RE: [IBIS-Users] ibschk- warnings

From: Mirmak, Michael <michael.mirmak_at_.....>
Date: Thu Jan 25 2007 - 08:38:11 PST
Sujit,
 
As mentioned by others here, the errors are due to mismatches between
your V-t table settling voltages and your I-V tables.  The V-t appears
"settled" to stable DC voltages, so the duration of your V-t tables may
not be the problem; other factors may be causing the mismatch.
 
One concern: your [Rising Waveform] and [Falling Waveform] use different
load resistances.  One set uses 50 ohms, while the other uses 500.  This
is not a problem in itself, but the V-t tables should usually be
generated into a load resistance roughly equivalent to the target system
transmission line impedance.  Is there a reason for using two different
load resistances?  The tables also only cover the cases of the pulldown
transistors turning on or the pullup transistors turning on; the
"turning off" cases are not covered (Rising only uses a 0V fixture,
while Falling only uses Vcc as a fixture).  "Turning off" cases can be
valuable in simulation.
 
Another concern, looking at the [Pulldown] table, is that it appears to
"double-count" power clamp effects shown in the [POWER Clamp] table.
 
You are also using S2IBIS2, which has since been upgraded to S2IBIS3.
The updated version may address clamp double-counting and prevent this
and other issues.
 
- Michael Mirmak
  Intel Corp.
  Chair, EIA IBIS Open Forum

________________________________

From: owner-ibis-users@server.eda.org
[mailto:owner-ibis-users@server.eda.org] On Behalf Of Sujit Kumar-r65837
Sent: Thursday, January 25, 2007 05:58
To: ibis-users@server.eda.org
Subject: [IBIS-Users] ibschk- warnings


hi ibis experts
ibschk run on an ibis generates following warnings:

i have following queries:
>  what could be the possible reason for such warnings ? 
>  as  file is passing throgh ibschk, so can i neglect the above
warnings ?

pls suggest.
.s2i and ibs file are attached for reference.



-- 

thanks
sujit kumar




+91-120-4396069
+91-09910168788 

<mailto:sujit@freescale.com> 


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Received on Thu Jan 25 08:38:39 2007

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