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

Russ (russ@ao.net)
Fri, 5 Sep 1997 09:54:29 -0400 (EDT)


On Thu, 4 Sep 1997, Chris Simon wrote:

> I am looking for a time domain lossy transmission line simulator for
> digital signals with bit rates of 1Gbit/sec and higher. I would like to
> get information on simulators that you have experince with.
>
> The simulator I'm looking for should include all of the following:
> 1. The results can be viewed in the time domain.
> 2. Transmission line models that include series resistance and
> inductance which are functions of frequency to ACCURATELY model skin
> effect. (i.e., a frequency dependent line model that is used to get time
> domain simulation results)
> 3. SPICE CMOS models and/or IBIS type non-linear models can be used
> as drivers and receivers
> 4. Arbitrary driver data patterns can be used (i.e., not limited to
> repetative signals)
>
> There is one other criteria, but I'm not certain that this one is required
> for signals with 150 to 200 pSec rise and fall times. Any opinions?
> 5. Includes the effect of dielectric losses.
>
> I am aware of several products that claim to meet these critria. Upon
> close inspection several of the lossy line models didn't really meet number
> 2. This seems to be the tough one.

Chris,

1. The latest intusoft spice has lossy tline models in which R,L,G, and
C parameters which can be defined as a function of frequency. I would
think Pspice would have this capability, but can't say for sure.
Can't say that I've tried either one for this issue.

2. As far as others, I've test driven ContecSpice way back on an early
version, it did have R vary as a function of frequency, and dielectric
loss (constant as a function of freq), but I believe inductance was
constant.

Fred B. is on this list so perhaps he can comment on this.

3. Professor Dean Neikirk has done some interesting work on a four-stage
ladder model which can easily run on even 2g6 SPICE (!). Check out:

http://weewave.mer.utexas.edu/MED_files/MED_research/Intrcncts/
Skin_Effect_Ldr/MTT_96_skn_ldr.html

4. It would be interesting if someone could provide some good emperical
info on dielectric loss vs. frequency for typical pwb dielectrics.

Russ

(retired S.I. cop)