[IBIS] RE: IBIS model of differential driver with programmable multi-tap preemphasis

From: Lance Wang <lwang_at_.....>
Date: Thu Jul 23 2009 - 13:50:59 PDT
Hi, Nitin,
Driver Schedule is a time scheduling function in the simulation. It can be
used for a time scheduling purpose which could contain more than one buffer
turn-rise/fall inside time period it describes. We can use this feature
(different buffers) for different pre-emphasis levels and schedule the time
for them turn-rise/fall. This is the basic concept to use for two tap
pre-emphasis. It should be able to for multi-tap pre-emphasis as well. 

Driver schedule has the limitation for changing pre-emphasis level or bit
width. You will have to change it manually or using different Driver
Schedule settings. So you will need to dig in your application to find out
if it can satisfy your requirement.

Spice macromodeling is the same or almost the same approaches as Arpad's.
Compare to AMS (especially VHDL-AMS). However, it almost totally removes the
simulator dependency as you described in your email. Spice modeling with
IBIS buffers can be used in almost all the big name simulators (HSpice,
Eldo, Cadence's, SiSoft's, Sigrity's, Ansoft's, and many, many more. Sorry
if I did not mention yours.). And many internal Spice simulators can do that
as well. (I will let others tell you.)  And I have to tell you sadly as an
IBIS lover, compare to IBIS Driver Schedule implementation in the Spice
simulator, Macromodling required functions (mainly parameter passing) are
much, much better in these simulators.
This is a huge advantage to your customers. In recent high-speed designs,
many channels still only need to have pre-emphasis driver to open eyes. It
does mean that they can use your chip (model) to design the new product
without extra cost of a new tool.

Hope this helps,

Lance Wang
IO Methodology Inc.

SIMDE™ V1.0 – Signal Integrity Model Development Environment
The complete IBIS / Spice Macromodel generation and validation tool
www.iometh.com/Product/SIMDE


-----Original Message-----
From: Nitin Kumar CHHABRA [mailto:nitin.chhabra@st.com] 
Sent: Thursday, July 23, 2009 1:28 AM
To: 'Lance Wang'; twesterh@sisoft.com; Arpad_Muranyi@mentor.com
Cc: ibis@server.eda.org; si-list@freelists.org; 'Nitin GUPTA'; 'Vishrant
GOYAL'
Subject: RE: IBIS model of differential driver with programmable multi-tap
preemphasis

Hi Arpad,
Thanks for your valuable input. 
You are right that I need the pure analog environment for simulation and so
IBIS-AMI/IBIS-AMS were not taken in account.
Since Input pattern is also unknown I could not use driver-scheduling.
The example approach you gave is exactly what we had followed, only
difference being I used ELDO-2009 for stimulus generation in place of
HSPICE.
But still the relationship of those signals was outside IBIS world and is
simulator dependent. We wanted to make IBIS model which could be used by any
common simulator for analysis.

Inside the IBIS file only, is there any method to cascade different models
i.e. output of one model becomes input to other and so on.

Hi Tod,
This is HDMI transmitter with multilevel tap-pre-emphasis , so IBIS-AMI is
not good solution.


Hi lance,
I am still not sure how to use Driver scheduling in this case. The input
pattern could change and depending on that pattern the required pre-emphasis
level could be activated. Depending on history of previous bits, the
particular level of tap is activated and pre-emphasis strength changes.
Could you please elaborate how to use driver scheduling in that case.
Spice macro-modeling is one of the best approaches for the same and almost
same as what Arpad had explained in his example. 
 

