RE: [IBIS-Users] RE: [IBIS] How to decide on simulation time.

Hello, Shrikant,

Itzahk's suggestion of 1 bit period is good.  I often use 5*Tr_slow, which
is comparable.  With experience, you will learn how long transitions take to
settle.

Use a tool, such as s2ibis3 or ibiscenter or Cadence's Model Integrity, to
extract the tables from the simulation output.  Please note that these tools
do NOT take evenly spaced points, so reducing time to improve sampling is
not necessary.  Once the tables are created, they can be manually truncated
once they have reached DC.  This will be fairly clear, since there will be
large gaps between points in the table.

As Itzhak noted, it is important to check the IBIS model using the IBIS
parser (ibischk4).  To do this, you need to put the buffer model into a
complete IBIS file.  I usually keep a dummy file around; the file has one
component with one pin, and that pin calls the new model.  Then I can simply
insert the model into the file and parse.

Please feel free to submit your finished IBIS file to the IBIS Model Review
Committee http://www.eigroup.org/ibis/support.htm.  This will allow it to be
reviewed by several EDA vendors in their respective tool flows.

Best regards,
Lynne Green


"IBIS training when you need it, where you need it."

Dr. Lynne Green
Green Streak Programs
http://www.greenstreakprograms.com
425-788-0412
lgreen22@mindspring.com




-----Original Message-----
From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf
Of Itzhak Peleg
Sent: Tuesday, March 04, 2008 3:20 AM
To: Shrikant G Kadadevar; ibis-user; ibis
Subject: [IBIS-Users] RE: [IBIS] How to decide on simulation time.

Hello Shrikant

It depends when the rising or falling get to the steady state level (DC
levels). Try to reduce the time to minimum in order to get good sampling of
the curve.

You can start with initial guess of 1*bit_time but if you get error or
warning about mismatch between V(t) and I(v) you will need to rerun and use
longer time.

  

Itzik Peleg, Senior Signal Integrity Engineer Marvell Israel Ltd.

Web site:  http://www.marvell.com
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-----Original Message-----
From: owner-ibis@server.eda.org [mailto:owner-ibis@server.eda.org] On
Behalf Of Shrikant G Kadadevar
Sent: Tuesday, March 04, 2008 11:30 AM
To: ibis-user; ibis
Subject: [IBIS] How to decide on simulation time.

Hello All,

Please can you help me to know, how we come to conclusion on the maximum

simulation time.
Should this value depends on frequency.
Suppose if i have 100MHz frequency buffer what must be maximum 
simulation time.
Should the value be equal to 1/100MHz or  1/(2*100MHz).
Or should it be independent.


Thanking you
Shrikant GK


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