Re: [SI-LIST] : IBIS Model Verification

nikolai@avanticorp.com
Mon, 14 Sep 1998 09:47:10 -0700 (PDT)

Hi SI and IBIS Gurus:

Can't anybody explain me what is the use of
Vmeas, Cref, Rref, and Vref
parameters in IBIS. In other words, how simulator can/should use them.

---------------
/
/- V_meas
/
------
->| |<-
delta_t

Does simulator need a parameter(s) to adjust so the user
can control delta_t = time from low to V_meas?
How about waveforms V(t) (and/or ramps), don't they
impose timing restrictions.

Thanks a lot for any clarification on this issue.

Nik Bannov

nikolai@avanticorp.com

:-) From owner-si-list@silab.Eng.Sun.COM Mon Sep 14 08:31 PDT 1998
:-) Date: Mon, 14 Sep 98 08:59 CDT
:-) From: beal@lisbon.eng.hou.compaq.com (Weston Beal)
:-) To: si-list@silab.Eng.Sun.COM, ariazi@anigma.com
:-) Subject: Re: [SI-LIST] : IBIS Model Verification
:-)
:-)
:-) > 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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:-) >
:-) >
:-)
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:-)

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