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Re: [BP] channel loss difference

Shannon,

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-----
From: Sawyer, Shannon [mailto:shannon.sawyer@INTEL.COM]
Sent: Wednesday, January 25, 2006 8:15 PM
To: STDS-802-3-BLADE@listserv.ieee.org
Subject: Re: [BP] channel loss difference

 

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.

 

-Shannon

 

From: Charles Moore [mailto:charles.moore@avagotech.com]
Sent: Wednesday, January 25, 2006 5:24 PM
To: STDS-802-3-BLADE@listserv.ieee.org
Subject: [BP] channel loss difference

 

guys,

     There was some discussion during the teleconference about the relative
channel losses of various channels provided by me and simulated by joe
and matt.  I looked at several of them ad fit them to Amax per 69A and found:

    channel          loss at Nyquist  fit at Nyquist

AgilentITTC_1016         25.1         25.6dB        
"Agilent TC Measured"    26.4         26.4dB
modITTC23withCoupler.s4p 22.3dB       22.6dB
ITTC_23                  23.1dB       23.0dB

The simulations joe did which i was citing were on "Agilent TC Measured"
and ITTC_23, which differ in fit (smoothed) loss at Nyquist by 3.4dB. 

Note some channels differ from their nominal loss at Nyquist because i picked
channels with an Mtc which would give the correct loss but they have Btc
values which shifts the whole line a bit.  The ISI should still be the same as
expected with the nominal loss.

                                         charles


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|       Charles Moore 
|       Avago Technologies
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