RE: Package Parasitics

Kim,

You cannot include the package parasitics in the pullup,
pulldown, and clamp IV curves. The IV curves are DC
characteristics, and there is no way you can describe
AC effects with them, such as inductance, and capacitance.
The best you can do with these is the resistive losses in
the package.

The AC part may be described in the waveforms (Vt curves),
but that is not the best or most correct way to go about it.

Arpad Muranyi
Intel Corporation
=============================================================

-----Original Message-----
From: Kim Helliwell [mailto:khelliwe@acuson.com]
Sent: Tuesday, April 24, 2001 2:46 PM
To: Jay Azurin
Cc: ibis-users@eda.org
Subject: Re: Package Parasitics

Jay Azurin wrote:
>
> Hello,
>
> I am new to the IBIS game so pardon my simplistic question. I would like
> to know the meaning of the values in an IBIS model:
>
> [Package]
>
> |variable typ min max
>
> R_pkg 250m 200m 300m
>
> L_pkg 8nH 5nH 12nH
>
> C_pkg 0.7pF 0.56pF 1.2pF
> |
>
> I have found other models that have these values set to zero:
>
>
> > > > [Package]
> > > > R_pkg 0 0 0
> > > > L_pkg 0 0 0
> > > > C_pkg 0 0 0
>
> Can you explain why these values are used, i.e. why the model would be
> realistic with no package parasitics?
>
> Thanks for your help.
>
> Best regards,
> Jay Azurin
> Motorola NetComm Applications

The package parasitics might be included in the pullup, pulldown, and clamp
curves in some way. While this is permissible (I think), it makes it much
harder to re-use the pullup/pulldown/clamp curves for any other package.
The
whole point of separating these effects is to allow re-use of the curves
with
different package models.

-- 
Kim Helliwell
Senior CAE Engineer
Acuson Corporation
Phone: 650 694 5030  FAX: 650 943 7260