[SI-LIST] negative propagation delay

  • From: Perry Qu <perry.qu@xxxxxxxxxxx>
  • To: si-list <si-list@xxxxxxxxxxxxx>
  • Date: Thu, 02 Oct 2003 15:02:34 -0400

Hi,

I'm using ICX for SI/timing analysis. One thing I noticed, if a driver
IBIS specified a large reference load (e.g., 50pF for uP), I will always
end up with a negative propagation delay since my actual loading is much
smaller compared with reference load.

Would like to understand how I should correct the number to reflect my
actual loading for timing analysis. I would think we can get the
internal logic delay of driver through: (Tco - time_to_Vmeas@reference
load); But then, how shall I add buffer delay for a real load and
propagation delay for a real load--taking into account all the
reflection effect (e.g., a daisy-chained bi-directional data bus).

Thanks

Perry

--
Perry Qu

Design & Qualification       |      600 March Road
Alcatel Canada               |      Ottawa, ON K2K 2E6, Canada

DID: (613) 7846720           |      FAX: (613) 5993642


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