Subject: Re: accuracy BIRD

From: Syed Huq <[email-masked]>
Date: Fri, 12 Mar 1999 16:00:33 -0800 (PST)

Hi,

Since the V/T tables allow keywords such as C_dut, R_dut, L_dut, doesn't
that imply that it DOES use the package numbers. I am a bit confused about
Stephen's statement below regarding old VT tables..

Syed.
Cisco Systems, Inc

> 
> On the question of "golden waveforms" vs. "regular old VT tables," Stephen
> Peters mentioned that there is a difference between the two.  Golden
> waveforms have the package while regular old VT tables do not.  Is there
> any syntactical construct within IBIS to differentiate between the two?
> Care to embellish here, Stephen?
> 
> Thanks all.
> 
> Greg
> 
> 
>

---

From: Stephen Peters <[email-masked]>
Date: Mon, 15 Mar 1999 09:54:07 -0800

Hello Syed, Greg:

  Sorry for the delayed response -- I was out of the office back week and
am just now getting back to my mail.  To elaborate:  I was trying to make
a distinction between at V/T table that is created by an output driving a
pure, non-reactive impedance, and a V/T table created with the output driving
a more complex load.  The *former* V/T table contains the data the simulator
needs/uses when building the output model.  Specifically, it describes how
the pullup and pulldown transistor turn on/off, and does not -- indeed, should
not -- contain any extra time constants due to reactive elements.   In the
latter case (complex, reactive impedences) the inclusion of these waveforms
is a check.  Given the model that was build with the first V/T tables, the 
question is can the simulator produce the waveform of the second case.

Hope this helps clarify things.

 Regards,
 Stephen Peters
 Intel Corp.