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DS125DF410: HEO Eye opening

Kawai
Guru 19785 points
Part Number: DS125DF410

Hi Team,

Jitter tolerance of DS125DF410 is > 0.6UI based on the datasheet.

Our customer's eye opening result using the EOM function is only 0.25UI, however, the device keeps lock and does not have an error.

Q1). Can you say, the device could be used as long as there is no error, even having small HEO ?

Q2). Would the eye width get small, like 0.2UI, if there is a large amount of low frequency jitter ?

Q3). Do you think this result is seen based on the high frequency jitter ?

Best Regards,

Kawai

  • 0
    TI__Mastermind 43795 points

    Hi Kawai,

    As the eye opening gets smaller, the specific type and frequency of jitter will determine if error free operation is possible.

    A1: The DF410 could be used in this application, but I would also recommend that some study is done to understand the type of jitter present on the input.

    A2: Low frequency (well below the bandwidth of the CDR) should all be tracked out by the CDR.  Since the eye monitor uses CDR derived clocking, I do not think it would show up in the eye monitor plot.

    A3: The jitter is likely composed of higher frequency components.  Low frequency Rj and Pj are filtered out by the CDR.

    Regards,

    Lee

  • 0 in reply to Lee Sledjeski
    Guru 19785 points
    Hi Lee-san,

    Thank you for your support.

    It seems better to find out what kind of jitter is included in their TX signal. Please allow me to discuss with you again after confirmation.

    Best Regards,
    Kawai