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firstly the delays are apparently in nanoseconds, so the us is definitely a typo, but in_cap in µF and res in mΩ don't work either.
8.473µF * 1185mΩ = 10.04µS
which is a delay about 5 or 6 orders of magnitude too high.
The absolute values of the capacitance and resistance values don't matter, so long as their product gives a reasonable delay scaling. My awareness of likely ASIC numbers is limited, but something like switching to pF for capacitance and keeping mΩ gives a plausible delay product while staying fairly close to physical reality, I think.
The text was updated successfully, but these errors were encountered:
The documentation for the units in the https://github.com/SymbiFlow/prjxray/blob/cb5f2a30633bf0d3ac91a9b5802790ac1da86736/docs/dev_database/common/tile_type.rst#pips-section doesn't seem to be correct.
Not only does it mention
us (nanoseconds)
which must be a typo, it doesn't seem to be consistent with what's actually in the database.Looking at a random PIP:
firstly the delays are apparently in nanoseconds, so the
us
is definitely a typo, butin_cap
in µF andres
in mΩ don't work either.8.473µF * 1185mΩ = 10.04µS
which is a delay about 5 or 6 orders of magnitude too high.
The absolute values of the capacitance and resistance values don't matter, so long as their product gives a reasonable delay scaling. My awareness of likely ASIC numbers is limited, but something like switching to pF for capacitance and keeping mΩ gives a plausible delay product while staying fairly close to physical reality, I think.
The text was updated successfully, but these errors were encountered: