Re: Enhanced Package Models

IBISens:

I have a major concern regarding PCB type description of packages.

1) A PCB description is open ended. i.e. it is not a parameterized model.
In that
sense it cannot be a conventional model.

2)If a "standard" PCB description is desired for Package model, it becomes a problem of
  a. Making sure companies support "standard" description like EDIF
  b. Make sure standards like EDIF can include IBIS buffer descriptions.

  In this case there is no "modelling" work need to be done by the IBIS
 committee and the problem becomes one of acceptence standards like EDIF by
  CAD companies.

>
> Hello Fellow IBISans:
>
> I have been tossing around ideas for enhancing package model
> descriptions by describing package pins as a series of transmission
> lines. In some cases a package modeled as a series of uncoupled transmission
> lines is adequate, in others a series of coupled transmission lines
> is required. I was thinking about enhancing the existing '.pkg'
> description to include both pin length info and the idea of each
> 'pin' (package stub) as having different sections. I've also spoken
> with Kellee Crisafulli at Hyperlynx about this and he has offered the
> idea of describing the package at a physical level using some sort of
> a PCB like description. His points in brief:
>
> 1. Simulator companies support coupled transmission line simulation
> by reading in PCB information. By treating the package as a
> 'PCB' we have a 'natural' way of getting package info into a simulator.
> 2. With this enhancement IBIS could then handle things like SIM modules,
> MCMs, etc.
>
> Some problems/questions:
> 1. Do we have to create a standard 'PCB' like description? There is an EDIF PCB
> standard, but does anybody support it? What would it take
> to create our own?
> 2. Getting CAD companies to output such a format (There is
> a company called Router Solutions whose business is to write reader/
> writers from any format to another).
> 3. Presently, packages are usually described in a purely mechanical
> way without the required dielectric info, layer stack up, etc.
> How can the user get this mechanical info into our description.
> 4. Are there possible proprietary issues involved with giving out
> physical package (construction) info?
>
>
> An alternative method is to supply the user with the electrical
> information only. For simple packages that can be represented by
> a series of uncoupled transmission lines it's a relatively
> straight forward, simple enhancement to the '.pkg' description. For
> coupled transmission lines it's a more complicated matrix style
> description, but doable. Points in brief:
>
> 1. It's a 'behavioral' description, which is consistent with what IBIS
> is all about.
>
> 2. For the matrix description there are several ways of extracting
> and presenting the coefficients in the matrix. The forum will have
> to decide on a consistent methodology.
>
> 3. For well behaved packages (i.e. ones that can be described with
> uncoupled transmission lines) a direct description for each
> pin would be simple and quick to implement, and for simulator
> companies to use.
>
>
> Of course, we can do both, or some combination of the two. I'd like
> to discuss this more at the meeting tomorrow, with an eye towards getting
> somthing concrete going.
>
> Best Regards,
> Stephen Peters
> Intel Corp.
>
>
>
>
Received on Fri Apr 7 08:45:02 1995