i have doubt on SOI FinFET that can we use the same cuurent and transconductance equations of MOSFET for FinFET if not can any one help in providing the equations
thanks in advance
This rather depends on what device models you are using. If (for example) you are using bsimcmg, you would find the equations for these in the documentation under "BSIM-CMG" (searching for bsimcmg would work too though). So run up cdnshelp from the MMSIM stream, and search for the model you want.
Or just open <MMSIMinstDir>/doc/spectremod/spectremod.pdf