RE: [IBIS-Users] C_Comp

 
Arpad,

Is that true?  I'm not trying to split hairs here, but I'd say that the VI
curves are generated from a Spice model that includes C_Comp effects.
Because the VI curves are derived from a DC sweep, however, the effect of
C_Comp drops out.

The point I'm trying to make - people don't need to "remove" C_Comp from a
Spice model to derive an IBIS model.

Todd.

Todd Westerhoff
High Speed Design Group Manager
Cisco Systems
1414 Massachusetts Ave - Boxboro, MA - 01719
email:twesterh@cisco.com
ph: 978-936-2149
============================================

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-----Original Message-----
From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf
Of Muranyi, Arpad
Sent: Wednesday, March 02, 2005 1:34 AM
To: ibis-users@eda.org
Subject: RE: [IBIS-Users] C_Comp

Lee,

The IBIS model's IV curve which determines its impedance does not include
any C_comp effects.  The Vt curves which are used to turn on and off the IV
curves do include the C_comp effect in their shape, but they do not effect
the DC nature of the IV curves.  Therefore we do need to add a capacitor to
account for the capacitive nature of the drivers (or receivers).  As stated
in another response, this is necessary for getting the correct reflections
in the simulations when a wave hits the model.

Arpad Muranyi
Intel Corporation
------------------------------------------------------------

-----Original Message-----
From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf
Of lee yang
Sent: Tuesday, March 01, 2005 8:58 PM
To: ibis-users@eda.org
Subject: [IBIS-Users] C_Comp

Hi,
Since the C_Comp effect is already embedded in the Spice model, hence, the
generation of IBIS model automatically includes the effect of it. I am
wondering, since the C_Comp effect is already included in the IBIS model,
why do we still need to put it in the IBIS file? Why it is so important?
Thanks a lot.
-Lee

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