Re: [IBIS-Users] Measurement deratings?


Subject: Re: [IBIS-Users] Measurement deratings?
From: Duane Mattheisen (duane.mattheisen@onsemi.com)
Date: Fri May 30 2003 - 10:50:38 PDT


Muranyi
   The IBIS file is clean, no jitter but, when I use Hyperlink 6.1
simulation software with a 4pF load to simulate the clean IBIS files I
get a jittery simulation. If I put a bigger load on the simulation the
jitter goes away.
 
               Thanks Duane M

"Muranyi, Arpad" wrote:
>
> Duane,
>
> It is not clear to me whether it is your measured data that is jittery,
> or the simulation results (with clean data in the IBIS file). If it is
> the former, you need to find ways to filter it before you put it into
> the
> IBIS model. If it is the latter, this could be a simulation tool issue.
> Which is it? Which tool are you using?
>
> Arpad
> ========================================================================
> =
>
> -----Original Message-----
> From: Duane Mattheisen [mailto:duane.mattheisen@onsemi.com]
> Sent: Thursday, May 29, 2003 5:14 PM
> To: Muranyi, Arpad
> Cc: ibis-users@eda.org
> Subject: Re: [IBIS-Users] Measurement deratings?
>
> Hello All
> All of my AC data tables are measured. But if I simulate an output
> of an IBIS model with a 4pF load I get a jittery edge. Even after
> putting more points in the data (20 to 50 points in the edge). I've
> tried smoothing the wave form and taking out any over/under shoot but
> the simulations still have a jittery edge. If I take out the AC data
> table and leave in the DV/DT information the wave forms look fine. Is
> there a fix to my problem? I work with CMOS logic devices.
>
> Thanks Duane M
> "Muranyi, Arpad" wrote:
> >
> > Tim,
> >
> > IBIS doesn't have to provide this derating construct in order for you
> > to make an IBIS model with derating. You measure your data, import it
>
> > into your favorite spreadsheet, and massage it. After that you can
> > make your IBIS model with the massaged data.
> >
> > Arpad ===============================================================
> >
> > -----Original Message-----
> > From: Timothy Coyle [mailto:timothy.coyle@sun.com]
> > Sent: Wednesday, May 28, 2003 8:48 AM
> > To: John Phillippe
> > Cc: ibis-users@eda.org
> > Subject: Re: [IBIS-Users] Measurement deratings?
> >
> > John Phillippe wrote:
> > >
> > > Hello,
> > > I am wondering how people match their IBIS simulations to silicon
>
> > > measurements. I read through the spec, and didn't see anything that
>
> > > looked like a derating type construct. So it is my understanding
> > > that when someone takes lab measurements of an I/O buffer, those
> > > data points are directly inserted into the ibis file, replacing the
> simulated data.
> > > Does this sound correct? Is there another way, to get simulations
>
> > > to more closely match measurements?
> > >
> > > --
> > > John Phillippe
> > > SPS, 32 Bit Embedded Controller Division, IC Creation
> > > Motorola - 512-895-1835
> > > Austin, TX - john.phillippe@motorola.com
> > >
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> > Hi John,
> > Not sure if you are talking about transmission line simulations or
> > just the IBIS data itself, but here is my 2 cents. If your IBIS file
> > was created from SPICE models, the real correlation should be between
> > your SPICE simulations and real silicon. A good methodology might be
> > to correlate your SPICE models to silicon, then translate your SPICE
> > models to IBIS, and correlate your IBIS file to your SPICE model. If
> > your SPICE models do not correlate well to silicon, you could extract
> > IBIS data from the bench and insert into your IBIS file. This should
> > make your IBIS file correlate better to silicon. It will be more
> > difficult to get your min and max data from the lab than from
> > simulation.
> >
> > Regards,
> > Tim
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