[SI-LIST] Re: Signal crossing Split plane
- From: "Vadim Heyfitch" <heyfitch@xxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Sun, 2 Dec 2007 15:51:24 -0800
Jean Pierre,
how can we be certain that your upcoming measurements are valid/accurate?
How can we all be sure you know how to use a VNA and are skilled in
de-embedding? If your measured data is in disagreement with Simbeor results,
how do we know that the field solver is incorrect - not your measurements?
And if it is the field solver that gives incorrect results, how do we know
that the results are wrong NOT because of your lack of experience with the
particular solver ( i.e., operator error)? (you mentioned 3 days - that's
how long it would take you to become proficient with Simbeor).
While these are tongue-in-cheek questions, they make a point: there are many
ways to mess up measurements as well as many ways to incorrectly setup a
field solver. When there is a disagreement between the measurements and a
solver result, it is just a reason to investigate further - not an
unequivocal condemnation of one or the other.
There is an interesting, relevant app note from Sonnet Software co-authored
with IBM. It considers a case study in which field solver disagreed with the
measurements and two other field solvers (which in turn agreed with the
measurements). After further investigation, it turned out that the on-wafer
calibration approach had a subtle build-in error. The fact that 2 out of 3
solvers confirmed the incorrect measurement did not make it right.
Here is the link:
http://www.sonnetusa.com/support/downloads/publications/0512_IEEE_MW_OnWaferCal_Rautio.pdf
(J. C. Rautio, and R. Groves, "A potentially significant on-wafer
high-frequency measurement calibration error," IEEE Microwave Magazine,
December 2005, pp. 94 - 100.)
Hopefully, when you perform your measurements with the purpose of validating
or debunking Simbeor, you will go into this exercise keeping an open mind.
Hopefully, you will share your analysis with the list even if it bodes well
for Simbeor. ;-)
Best,
Vadim
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On Dec 1, 2007 4:28 PM, Jean-Pierre Maurice <
mauricejeanpierre@xxxxxxxxxxxxxx> wrote:
> Yuriy,
> stop confusing yourself and others with lengthy emails and explanations
> that
> have no proof.
>
> Which of the references you quote in the 40s or any other EM principle
> warrants you to model discontinuities the way you do in your application
> notes? I went through all the examples in your website using the link you
> provided (http://www.simberian.com/AppNotes.php) and realized that you
> don't
> have even one example where you correlated your simulations with
> measurements. Why? Are you hiding something?
>
> At the beginning, Lee advised you to do some measurements. Charles also
> said
> the very thing, but in a rather harder way.
>
> I may disagree with the way Charles pointed this out to you, but there is
> a
> lot of truth in everything he said, especially regarding your models.
> Indeed, the models in your application notes are not correct and also
> misleading, I would say. You make terrible claims about your solver's
> ability to compute complex multilayer geometries and yet provide no
> example
> to make your case solid.
>
> In the case of via-hole modeling; If you have now learned and agree that
> via-holes are not just barrels and pads as you represent them in your
> notes,
> and if you now also agree that you need to be far away with your ports,
> then
> why do you still have these unrealistic models in your application notes?
> You even go as far as posting them in this list. By doing so, you mislead
> the young and unexperienced. You even mislead the users of your solver. If
> you claim that any of the models (multilayer geometries, slots, via,
> planes,
> transmission lines, etc) in your application notes is correct, then show
> us
> how they match with measurement results.
>
> There are also a lot of weakness in the way you explain some fundamental
> issues which do not reflect the 25 years of experience you claim to have.
> Unlike Charles, I will not talk about that openly in this forum. May be
> privately, if you permit me. You even forge explanations to justify your
> solver and models. This is inappropriate.
>
> I am now on holidays. When I get back to work, I would like to evaluate
> your
> solver using some of our multilayer geometries (if you provide me the 3
> day
> evaluation license you promise on your website). As long as I don't see
> any
> good correlation with measurements and your simulation models are also
> weak,
> then there is no way I can believe you.
>
> Chris: I don't think Yuriy is the person to ask questions concerning real
> PCB designs when he can not provide realistic examples in the application
> notes of his own solver. If you don't believe me, use the link given
> above.
> Charles too is a bit impolite, I would say. There are a lot of other well
> respected experts in this forum (Steve, Istvan, Lee, Eric Bogatin etc)
> from
> whom I learn a lot. I think they will give you real answers, not some
> theory
> that does not help.
>
> Best regards
> Jean Pierre
>
>
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