RE: [SI-LIST] : inductance extracted by ansoft SI3D

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From: Jeff Walden ([email protected])
Date: Sat Jul 15 2000 - 08:22:04 PDT

> 1. The inductance extracted by Ansoft SI 3D is partial inductance or
> loop inductance or it depends?

Capacitance & inductance are calculated by Boundary Element Modeling (BEM)
using Multipole Acceleration. They used to describe explicitly as a DC
static solver on their web site. Resistance is calculated by FEM. As far
as the question is concerned ... it depends. The answer is long as it
depends on boundary conditions as well as model configuration.

> 2.For a via through several power and ground planes, does the SI 3D
> consider the effects of those planes when doing the extraction?

For this I believe you need a full wave solver such as their HFSS. Edge
rate (frequency content) & geometry really are the factors. If you edge
rate is slow compared to the geometry, then the complication of an
additional solver MAY not be necessary. But, since we MAY not know all
those rules of thumb & guidelines, take no chances & use a full wave because
you probably do have edge rates which are "fast". Your investment in
understanding a refined full wave solver will be worth it.

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