Thanks and regards,
Nitin


-----Original Message-----
From: si-list-bounce@freelists.org [mailto:si-list-bounce@freelists.org] On
Behalf Of Lance Wang
Sent: Wednesday, July 22, 2009 8:49 PM
To: ibis@server.eda.org; si-list@freelists.org
Subject: [SI-LIST] Re: [ibis-macro] IBIS model of drifferential driver with
programmable multi-tap preemphasis

Nitin,
Additional to Arpad's comments:
There is a possibility to use Driver Schedule for multi-tap pre-emphasis
buffer modeling. I did a presentation in 2005 and showed it works for 4 tap
in the presentation below: (page 41)
http://www.vhdl.org/pub/ibis/summits/mar05j/wang.pdf

Also, you could do Spice-macromodeling with IBIS buffer models for
pre-emphasis. The benefits for it are faster and can be used in the most of
Spice simulators. Users will not be requested to cost more for new tools.

http://iometh.com/Product/SIMDE/Macromodeling.pdf
http://www.vhdl.org/pub/ibis/summits/oct06b/wang.pdf

Hope this helps,

Lance Wang
IO Methodology Inc.

SIMDET V1.0 - Signal Integrity Model Development Environment
The complete IBIS / Spice Macromodel generation and validation tool
www.iometh.com/Product/SIMDE



-----Original Message-----
From: si-list-bounce@freelists.org [mailto:si-list-bounce@freelists.org] On
Behalf Of Muranyi, Arpad
Sent: Wednesday, July 22, 2009 10:54 AM
To: ibis@server.eda.org; si-list@freelists.org
Subject: [SI-LIST] Re: [ibis-macro] IBIS model of drifferential driver with
programmable multi-tap preemphasis

Nitin,

If you have access to the stimulus, you could pull this off
with the Driver Schedule or even without it, but that would
be a semi official IBIS solution because it may not work in
all tools.  For example, if you do it with the HSPICE B-element,
you could make a B-element for each stage of your buffer,
and then make a special stimulus generator which reproduces 
the bit pattern dependent waveforms for the input to each
B-element (buffer stage).  This way the stages of your buffer
would still be IBIS models, but the relationship between them
would be outside the IBIS world.

Another way to do it would be to use the *-AMS extensions of
IBIS.  This way you could make a completely official model
for the entire buffer.  However, not all IBIS tools have
implemented the *-AMS extensions of IBIS, although there are
several tools with Verilog-A support which may be sufficient
for what you want to do.

I hope this helps.

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

-----Original Message-----
From: ibis-macro-bounce@freelists.org
[mailto:ibis-macro-bounce@freelists.org] On Behalf Of Nitin Kumar
CHHABRA
Sent: Wednesday, July 22, 2009 7:14 AM
To: ibis@server.eda.org; si-list@freelists.org
Cc: vishrant.goyal@st.com; nitin.chhabra@st.com; nitin.gupta@st.com
Subject: [ibis-macro] IBIS model of drifferential driver with
programmable multi-tap preemphasis

Hi experts,

We want to develop  the IBIS model for a differential driver with pre 
emphasis .
The driver has three tap with programmable pre emphasis options.

Does anyone came across such IBIS or could provide some IDEA how to 
proceed for the same.
Using Driver Scheduling, we are able to make model for first tap pre 
emphasis  buffer.
But we cannot accommodate the second  and third tap  options as they 
require previous bit histories.

with regards,
Nitin
 



---------------------------------------------------------------------
IBIS Macro website  :  http://www.eda.org/pub/ibis/macromodel_wip/
IBIS Macro reflector:  http://www.freelists.org/list/ibis-macro
To unsubscribe send an email:
  To: ibis-macro-request@freelists.org
  Subject: unsubscribe

------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@freelists.org with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@freelists.org with 'help' in the Subject field


List technical documents are available at:
                http://www.si-list.net

List archives are viewable at:     
		http://www.freelists.org/archives/si-list
or at our remote archives:
		http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
 		http://www.qsl.net/wb6tpu
  


------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@freelists.org with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@freelists.org with 'help' in the Subject field


List technical documents are available at:
                http://www.si-list.net

List archives are viewable at:     
		http://www.freelists.org/archives/si-list
or at our remote archives:
		http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
 		http://www.qsl.net/wb6tpu
  





-- 
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
Received on Thu Jul 23 13:55:07 2009

This archive was generated by hypermail 2.1.8 : Thu Jul 23 2009 - 13:55:55 PDT