Subject: ibis-users V1 #15
From: owner-ibis-users@ (ibis-users)
To: [email-masked]

ibis-users           Monday, January 6 2003           Volume 01 : Number 015

----------------------------------------------------------------------

Date: Fri, 3 Jan 2003 09:10:08 -0800 
From: "Peters, Stephen" <[email-masked]>
Subject: [IBIS-Users] Agenda, IBIS Open Forum Teleconference 1/10

		     IBIS Open Forum Meeting Agenda
			      for 1/10/03

		 Bridge Number    Reservation #   Passcode
             1-916-356-2663   2               6877145

All meetings are 8:00 AM to 9:55 AM Pacific Time.  When you call into the 
meeting, ask for the IBIS Open Forum hosted by Stephen Peters and give the
Reservation Number and Passcode.

8:00 Check-In, Intros, Announcements                         Peters

     - Intros of New IBIS Participants, Meeting Quorum       Peters
     - Call for Patents                                      Peters
     - Membership Update and Treasurers Report               Peters
     - Review of Previous Meeting's Minutes (and ARs)        Peters
     - Miscellany/Announcements                              All
     - Press & Web Page Updates                              Huq, All
     - New Models Available, Library Update                  Leventhal, All
     - Opens for New Issues                                  All

8:15 Administrative and Project Discussions

     International/External Progress
     - IEC 62014-3 (ICEM) Integrated Circuits Electromagnetic 
       Model Proposal (IEC 93/67/NP IBIS and EMC Simulation) Perrin/Peters

     Election of IBIS Secretary                              Peters

     DesignCon2002 IBIS Summit Meeting Planning              Peters

     DATE2003 European IBIS Summit Meeting Planning          Ross

     IBIS Version 4.0 Parser Funding                         Peters

     IBIS Quality Committee                                  Katz

     IBIS Model Review Committee                             Green

     New Administrative Issues                               All

8:45 Technical Discussion

     IBIS Connector and Futures Group Report                 Peters/Green

     BIRD75.8 - Multi-Lingual IBIS Model Support             Ross/Muranyi
     BIRD77.2 - Differential Subparameter Additions          Ross
                (votes)

     BIRD78.1 - Comment Line Length Limit                    Green
                (vote)

     BIRD80.1 - Add External Reference Column to Pin Mapping   Mirmak
                Keyword

     BIRD81 - Clarify Usage Rule for [Pin] I/O Model         Green/Wang
              Assignment

     ibischk3 Status                                         Ross
     - BUG71 - Monotonic Checking for Combined I-V Tables    Haller
     - BUG74 - Missing Timing Test Load Warning Messages     Haller
     - BUG78 - Clamp Current Double Counting Test            Leventhal/Ross
               (not classified)

     New Technical Issues                                    All

9:50 Wrap Up and Next Meetings Plans                         Peters

9:55 Sign Off

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------------------------------

Date: Fri, 3 Jan 2003 23:51:32 -0800
From: "Hazem Hegazy" <[email-masked]>
Subject: RE: [IBIS-Users] [Fwd: Validation of IBIS model]

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Hi,
I'm not sure of the model quality because of the followings:
- -          The number of point in the rising and falling edges is quit a
few before it reach steady state.
- -          There are Rising to gnd and Falling to VDD only V-T data, I
strongly recommend to have the other two (Rising to VDD and Falling to
ground).
- -          There is C_Fixture = 30p in the V-T data!! This is not
recommended while you generate the IBIS model wave forms, Please
regenerate the V-T tables without these capacitance.
- -          The C_comp value must be calculated and optimized in order to
get complete overlay with SPICE.
 
I think that all of these might be the cause.
One more thing, I noticed also from the validation you sent in this mail
the SPICE simulation reaches 2.7 as a steady state, while the IBIS
simulation reached 2.4 !!
 
BR,

 
Hazem Hegazy, M.Sc.
IBIS Modeling Engineer
QualiM
http://www.qualim.com/
Phone: (+20) 106052154
E-mail: [email-masked]
 
- -----Original Message-----
From: [email-masked]
[mailto:[email-masked]] On Behalf Of Anshuli Goel
Sent: Friday, January 03, 2003 4:48 AM
To: Ingraham, Andrew; [email-masked]
Subject: RE: [IBIS-Users] [Fwd: Validation of IBIS model]

Hi Andy 
Thanx for the reply. That problem was actually because of timestep used
in simulation. I used a finer 
timestep and my problem vanished. 
But I have other problem. I am using the following setup for validating
the IBIS model. I hook up buffer 
subckt once and once i hookup IBIS model with the rest of the setup. 

