[SI-LIST] Re: symmetry vs length matching for diff signals

Dear Cortex,

Your question is a good one!!

Actually, I have devoted lots of thought and research to this subject. =
It
seems to me
that there is no universal definition or a mathematical formula for
distinguishing=20
loosely vs. tightly coupled.

However, you may find the following qualitative definition helpful:

When the separation of the two traces is relatively large, so that the
coupling of each line
to the reference planes exceeds the mutual coupling of traces, then the =
pair
is said to be
"loosely coupled". When the two traces are sufficiently close, so that =
the
lines are coupled=20
more strongly to each other than to the reference planes, then they are
referred to as "tightly
Coupled".

Also see my article, "Differential Signals Routing Requirements, Part =
II",
Printed Circuit Design & Manufacture, March 2004, P.20 (the paper is
available on line).
=20

Best Regards,

Abe=20

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] =
On
Behalf Of Cortex Chen
Sent: Tuesday, November 30, 2004 3:31 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: symmetry vs length matching for diff signals


Dear Abe Riazi,
How to determine the tightly and loosely coupled pairs?

Regards,

Cortex




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 =20





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