CDCM6208: About requirement of Input clock stability and tolerance

Sho Ogane

Part Number: CDCM6208

Hi all

Input frequency variate +130mmp->-10ppm.
Is this variation problem?
I think this variation causes LOS or out of lock
Please let me know what must be the stability and tolerance requirement of input frequency.

Best Regards,
Sho

over 6 years ago

0 Timothy T over 6 years ago

TI__Mastermind 28550 points

Hello Sho-san,

The tuning gain of the CDCM6208 is very high, a small change in reference PPM wouldn't cause an out of lock issue. There is not a spec for this parameter, but...

* The input frequency accuracy at lock time is of no concern. As long as the programmed dividers result in a VCO frequency in the valid VCO range, no problem.
* Once locked, there is a limit to the amount you can drift. However I expect < 200 ppm variation would have no trouble.

73,
Timothy

0 Sho Ogane over 6 years ago in reply to Timothy T

Genius 5575 points

Hi Timothy-san

Thank you for your reply.

I understood your comment.,
>>I expect < 200 ppm variation would have no trouble.

I think that variation of input during VCO calibration causes trouble, no problem?

Best Regards,
Sho

0 Madhu Balasubramanian over 6 years ago in reply to Sho Ogane

TI__Expert 4400 points

Ogane-san, the calibration word has enough range to not cause unlock when input varies a bit as you specified during the VCO calibration.

0 Sho Ogane over 6 years ago in reply to Madhu Balasubramanian

Genius 5575 points

Hi Madhu-san

Thank you for your reply.
I understood your comment.

Best Regards,
Sho

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CDCM6208: About requirement of Input clock stability and tolerance