RE: [IBIS-Users] C_Comp

Tom,

I think we are both correct.  It just depends on what we
mean by our words.  Does "include C_comp effect" mean
included in the chip from which the measurement is
made, or included in the data that you get in the
measurement?  You are probably talking about the first,
while I was talking about the second.

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

-----Original Message-----
From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf Of Todd Westerhoff (twesterh)
Sent: Wednesday, March 02, 2005 4:02 AM
To: ibis-users@eda.org
Subject: 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
============================================

"Always do right.
 This will gratify some people and astonish the rest."

- Mark Twain


-----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

_________________________________________________________________
Get an advanced look at the new version of MSN Messenger. 
http://messenger.msn.com.my/Beta/Default.aspx

|------------------------------------------------------------------
|For help or to subscribe/unsubscribe, email majordomo@eda.org with just

|the appropriate command message(s) in the body:
|
|  help
|  subscribe   ibis       <optional e-mail address, if different>
|  subscribe   ibis-users <optional e-mail address, if different>
|  unsubscribe ibis       <optional e-mail address, if different>
|  unsubscribe ibis-users <optional e-mail address, if different>
|
|or email a written request to ibis-request@eda.org.
|
|IBIS reflector archives exist under:
|
|  http://www.eda.org/pub/ibis/email_archive/  Recent 
| http://www.eda.org/pub/ibis/users_archive/  Recent
|  http://www.eda.org/pub/ibis/email/          E-mail since 1993

|------------------------------------------------------------------
|For help or to subscribe/unsubscribe, email majordomo@eda.org with just 
|the appropriate command message(s) in the body:
|
|  help
|  subscribe   ibis       <optional e-mail address, if different>
|  subscribe   ibis-users <optional e-mail address, if different>
|  unsubscribe ibis       <optional e-mail address, if different>
|  unsubscribe ibis-users <optional e-mail address, if different>
|
|or email a written request to ibis-request@eda.org.
|
|IBIS reflector archives exist under:
|
|  http://www.eda.org/pub/ibis/email_archive/  Recent  
| http://www.eda.org/pub/ibis/users_archive/  Recent
|  http://www.eda.org/pub/ibis/email/          E-mail since 1993
|------------------------------------------------------------------
|For help or to subscribe/unsubscribe, email majordomo@eda.org
|with just the appropriate command message(s) in the body:
|
|  help
|  subscribe   ibis       <optional e-mail address, if different>
|  subscribe   ibis-users <optional e-mail address, if different>
|  unsubscribe ibis       <optional e-mail address, if different>
|  unsubscribe ibis-users <optional e-mail address, if different>
|
|or email a written request to ibis-request@eda.org.
|
|IBIS reflector archives exist under:
|
|  http://www.eda.org/pub/ibis/email_archive/  Recent
|  http://www.eda.org/pub/ibis/users_archive/  Recent
|  http://www.eda.org/pub/ibis/email/          E-mail since 1993

|------------------------------------------------------------------
|For help or to subscribe/unsubscribe, email majordomo@eda.org
|with just the appropriate command message(s) in the body:
|
|  help
|  subscribe   ibis       <optional e-mail address, if different>
|  subscribe   ibis-users <optional e-mail address, if different>
|  unsubscribe ibis       <optional e-mail address, if different>
|  unsubscribe ibis-users <optional e-mail address, if different>
|
|or email a written request to ibis-request@eda.org.
|
|IBIS reflector archives exist under:
|
|  http://www.eda.org/pub/ibis/email_archive/  Recent
|  http://www.eda.org/pub/ibis/users_archive/  Recent
|  http://www.eda.org/pub/ibis/email/          E-mail since 1993