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CDCE813-Q1: performance of Jitter Cleaner

K.Yaita
Guru 29690 points
Part Number: CDCE813-Q1
Other Parts Discussed in Thread: CDCEL913

Hi Team,

My customer is evaluating CDCE813-Q1 and CDCEL913 in his Serdes system like the following application.



He replaced these chips on his board and found output jitter performance of CDCE813-Q1 is better than CDCEL913.
So I would like to ask the following.

1)
Datasheet of CDCEL813-Q1 shows "Jitter Cleaner" in subject, on the other hand CDCEL913 doesn't show it.
Do you recommend CDCEL813-Q1 for jitter cleaner?
I would also like to know if there is any difference of jitter transfer performance between CDCEL813-Q1 and CDCEL913.

2)
Is there any difference of PSRR performance between CDCEL813-Q1 and CDCEL913?
I heard there is power supply noise in his system so I would also like to know it.

Best Regards,
Yaita / Japan disty

  • 0
    TI__Expert 8865 points
    Hello Yaita
    There might be performance differences between CDCE813-Q1 and CDCEL913. VDDout in CDCEL913 is 1.8V while in CDCE813-Q1, it should be 2.5-3.3.
    We have not released CDCEL813-Q1.
    Can you please clarify which part you are see better in Jitter performance and which parts are you comparing and what VDDout you are using?
    CDCE813-Q1 can be used as a medium performance jitter cleaner applications as specified on the title page of CDCE813-Q1.
    Best regards
    Puneet
  • 0 in reply to Puneet Sareen
    Guru 29690 points

    Hi Puneet-san,

    I apologize CDCEL813-Q1 is typo, CDCE813-Q1 is correct.

    ＞Can you please clarify which part you are see better in Jitter performance and which parts are you comparing and what VDDout you are using?
    I heard CDCE813-Q1 (VDDout=2.5V) is better jitter performance than CDCEL913 (VDDout=1.8V) in his evaluation result.

    My customer needs VDDout=1.8V but will decide to use CDCE813-Q1 if CDCE813-Q1 has better jitter performance than CDCEL913 inherently.

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Expert 8865 points
    Hello Yaita
    Due to the difference in the output supplies, i would expect slight difference in the performances of CDCE813-Q1 & CDCEL913 parts. If VDDout=1.8, CDCE813-Q1 might not be the right choice, but it should still work. The output drive strength will be weaker as the output stages are designed for VDDout=2.5V - 3.3V. Also the jitter performance might get worse in this case.
    Best regards
    Puneet
  • 0 in reply to Puneet Sareen
    Guru 29690 points

    Hi Puneet-san,

    My customer evaluated CDCE813-Q1 with VDDOUT=2.5-3.3V and CDCEL913 with VDDOUT=1.8V , and then
    he found output jitter performance of CDCE813-Q1 is better than CDCEL913.

    Do you think the result is caused by the difference of jitter performance between CDCE813-Q1 and CDCEL913?

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    Expert 2155 points

    Hi Puneet-san、

    Please allow me to get into this discussion.

    The things we want to know are:

    Q1. Are there any differences on PSRR of CDCE813 and CDCE/L913.

    Q2. Are there any differences on PLL bandwidth of CDCE813 and CDCE/L913.

    The reason why we came up these questions is that when we tested CDCE813
    and CDCE/L913 CDCE/L913 showed larger jitter than CDCE813.
    We would like to know the reason why they show different jitter performance.
    I suspect PSRR and/or PLL bandwidth may contribute to the jitter difference.
    If there are any factors, please let us know.

    Mita

  • 0 in reply to user4779049
    TI__Expert 8865 points
    Hello Mita,
    Below are my comments:
    Q1. Are there any differences on PSRR of CDCE813 and CDCE/L913.
    A: CDCE813 has higher voltage output stage compared to CDCEL913. The PSRR is different for those two output buffers.
    Q2. Are there any differences on PLL bandwidth of CDCE813 and CDCE/L913.
    A: There should be no difference in PLL bandwidth.
    Best regards
    Puneet
  • 0 in reply to Puneet Sareen
    Expert 2155 points

    Puneet-san,

    Thank you for the answers.

    Mita