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DS125DF111: Jitter tolerance

Jonathan Navor
Genius 9475 points
Part Number: DS125DF111

Hi Team,

Could you help please help? We have question regarding DS125DF111 a multi protocol CDR.

First: the jitter tolerance is speciified at 10G in the data sheet
what about the jitter tolerance going to halve or quarter data rate?
is it still about 0.7ui?
2nd inquiry:it is about the signal detect functionality
In reg. 0x14[5:2] the signal detect - assert and deassert - could be changed.
but there is no informatuion within the data sheet in which range the signal detect will change.
could we provide some numbers here? Thank you.
Best regards,
Jonathan
  • +1
    TI__Mastermind 35813 points

    Hi Jonathan,

    We would expect the jitter tolerance to be comparable across different data rates.

    Unfortunately for this device, I don't have any specific threshold values that are associated with the assert/de-assert values.  With that said, as 0x14[5:4] is increased, we expect the assert threshold to increase.  As 0x14[3:2] is increased, we also expect the de-assert threshold to increase.

    Thanks,
    Drew

  • 0 in reply to Drew Miller1
    TI__Genius 9475 points

    Hi Drew,

    We have a follow up question from the customer.

    The differential input resistance of the retimer DS125DF111 is typically 100Ohm (see data sheet, page 7). When the retimer is seeing now a pure single ended input having a transmission line of 50Ohm, is this still terminated accordingly within the retimer? What would be the best wiring of the retimer in a single ended operation mode at the input - the not used input terminated via AC coupling to 50Ohm?

    When the single ended input having a voltage swing from about 100mVp-p is this still in the working range of the retimer?

    Best regards,

    Jonathan

  • +1 in reply to Jonathan Navor
    TI__Mastermind 35813 points

    Hi Jonathan,

    Yes this device will also be terminated accordingly for single end operation.  Typically the RX termination is composed of two 50 Ohm resistors tied to a common node.  This creates 100 Ohm differential termination and 50 Ohm single ended termination.

    In regards to having a single ended input, this would likely work, but keep in mind that the signal will be subject to common mode noise.  As you suggested, I would terminate the unused input via an AC coupling capacitor to 50 Ohm.

    Thanks,

    Drew

  • 0 in reply to Drew Miller1
    TI__Genius 9475 points

    Hi Drew,

    We do have a follow up quetion. The question about the voltage swing is still open:
    When the single ended input having a voltage swing from about 100mVp-p is this still in the working range of the retimer?
    Could you give a feedback?

    Best regads,

    Jonathan

  • 0 in reply to Jonathan Navor
    TI__Mastermind 35813 points

    Hi Jonathan,

    What is the transmit amplitude of the signal?  If the high frequency content of the signal is 100mVp-p at the retimer's receiver, this is likely recoverable via the CTLE stage of the retimer.

    Thanks,

    Drew

  • 0 in reply to Drew Miller1
    TI__Genius 9475 points

    Hi Drew,

    Thank you for your support. You may close this thread.

    Best regards,

    Jonathan