[SI-LIST] Re: Do you ever measure any of the things you model?
- From: Scott McMorrow <scott@xxxxxxxxxxxxx>
- To: Tom Dagostino <tom@xxxxxxxxxxxxx>
- Date: Fri, 28 Mar 2008 20:54:33 -0400
I'll follow on to what Tom said. Your question is a good one, but maybe
too general. At Teraspeed Consulting, we've spent the last 6 years,
investing much in time, equipment and test vehicles to validate our
models. Fortunately, once a particular modeling method has been
validated, we can then use them to improve our measurement techniques,
with improved RF/Probe launches, waveguide transitions, material
properties information, and de-embedding structures and techniques. As
a bonus, we've had the opportunity to correlate models created through
multiple different field solver methods, and have had measurement
results that match simulation to 40 GHz.
We have a high confidence in the passive device and channel modeling
that we do. We've been able to correlate 3D full-wave electromagnetic
models of MLCC capacitors, RF connectors, and signal connectors to
transient and frequency domain measurements with very high accuracy.
We've spent a good deal of time measuring and understanding material
properties, for better worst case simulation model correlation.
Unfortunately, we find the the "weak link" is often manufacturer's
models of the silicon. We wish that some of our vendors would do a
better job.
Scott
Scott McMorrow
Teraspeed Consulting Group LLC
121 North River Drive
Narragansett, RI 02882
(401) 284-1827 Business
(401) 284-1840 Fax
http://www.teraspeed.com
Teraspeed® is the registered service mark of
Teraspeed Consulting Group LLC
Tom Dagostino wrote:
> Actually that is one of the things we do around here on a lot of projects..
> For example we will run a field solver to get a model of a structure, build
> a board with that structure and then make scope or VNA measurements to
> validate or tweak the model. We have even cross sectioned things to get a
> better understanding about what was going on in the device.
>
> Tom Dagostino
> Teraspeed(R) Labs
> 13610 SW Harness Lane
> Beaverton, OR 97008
> 503-430-1065
> 503-430-1285 FAX
> tom@xxxxxxxxxxxxx
> www.teraspeed.com
>
> Teraspeed Consulting Group LLC
> 121 North River Drive
> Narragansett, RI 02882
> 401-284-1827
>
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
> Behalf Of Ken Cantrell
> Sent: Friday, March 28, 2008 4:10 PM
> To: Max Artusy; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: Do you ever measure any of the things you model?
>
> Perhaps you suspect incorrectly.
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Max Artusy
> Sent: Friday, March 28, 2008 5:32 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Do you ever measure any of the things you model?
>
>
> I notice that you all are most concerned with your model.
>
> Now by the scientific method, you have a hypothetical solution, produced by
> your model.
>
> The next step is to EVALUATE the result.
>
> That is done with a very good scope.
>
> No one ever seems to comment on this, leading me to suspect you only model.
>
> You know they did that with the Hubble space telescope.
>
> That technique produced one of the most expensive service calls in history.
>
> Once modeled, they should have TESTED the thing.
>
> Testing goes hand in hand with modeling, on the assumption that the model is
> incomplete.
>
> No measurement, saves lots of time. Any naive manager just loves to save
> test time.
>
> "Our models are perfect, you know" says he. ( He missed point of Scientific
> method, entirely)
>
> So what kind of scope and what kind of probing technique do you use?
>
> How do you ground your probe setup to the PCB, as a place to start?
>
> How much noise on the ground??
>
> What is the exact construction of the probe interface to the PCB?
>
> This all counts, in high performance probing.
>
>
> Max Artusy
>
>
>
>
>
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