🚀 go-pugleaf

We are having some difficulties with our simulation tools and would
appreciate any advice we can get.

Crystal:

It seems that the node resistance values that Magic extracts can be
grossly incorrect.  The algorithm it uses (finding a rectangle from
the area and perimeter of the layer) is very bad with long thin
rectangles through which the signals travel across the thin side.  For
example:

              == <- Poly
              ==
      -------X==X-------
      |     |X==X|     |
      |Pdiff|X==X|Pdiff|
      |     |X==X|     |
      | Con-|X==X| Con-|
      | tact|X==X| tact|
      |     |X==X|     |
      -------X==X-------
             ^  ^
	    Pdiffusion

Magic will extract the resistance of the thin layer of Pdiffusion as
if the signal was flowing from top to bottom rather than from left to
right.  So, if this diffusion was 1 lambda wide by 10 lambda tall then
the extracted resistance would be 10 times the sheet resistance of
pdiffusion rather than 0.1 times the sheet resistance.  This is an
estimate that is 100 times larger than we want.

Crystal uses these resistance estimates in its algorithm for finding
the critical path of a circuit.  Not only do the critical paths end up
having extremely pessimistic delays but it seems questionable whether
it has found the critical path at all.

We would like to know whether anyone has found a way to deal with this
problem.  Hand-extraction seems like a particularly tedious and
error-prone solution, especially on very large circuits.


Spice:

We are interested in what spice level 2 parameters people are using
for the fabrication through MOSIS service.  Why are you using those
particular parameters and where did you get them? 
 

Thanks for your help,

Scott Kalter  <sdk@cs.ucla.edu>
Jae Cho       <jcho@cs.ucla.edu>