Hi Andy 
Thanx for the reply. That problem was actually because of timestep used
in simulation. I used a finer 
timestep and my problem vanished. 
But I have other problem. I am using the following setup for validating
the IBIS model. I hook up buffer 
subckt once and once i hookup IBIS model with the rest of the setup. 
  
The load changes from open circuit to matched load to short circiuit. 
I see some ringing in matched load case with IBIS model simulation which
is not captured in SPICE 
simulation . (For open load and short circuit load my results are
matching) 
Why the results at matched load are not matching ? 
The parameters for Tx is Z0=50ohm and Td=0.4ns 
Input has 1ns risetime. 
I am attaching the IBIS model and s2ibis2 script also. 
Waveform with ringing (IBIS simulation) 

Waveform without ringing(SPICE simulation using the subckt) 

Regards 
Anshuli 
Ingraham, Andrew" wrote: 
  The "ringing" that I see with the SPICE model, looks more like some
sort of numerical oscillation that you 
  sometimes get in SPICE, and not real ringing.  This numerical
oscillation is an uncommon but occasional 
  artifact of SPICE.  If present, it can usually be eliminated by using
.OPTION METHOD=GEAR rather 
  than the default TRAPezoidal method. 
  You don't say how long the transmission line is, but it is probably
not causing the sub-nanosecond wiggles 
  that you are seeing on the SPICE model waveform. 
  If it isn't numerical oscillation, another place to look would be the
package parasitic modeling.  Either the 
  IBIS model, or the simulator's use of it, might have simplified the
circuit representation of the package, 
  compared to the SPICE model. 
  Regards, 
  Andy 
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<body lang=3DEN-US link=3Dblue vlink=3Dblue style=3D'tab-interval:.5in'>

<div class=3DSection1>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Hi,<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>I&#8217;m not sure of the model =
quality
because of the followings:<o:p></o:p></span></font></p>

<p class=3DMsoNormal =
style=3D'margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo1;
tab-stops:list .5in'><![if !supportLists]><font size=3D2 color=3Dnavy =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial;mso-fareast-font-family:Arial=
;
color:navy'><span style=3D'mso-list:Ignore'>-<font size=3D1 =
face=3D"Times New Roman"><span
style=3D'font:7.0pt "Times New =
Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
</span></font></span></span></font><![endif]><font size=3D2 color=3Dnavy
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:navy'>The
number of point in the rising and falling edges is quit a few before it =
reach
steady state.<o:p></o:p></span></font></p>

<p class=3DMsoNormal =
style=3D'margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo1;
tab-stops:list .5in'><![if !supportLists]><font size=3D2 color=3Dnavy =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial;mso-fareast-font-family:Arial=
;
color:navy'><span style=3D'mso-list:Ignore'>-<font size=3D1 =
face=3D"Times New Roman"><span
style=3D'font:7.0pt "Times New =
Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
</span></font></span></span></font><![endif]><font size=3D2 color=3Dnavy
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:navy'>There
are Rising to gnd and Falling to VDD only V-T data, I strongly recommend =
to
have the other two (Rising to VDD and Falling to =
ground).<o:p></o:p></span></font></p>

<p class=3DMsoNormal =
style=3D'margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo1;
tab-stops:list .5in'><![if !supportLists]><font size=3D2 color=3Dnavy =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial;mso-fareast-font-family:Arial=
;
color:navy'><span style=3D'mso-list:Ignore'>-<font size=3D1 =
face=3D"Times New Roman"><span
style=3D'font:7.0pt "Times New =
Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
</span></font></span></span></font><![endif]><font size=3D2 color=3Dnavy
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:navy'>There is
C_Fixture =3D 30p in the V-T data!! This is not recommended while you =
generate
the IBIS model wave forms, Please regenerate the V-T tables without =
these
capacitance.<o:p></o:p></span></font></p>

