Re: [SI-LIST] : Prior Art: FR-4 lossy W models

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From: D. C. Sessions (si-list@lumbercartel.com)
Date: Thu Jan 04 2001 - 09:20:09 PST


On Thursday 04 January 2001 09:59, you wrote:
# At that trace width, you ar going to have more trouble with skin effect
# losses than losses in FR-4. FR-4 isn't that bad compared to the other
# choices. I do lots of 2.5 GB/s signalling in FR-4 over surprising
# distances.

These generally require some degree of equalization. One of the things
we're trying to settle. And, as much previous SI-LIST traffic has pointed
out, the use of FR-4 affects the amount of skin effect due to surface
quality issues.

Thus my request for lab-correlated lossy models. I do *not* trust
pure theory in this situation.

# Might be worth it to do a little analytical work with a tool like ADS from
# HP. The results will prove enlightnening.

Alas, we're a deep-in-the-silicon group and don't have direct PWB
resources. We're just trying to do some preliminary work for first-pass
cell design.

# It would be useful if you identified yourself in your mail.

And here I thought I had -- D. C. Sessions (yes, that's a name.)
Fairly public sort of identitiy; Philips Semiconductors I/O design
engineer, chair of JEDEC's JC-16 committee on signaling standards,
stuff like that.

I'm flattered by the mail about the signature block, but must admit
that it's a blatant ripoff of Proverbs.

# D. C. Sessions wrote:
#
# > One of our engineers is working on some ludicrously fast signaling that
# > customers (IMHO foolishly) want to do on FR-4 instead of something
# > sensible. Then again, I suppose I shouldn't complain if they save money
# > on the material and spend it on the silicon...
# >
# > Anyway, rather than reinvent the wheel he's looking for some coupled
# > differential line models for ~110 ohm FR-4 (the usual 5 mil traces etc.)
# > Which leads me to suspect that there's a need for a prior-art repository.
# >
# > In the meantime, does anyone have reasonable lossy models that they
# > want to contribute?

-- 
| The race is not always to the swift, nor the battle to the strong. |
| Because the slow, feeble old codgers like me cheat.                |
+--------------- D. C. Sessions <dcs@lumbercartel.com> --------------+

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