[SI-LIST] Re: Using general purpose computer tools to solve SI problems
- From: "John Thomas" <jthomas@xxxxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Tue, 28 Sep 2004 14:22:10 -0500
Mike,
The reliability field designated spreadsheets as the 4th lie a long time
ago. You're right, though, I should have put that disclaimer in there.
I've made the mistakes and still often receive spreadsheets with them.
I still try to make a point of looking behind the summary cells to see
how the results are derived. The most aggravating, though, is receiving
a spreadsheet that has results manually entered, forcing me to really
dig in to find where the formula resides that gave the result. It can
literally take days on large spreadsheets.
Best regards,
John
-----Original Message-----
From: Mike Brown [mailto:bmgman@xxxxxxxxxx]=20
Sent: Monday, September 27, 2004 9:01 PM
To: John Thomas
Cc: si-list@xxxxxxxxxxxxx
Subject: Re: [SI-LIST] Re: Using general purpose computer tools to solve
SI problems
John,
I'm sure that you have heard the old saw about 3 kind of lies: Lies,
damned lies, and statistics.
Modern science has added a 4th kind of lie : spreadsheets. ;-)
That having been said, I use spreadsheets extensively, with
HSPICE-extracted buffer and trace delays for board-level timing
analysis. Spreadsheets are a great example of a DIGO unless they are
well-constructed and reviewed. DIGO? Data In, Garbage Out. I've been
burned by failure to thoroughly review the design of such a spreadsheet.
Once burned, twice cautious.
Regards
Mike
John Thomas wrote:
> I've performed some simple signal propogation/loading analysis with=20
> Excel and another engineer later reproduced the findings with PSPICE.
> I've also performed a 2D field analysis using the iterative=20
> calculation functionality of Excel. The graphic representation was
nice.
>=20
> A background heavy in reliability engineering has taught me the value=20
> of the spreadsheet as a tool for engineering analysis, starting with=20
> an early version of Lotus 1-2-3 (1985 or so). More recent experience=20
> has pulled on that knowledge to use it heavily in production yield=20
> analysis and machine/process throughput models. Learning the power=20
> tools, especially the analysis package and the VB macro language, has=20
> made Excel my most-used tool.
>=20
> John Thomas
>=20
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx=20
> [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Ray Anderson
> Sent: Monday, September 27, 2004 10:45 AM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Using general purpose computer tools to solve SI=20
> problems
>=20
>=20
> Engineers quite often utilize specialized software to solve=20
> specialized problems in their work. A few general examples of these=20
> tools might be:=3D20 spice simulators, field solvers, model =
generators,=20
> netlist generators etc. The list goes on and on.
>=20
> As has been discussed recently, sometimes more general purpose=20
> computing tools such as spreadsheets can be used to advantage to solve
> engineering problems if applied appropriately. In the example of the=20
> spreadsheet, even though the most common use of the tool is to=20
> automate 'book keeping' functions, beneath the hood lives a powerful=20
> math engine and graphics interface. Quite often those intrinsic=20
> qualities of the tool can be utilized in imaginative ways to solve=20
> engineering problems that would otherwise require specialized software
> that might not be available to the user.
>=20
> The non-availability might be due to the fact that the type of problem
> to be solved is uncommon enough that acquisition of a special tool=20
> isn't cost effective, that a commercial tool is cost prohibitive, or=20
> perhaps that a tool designed to solve some particular problem just=20
> does not exist.
>=20
> I was wondering if list members might share (the concept, not=20
> necessarily the tool) examples of innovative uses of general purpose=20
> computing tools to solve problems that they've either used or seen=20
> used.
>=20
> To start off, I'll volunteer the use of an Excel spreadsheet to=20
> recursively calculate the DC drop on a PCB from the VRM to the core=20
> power pins of a CPU packaged in a BGA package accounting for PCB=20
> cutouts, swiss-cheesing effects of anti-vias etc. There have recently=20
> become available elegant commercial tools that very accurately deal=20
> with this problem, however, in the past the problem of determining=20
> and visualizing these distributed voltage drops accurately (or even
> inaccurately) has been problematic.
>=20
> One other example, although not strictly SI related, is a shareware=20
> application a friend of mine developed called MultiNEC. Based on the=20
> Excel spreadsheet and utilizing the VB macro capability of that tool,=20
> it performs pre and post processing functions for NEC (Numerical=20
> Electromagnetic Code) simulations. It allows antenna geometries to be=20
> defined and then it generates the appropriate input decks for the=20
> simulator. It also analyzes and graphically plots the results from the
> NEC solve engine. Interface from the spreadsheet to the NEC simulator=20
> is seamless. There are many other capabilities integrated as well=20
> which all depend on the spreadsheet framework.
>=20
> I for one, would be interested in learning of other interesting=20
> applications of general purpose computing tools that engineers have=20
> come up with to deal with SI and other engineering problems. If anyone
> actually wants to share a particular tool that would be great, but=20
> just the general knowledge of what has been or can be done may provide
> the impetus for others to develop their own applications.
>=20
>=20
> -Ray Anderson
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