[SI-LIST] Stimulus dilemma for pwr/gnd model
- From: agathon <hreidmarkailen@xxxxxxxxx>
- To: si-list <si-list@xxxxxxxxxxxxx>
- Date: Mon, 23 Apr 2007 17:51:04 -0700
Hello all,
Once I have some kind of assumed good system model for a power rail, ideally
I'd like to have already finished an extraction of I vs. t for worst case
pwr bump of the chip -- from simulation using a best-accuracy tool. Later
on, in an ideal world where time, etc., are cheap I'd like a bare-die
profile of the same, gotten from measurements -- for each worst case pwr
bump.
I'd use this as behavioral current stimulus for my PDN in simulations.
Specifically, the I vs. t for peak would be for peak CHANGES in I --- that
is, from chip's state changes that produce the largest swing in I and slew
rate. With no credible stimulus, all the SI tool time is useless for pwr
integrity.
My question:
The above two ways to generate such stimulus are actually damn costly,
especially if decision makers aren't forward looking and there's no time to
go back & do it "right".
Yet I can get SI tools as part of the normal course and generate the pwr
models.
Next best thing: turn the problem around .....
1. invent [I vs. t] stimulus based on estimates from real chip sim data &
models
2. find the worst case stimulus (guaranteed to be unrealistic)
3. yet, this will find the worst case swing (peak & slew rate cases), though
time scale will be a total WAG (a guess) ---> may still have some value
Any thoughts...?
-Agathon
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