LMK00301: LMK00301 clock jitter is too large

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Frank Xiao

Replies: 2

Views: 57

Part Number: LMK00301

HI team,

My customer is using the LMK00301 now.  When they did the test with LMK00301 and competitor device. The same layout  and the same board. But our QA4 and NQA4 jitter is 2.5PS, but other buffer QA4 and NQA4 clock jitter is  only 876fs. Do we have some ideas about the phenomenon? Thanks.

 LMK00301 

The competitor

• LMK00301

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Frank Xiao

• Aug 10, 2020 2:43 AM
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2 Replies

• Genius 11870 points

  

  Frank Xiao

  

  • Aug 10, 2020 6:31 AM

  The channel 0 (QA0 and NQA0) performance is good enough for TI device. Although the QA4 and NQA4 layout aren't good enough. But competitor devices can be used here, but our device QA4 has the issue. Could you please share some suggestions? Thanks.

  

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• Genius 16060 points

  

  Lane Boyd

  

  • Aug 10, 2020 5:03 PM

  In reply to Frank Xiao:

  Hi Frank,

  Thanks for the info. From the measurements shared, it is clear that LMK00301 has higher jitter than the competitor device due to the presence of spurs at harmonics of ~95kHz. In the absence of these spurs, jitter performance of both devices will be much lower.

  What is causing the 95kHz spurs? Is it another clock in the system? Perhaps these spurs are present on the input clock? What are your options to reduce the amplitude of the spurs?

  Kind regards,
  Lane

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