Re: Vmeas

"Amir Shavit (r56010)" wrote:
>
> Hi,
> I'm cuurrently working on an ibis model. I'v encountered some problem
> with this parameter since it is different for rising and falling time. I
> don't know what it should be equal to, since there are 2 different
> values.
> Thanks for your answers
> Amir Shavit
> Motorola Semiconductors Israel

Shalom Amir.

I'm a bit puzzled about the "different rising and falling" cases.
Are the defined timing points for the device you're working with
actually specified differently for the two directions? The reason
I ask is because it's very hard to have a setup time, for instance,
which is different for rising and falling edges.

Vmeas _should_ be the point at which the characterized ("data sheet")
timing is defined. This is usually 1.5v for LVCMOS, but is sometimes
50% of supply (a better way), 40% of supply (PCI and AGP), or an
external threshold (SSTL, HSTL, GTL, Rambus, etc.)

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D. C. Sessions
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