Re: [BP] channel loss difference

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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

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