<p class=3DMsoNormal =
style=3D'margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo1;
tab-stops:list .5in'><![if !supportLists]><font size=3D2 color=3Dnavy =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial;mso-fareast-font-family:Arial=
;
color:navy'><span style=3D'mso-list:Ignore'>-<font size=3D1 =
face=3D"Times New Roman"><span
style=3D'font:7.0pt "Times New =
Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
</span></font></span></span></font><![endif]><font size=3D2 color=3Dnavy
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:navy'>The
C_comp value must be calculated and optimized in order to get complete =
overlay
with SPICE.<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>I think that all of these might be =
the
cause.<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>One more thing, I noticed also from =
the
validation you sent in this mail the SPICE simulation reaches 2.7 as a =
steady
state, while the IBIS simulation reached <span class=3DGramE>2.4 =
!!</span><o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>BR,<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<div>

<p class=3DMsoNormal><b style=3D'mso-bidi-font-weight:normal'><font =
size=3D3
color=3Dblue face=3D"Monotype Corsiva"><span =
style=3D'font-size:12.0pt;font-family:
"Monotype =
Corsiva";color:blue;font-weight:bold;mso-bidi-font-weight:normal;
mso-no-proof:yes'>Hazem Hegazy</span></font></b><font color=3Dnavy><span
style=3D'color:navy;mso-no-proof:yes'>, =
M.Sc.<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 color=3Dnavy face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt;color:navy;mso-no-proof:yes'>IBIS Modeling =
Engineer<o:p></o:p></span></font></p>

<p class=3DMsoNormal><b style=3D'mso-bidi-font-weight:normal'><font =
size=3D4
color=3Dred face=3D"Times New Roman"><span =
style=3D'font-size:14.0pt;color:red;
font-weight:bold;mso-bidi-font-weight:normal;mso-no-proof:yes'>QualiM<o:p=
></o:p></span></font></b></p>

<p class=3DMsoNormal><font size=3D3 color=3Dnavy face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt;color:navy;mso-no-proof:yes'><a
href=3D"http://www.qualim.com/">http://www.qualim.com/</a><o:p></o:p></sp=
an></font></p>

<p class=3DMsoNormal><font size=3D3 color=3Dnavy face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt;color:navy;mso-no-proof:yes'>Phone: (+20) =
106052154<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 color=3Dnavy face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt;color:navy;mso-no-proof:yes'>E-mail: <a
href=3D"mailto:[email-masked]">[email-masked]</a><o:p></o:p></span></=
font></p>

</div>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D2 =
face=3DTahoma><span
style=3D'font-size:10.0pt;font-family:Tahoma'>-----Original =
Message-----<br>
<b><span style=3D'font-weight:bold'>From:</span></b>
[email-masked] [mailto:[email-masked]] =
<b><span
style=3D'font-weight:bold'>On Behalf Of </span></b>Anshuli Goel<br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> =
</span></font><st1:date
Month=3D"1" Day=3D"3" Year=3D"2003"><font size=3D2 face=3DTahoma><span =
style=3D'font-size:
 10.0pt;font-family:Tahoma'>Friday, January 03, =
2003</span></font></st1:date><font
size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;font-family:Tahoma'> </span></font><st1:time
Hour=3D"4" Minute=3D"48"><font size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;
 font-family:Tahoma'>4:48 AM</span></font></st1:time><font size=3D2 =
face=3DTahoma><span
style=3D'font-size:10.0pt;font-family:Tahoma'><br>
<b><span style=3D'font-weight:bold'>To:</span></b> Ingraham, Andrew;
[email-masked]<br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> RE: [IBIS-Users] =
[Fwd:
Validation of IBIS model]</span></font></p>

<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'>&nbsp; <br>
Hi Andy <o:p></o:p></span></font></p>

<p style=3D'margin-left:.5in'><font size=3D3 face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt'>Thanx for the reply. That problem was =
actually because
of timestep used in simulation. I used a finer <br>
timestep and my problem vanished. <o:p></o:p></span></font></p>

<p style=3D'margin-left:.5in'><font size=3D3 face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt'>But I have other problem. I am using the =
following
setup for validating the IBIS model. I hook up buffer <br>
subckt once and once i hookup IBIS model with the rest of the setup. =
<o:p></o:p></span></font></p>

<p style=3D'margin-left:.5in'><font size=3D3 face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt'><img border=3D0 width=3D640 height=3D278 =
id=3D"_x0000_i1025"
src=3D"cid:[email-masked]"><br>
&nbsp; <o:p></o:p></span></font></p>

