CMOS Capacitances

   SPICE MODEL PMOS                 ___                      _________
                       __/\  ______|   | Source             |         |
      CGS             |    \/ RS   |___|                    |   ___   |
         _____________|__________                           |  |   |  |
       _|_     _|_        _|_   _|_                         |  |___|  |
 Gate  ___    / _ \ I_ds  \ /   ___ CBS                     |         |
  ___   |     \/ \/   |   _V_    |                          |___   ___|
 |   |__|     /\_/\   V    |_____|     ___            _________|   |_________
 |___|  |___  \___/     ___|     |____|   | Bulk     |         |   |         |
        |   |   |      |  _|_   _|_   |___|          |   ___   |   |   ___   |
       _|_  |__/|\__||_|   ^    ___                  |  |   |  |   |  |   |  |
       ___      |   ||    /_\    |  CBD              |  |___|  |   |  |___|  |LENGTH
        |_______|__________|_____|                   |         |   | CONTACT |
       CGD        CGB |             ___              |_________|   |_________|
                      |__/\  ______|   | Drain       WIDTH     |___|
                           \/ RD   |___|                     GATE_WIDTH

                  (G)
           (D)   ___|__   (S)        (B)         (Sub)
           _|_  |______|  _|_        _|_          _|_
    ______|___|_|______|_|___|______|___|________|___|__  _
     |  |   P+  | <++++|   P+  |  |   N+  | |  |   P+  |     Xj
     |   \_____/        \_____/    \_____/  |   \_____/   _
     |                NWELL                 |
   _ | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _| _ _ _
    \/      nbl2                            \/PBL
    /\ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _/\ _ _
 
 CapJunction =     BottomCapacitance*Width*Depth  + SideCapacitance*2*(Width+Depth);
 CapOxide =        (e_r*e0*Width*Length)/Thickness;
 CapOverlap =      OverlapCapacitance*Width;