Re: Deficiencies in measuring input jitter tolerance
Mike,
Sorry about the delay in replying.
You are right in saying that IEEE Draft P802.3ae/D3.0, March 26/2001
specifies only 0.05UI sinosoidal added jitter. The rest is 0.35UI DJ
and 0.015UI rms RJ.
The question I was raising is how to generate DJ and RJ consistently. The
draft 3.0 does specify the property of RJ but doesn't specify a methodology
for generating it. I was suggesting that we could define a worst case way of generating the effect of these two types of jitter. Today, in
absence of any other method, engineers use sinosoidal modulation which was my concern.
In conclusion, our idea of testing IJT (input jitter tolerance) of the receiver
appears to complement whatever is outlined in the draft and not contradicting it.
The method we proposed tests set-up and hold time and input phase offset (or
input phase alignment) of the receiver phase detector and retimer flip-flop.
The set-up/hold time and the phase aligment limit the very high frequency
jitter tolerance which is most important in serial digital data communication.
The sinusoidal method is still very useful as it validates that the receiver has
loop bandwidth over 4MHz.
Regards
Atul
Mike Dudek wrote:
> The input jitter tolerance that was voted in for the draft 3.0 does not suffer from the problem you are bringing up. The jitter
> proposed in the test contains only 0.05UI (from memory) sinusoidal jitter. The remaining 0.5UI of jitter is a combination of Dj
> including DCD and random gaussian jitter.
>
> Bharat Tailor wrote:
>
> > Serial PMDers,
> >
> > Attached is a note (hopefully small enough to get through the reflector)
> > explaining some deficiencies we see in current input jitter tolerance
> > measurement methodologies. We propose an alternate method for
> > consideration by the group.
> >
> > Best Regards,
> >
> > Bharat Tailor
> > Gennum Corporation
> >
> > ------------------------------------------------------------------------
> > Name: The Deficiencies in Measuring Input Jitter Tolerance v21.pdf
> > The Deficiencies in Measuring Input Jitter Tolerance v21.pdf Type: Portable Document Format (application/pdf)
> > Encoding: base64