RE: [SI-LIST] : Inner vs. Outer Layer Routing

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From: Chris Padilla (cpad@cisco.com)
Date: Tue Dec 21 1999 - 17:59:00 PST


I'd still like to hear about differential-mode versus common-mode currents/
radiation on a differential line. I know we have a common-mode element.
My main question is how much in relation to inner and outer layer routing
of this differential pair.

Thanks a lot for this discussion--very enlightening to us young EMI/SI
engineers trying to apply theory to the real world.

----->Chris

At 12:57 PM, you wrote:
>Hi, everybody:
>
>Microstrip and stripline have their own advantage. Stripline normally has
>less inductance and less dispersion. However, 3D interconnect in stripline
>may create very strong radiation. Some person mentioned that stripline
>radiates less. Such a conclusion is true when you have only the horizontal
>straight lines or horizontal bends. However, if you have vertical
>interconnects in a stripline circuit, the vertical interconnects may create
>very strong radiation. It is the so-called parallel plate mode, and this
>mode does not have any cut off frequency. Normally, microwave designers use
>shorting pin between the two ground planes at the proximity of 3D
>interconnects to suppress the parallel plate mode. 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
>----------------------------------------------------------------------------
>------------
>>
>
>
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