I think I should plot the Ids-Vgs and Isq(so called sheet specific current)-Vgs with cadence.
I've never heard of a
sheet specific current, sorry. Is it possible that you mix it up with a
process specific current or
Technology Current (called in
Binkley's book)? This is defined as the drain current of a MOSFET with W/L=1 @ Vgs=Vth0 and Vds=Vsupply/2 . The threshold voltage Vth0 you can find in the MOSFET's model file, Vsupply is the recommended supply voltage for this MOSFET. (Vds=Vsupply/2 is my own interpretation: it's the
mean operation voltage for a MOSFET in a circuit, and should reside in the saturation region for a MOSFET in such an operation condition.)
This
Technology Current TC is the basis for the
Inversion Coefficient IC of a MOSFET in its specific operation condition: IC = Ids/(TC*(W/L)).
Of course this
Technology Current may (a little) be different for transistors with L=Lmin and L>Lmin , because for Lmin - in such operation condition -
carrier velocity saturation and also
vertical field mobility reduction (VFMR) will reduce Ids, and so the TC value. So I usually measure
two different TC values for MOSFETs of a certain process: one for L=Lmin and one for L=5*Lmin , and of course separately for nMOS and pMOSFETs, and for each available MOSFET type in the PDK, which I'd use in my circuit.