Re: [IBIS-Users] way to extract rising and falling waveform in differential cells

Akhilesh,

In the example you gave earlier, the simulation was at 250 MHz (2 ns high and 2 ns low) and the waveform had just about reached the other state when it was being switched again. Attempting to simulate this much faster (622 MHz or 1 GHz), with IBIS, is probably doomed to failure because of IBIS's limitations. This is sometimes known as "over-clocking" the IBIS model, because the model hasn't reached the other state yet when it is being clocked again in the other direction. Some simulators handle this situation very poorly, so you could see very poor IBIS vs. SPICE correlation at such faster frequencies.

Regards,
Andy

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Received on Sun Dec 19 06:21:54 2004