[SI-LIST] :What do inputs do? monotonic signals at SDRAM-, SSRAM - and FEPROM-a dress inputs

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From: Mellitz, Richard (richard.mellitz@intel.com)
Date: Mon Feb 14 2000 - 19:45:21 PST


Use to be: monotonic signals at SDRAM-, SSRAM- and FEPROM-a dress inputs
... and other similar topic's.

Certain signals are just a SI fact of life. The question to ask is "just
what do these type of signals do to receivers". The answer is "let's just
find out".
I've be asked by a few to post the presentation I did a few weeks ago at the
IBIS Summit in Santa Clara. The follow explains how figure out receivers and
visualize the results. I got the idea from a colleague here at Intel, Alex
Levin, who has done extensive work with the application of Monte Carlo
methodologies.

ftp://63.225.95.1/pub/IBIS_SUMMIT_00_rcvr_modeling.zip
~700KB pdf in zip ...You'll have to figure it out without my babble :-)

Once an analysis is carried out, the information on performance can be used
to create guard bands, specs on monotonic behavior, slew rate dependence,
ringback tolerance, or whatever. Its up to the vendor to determine just how
to use the data, e.g. create a behavioral model, special spec, etc. Also,
the results of this directly affects certain historic timing parameters such
as setup and hold.

The real interesting thing for me was on page 9. Its a response to monotonic
edges. There are "mountains of peril" surrounded by "valleys of
performance". So even with spice, you could get fooled into thinking you had
solid system. This could be the case where the corners you simulated never
bump into the mountains. Maybe this can explain why vendors only define
monotonic signals but users find they work just fine in a given system.

Many of you receiver designers may want to use the method above to give us
poor users a better understanding how we can scrub some picoseconds.

Rich Mellitz,
Intel
 

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