<p style=3D'margin-left:.5in'><font size=3D3 face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt'>Hi Andy <o:p></o:p></span></font></p>

<p style=3D'margin-left:.5in'><font size=3D3 face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt'>Thanx for the reply. That problem was =
actually because
of timestep used in simulation. I used a finer <br>
timestep and my problem vanished. <o:p></o:p></span></font></p>

<p style=3D'margin-left:.5in'><font size=3D3 face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt'>But I have other problem. I am using the =
following
setup for validating the IBIS model. I hook up buffer <br>
subckt once and once i hookup IBIS model with the rest of the setup. =
<br>
&nbsp; <o:p></o:p></span></font></p>

<p style=3D'margin-left:.5in'><font size=3D3 face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt'>The load changes from open circuit to matched =
load to
short circiuit. <br>
I see some ringing in matched load case with IBIS model simulation which =
is not
captured in SPICE <br>
simulation . (For open load and short circuit load my results are =
matching) <br>
Why the results at matched load are not matching ? <br>
The parameters for Tx is Z0=3D50ohm and Td=3D0.4ns <br>
Input has 1ns risetime. <o:p></o:p></span></font></p>

<p style=3D'margin-left:.5in'><font size=3D3 face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt'>I am attaching the IBIS model and s2ibis2 =
script also.
<o:p></o:p></span></font></p>

<p style=3D'margin-left:.5in'><font size=3D3 face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt'>Waveform with ringing (IBIS&nbsp;simulation) =
<o:p></o:p></span></font></p>

<p style=3D'margin-left:.5in'><font size=3D3 face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt'><img border=3D0 width=3D622 height=3D456 =
id=3D"_x0000_i1026"
src=3D"cid:[email-masked]"><o:p></o:p></span></font></p>

<p style=3D'margin-left:.5in'><font size=3D3 face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt'>Waveform without =
ringing(SPICE&nbsp;simulation using
the subckt) <br>
<img border=3D0 width=3D570 height=3D361 id=3D"_x0000_i1027"
src=3D"cid:[email-masked]"><br>
&nbsp; <o:p></o:p></span></font></p>

<p style=3D'margin-left:.5in'><font size=3D3 face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt'>Regards <br>
Anshuli <br>
Ingraham, Andrew&quot; wrote: <o:p></o:p></span></font></p>

<p style=3D'margin-left:.5in'><font size=3D3 face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt'>&nbsp; The &quot;ringing&quot; that I see =
with the
SPICE model, looks more like some sort of numerical oscillation that you =
<br>
&nbsp; sometimes get in SPICE, and not real ringing.&nbsp; This =
numerical
oscillation is an uncommon but occasional <br>
&nbsp; artifact of SPICE.&nbsp; If present, it can usually be eliminated =
by
using .OPTION METHOD=3DGEAR rather <br>
&nbsp; than the default TRAPezoidal method. =
<o:p></o:p></span></font></p>

<p style=3D'margin-left:.5in'><font size=3D3 face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt'>&nbsp; You don't say how long the =
transmission line
is, but it is probably not causing the sub-nanosecond wiggles <br>
&nbsp; that you are seeing on the SPICE model waveform. =
<o:p></o:p></span></font></p>

<p style=3D'margin-left:.5in'><font size=3D3 face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt'>&nbsp; If it isn't numerical oscillation, =
another
place to look would be the package parasitic modeling.&nbsp; Either the =
<br>
&nbsp; IBIS model, or the simulator's use of it, might have simplified =
the
circuit representation of the package, <br>
&nbsp; compared to the SPICE model. <o:p></o:p></span></font></p>

<p style=3D'margin-left:.5in'><font size=3D3 face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt'>&nbsp; Regards, <br>
&nbsp; Andy <o:p></o:p></span></font></p>

<p style=3D'margin-left:.5in'><font size=3D3 face=3D"Times New =
Roman"><span
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------------------------------

Date: Sat, 4 Jan 2003 11:49:12 +0900
From: =?ks_c_5601-1987?B?wMzBvryu?= <[email-masked]>
Subject: [IBIS-Users] modeling ODT(On-Die-Termination) for DDR II 

Hi IBIS users, 

I'm currently modeling an ODT(On-Die-Termination) for DDR II.
It's really confusing me. Forum has an Answer for DDR II ?
How do I/O buffer (receiver mode) Pullup / Pulldown Curve modeled ?
Does anyone has experience in modelling ODT? 

