RE: [IBIS-Users] V/T Window adjustment

Hello Shiv,

A related question - regarding trimming V/T curve dead-times AND
correlating simulations with Spice - was raised by a colleague of yours
on the IBIS reflector on May 14, 2007. His name was 
    Akhilesh Chandra - akhilesh.chandra@st.com

I think the dialog - on the IBIS reflector - with Akhilesh should
contain enough information to answer your question. I suggest you check
the IBIS reflector archives - starting 14 May, which will contain a
record of the dialog with Akilesh. You might want to contact Akilesh
directly.

Regards,
Cary Mandel

-----Original Message-----
From: Shiv Harit MATHUR [mailto:shiv.mathur@st.com] 
Sent: 30 May 2007 05:39
To: rrwolff@micron.com; twesterh@sisoft.com; Mandel, Cary
Cc: ibis-users@eda.org
Subject: Re: [IBIS-Users] V/T Window adjustment

Hello,

Thanks allot for your prompt and very useful suggestions. 

As you said we can trim off V/T curves dead-times, maintaining corner
correlation intact while losing out synchronisation across corners.
Now if i do so, then how can we validate our model ??

Also, does there exist some way to add these trimmed delay values in the
model or the tool for different corners.
I think the dead-time value should be added to the internal delay value
to avoid overclocking.

Regards
Shiv Harit Mathur



rrwolff@micron.com wrote:

>Shiv,
>
>I have modeled similarly fast switching buffers by removing leading 
>"dead" time from the V-t waveforms.  I treat min, typ, and max corners 
>as independent sets of V-t curves.  Make sure to remove the same amount

>of time from all 4 min curves, typ curves, or max curves to maintain 
>the correct timing between the curves to different termination 
>voltages.  I also document in the Notes section of the model the amount

>of time I shift the typ relative to the max and the min relative to the

>max (in case someone wants to match up the spice model to the IBIS
model).
>
>You only show one set of V-t waveforms in the attached JPEG, but 
>assuming that these curves represent the earliest switch times, I would

>trim off approximately the following delay times from the three
corners:
>
>Max: 90ps
>Nom: 175ps
>Min: 350ps
>
>I suggest you submit your model to the IBIS Model Review Committee when

>you are done and ready for a final check.
>
>Regards,
>Randy
>
>Randy Wolff
>SI Modeling Manager
>Signal Integrity R&D Group
>Micron Technology, Inc. 
>
>
>-----Original Message-----
>From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On 
>Behalf Of Shiv Harit MATHUR
>Sent: Tuesday, May 29, 2007 4:14 AM
>To: ibis-users@eda.org; ibis-users@eda.org
>Cc: Shiv Harit MATHUR
>Subject: [IBIS-Users] V/T Window adjustment
>
>Hello Experts,
>
>I am trying to model a buffer whose freq of operation is 1.5Ghz (time 
>period = 666ps).
>While extracting the V/T curve for the buffer we need to take up a 
>window of not less than 800ps to cover all the three waveforms. The 
>buffer delay in MAX,NOM and MIN CORNERS is 130.31ps, 228.44ps and 
>424.08ps respectively.
>
>Please find the snapshot view of the rising output waveform "TXP" of 
>the buffer in three corners, "SB" is the Input data given to the buffer

>(the
>  delay values are almost same for the falling stimuli also)
>
>Now the problem is that if I extract and dump these values in the IBIS 
>model, the model will certainly fail in the worst and typical cases as 
>the bit time is 333ps (< V/T window size). Although it will give a good

>match only if MAX corner is considered.
>
>Can anybody please suggest, what could be done for this case in order 
>to model the behaviour of the buffer correctly in all three corners ?
>
>Regards
>Shiv Harit Mathur
>STMICROELECTRONICS PVT LTD
>INDIA
>
>--
>This message has been scanned for viruses and dangerous content by 
>MailScanner, 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