Subject: Comments on BIRD 28

From: Stephen Peters <[email-masked]>
Date: Fri, 19 May 1995 12:41:43 -0700

Hello Fellow IBISans:

On 5/19 Jon Powell wrote

>Stephen,
>It is unclear to me how one would specify more than one matrix.
>Are you supposed to be able to?
>Perhaps a more detailed example?
>
>jon

     If the question is 'can more than one section in a package
stub description use the matrix subparameter', the answer is yes.
For example, if the pin statement is as follows:

[Pin Number]
A1  L: 1.0n, Len: 0.5 Matrix, Len: 0.7 Matrix, C: 0.5pf
 .
 .
 .
A5  L: 1.0n, Len: 0.4 Matrix, Len: 0.6 Matrix, C: 0.5pf 
 .
 .
 .

You would use the [Model Data]/[End Model Data] keywords as
shown to denote the two matrices.

[Model Data] section 2
 .
 .
 .
[End Model Data] section 2

[Model Data] section 3
 .
 .
 .
[End Model Data] section 3

  If one wants to group a section from a specific group of
pins (package stubs) into their own matrix seperate from others,
it is possible; it's just not done explicitly in the spec.  The
existing matrix definition does contain all the data needed
to create 'sub-matrices' (is that the correct word?) for
specific groups of pins. In one of my previous e-mails I gave the 
following example in which pins 1 and 2 couple, 5, 6 and
7 couple, and 9 and 10 couple.

____
    |-------- Pin1   sig1
    |-------- Pin2   sig2
    |-------- Pin3   GND   (sorry, don't know what happened to pin 4)
    |-------- Pin5   sig5
    |-------- Pin6   sig6
    |-------- Pin7   sig7
    |-------- Pin8   PWR
    |-------- Pin9   sig9
    |-------- Pin10, sig10
____|

  By using the sparce matrix description one can specify explicitly 
which pins effect the other.  From the data in that section's matrix
a user can create individual matrices containing pins 1/2, 5/6/7, 
and pins 9/10.  For Jon's example where each pin on a package
couples to to the two adjacent pins only, the banded matrix 
description fits the data quite nicely.

     I hope this answers the question

       Best Regards,
       Stephen