can decide whether the eye diagram is okay or not? To clarify the question, I brought a capture that I took before. It's for checking if PCIe 2.0 can be linked up. The input eye height is 124.69 ps and the output eye height is 113.12 ps. How do I judge whether this difference is in the level of 'okay' or in the level of 'EQ modification required'?

My question is not confined to the PCIe case. I want to know if there is a general rule to judge the eye diagram. Is there any specification defined by any institute, which is based on protocols, data rate, BER etc.?

- before the redriver

- after the redriver

  • Hi Kim,

    This depends on the receiver that is attached to the redriver output. In the receiver, there could be minimum eye opening parameter for error free operation.  This parameter specifies if this eye opening is good enough.

    Regards,, Nasser