Re: [SI-LIST] : IBIS Model Verification

Weston Beal (beal@lisbon.eng.hou.compaq.com)
Mon, 14 Sep 98 08:59 CDT

> From: Abe Riazi <ariazi@anigma.com>
> To: "'si-list@silab.eng.sun.com'" <si-list@silab.Eng.Sun.COM>
> Cc: "'greg.edlund@digital.com'" <greg.edlund@digital.com>
> Subject: [SI-LIST] : IBIS Model Verification
> Date: Sat, 12 Sep 1998 09:15:13 -0700
>
...
CHOP
...

> It is interesting to note that before simulating a models as a
> "driver", it requires
> "calibration" (in addition to verification) to obtain the proper
> Time_To_Vm value. Simulations
> using uncalibrated driver models will yield incorrect timing parameters
> (for example false
> flight time values).

TIME_TO_VM is QUAD syntax, not IBIS. As Abe stated, this is very
important, actually required, in order to get correct timing from
simulation. The TIME_TO_VM in QUAD models implicitly includes the
timing reference load which is described explicitly in IBIS with Vmeas,
Cref, Rref, and Vref. I can understand why these parameters are
optional in IBIS, but I strongly believe that the parser should issue a
warning if they are absent. I constantly get IBIS files with no timing
reference load. I think that most IBIS creator don't know what these
parameters are for, and leave them out because they are optional. For
timing simulations they are ESSENTIAL! Required! Imperative! Did I
mention they're important?

If you create IBIS files, please, oh pretty please, include the timing
reference load parameters, Vmeas, Cref, Rref, and Vref on all drivers.

Thanks,
Weston Beal

>
> Best Regard,
>
> Abe Riazi
> SI Engineer
> Anigma, Inc.
>
> email: ariazi@anigma.com
>
>
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