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Shannon,
I
don't see a compelling argument against 0.75 m, except I will then request to
upload corresponding Molex channels to the library so we can study them a bit
closer. With 0.75 m we're covering probably 99% of the market applications. I
would like the new 0.7 m target be spelt out in the document, if we end up
adopting it.
Gourgen
-----Original Message-----
From: Sawyer, Shannon [mailto:shannon.sawyer@INTEL.COM] Sent: Sunday, January 29, 2006 1:34 PM To: STDS-802-3-BLADE@LISTSERV.IEEE.ORG Subject: Re: [BP] channel loss difference John, et
al, I’m not going to be in In my opinion, Charles, Matt, and I
have the most accurate perspective of the problem since we’ve actually performed
and published EIT testing on real transceivers. For KX, KX4 and KR testing,
Charles and I used a channel that closely matched the Goergen channel (26dB@5.16GHz) and saw crosstalk tolerances of
450, 180, and ~2mV@BER 1E-12 respectively. The power summed crosstalk from Tyco,
Molex, and Intel NEXT, FEXT shows 20-100mVp@BER 1E-12 aggression to the thru
signal, so the crosstalk tolerance limits are in the ballpark. Matt found that
crosstalk tolerance results on a ~23dB@5.16GHz channel were ~30mV below the 20dB
channel for KR operation. EIT test results documents are
here: http://grouper.ieee.org/groups/802/3/ap/public/jun05/sawyer_02_0605.pdf http://grouper.ieee.org/groups/802/3/ap/public/sep05/sawyer_01_0905.pdf http://grouper.ieee.org/groups/802/3/ap/public/sep05/brown_01_0905.pdf Real measured data is a compelling
argument, and so far we have seen, 4 out of 4 vendors (2 unpublished) that are
either borderline or failing EIT (last Fall’s definition) testing for KR. The
802.3ap channels’ PCBs and connectors were designed years ago for ~XAUI data
rates, and appear to be the best opportunity for improvement (larger signal with
reduced PNA, hence reduced DCD) in this system to enable KR operation.
Is there a compelling argument
against a 0.75m channel? - From: DAmbrosia, John
F [mailto:john.dambrosia@TYCOELECTRONICS.COM] Technically speaking
only Cases 1,2,and 3 fail the 20dB spec at Nyquist.
You need to be careful
in making a statement like going to a 20dB channel. As you pointed out
many channels failed that number, but I believe those are all the 1m channels or
stub limited channels that are failing it. The channels that are meeting
that the number in general are the 0.75m. The potential ramifications
could be that to meet the 20dB channel we consider changing our reach objective
to 0.75m. John -----Original
Message----- Charles, The
difference (no pun intended) shows up in the differential vs single ended
S-Parameters. I plotted SDD21 and S21 for modITTC23withCoupler.s4p, and there is
1.428dB difference at 5.160GHz. See attached. Sorry I
had to be at another meeting at noon, but I like the idea of going to a 20dB
channel. In my opinion that’s the lever big enough to get a real system working.
Unfortunately several (8 Molex, 4 Tyco, 3 Intel) channels violate that SDD21 up
to 5GHz. See attached. - From: Charles Moore
[mailto: guys, -- |--------------------------------------------------------------------|| Charles Moore | Avago Technologies| Image Solutions Division| charles.moore@avagotech.com| (970) 288-4561|--------------------------------------------------------------------| |