Best Regards, 
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------------------------------

Date: Mon, 06 Jan 2003 13:40:36 +0530
From: Anshuli Goel <[email-masked]>
Subject: [IBIS-Users] Validation of IBIS model

Hello Hazem

Thanx for pointing out these problems with the model . I have a few
questions though ?

1. Why the response at short and open load matching ? (Is it because
there I don't have any load resistance )

2. How do I change the step size of rising and falling waveforms in
s2ibis2 scripts ? (By default it is 0.2ns)

3. How do I take into account of the load which is capacitive in nature
( I had posted this question earlier on this reflector and I got the
answer from ("Mike LaBonte" <[email-masked]>) that for this purpose
I should use the
R_f  V_f  V_f_min  V_f_max  L_f  C_f  R_d  C_d  L_d  etc parameters for
that purpose)

4. I don't understand about the four    waveforms that you have
referred.  Can you point me out to some doc or some thing on that . How
does s2ibis2 generates these 4 waveforms or do I need to do smiulations
in spice and put the waveforms in IBIS. if I do that what is the syntax
in IBIS model for that ?

Regards
Anshuli

Hazem Hegazy wrote:

I'm not sure of the model quality because of the followings:

   -          The number of point in the rising and falling edges is
quit a few before it
     reach steady state.

   -          There are Rising to gnd and Falling to VDD only V-T data,
I strongly recommend
     to have the other two (Rising to VDD and Falling to ground).

   -          There is C_Fixture = 30p in the V-T data!! This is not
recommended while you
     generate the IBIS model wave forms, Please regenerate the V-T
tables without these
     capacitance.

   -          The C_comp value must be calculated and optimized in order
to get complete
     overlay with SPICE.

I think that all of these might be the cause.

One more thing, I noticed also from the validation you sent in this mail
the SPICE
simulation reaches 2.7 as a steady state, while the IBIS simulation
reached 2.4 !!

BR,

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------------------------------

Date: Mon, 06 Jan 2003 18:36:01 +0530
From: Anshuli Goel <[email-masked]>
Subject: Re: [IBIS-Users] Validation of IBIS model

- --------------E2FA72987CA7AE30CF843979
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

Hello Hazem

Sorry for bombarding you with so many mails.
I picked up the data for rising and falling waveform from directly the
files made by s2ibis2 script and now I don't see and ringing. So I guess
the problem that I had was due to bigger timestep. Now I am closely
matching with the results of spice and IBIS model but except one trouble.

IBIS output

SPICE output

If you see at the waveforms the edges of IBIS output is sharper as compared
to spice output. Otherwise the rise time and voltage level is closely
matching . Why I am getting these sharp edges. I still have only 1 Rising
and 1 falling waveform  . So does it have to do something with this ? ???

Thanx for the help .

Regards
Anshuli

Anshuli Goel wrote:

