Re: [SI-LIST] : skin effect and transmission line simulators

J. Eric Bracken (bracken@ansoft.com)
Thu, 04 Sep 1997 15:55:11 -0400

Hi,

The new release (3.0) of Maxwell 2D Extractor from Ansoft can do what
you want. It's currently in beta.

We analyze the frequency dependence of resistance and inductance
using a full finite element model of the conductor cross-section.
This lets us compute the actual current distribution within the
wires, and how it changes with frequency.

The frequency sweep is done using AWE-like acceleration techniques,
so it's much faster than doing one frequency point at a time.

We can create Spice models that represent the frequency dependence
of R and L. These models can be analyzed in the time or frequency domain,
with nonlinear transistor-level driver and receiver models, in our
Spice or your own. Of course, you can excite with any kind of
waveform you choose--periodic or not.

This type of modeling handles dispersion, attenuation, and the
effects of skin effect losses on crosstalk; you can also model the
skin effect in your ground plane as well as in your signal line.

Regards,

--Eric Bracken

>>>>> "Chris" == Chris Simon <simon@mcc.com> writes:

Chris> I am looking for a time domain lossy transmission line
Chris> simulator for digital signals with bit rates of 1Gbit/sec
Chris> and higher. I would like to get information on simulators
Chris> that you have experince with.

Chris> The simulator I'm looking for should include all of the
Chris> following: 1. The results can be viewed in the time
Chris> domain. 2. Transmission line models that include series
Chris> resistance and inductance which are functions of frequency
Chris> to ACCURATELY model skin effect. (i.e., a frequency
Chris> dependent line model that is used to get time domain
Chris> simulation results) 3. SPICE CMOS models and/or IBIS type
Chris> non-linear models can be used as drivers and receivers 4.
Chris> Arbitrary driver data patterns can be used (i.e., not
Chris> limited to repetative signals)

Chris> There is one other criteria, but I'm not certain that this
Chris> one is required for signals with 150 to 200 pSec rise and
Chris> fall times. Any opinions? 5. Includes the effect of
Chris> dielectric losses.

Chris> I am aware of several products that claim to meet these
Chris> critria. Upon close inspection several of the lossy line
Chris> models didn't really meet number 2. This seems to be the
Chris> tough one. I am going to take a detailed look at Microwave
Chris> Design System (MDS) from Hewlett-Packard, although someone
Chris> told me that the current version doesn't meet number 3
Chris> above. I would be interested in hearing which of the above
Chris> criteria are met by other tools, or whether a future
Chris> revision will incorporate these features. If you know how
Chris> the following tools stack up, especially with regard to
Chris> number 2, I would appreciate hearing from you. Quad
Chris> Design, Quantic, Interconnectix/Mentor Graphics, Pacific
Chris> Numerix, Cadence SigNoise, ApSim/Contec, EMC-workbench,
Chris> others?

Chris> Chris Simon

--
J. Eric Bracken, Ph.D.                          Tel: 1.412.261.3200 x135
Group Leader, Signal Integrity R&D              Fax: 1.412.471.9427
Ansoft Corp., Four Station Square, Suite 660    bracken@ansoft.com
Pittsburgh, PA USA 15219-1119                   http://www.ansoft.com