@User @User: I can't remember which of you two brought this up, but you are right: The MiM capacitor plate value is 2fF/um^2, not 1fF/um^2 as I said, and as I have plugged into magic's device generator script. Of course, ultimately the simulation is done by passing width and length, not by value, so the value shown in magic is for reference only. Nevertheless it should not be off by a factor of 2! I would probably have noticed the discrepancy when designing the POR circuit, except that I was targeting a value for the time to charge, and just sized the caps to adjust to the desired simulated time rather than computing the value. I will fix the error in the device generator now.