[SI-LIST] Re: Jitter transfer vs. accumulation
- From: Vinu Arumugham <vinu@xxxxxxxxx>
- To: scott@xxxxxxxxxxxxx
- Date: Fri, 23 Mar 2007 09:49:49 -0700
May be we need to clear up the terminology/definitions.
By RMS jitter I think George is referring to RJ rms or the 1-sigma value
of the gaussian. This I think is bounded as George has repeatedly stated.
The peak-peak RJ of course is unbounded and depends on the number of
samples. I think George has referred to this as phase jitter.
Comments from Steve and Alfred seemed to suggest that the RJ rms, the
1-sigma of the gaussian itself is unbounded.
Steve, Alfred could you please clarify if that is what you meant/observe?
Thanks,
Vinu
Scott McMorrow wrote:
>George
>
>I have a quick question. You said:
>
>"The VCO RMS jitter is bounded, and so is the PLL RMS jitter. The RJ
>distribution takes on a true Gaussian waveform."
>
>My meager understanding of this is that Rj is by definition unbounded. And the
>presence of a true Gaussian distribution (when all other deterministic
>components have been subtracted out) is an indication of this unboundedness.
>And yes, theoretically it will approach infinity at infinite time. However,
>because the random component is so low, it "seems" to be bounded within a
>specific BER confidence level. Which is why we have repeatability in
>measurements. My contention is that Rj is much smaller than most people
>believe or are able to measure, and that it is low probability deterministic
>noise components that dominate the jitter spectrum. Unfortunately, these can
>also tend to have near-gaussian distributions, mucking up the measurement
>apparatus.
>
>If what I say above is correct, then what you describe above is truly
>unbounded jitter, taking on a Gaussian distribution.
>
>Do you agree?
>
>
>best regards,
>
>Scott
>
>
>
>
>Scott McMorrow
>Teraspeed Consulting Group LLC
>121 North River Drive
>Narragansett, RI 02882
>(401) 284-1827 Business
>(401) 284-1840 Fax
>
>http://www.teraspeed.com
>
>Teraspeed® is the registered service mark of
>Teraspeed Consulting Group LLC
>
>
>
>
>>
>>
>>
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