how to add the mos As,Ad,Ps,Pd (area of source & diff, perimeter of ....) in cadence? i.e. what are their equations? and can i enter them as equations? or i have to change them every time i change a mos dimensions.
These parameters depend on your layout. It is hard to define a equation only by Width and Length. Normally the parameters are extracted from layout by LVS. BSIM model have default valuses for these parameters.