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[SI-LIST] Re: Stub Definition
- From: "DAmbrosia, John F" <john.dambrosia@xxxxxxxxxxxxxxxxxxx>
- To: "'djohnson@xxxxxxxxxxxxxx'" <djohnson@xxxxxxxxxxxxxx>,nbhandari@xxxxxxxxxxxxxxxxxxx, doug@xxxxxxxxxx, si-list@xxxxxxxxxxxxx
- Date: Thu, 9 May 2002 08:30:08 -0400
Everyone,
Would also like to point to papers presented by Tyco Electronics. The first
paper does an in-depth look at optimizing the design of the padstack
(including counterboring) to improve performance. The second paper was a
joint paper with Gennum, a leading chip company in adaptive equalization,
where the impact of layer connection in combination with their technology
was examined. In this paper, data rates up to 12 Gb/s through the HM-Zd
connector and Gennum technology were shown for distances up to 22 inches
through FR4.
Hope this helps.
John D'Ambrosia
Manager, Semiconductor Relations
Tyco Electronics Corporation
email - john.dambrosia@xxxxxxxxxxxxxxxxxxx
-----Original Message-----
From: David Johnson [mailto:djohnson@xxxxxxxxxxxxxx]
Sent: Wednesday, May 08, 2002 6:57 PM
To: nbhandari@xxxxxxxxxxxxxxxxxxx; doug@xxxxxxxxxx;
si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Stub Definition
Doug,
A stub is a section of unterminated transmission line branching
off the transmission line of interest. Actually the branch line is
terminated in an open circuit.
Dave
-----Original Message-----
From: Nitin Bhandari [mailto:nbhandari@xxxxxxxxxxxxxxxxxxx]
Sent: Wednesday, May 08, 2002 3:32 PM
To: doug@xxxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Stub Definition
Hi Doug,
Generally speaking, if the stub length is less then 1/6 of the
electrical
length of the signal edge, then the stub can be treated as a lumped
element
instead if a distributed element. How much lumped (or distributed)
discontinuity is too much depends on your application as Mike suggests.
Regards,
Nitin
-----Original Message-----
From: Michael_Greim@xxxxxxxx [mailto:Michael_Greim@xxxxxxxx]
Sent: Wednesday, May 08, 2002 3:17 PM
To: doug@xxxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Stub Definition
Hi Doug,
Some of the papers done by amp, teradyne,
etc regarding via effects on Ghz level signalling
show that even the stub length of the via can
have a big impact. This is part of the reason
behind counterboring the via to remove this stub
length.
I think that like most things in signal integrity
land, I suspect that the answer to this will be=20
'It depends'. Depending on how many you have, how
long they are, where they are and how fast you are=20
running will all have an effect on how long is long.
Just my 0.02
MG
-----Original Message-----
From: Doug Brooks [mailto:doug@xxxxxxxxxx]
Sent: Wednesday, May 08, 2002 4:55 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Stub Definition
This may be too simple a question for this high-powered group!
Is there an agreed upon definition for the word "stub" as in the case
of a=20
stub on a PC board?
Is there an agreed upon length beyond which a stub becomes a problem?
Doug Brooks
_____________________________________________________________________
UltraCAD Design, Inc. Celebrating 10 years of design excellence!=20
http://www.ultracad.com
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