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LMK04803: phase noise data with 10Mhz reference

Nate Enos
Genius 9430 points
Part Number: LMK04803
Other Parts Discussed in Thread: LMK03806, LMK04806

Hello,

Posting for a colleague. 

I’ve found out that the LMK04803/LMK04806 and LMK03806 have worse jitter at their outputs when using 10MHz reference instead of 100MHz.

We use OCXO 501-27501-01 from Wenzel as 10MHz reference.

 

I understand that the output jitter is heavily dependent on the slew rate of the reference input beside the phase noise etc.

Do you have any measurement data or reports for output jitter (or phase noise) vs. reference input frequency? 

Thank you,

Nate

  • 0
    TI__Expert 8865 points
    Hello Nathaniel,
    Are you using LMK04803/LMK04806 in the single PLL mode?
    Generally if you operate the PLL with lower phase detector frequency, the PLL noise gets higher, that is why we recommend to operate the PLL with higher phase detector frequencies.
    You can use the Clock Design Tool or the Webbench tool to simulate the Phase noise for different phase detector frequencies. You can also then play with the PLL bandwidth to see what best you can get.
    Best regards
    Puneet
  • 0 in reply to Puneet Sareen
    TI__Genius 9430 points

    Thanks for the help Puneet. 

    I'm not sure if they are using single PLL mode, but I can check. 

    So just to make sure I understand, we don't have any captured data for this use case, but we should be able to get a pretty good idea of performance with our simulation tools? I'll recommend taking a look at those. 

    Thanks,

    Nate 

  • 0 in reply to Nate Enos
    TI__Expert 8865 points
    Hello Nate,
    Yes thats true. They should use the simulation tool like i mentioned. There is a good co-relation between what they will get from the tool and what they will measure.
    Best regards
    Puneet