RE: [IBIS] RE: [IBIS-Users] V-T different durations

Thank you Lance, particularly for the 2nd point;

Thank you Tim, to inform me about the potential over-clocking problem;

Thank you all for your useful answers.

Regards,
Fabio

From: owner-ibis@eda.org [mailto:owner-ibis@eda.org] On Behalf Of Lance Wang
Sent: Friday, July 08, 2011 8:55 PM
To: ibis@eda.org
Subject: [IBIS] RE: [IBIS-Users] V-T different durations

Hi, Fabio,
I think 3 important things need to be kept in mind when you generate IBIS buffer model V-T curves:

1. Starting time point: simulators do differently if you have different time value at starting point for different V-T curves. To prevent it, always use the same time Zero point for all V-T curves, at least for the pair (rising/falling) using the same load conditions;

2. The end time point: As Tim pointed out, the most of simulators can handle it correctly when the end points are different. The most important thing for the end points is to have it stabled. The simulators will do the different things if the simulators need to guess what it is after that.

3. Have the enough points among transition period. This will give a lot of better simulation results compared with using the even-spacing points in V-T curves. (it is what S2ibis produces.)

Hope this helps,

Lance Wang

SimDE(tm) IBIS Validator - Make sure it runs accurately. FREE!
www.iometh.com/Product/IBISValidator<http://www.iometh.com/Product/IBISValidator>

From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf Of Graham Kus
Sent: Friday, July 08, 2011 1:52 PM
To: 'Fabio BRINA'; 'ibis-users'
Subject: RE: [IBIS-Users] V-T different durations

Hi Fabio,
One thing to keep in mind is that S2IBIS defaults to a transient time of 10ns. So you will need to add the keyword to your s2ibis file to lengthen this time to accommodate the longest transient time to prevent data truncation.

Regards,
-Graham

Link:
http://www.ece.ncsu.edu/erl/abstracts/s2ibis2_doc.html
[Sim time] t
        t = Spice transient simulation time
        Optional.
        Default: t = 10ns.
       Describes the transient simulation time to be used by Spice.

From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf Of Timothy Coyle
Sent: Friday, July 08, 2011 11:02 AM
To: 'Fabio BRINA'; 'ibis-users'
Subject: RE: [IBIS-Users] V-T different durations

Hi Fabio,
I asked this same question a few months ago and from what I recall the responses were that most modern EDA tools can properly account for the different VT length durations and it is not an IBIS spec violation. I was concerned with potential over-clocking situations based upon the different VT duration lengths. I have not done any follow up testing myself.

I have run into issues with some EDA tools that in certain situations do have problems with these types of models. So you may want to do some testing at least with one EDA tool to make sure it's not going to produce unexpected results.

Best,

Tim

From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf Of Fabio BRINA
Sent: Friday, July 08, 2011 10:24 AM
To: 'ibis-users'
Subject: [IBIS-Users] V-T different durations

Hello experts,

  a simply question (I suppose!) :

   Can I have different durations for the four V-T waveforms ?

   Till today I generated Rising0, Rising1, Falling0, Falling0 curves
    using the same durations, but Can I have the following situations:
    Rising0 --> 12 ns duration
    Rising1 --> 10ns duration
   Falling0 --> 8ns duration
    Falling1 --> 11ns duration

   Standard does not preclude it, but can cause problems to user?

 Thank you in advance.

Fabio

--
This message has been scanned for viruses and
dangerous content by MailScanner<http://www.mailscanner.info/>, and is
believed to be clean.
--
This message has been scanned for viruses and
dangerous content by MailScanner<http://www.mailscanner.info/>, and is
believed to be clean.
Conexant E-mail Firewall (Conexant.Com) made the following annotations
---------------------------------------------------------------------
********************** Legal Disclaimer ****************************
"This email may contain confidential and privileged material for the sole use of the intended recipient. Any unauthorized review, use or distribution by others is strictly prohibited. If you have received the message in error, please advise the sender by reply email and delete the message. Thank you."
**********************************************************************
---------------------------------------------------------------------
--
This message has been scanned for viruses and
dangerous content by MailScanner<http://www.mailscanner.info/>, and is
believed to be clean.
--
This message has been scanned for viruses and
dangerous content by MailScanner<http://www.mailscanner.info/>, and is
believed to be clean.
-- 
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.
--------------------------------------------------------------------
|For help or to subscribe/unsubscribe, e-mail majordomo@eda-stds.org
|with 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 e-mail a request to ibis-request@eda-stds.org.
|
|IBIS reflector archives exist under:
|
|  http://www.eda-stds.org/pub/ibis/email_archive/ Recent
|  http://www.eda-stds.org/pub/ibis/users_archive/ Recent
|  http://www.eda-stds.org/pub/ibis/email/         E-mail since 1993