RE: [IBIS-Users] Error message from IBIS parser.

Anguraj and Lars,

The error message results from a mismatch between your I-V tables and
the "settled" starting and ending points of your V-t tables.  The parser
treats any mismatch between 2% and 10% as worthy of a warning.
Mismatches greater than 10% will cause an error.

Recall that the V-t tables should start and end at a voltage determined
by the voltage division of the circuit containing R_fixture, V_fixture
and the "on" resistance of your pullup or pulldown.  Long before and
long after transitions, your V-t tables should effectively be at DC.
Therefore, you should be able to match these starting and ending DC V-t
table values to the voltage-intercept of a load-line, with value of
R_fixture, drawn across your I-V table.  If the V-t start/end points and
the load-line intercepts don't match, a warning or error will be issued.

Running the simulation longer could help the issue at the *end* of the
table, but may not help the mismatch at the beginning.  I would not
recommend changing the R_fixture of your model alone, unless you are
generating new V-t tables using that new value.  

The process for matching is documented in the IBIS Cookbook:
http://www.eda-stds.org/ibis/cookbook/cookbook-v4.pdf.  Please consult
this document for further detail.

I would also suggest using the latest parser (ibischk4), to ensure that
the error message is not the result of any previously-detected bug in
ibischk3.

Good luck!

- Michael Mirmak
  Intel Corp.
  Chair, EIA IBIS Open Forum

-----Original Message-----
From: owner-ibis-users@server.eda.org
[mailto:owner-ibis-users@server.eda.org] On Behalf Of Lars Snith
Sent: Wednesday, October 18, 2006 06:04
To: Anguraj.K
Cc: ibis-users@server.eda.org
Subject: Re: [IBIS-Users] Error message from IBIS parser.

Hello Anguraj,

I'm not an expert, but I have encountered this a few times.
I usually try (either of) the following:
1) Run the simulation for a little bit longer
2) Increase R_fixture (or add another curve)

Best regards,  Lars Snith


Anguraj.K wrote:
> Hi IBIS Experts,
> 
> A quick help!
> 
> When do I get this  ERROR message fron ibis parser (ibischk3)?
> The [Rising Waveform]
>      with [R_fixture]=50 Ohms and [V_fixture_min]=1.71V
>      has MIN column DC endpoints of  0.86V and  1.59v, but
>      an equivalent load applied to the model's I-V tables yields
>      different voltages ( 0.82V and  1.49V),
>      a difference of  6.87% and 14.93%, respectively.
> 
> Any input would be of great help!
> 
> Thanks,
> Anguraj

-- 
Those who can, Do
Those who can't, Simulate
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