[IBIS-Users] VT Data Length Mismatch and Over Clocking

Hi,

I'm starting to run across quite a few IBIS models that have different time
lengths in the V-T waveforms even for corresponding loads. For example, a
Rising Waveform with 50 Ohms to Ground may have a total time of 5ns but the
equivalent Falling Waveform with 50 Ohms to Ground may have a total time of
10ns. So between the four different V-T waveforms they can all have a
different total time length. All of the waveforms transition to a "steady
state" but I'm wondering if this will cause potential problems in IBIS
simulators?

I know a lot of IBIS simulators say they can handle an over-clocked IBIS
model but will this cause even more issues? I've also actually started to
see a few models that say they must be over clocked to run properly
(apparently model developer had issues getting VT waveform to reach steady
state within bit time)

I would think that the VT waveform total lengths should be matched based
upon that they are used to define rise/fall transitions but clearly it all
depends on how EDA IBIS simulator processes this data. It's difficult to do
this type of correlation in multiple tools and without access to the
original SPICE model but wanted to see if anyone else is running into this
issue or can see potential issues with this type of model?

Best,

Timothy Coyle

President

Signal Consulting Group LLC

405 Western Ave #430

South Portland, ME 04106

Tel: 617.297.2566

Email: <mailto:tim.coyle@siconsultant.com> tim.coyle@siconsultant.com

Web: <http://www.siconsultant.com/> http://www.siconsultant.com

 <http://www.sharksim.com/> SharkSim - Signal Integrity IBIS Modeling
Software

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