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

From: Lee Ritchey ([email protected])
Date: Sat Jan 15 2000 - 12:18:11 PST

The thing moving is an electromagnetic field. Analyzing the problem in terms of current flow is not useful in this case.

Jian Zheng wrote:

> 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,
>
> ----------------------------------------------------------------------------
> ------------
> 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
> ----------------------------------------------------------------------------
> ------------
>
> > -----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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> >
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