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

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From: Neven Pischl (npischl@cisco.com)
Date: Fri Jan 14 2000 - 13:26:20 PST


It is very fortunate that the electrons at the corner A will be slowed down, because if they are too fast they can cause disastrous effects like flying off the traces, as I red somewhere some time ago :) Luckily, it is only the fast electrons that can fly off, the slow ones will stay on the trace - :) again.

Neven Pischl

At 11:10 AM 1/14/00 -0800, 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: owner-si-list@silab.eng.sun.com
>> [mailto:owner-si-list@silab.eng.sun.com]On Behalf Of Jeff Seeger
>> Sent: Friday, January 14, 2000 10:05 AM
>> To: si-list@silab.eng.sun.com
>> 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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