[SI-LIST] Re: relationship between reeceiver jitter transfer and jitter tolerance

  • From: "Cheng, Chris" <chris.cheng@xxxxxx>
  • To: "vinu@xxxxxxxxx" <vinu@xxxxxxxxx>, "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>
  • Date: Mon, 30 Jul 2012 21:21:46 +0000

> For jitter frequencies above the corner frequency, jitter transfer is 0. For 
> jitter frequencies below the corner frequency, jitter transfer asymptotically 
> approaches 1
Are you confusing reference clock jitter tolerance with input jitter tolerance 
? If the above statement is true, I can have my input jitter to infinity above 
"corner frequency" and the transfer will still be zero so my wonder receiver 
can tolerance jitter of any amplitude above the corner frequency. How does the 
actual signals get through then ? :-)

Chris Cheng
Distinguished Technologist , Electrical Hewlett-Packard Company
   
 +1 510 413 5977 / Tel
chris.cheng@xxxxxx / Email
4209 Technology Dr
Fremont, CA 94538
USA

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On 
Behalf Of Vinu Arumugham
Sent: Monday, July 30, 2012 12:22 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: relationship between reeceiver jitter transfer and 
jitter tolerance

Chris,

"What if I modify slightly the definition of jitter tolerance to the receiver 
as, how much jitter can be applied to the input (instead of reference clock) 
before you have a receiver error."
Specifications such as XAUI,XFI,SFI,XLAUI,CEI use this modified definition. 
Most of them do not specify reference clock jitter.

Instead of using the UI as the break point perhaps the corner frequency of the 
tolerance vs. frequency curve should be used (usually Fbaud/1667). For jitter 
frequencies above the corner frequency, jitter transfer is 0. For jitter 
frequencies below the corner frequency, jitter transfer asymptotically 
approaches 1.

Thanks,
Vinu

On 07/27/2012 07:07 PM, Cheng, Chris wrote:
> Hi there,
>
> I think the classical definition of jitter transfer is related to how much 
> jitter at the input of receiver get transfered to the output of the receiver.
> The classical definition of jitter tolerance is related to how much input 
> reference clock jitter is acceptable for a given bit error rate.
> What if I modify slightly the definition of jitter tolerance to the receiver 
> as, how much jitter can be applied to the input (instead of reference clock) 
> before you have a receiver error.
> A practical way of doing the above is to send a known pattern such as CJTPAT 
> to a receiver and then modulate it with a fixed frequency jitter. The minimum 
> jitter amplitude that will trigger errors will be defined as jitter tolerance 
> as above.
> So my question is, if one does the experiment above and plot out the jitter 
> tolerance vs. frequency. How does that receiver jitter tolerance related to 
> the receiver transfer curve ?
> Can I interpret the receiver jitter tolerance and transfer relationship as:
> a) For jitter tolerance > UI, the jitter transfer is 1 or unity
> b) For jitter tolerance < UI, the jitter transfer = UI - jitter tolerance - 
> "some constant"
> where "some constant" is probably related to the setup and hold 
> requirements of the receiver
>
> Thanks in advanced,
>
> Chris Cheng
> Distinguished Technologist , Electrical Hewlett-Packard Company
>   
> +1 510 413 5977 / Tel
> chris.cheng@xxxxxx / Email
> 4209 Technology Dr
> Fremont, CA 94538
> USA
>   
>
>
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