RE: Rising/Falling waveform and Ramp keywords

Alan,

50 Ohm is not required only if you make an IBIS1.1 model.
In IBIS version 2.1 and above you can use anything you want,
you just have to specify what you used in the R_fixture and/or
R_load sub-parameters.

Arpad Muranyi
===========================================================

-----Original Message-----
From: Alan Hilton-Nickel [mailto:ahilton@transmeta.com]
Sent: Friday, December 15, 2000 11:20 AM
To: Peters, Stephen
Cc: ibis-users@eda.org
Subject: Re: Rising/Falling waveform and Ramp keywords

"Peters, Stephen" wrote:
> Note that for a standard CMOS buffer the cookbook recomends including four
> waveforms: two rising, one with the buffer driving 50 ohms to VCC and
> another with the buffer driving 50 ohms to gnd, and two falling, same
> conditions. For more info, check out the IBIS cookbook at
>

Stephen,

I am a little uncomfortable with specifying a waveform into a 50 ohm
load, when we tell our customers to use a 60 ohm characteristic
impedance on their board. Would it screw the IBIS modeller up if we gave
a waveform into a 60 ohm load? I would think it would be more
representative (if not more accurate) of what the driver would see in
normal use.

Alan Hilton-Nickel
Transmeta Corp

 
Received on Fri Dec 15 11:37:08 2000