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Jitter measurement of TNETE2201B

itabi
Expert 1295 points
Other Parts Discussed in Thread: TNETE2201B

Hi,

My customer is considering TNETE2201B.

1.When measuring Jitter in REFCLK, how should frequency setting of TIE Filter(Oscilloscope) be done?
　(?MHz ---> ?MHz)
　When my customer measured without TIE filters, deterministic jitter was 65.70ps.

2.The spec of the jitter is 40ps by mentioning of datasheet(page7).
　Is this spec a value which added Random jitter to deterministic jitter?

Best regards,
itabi

  • 0
    TI__Expert 3625 points
    Is customer having a problem with the device or is it a general question.
  • 0 in reply to WIN Maung
    TI__Prodigy 10 points
    itabi, just for clarification, you are trying to measure the jitter on the REFCLK that is supplied to the TNETE2201B, is that correct?
    typically jitter measurements do not require any filtering. However, PLLs and CDRs are designed to track low frequency jitter and filter high frequency jitter. For that reason you may be able to ignore the high frequency jitter that maybe on the REFCLK you are measuring. if you use a filter, it should be a low pass filter as where the cutoff frequency depends on you REFCLK frequency.
    to # (2): the REFCLK jitter spec is the total jitter the REFCLK is allowed to have (random + deterministic jitter).
    So the REFCLK you supply the TNETE2201B should have less than 40ps of total jitter.
    let me know if you have follow up questions.
    Franz Kuhlmann, TI
  • 0 in reply to Franz Kuhlmann
    Expert 1295 points
    Franz Kuhlmann-San,

    Thank you for your answer.

    Regards
    itabi
  • 0 in reply to Franz Kuhlmann
    Expert 1295 points

    Franz Kuhlmann-San,

    When inputting REFCLK with jitter(about 80ps), what kind of problem is considered?

    Is there possibility that a problem happens to the function?
    or
    Does the jitter of output just become bad?

    Best regards,
    itabi