> Hello Hazem
>
> Thanx for pointing out these problems with the model . I have a few
> questions though ?
>
> 1. Why the response at short and open load matching ? (Is it because
> there I don't have any load resistance )
>
> 2. How do I change the step size of rising and falling waveforms in
> s2ibis2 scripts ? (By default it is 0.2ns)
>
> 3. How do I take into account of the load which is capacitive in nature
> ( I had posted this question earlier on this reflector and I got the
> answer from ("Mike LaBonte" <[email-masked]>) that for this purpose
> I should use the
> R_f  V_f  V_f_min  V_f_max  L_f  C_f  R_d  C_d  L_d  etc parameters for
> that purpose)
>
> 4. I don't understand about the four    waveforms that you have
> referred.  Can you point me out to some doc or some thing on that . How
> does s2ibis2 generates these 4 waveforms or do I need to do smiulations
> in spice and put the waveforms in IBIS. if I do that what is the syntax
> in IBIS model for that ?
>
> Regards
> Anshuli
>
> Hazem Hegazy wrote:
>
> I'm not sure of the model quality because of the followings:
>
>    -          The number of point in the rising and falling edges is
> quit a few before it
>      reach steady state.
>
>    -          There are Rising to gnd and Falling to VDD only V-T data,
> I strongly recommend
>      to have the other two (Rising to VDD and Falling to ground).
>
>    -          There is C_Fixture = 30p in the V-T data!! This is not
> recommended while you
>      generate the IBIS model wave forms, Please regenerate the V-T
> tables without these
>      capacitance.
>
>    -          The C_comp value must be calculated and optimized in order
> to get complete
>      overlay with SPICE.
>
> I think that all of these might be the cause.
>
> One more thing, I noticed also from the validation you sent in this mail
> the SPICE
> simulation reaches 2.7 as a steady state, while the IBIS simulation
> reached 2.4 !!
>
> BR,
>
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<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
<html>
Hello Hazem
<p>Sorry for bombarding you with so many mails.
<br>I&nbsp;picked up the data for rising and falling waveform from directly
the files made by s2ibis2 script and now I don't see and ringing. So I
guess the problem that I&nbsp;had was due to bigger timestep. Now I am
closely matching with the results of spice and IBIS model but except one
trouble.
<p>IBIS&nbsp;output
<br><img SRC="cid:[email-masked]" height=504 width=513>
<br>&nbsp;
<p>SPICE&nbsp;output
<br><img SRC="cid:[email-masked]" height=361 width=570>
<br>&nbsp;
<p>If you see at the waveforms the edges of IBIS output is sharper as compared
to spice output. Otherwise the rise time and voltage level is closely matching
. Why I am getting these sharp edges. I still have only 1 Rising and 1
falling waveform&nbsp; . So does it have to do something with this ? ???
<p>Thanx for the help .
<p>Regards
<br>Anshuli
<br>&nbsp;
<p>Anshuli Goel wrote:
<blockquote TYPE=CITE>Hello Hazem
<p>Thanx for pointing out these problems with the model . I have a few
<br>questions though ?
<p>1. Why the response at short and open load matching ? (Is it because
<br>there I don't have any load resistance )
<p>2. How do I change the step size of rising and falling waveforms in
<br>s2ibis2 scripts ? (By default it is 0.2ns)
<p>3. How do I take into account of the load which is capacitive in nature
<br>( I had posted this question earlier on this reflector and I got the
<br>answer from ("Mike LaBonte" &lt;[email-masked]>) that for this
purpose
<br>I should use the
<br>R_f&nbsp; V_f&nbsp; V_f_min&nbsp; V_f_max&nbsp; L_f&nbsp; C_f&nbsp;
R_d&nbsp; C_d&nbsp; L_d&nbsp; etc parameters for
<br>that purpose)
<p>4. I don't understand about the four&nbsp;&nbsp;&nbsp; waveforms that
you have
<br>referred.&nbsp; Can you point me out to some doc or some thing on that
. How
<br>does s2ibis2 generates these 4 waveforms or do I need to do smiulations
<br>in spice and put the waveforms in IBIS. if I do that what is the syntax
<br>in IBIS model for that ?
<p>Regards
<br>Anshuli
<p>Hazem Hegazy wrote:
<p>I'm not sure of the model quality because of the followings:
<p>&nbsp;&nbsp; -&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
The number of point in the rising and falling edges is
<br>quit a few before it
<br>&nbsp;&nbsp;&nbsp;&nbsp; reach steady state.
<p>&nbsp;&nbsp; -&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
There are Rising to gnd and Falling to VDD only V-T data,
<br>I strongly recommend
<br>&nbsp;&nbsp;&nbsp;&nbsp; to have the other two (Rising to VDD and Falling
to ground).
<p>&nbsp;&nbsp; -&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
There is C_Fixture = 30p in the V-T data!! This is not
<br>recommended while you
<br>&nbsp;&nbsp;&nbsp;&nbsp; generate the IBIS model wave forms, Please
regenerate the V-T
<br>tables without these
<br>&nbsp;&nbsp;&nbsp;&nbsp; capacitance.
<p>&nbsp;&nbsp; -&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
The C_comp value must be calculated and optimized in order
<br>to get complete
<br>&nbsp;&nbsp;&nbsp;&nbsp; overlay with SPICE.
<p>I think that all of these might be the cause.
<p>One more thing, I noticed also from the validation you sent in this
mail
<br>the SPICE
<br>simulation reaches 2.7 as a steady state, while the IBIS simulation
<br>reached 2.4 !!
<p>BR,
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