Simulating a circuit consisting of MOSFETs
Every transistor in this schematic is probably operating primarily as a switch.  So they all move at some point in time between off and triode.  A MOSFET is in saturation if Vds > (Vgs - Vt) (for an NMOS, or |Vds| > |Vgs - Vt| if you prefer for PMOS with Vds, Vgs, Vt &lt; 0).  A decent simulator should be able to report the device threshold for biased transistor. Normally we care about maintaining a device in saturation if we want high output impedance, usually when used as a current source or an amplification stage.  Charge pumps are essentially switch and capacitor networks for pushing charge around, so the region of operation is less of a concern here.