[SI-LIST] Re: Do you ever measure any of the things you model?

  • From: "Tom Dagostino" <tom@xxxxxxxxxxxxx>
  • To: "'Ken Cantrell'" <Ken.Cantrell@xxxxxxxxxxxxxxxx>, "'Max Artusy'" <max5461@xxxxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
  • Date: Fri, 28 Mar 2008 16:50:11 -0700

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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