RE: [IBIS-Users] problem with the rising and falling waveforms

Lets try some simple evaluation first.

1,  Have you done any analysis of your tables? Have you plotted the VT and
IV curves?  Do they look reasonable? Do you know what reasonable is for this
buffer? Do the transitions complete?  Is there sufficient number of points
in all curves?  Are the IV curves what you expect?  If the buffer is a CMOS
totem pole does the pullup have zero current at Vdd?  Do you have reasonable
clamp curves?

2, do you find it funny that you have a buffer that has a 3.6 volt supply (I
assume that because your termination voltage V_fixtrue_max is usually Vdd)
but your IV curve load line is predicting 4.4V?

3, Is your setup for simulation correct?  Do you have the proper supplies to
the proper nodes?





Tom Dagostino
Teraspeed Labs
13610 SW Harness Lane
Beaverton, OR 97008
503-430-1065
http://www.teraspeed.com
tom@teraspeed.com

Teraspeed Consulting Group LLC
121 North River Drive
Narragansett, RI 02882
401-284-1827

Teraspeed is the registered service mark of
Teraspeed Consulting Group LLC

-----Original Message-----
From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org]On
Behalf Of lgreen
Sent: Friday, May 20, 2005 10:51 AM
To: 'Vivek Kumar Sundriyal'; ibis-users@eda.org;
owner-ibis-users@eda.org
Subject: RE: [IBIS-Users] problem with the rising and falling waveforms


Hi, Vivek,

Two items:
1) The V-t curves should have "zero slope" at both ends.
2) There I-V tables need a small enough step size so the linear
interpolation is accurate where the load line crosses.
Either (or both) of those could cause the parser report that you are seeing.
Drawing a load line on the I-V table can help identify the problem.

Another thought: Is 100 Ohms the usual transmission line impedance for
designs using this device?  Is this same resistance used for the [Ramp]
section?

Best regards,
Lynne


"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 Vivek Kumar Sundriyal
Sent: Friday, May 20, 2005 3:22 AM
To: ibis-users@eda.org; owner-ibis-users@eda.org
Subject: [IBIS-Users] problem with the rising and falling waveforms


Hi  ,

On running the IBISCHK4 on a generated IBIS model, I get the following error
:

ERROR - Model K3B07LG24Q7_QQ60: The [Rising Waveform]
      with [R_fixture]=100 Ohms and [V_fixture_max]=0V
      has MAX column DC endpoints of  0.00V and  3.46v, but
      an equivalent load applied to the model's I-V tables yields
      different voltages ( 0.00V and  4.23V),
      a difference of  0.03% and 18.33%, respectively.
ERROR - Model K3B07LG24Q7_QQ60: The [Rising Waveform]
      with [R_fixture]=100 Ohms and [V_fixture_max]=3.6V
      has MAX column DC endpoints of  0.11V and  3.60v, but
      an equivalent load applied to the model's I-V tables yields
      different voltages ( 0.11V and  4.40V),
      a difference of  0.04% and 18.69%, respectively.


Can anyone guide me on the cause of this error ? And how can I get over with
it ?

Thanks ,

Vivek



|------------------------------------------------------------------
|For help or to subscribe/unsubscribe, email majordomo@eda.org with just
|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 email a written request to ibis-request@eda.org.
|
|IBIS reflector archives exist under:
|
|  http://www.eda.org/pub/ibis/email_archive/  Recent
| http://www.eda.org/pub/ibis/users_archive/  Recent
|  http://www.eda.org/pub/ibis/email/          E-mail since 1993


|------------------------------------------------------------------
|For help or to subscribe/unsubscribe, email majordomo@eda.org
|with just 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 email a written request to ibis-request@eda.org.
|
|IBIS reflector archives exist under:
|
|  http://www.eda.org/pub/ibis/email_archive/  Recent
|  http://www.eda.org/pub/ibis/users_archive/  Recent
|  http://www.eda.org/pub/ibis/email/          E-mail since 1993

|------------------------------------------------------------------
|For help or to subscribe/unsubscribe, email majordomo@eda.org
|with just 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 email a written request to ibis-request@eda.org.
|
|IBIS reflector archives exist under:
|
|  http://www.eda.org/pub/ibis/email_archive/  Recent
|  http://www.eda.org/pub/ibis/users_archive/  Recent
|  http://www.eda.org/pub/ibis/email/          E-mail since 1993