Re: [SI-LIST] : W element correlation with measured data

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From: Jim Freeman (freeman@broadcom.com)
Date: Fri Dec 17 1999 - 16:08:11 PST


Hi Vadim,
    This may not be relavant, but I just attended the Ansoft class on the Pacific Numerics part and found that the PEEC method will break up the conductor
into filaments and If the mesh is properly specified, it will model frequency effects.

Jim Freeman

"Heyfitch, Vadim" wrote:

> Jim,
>
> It's my understanding that Ansoft's Maxwell does not creat any mesh
> into the conductor bulk (or skin) when you are extracting AC values. Instead
> it only creates the surfice mesh. Therefore there is no point in specifying
> 500 MHz instead of 100 MHz just to make sure that the is enough mesh layers
> within the skin depth. Please correct me if this is a misconception on my
> part.
>
> Vadim
>
> > -----Original Message-----
> > From: Jim_Foppiano@Dell.com [mailto:Jim_Foppiano@Dell.com]
> > Sent: Thursday, December 16, 1999 7:18 AM
> > To: si-list@silab.eng.sun.com
> > Subject: RE: [SI-LIST] : W element correlation with measured data
> >
> >
> > All,
> >
> > I want to warn everyone that hspice is extremely sensitive to
> > time step.
> > The time step I used in the .sp file produced the results shown.
> > If you vary time step you can get different answers. Also the
> > meshing in Ansoft is sensitive to geometry. I specified frequencies
> > of 100 MHz for the cable geometry and 500 MHz for the stripline
> > geometry in order to avoid problems in skin depth meshing.
> > Ansoft as well as any FE solver at some point may not be able to
> > handle high Aspect ratios (thin wide conductors).
> > Even a round conductor can start to look like a plane at sufficiently
> > high a frequency in terms of skin depth.
> > Regards,
> >
> > Jim
> >
> >
> > Jim Foppiano
> > Signal Integrity
> > jim_foppiano@dell.com
> > (512)-723-3914
> >
> >
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