RE: [SI-LIST] : Linpar 2-D field solver experiences?

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From: Larry Miller (ldmiller@nortelnetworks.com)
Date: Thu Nov 30 2000 - 12:03:57 PST


***WHERE*** do you get Linpar, please? The only references I find are to a
1992 book/disk package with a DOS version.

I would really appreciate a pointer to where I can get it from someone!

Thanks,

Larry Miller

> -----Original Message-----
> From: MikonCons@aol.com [SMTP:MikonCons@aol.com]
> Sent: Thursday, November 30, 2000 10:47 AM
> To: si-list@silab.eng.sun.com
> Subject: Re: [SI-LIST] : Linpar 2-D field solver experiences?
>
> In a message dated 11/21/00 9:58:22 PM Pacific Standard Time,
> chengson@juniper.net writes:
>
>
>
>
>
> Has anybody used the Linpar CAD 2-D field solver?
> I've used ansoft, CALIF, Greenfield, Pacific Numerix,
> and have recently come across Linpar.
>
> Linpar seems to be a very easy to use CAD tool, and
> seems very cost effective (sub $500) for a general
> purpose 2-D field solving tool for simulating impedance
> and crosstalk.
>
>
>
>
>
>
>
> Dave:
>
> I have not tried the latest Windows version of LINPAR, but I have used
> MSDOS
> versions of both LINPAR and its companion program LINRES for almost a
> decade
> with very positive results/success. I also have used Agilent's APPCAD,
> Polar's CITS25, and UltraCAD's T-Line Calculator. Relative to the real
> world
> (i.e., documented by measurement on known physical layups), LINPAR has
> been
> one of the best.
>
> A MAJOR ADVANTAGE of LINPAR over the other free (or low cost) programs is
> that it can address multiple traces, including different sizes,
> simultaneously. Because of the coupling of adjacent traces in today's
> densely
> routed boards, the individual trace loading and crosstalk is important to
> all
> SI engineers. Most pay an arm and a leg for CAD programs that (rightly)
> address this issue, but their accuracy (as you might have noticed) has
> often
> been questioned in this SI forum.
>
> The (purely text) output is in the form of L-R-C-G matrices, as well as Er
>
> (effective), propagation speed, and individual trace impedances. For
> crosstalk and waveform simulations, these matrices must then be imported
> into
> the LINRES program, sources and loads defined and saved into additional
> files, and then run. The simulation plots from LINRES are very basic, but
> I
> have compared the results with HSPICE W-element simulations and FOUND
> NEGLIGIBLE DIFFERENCE (except in the HORRENDOUS difference in price).
>
> However, LINPAR/LINRES (MSDOS) has definite limitations. The ease of use
> is
> cumbersome to execute several combinations of trace widths, trace spaces,
> dielectric thicknesses, Er values, etceteras. Because of the original
> MSDOS
> program size limitations (from a decade ago), more complex structures are
> limited in size. And, with today's thin dielectrics, stripline trace
> thickness and shape has an impact on the impedances and crosstalk that is
> not
> accounted for (infinitely thin traces are the default for stripline),
> unless
> you draw a full 2D picture of the configuration. This latter approach is
> cumbersome and time consuming, but can be done. The infinitely thin traces
>
> yield higher (~5%) Zo predictions than reality unless the dielectric
> thickness is >5 x trace thickness. However, microstrip trace thicknesses
> ARE
> accounted for.
>
> NOTE: The newer Windows version of LINPAR may have corrected all of the
> above
> negatives/limitations. Further comments from any who have tried it are
> kindly
> solicited.
>
> Dave, if you have received other responses NOT sent to the SI List, could
> you
> summarize them and post them?
>
> Mike
> Michael L. Conn
> Owner/Principal Consultant
> Mikon Consulting
> (408)727-5697
>
> *** Serving Your Needs with Technical Excellence ***

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