Re: AC warning messages

Did I say "ECL requires a pullup"? Delete that. Bob's response
covers this issue well, and with no evidence of the dyslexia I
seem to be experiencing today.

Mike LaBonte
Cadence

Mike LaBonte wrote:
>
> Kim,
>
> Ibischk3 figures out what voltage the buffer will settle at when
> only the VI curves are used to drive the test loads. That is where
> 0.01V (pulldowm mode) and 2.37V (pullup mode) come from. The voltages
> at the beginnings and ends of the waveforms should match these DC
> levels.
>
> Your second warning implies that the VI curves are delivering no
> current at all. That makes sense to me, because ECL requires a
> pullup, and this test fixture is giving it just a pulldown. Does
> anyone know what the test fixtures should be for ECL?
>
> Mike
>
> Kim Helliwell wrote:
> >
> > When ibischk3 issues a warning like:
> >
> > WARNING - Model 'LVT162245_IO': TYP AC Rising Endpoints ( 0.01V, 2.45V) not within
> > 0.049V (2%) of ( 0.01V, 2.37V) on VI curves for 50 Ohms to 0V
> >
> > where do the expected limits (0.01V, 2.37V) come from? The reason I ask is
> > that I am getting a warning more like:
> >
> > WARNING - Model 'ECLout': TYP AC Rising Endpoints (-1.72V, -0.98V) not within
> > 0.015V (2%) of (-2.00V, -2.00V) on VI curves for 50 Ohms to -2V
> >
> > where the upper and lower limits are the same, and that simply doesn't make sense.
> >
> > Also: how serious a problem is this? Do some or all simulators have problems with
> > this sort of warning?
> >
> > --
> > Kim Helliwell
> > Senior CAE Engineer
> > Acuson Corporation
> > Phone: 650 694 5030 FAX: 650 943 7260
 
Received on Thu Oct 19 11:36:46 2000