FreeLists / si-list / [SI-LIST] Re: Basic IBIS I/V curve question

["Ingraham, Andrew" <Andrew.Ingraham@xxxxxx>]

> I am confused here. I though that even though the curves are VCC
> relative on
> IBIS
> it does matter the voltage at which the VI curves where extracted.
 
Yes it does.

I wrote that the curves and supply voltage are independent, "ideally."
In reality, the drive strength of real devices, as measured in a
Vcc-relative way, does depend on the supply voltage.

But IBIS is not detailed enough to show that dependency.  So when you
use a model, you could use the minimum curve with something other than
the minimum supply voltage.  The results ought to be conservative,
because the real device would be slightly stronger/faster, at that
supply voltage, than that dictated by the minimum I-V curve that the
simulator uses.

Some simulators (such as Hspice) let you choose the supply voltage
separately from the I-V curve.  Others may make them linked so that you
can't do that.

Regards,
Andy



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