[SI-LIST] Re: Remove Ground underneath Differential signal isdeserved or not?

Scott:

I find your recommendation on "random interval" via stitching interesting.
This can be applied not only on guard trace but other cases when we need to do
via stitchings. I call it a "spread spectrum" technique, as we reduce the
peak amplitude of one sharp resonance and spread the energy a little bit.

Regards

Perry

Scott McMorrow wrote:

> Lee,
>
> > What I show in my class is that guard traces are always LC networks that
> > resonate at some frequency and can and do turn into bandpass filters
> > at some
> > frequencies.  I demonstrate this will actual failed circuits.
> >
> >
> This is exactly why Mike Conn and myself recommend stitching guard
> traces to ground at random intervals across the length.  The average
> spacing of the via sites should be 1/10 of the wavelength of the fast
> signal frequency or equivalent risetime that will be present on this
> trace.  These stitch vias to ground will eliminate the problems which
> you have alluded to.  They are backed by extremely good analytical and
> experimental science.
>
> Best regards,
>
> Scott
>
> --
> Scott McMorrow
> Teraspeed Consulting Group LLC
> 2926 SE Yamhill St.
> Portland, OR 97214
> (503) 239-5536
> http://www.teraspeed.com
>
> --
> Scott McMorrow
> Teraspeed Consulting Group LLC
> 2926 SE Yamhill St.
> Portland, OR 97214
> (503) 239-5536
> http://www.teraspeed.com
>
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--
Perry Qu

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