# RE: [SI-LIST] : What's your favourite Screwy SI Concept?

From: Jian Zheng ([email protected])
Date: Fri Jan 14 2000 - 11:10:25 PST

Hi:

In fact, the flow of electric current is very similar to the flow of water
current.

| |
| |B______
|
|A__________

When you have a bend, the current will take a short cut at the corner B. The
current at the corner A will be slowed down. For the electric current, the
slow down at corner A will create reflection from the corner. The short cut
at the corner B will make the electric path shorter than measured along the
center line. For standard PCB, the reflection from the corner is very small.
However, I understand that the electrical length is very important in clock
synchrinization. Accumulation of the shortening of electrical path at angles
may have effect to SI. Thanks!

Best regards,

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Jian-X. Zheng, Ph.D
Zeland Software, Inc., 39676 Mission Blvd., Fremont, CA 94539, U.S.A.
Tel: 510-797-8109, Fax: 510-797-8241, Web: http://www.zeland.com
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> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of Jeff Seeger
> Sent: Friday, January 14, 2000 10:05 AM
> To: [email protected]
> Subject: Re: [SI-LIST] : What's your favourite Screwy SI Concept?
>
>
> Tom Dagostino wrote:
> >
> > Bending a wire keeps a uniform cross section. Putting a corner
> in a trace
> > adds extra C at the corner from a larger area.
> >
> And herein lies the arguement, I believe.
>
> Perhaps those who argue against "right angles" envision a
> geometry where the line has a squared corner both on the
> inside of the elbow and the outside.
>
> I would wager that those who claim no material effect are
> working with the usual CAD system/photoplotter geometry of
> a squared corner inside the elbow and a radiused one on the
> outside.
>
> An attempt at ascii art:
>
> "Right Angle" "Standard Practice"
>
> \ \ \ \
> \ \ \ \
> > > > )
> / / / /
> / / / /
>
> HTH,
> --
>
> Jeff Seeger Applied CAD Knowledge Inc
> Chief Technical Officer Tyngsboro, MA 01879
> jseeger "at" appliedcad "dot" com 978 649 9800
>
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