Ali,
Please clarify something. Joel is
talking about only de-embedding the SMA connector, not the backplane connectors
which are in between TP1 and TP4.
John
-----Original
Message-----
From: Ali Ghiasi
[mailto:aghiasi@broadcom.com]
Sent: Wednesday, August 18, 2004
3:22 PM
To: joel@force10networks.com
Cc: STDS-802-3-BLADE@listserv.ieee.org;
Jeff Cain; Peter Tomaszewski; DAmbrosia, John F; Scott Bardone; Steve Dreyer;
Joe M Abler; Glen Koziuk; goleynick@fciconnect.com; Graeme Boyd;
j.mitchell@winchesterelectronics.com; m_oltmanns@littoninterconnect.com; Petre
Popescu; Kok-Wui Cheong; Brian Seemann; Mike Lerer; Hoss Rahbar; Schelto Van
Doorn; Anthony Sanders; Pete Hanish; Cathy Liu; john.cagle@hp.com; Majid
Barazande-Pour; Bill Woodruff; Luke Chang; William Peters; Adam Healey; Michael
Altman; Richard Wolcott; Herman Eiliya; Zhi Wong; Bill Hoppin; Tom Gray; David
Law; Doug Day; Charles Moore; David McCallum; Roland Moubarak; Tom Palkert;
mike_resso@agilent.com; Mary Mandich
Subject: Re: [BP] Revised
S-parameters
Joel
Joel Goergen wrote:
Ali,
We have been focusing on this for several months now. I think Steve has
presented nothing new that hasn't been published and, at a min, agreed to in
some form of straw poll.
I am not
disagreeing that these were agreed in the straw poll, I just didn't
participated in some
of earlier meeting.
I would like to offer a thought ...
For the channel ... we use the SMA and SMA foot print that allows for a clean
launch. At both ends of the channel. This allows us to see the
SDD11/SDD22 without doing a major de-embedding and still allow for freq to 12.5Ghz.
How can you
define a channel "backplane" but not define a minimum attribute for
the connector.
There is no reason to de-embed the connector as the connector is part of the
channel. A compliant
channel must meet an specified transmission and reflection property which
include connector.
For the tp1 and tp4 ... we then let the tx (tp1) handle the BGA and via, the
rx(tp4) handle the via, both cap pads, both via and BGA pad. It will be
easier to do the de-embedding and specify the SDD11/SDD22 as seen by the chip
from the channel.
The
methodology specified currently in BP is suitable for chip to chip applications
but not for backplane.
Where do you handle connector effect and multiple reflection between the
connector-IC? In 4Gig FC we addressed some of these issues and do specify
the channel which include the connector.
Thanks,
Ali
Just my own thoughts .....
-joel
Ali Ghiasi wrote:
Steve
Looking at your channel model, I see the return loss up to 15 GHz is
better than 12 dB.
How do you get -12 dB return loss at 15 GHz with connectors, what kind
of connector
are you assuming? The most challenging effect are the primary
reflection between
silicon and the connector at this speed.
Thanks,
Ali
Stephen D. Anderson wrote:
All:
I updated the synthesized S-parameter files that I presented in
Portland. The new revision provides a much better NEXT file. The
Thru
file was also improved so that SDD11 magnitude has ripples. You may
recall that the previous SDD11 magnitude was flat over most frequencies
of interest and that this was viewed as unrealistic.
These are intended to match the NEXT and Thru templates that we
have
thus far agreed on.
If you see anything blatantly wrong with the files, please let me
know.
Regards,
Steve A.