google
docs/rules/rcx: update resistance-values
Fixes #359
TESTED=https://skywater-pdk--377.org.readthedocs.build/en/377/rules/rcx.html#resistance-values
This corrects the main errors in the documentation. From what I have in the magic tech file, though, it appears that the entry for Nwell should be changed from 1700000 to 950000.
@RTimothyEdwards can you also update the source spreadsheet (https://docs.google.com/spreadsheets/d/1oL6ldkQdLu-4FEQE0lX6BcgbqzYfNnd1XA8vERe0vpE/edit#gid=1059412464) as I'm importing the data from here.
Also, the file should probably have some indication that the values are for the nominal process corner, as opposed to the low and high resistance corners. Ideally, all three values for low/nominal/high should be in the file, as well as values for the A and B process variants (A=original, B=ReRam).
Do we have the data for A and B / various corners in another spreadsheet? or should we be sourcing it from https://github.com/RTimothyEdwards/open_pdks/blob/5ed94ffe0059046164bfb97f670fab648fa90602/sky130/magic/sky130.tech#L5202 instead?
@proppy : All data for variant B (ReRAM support) is derived from values for variant A by adjusting for the height difference of metals starting at metal2 (plus the via between metal1 and metal2 doubles in height and therefore doubles in resistance). I was hoping we could get measured values, but I suppose I should publish all values in the spreadsheet and make a note that they are simply derived values based on the known difference in the metal stack.
