Subject: RE: [IBIS-Users] Problem in ibs file generated by s2ibs2
From: Mike LaBonte (milabont@cisco.com)
Date: Mon Jun 16 2003 - 12:35:33 PDT
I forgot about that part. What I did is:
1) Change SWEEP_STEP_DEFAULT from 0.1 to 0.01 in s2ibis.h
2) Take out the 3 places in setupVoltages() where sweepStep is adjusted
in a binary fashion:
/* while ( ( fabs( *sweepRange_P / *sweepStep_P ) + 1 ) >
MAX_TABLE_SIZE )
*sweepStep_P *= 2; */
3) Add sweepStep adjustment at the very end of setupVoltages():
/*------------------------------------------------------------------
* (18jan2001) Adjust the sweepStep to keep the table size within
limits.
* The SWEEP_STEP_DEFAULT has been decreased from 0.1V to 0.01V. The
* binary multiplication algorithm has been replaced by a stepping
* algorithm that leaves the final value at some multiple of the
default.
* This change provides a number of VI points that is close to
* MAX_TABLE_SIZE.
*------------------------------------------------------------------*/
{
double sweepStepInc = *sweepStep_P;
while ( ROUND(*sweepRange_P / *sweepStep_P) >= MAX_TABLE_SIZE )
*sweepStep_P += sweepStepInc;
}
Mike
-----Original Message-----
From: Eric Hsu [mailto:owner-ibis-users@eda.org]On Behalf Of Eric Hsu
Sent: Monday, June 16, 2003 2:56 PM
To: Mike LaBonte
Cc: Frank Dunlap; Ibis-Users (E-mail)
Subject: RE: [IBIS-Users] Problem in ibs file generated by s2ibs2
Hi Mike and IBIS experts,
According to previous your suggestion to fix data jumping issue, we get the
ibis model as follows:
Case1(#define DIODE_DROP_DEFAULT 1.0)
-3.3000 0.000A 0.000A 0.000A
-3.1000 0.000A 0.000A 0.000A
-2.9000 0.000A 0.000A 0.000A
-2.7000 0.000A 0.000A 0.000A
-2.5000 0.000A 0.000A -10.0000mA
-2.3000 0.000A 0.000A -10.0000mA
-2.1000 0.000A 0.000A 0.000A
-1.9000 -10.0000mA 0.000A 0.000A
-1.7000 -10.0000mA 0.000A -10.0000mA
-1.5000 -10.0000mA 0.000A -10.0000mA
<---(jumping point)
-1.0000 -44.0000mA -10.0000mA -64.0000mA <---
-0.9000 -53.0000mA -17.0000mA -79.2000mA
-0.8000 -67.3000mA -23.0000mA -87.3700mA
-0.7000 -66.9500mA -30.0000mA -83.6600mA
...
...
...
P.S.--- no error flag by ibischk3.
Case2(#define DIODE_DROP_DEFAULT 0.7)
-3.3000 0.000A 0.000A 0.000A
-3.2488 0.000A 0.000A 0.000A
-3.1976 0.000A 0.000A 0.000A
-3.1464 0.000A 0.000A 0.000A
-3.0952 0.000A 0.000A 0.000A
-3.0440 0.000A 0.000A 0.000A
-2.9928 0.000A 0.000A 0.000A
-2.9416 0.000A 0.000A 0.000A
-2.8904 0.000A 0.000A 0.000A
-2.8392 0.000A 0.000A 0.000A <---(jumping
point)
-0.6888 -66.5200mA -30.7000mA -83.0900mA <---
-0.6376 -64.1500mA -33.7700mA -80.3100mA
-0.5864 -61.2330mA -35.3200mA -77.0500mA
...
...
...
P.S.--ERROR (line 156) - More Than 100 Voltage Points Provided For
Pulldown/Pullup.
There are couple problems I would like to solve,
First, while modify from 1.0 to 0.7, it seems cause bigger jump from 0.5 to
2.1 (1.5-1.0 and 2.8-0.7), is there anything else cause this problem?
Second, by setting 0.7 as diode default, it will generate over 100 point in
pulldown and pullup tables, and ibischk3 complain error for that. Do we need
to update ibischk3? Or any solution we can fix it?
Third, if comparing sweep voltage point from two case, you can see case1 is
0.2 or 0.1V, but in case2 it always keep 0.512V. It suppose to like this? Or
we also change other parameter, such "sweep_step_default" in s2idflt.h file?
Best Regards,
Eric Hsu
Interface Technologies
NetLogic Microsystems, Inc.
450 National Ave.
Mountain View, CA 94043
650-961-6676 x198
This e-mail contains NetLogic Microsystems, Inc. Confidential information
-----Original Message-----
From: Mike LaBonte [mailto:milabont@cisco.com]
Sent: Wednesday, May 14, 2003 11:53 AM
To: Syed Huq; Birendra Rana
Cc: ibis-users@server.eda.org
Subject: RE: [IBIS-Users] Problem in ibs file generated by s2ibs2
The fixed s2ibis2 prints 4 digits after the decimal instead of 2. With only
2 digits, voltage differences less than 10mV between points make them appear
identical.
Also there is a parameter in s2idflt.h:
#define DIODE_DROP_DEFAULT 1.0
This is used by s2ibis2 to jump around in the SPICE data to find beginnings
and ends of "linear" and "non-linear" regions. On lower voltage devices the
1V value makes s2ibis2 jump too far and pick up wrong data or ignore data.
Change the value to 0.7, recompile, and s2ibis2 will work better.
Mike LaBonte
> -----Original Message-----
> From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org]On
> Behalf Of Syed Huq
> Sent: Wednesday, May 14, 2003 12:12 PM
> To: Birendra Rana
> Cc: ibis-users@eda.org
> Subject: Re: [IBIS-Users] Problem in ibs file generated by s2ibs2
>
>
> First of all, you are using an older version of s2ibis2. You should
> download the s2ibis2_fix.tar.Z
>
> I have seen these repetition of data points. Not sure what causes it.
> You have to delete them to clean up the file.
>
> Delete everything below 3.6V as well as one of the -0.9 entries.
>
> Syed
>
> On Wed, 2003-05-14 at 04:56, Birendra Rana wrote:
> > Hi all,
> >
> > I have generated an IBIS Model for an I/O buffer using s2ibis2 script.
> > Interestingly the generated ibs file has entries in the Pull down
> > table as follows :
> >
> > [Pulldown]
> > | voltage I(typ) I(min) I(max)
> > |
> > -1.80 -42.50mA -54.11mA -28.61mA
> > .
> > .
> > .
> > -0.90 -36.68mA -30.62mA -38.74mA
> > -0.90 -36.68mA -30.62mA -38.74mA <-
> > Repetition of above data
> > -0.80 -37.07mA -29.68mA -41.00mA
> > .
> > .
> > .
> > 0.00 0.36uA 2.61nA 2.86uA
> > .
> > .
> > .
> > 3.60 94.05mA 80.81mA 0.11A
> > 0.00 -1.80A 0.11kA -92.95A <-
> > ?????
> > -137.28 -1.70A -99.02A -82.08A <-
> > ?????
> > 3.60 94.05mA 80.81mA 0.11A <-
> > Repetition of 3.60V entry data
> >
> > Similar kind of entries (like the repetition of -0.90V and 3.60V data
> > and extra 2 rows) are there in the Pullup table. The ".out"
> > files however look alright.
> >
> > Any reasons for these extra / repetitive entries ?
> >
> > Regards,
> >
> > Birendra
> > **************************Disclaimer************************************
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