smlogan
Community Member
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Posts: 51
Boston, MA
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iccc wrote on Jul 10th, 2007, 10:48pm:Hi,all
As we know the OC 192 SONET specification applies to 10 Gbit/s data rates, and specifies three benchmark specifications that must be met by CDR circuits -jitter generation, jitter tolerance, and jitter transfer.
1 Is the jitter bandwith as narrow as 120kHz?
Yes. The ITU and ANSI standards specify this. There is a long history and some controversy concerning the 120 kHz bandwidth requirement.
2 Where can i download the the OC 192 SONET specifications?
The standards must be purchased from either ITU (intenational standard) or ANSI. They are not in the public domain. Your company may have a membership that will allow you to download the documents.
3 How to solve the problem between jitter tolerance and jitter transfer as mentioned at the end of chap.9 in Behzad Razavi'book "the design of integrated circuits for optical communications"?
I do not have Razavi's book, but the issue relates, I believe to the trade-off between jitter tolerance requirements and the narrow loop bandwidth requirement of an OC-192 data recovery system. Careful design and the use of a high Q based CDR or phase-locked loop is one means of approaching the design. An alternative approach involves cascading a high bandwidth loop with a low bandwidth loop to provide the necessary tolerance, jitter generation and jitter transfer performance.
It is a challenge none the less.
Shawn
Any good papers are greatly appreciated.
thanks
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