[ibis-macro] Re: Suggestion for a new macro library element

  • From: Bob Ross <bob@xxxxxxxxxxxxx>
  • To: kwillis@xxxxxxxxxxx
  • Date: Sun, 05 Feb 2006 15:16:20 -0800

Hi:

I support the concept of scaling, especially for all I-V tables
because the tables are referenced to specified voltages in
a manner that corresponds to physical scaling of strengths.

If V-T scaling is used, it should be scaled by a first order
linear equation y = ax + b to add tranlation so that the
time response is scaled with respect to a proper start of
transition time.

I like and have also used scaling.  However, there are some
technical implications and unexpected interactions, some of
which I will mention at the IBIS Summit.

Bob

Ken Willis wrote:

Hi,

We use the VI scaling quite a bit in our SPICE-based behavioral
MacroModeling,
and have found it very useful.

Ken 

-----Original Message-----
From: ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Muranyi, Arpad
Sent: Thursday, February 02, 2006 12:05 PM
To: ibis-macro@xxxxxxxxxxxxx
Subject: [ibis-macro] Re: Suggestion for a new macro library element

Hello everyone,

Paul's question raises another thought in my mind.
We talked about adding scaling coefficients to the IBIS buffer building
blocks in the macro model library a long time ago.  In the heat of
discussing bugs with with the vendors and trying find solutions for them
I completely forgot about them in my coding.

Paul question reminded me to this discussion and as far as I remember we
said way back when that we should implement static scaling coefficients
for the I-V curves to be able to scale the buffer strength, and perhaps
another static coefficient to scale the time axis of the V-t curves to
be able to scale the edge rate of the buffer.

This would be relatively easy to implement, but before I did anything I
would like to confirm once more whether I should do it.  Please comment.

I would also like to encourage everyone to respond to Paul's question.
An element like that can be added easily.  The question in my mind is
whether it is viewed as a practical addition, and whether substitution
for SPICE-only vendors is an issue or not.  (I believe they could use a
subcircuit to contain the 8 sources).

Thanks,

Arpad
==========================================================

-----Original Message-----
From: ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Paul Fernando
Sent: Wednesday, February 01, 2006 3:31 PM
To: ibis-macro@xxxxxxxxxxxxx
Subject: [ibis-macro] Suggestion for a new macro library element

Right now scaling is done by instancing 8 current sources in each
template, for each buffer that is scaled. For example, when modeling a
4-tap pre-emphasis bufer, 3*8 current sources must be instanced.
I suggest we lump them (the 8 current sources) into a macro library
element.
Looking forward to your feedback.

Regards,
Paul

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Bob Ross
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