Re: MOS capacitor Model.
You might be better off to use a MOSFET of appropriate geometry.
But some MOSFET models converge poorly with shorted terminals.
Suppose you began with the desired moscap value, picked off the
gate geometry, simulated an equal geometry MOSFET-as-cap,
and picked off its Cdb, Csb, Cbs (well-sub) parasitics and put them
in as pcapacitors (if C-V junction nonlinearity is not a concern)
or correct-area, correct-type diodes that are lvsIgnored?