At 02:32 PM 7/20/99 -0700, you wrote:
>Mark Nass wrote:
>> There has been some discussion recently about parameters of parts
>> specified into 40pf caps and accuracy of models. I generate this type
>> of data for our devices for our own use and our customers. So I am
>> curious as to what people think would be the optimal way to generate
>> Tco, Tsu, jitter parameters and IBIS models so that they would be confident
>> they were getting exactly what they needed for signal integrity and timing
>> analysis. Any feedback?
>If you had to pick just one load, it would be 50 ohms. Notice I didn't
>write "50 ohms and 30 pf" or anything like it. To get the best sims we
>need the high-frequency content of output waveforms, and artificially
>filtering it out by adding a lowpass is not exactly helpful.
>Of course, we need both the turnon and turnoff responses for both
>the pullup and pulldown paths, so that's four tables (rising into
>50 ohm pullup, falling into 50 ohm pulldown, rising into 50 ohm pulldown,
>and falling into 50-ohm pullup.
>Output timing should be to the 10% (initial) point of the edge. That's
>easy to plug in as Vmeas so that the timing numbers add up, and also
>easy enough to measure on a tester so that you're actually testing to
>the critical design parameter.
>No lumped caps anywhere (was this a surprise?)
>D. C. Sessions
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