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All,
Since time did not allow the conversation last week, I would like to talk further on the reflector to understand the opposition to the different channels that were proposed.
I will point to my test cases as a starting point, but the conversation really applies to all of the channels.
As I see it, we have the following types of impairments in the total system-
1. Loss dominated
2. Significant stub effects that cause deep nulls
3. Ripple in the channel
4. NEXT
5. FEXT
6. Return Loss
I believe most of the opposition arose from 1, 2, 3 and 6, but would like to have this conversation now.
The comments that I heard regarding my channels were the following -
· The data is not freely available. - This is no longer true, as I indicated last week.
· The data violates the informative channel model. I believe there were different cases where this happened.
o Case 1 had minor ripple below the mask.
o Cases 2 and 3 were margin cases that the Signaling Ad Hoc had requested.
o Case 6 came from a 22" link with top layer backplane connections. This channel was justified for its potential appearance in systems where all cost was being minimized, so counterboring was not assumed.
o Case 7 had a resonance ripple at approximately -55dB at 11 GHz. Once again this was a test case asked for by the Signal Ad Hoc to examine channel ripple. Otherwise up to 11 Ghz it is 5 to 15 dB above the informative mask
· Return loss is too high. In my opinion, this is a contradictory statement. The mask that I proposed that fit my data was not as aggressive as Joel's channels (#1,2,3,6,7,8,14,17,18). All of these models violated the proposed SDD11 mask in the lower frequency region, which I proposed.
· The data hadn't been seen. This is a partially true statement. Tyco has been diligent in presenting the data as quickly as gathered and processed. The SDD21 channel data for Cases 2, 4,5,6, and 7 was posted to the Signaling Ad Hoc reflector for the Sept 9 meeting.
So I reviewed Joel's data that was proposed
Case #1 - 4
Case #2 - 7_3_7 (4000-13) Total 17" has xtalk
Case #3 - 10_3_10 (4000-13) Total 23"
Case #6 - 4_10_4 (4000-13) Total 18"
Case #7 - 7_10_7 (4000-13) Total 24" has xtalk
Case #8 - 10_10_10 (4000-13) Total 30"
Case #14 - 3_3_15_7 (4000-13) Total 29"
Case #17 - 7_20_7 (4000-13) Total 34" has xtalk
Case #18 - 10_20_10 (4000-13) Total 40"
All of these test channels are well above the channel model. We will still need a test case that falls very closely on the informative channel model, which is where the Tyco channels 1 - 3 are falling (with included margin cases). From both IBM and LSI's analysis these channels were solvable. The StatEye analysis results were much more pessimistic (which is an on-going problem with StatEye that is being investigated) than the analysis of these companies and the crosstalk was not applied properly.
So to me it looks like overall loss isn't necessarily the big problem. Loss can be very advantageous, as was demonstrated at last week's meetings, as to how it can actually help reduce xtalk and return loss. Ripple and nulls on the other hand appear to be the bigger problem.
So I would like to open up discussion as to which Tyco channels people were most concerned about. Also, I do not know what to propose for a "weighting" scheme, so any suggestions on this would be of extreme use in helping us to reach consensus and move forward.
John D'Ambrosia
Manager, Semiconductor Relations
Global CC&CE
Tel 717.986.5692
Fax 717.592.2470
Cell 717.979.9679