The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Design >> Mixed-Signal Design >> CDR specification
https://designers-guide.org/forum/YaBB.pl?num=1163587659

Message started by Visjnoe on Nov 15^th, 2006, 2:47am

Title: CDR specification
Post by Visjnoe on Nov 15^th, 2006, 2:47am

Dear all,

recently, somebody specified a CDR (using a PLL) with following specification: the incoming data has a peak-to-peak jitter of 2ns, we would like for the output clock to have a peak-to-peak jitter of 100ps.

I think - but maybe I'm wrong- that this specification makes no sense: normally, for CDR, one specifies jitter transfer, jitter generation and jitter tolerance. The jitter tolerance mask provides the designer with a specification of the jitter amplitude versus frequency. This way, he can start the CDR PLL design.

However, given the just the 'time-domain' jitter of the incoming data, I think the PLL design can not be started, since the frequency distribution of the jitter is not know.

That being sad, I also think it is impossible to measure the jiter versus frequency for a given data/bit stream (no experience here).

Can somebody provide me with a second opinion on this?

Kind Regards

Peter