[SI-LIST] Re: Using general purpose computer tools to solve SI problems

  • From: Mike Brown <bmgman@xxxxxxxxxx>
  • To: jthomas@xxxxxxxxxxx
  • Date: Mon, 27 Sep 2004 21:01:01 -0500

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
> Excel and another engineer later reproduced the findings with PSPICE.
> I've also performed a 2D field analysis using the iterative calculation
> functionality of Excel.  The graphic representation was nice.
> 
> A background heavy in reliability engineering has taught me the value of
> the spreadsheet as a tool for engineering analysis, starting with an
> early version of Lotus 1-2-3 (1985 or so).  More recent experience has
> pulled on that knowledge to use it heavily in production yield analysis
> and machine/process throughput models.  Learning the power tools,
> especially the analysis package and the VB macro language, has made
> Excel my most-used tool.
> 
> John Thomas
> 
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [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
> problems
> 
> 
> Engineers quite often utilize specialized software to solve specialized
> problems in their work. A few general examples of these tools might be:=20
> spice simulators, field solvers, model generators, netlist generators
> etc. The list goes on and on.
> 
> As has been discussed recently, sometimes more general purpose computing
> tools such as spreadsheets can be used to advantage to solve engineering
> problems if applied appropriately. In the example of the spreadsheet,
> even though the most common use of the tool is to automate 'book
> keeping' functions, beneath the hood lives a powerful math engine and
> graphics interface. Quite often those intrinsic qualities of the tool
> can be utilized in imaginative ways to solve engineering problems that
> would otherwise require specialized software that might not be available
> to the user.
> 
> 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
> isn't cost effective, that a commercial tool is cost prohibitive, or
> perhaps that a tool designed to solve some particular problem just does
> not exist.
> 
> I was wondering if list members might share (the concept, not
> necessarily the tool) examples of innovative uses of general purpose
> computing tools to solve problems that  they've either used or seen
> used.
> 
> To start off, I'll volunteer the use of an Excel spreadsheet to
> recursively calculate the DC drop on a PCB from the VRM to the core
> power pins  of a CPU packaged in a BGA package accounting for PCB
> cutouts, swiss-cheesing effects of anti-vias etc. There have recently
> become available elegant commercial tools that very accurately deal with
> this problem, however, in the past  the problem of  determining and
> visualizing these distributed voltage drops accurately (or even
> inaccurately) has been problematic.
> 
> One other example, although not strictly SI related, is a shareware
> application a friend of mine developed called MultiNEC. Based on the
> Excel spreadsheet and utilizing the VB macro capability of that tool, it
> performs pre and post processing functions for NEC (Numerical
> Electromagnetic Code) simulations. It allows antenna geometries to be
> defined and then it generates the appropriate input decks for the
> simulator. It also analyzes and graphically plots the results from the
> NEC solve engine. Interface from the spreadsheet to the NEC simulator is
> seamless. There are many other capabilities integrated as well which all
> depend on the spreadsheet framework.
> 
> I for one, would be interested in learning of other interesting
> applications of general purpose computing tools that engineers have 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 just
> the general knowledge of what has been or can be done may provide the
> impetus for others to develop their own applications.
> 
> 
> -Ray Anderson
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