One way is to use the concept of ICMR , & the other procedure is by using the tool (cadence)
Following are the steps for doing that :
1. Make a gedit file with name "saveops.scs" and mention different transistors M1, M2, M3 etc in that file with
the syntax,
SAVE OPPOINT MX;
where X is 1,2,3,4....
2. Save the file.
3. Add the file in model libraries while doing dc simulation
4. Do the parametric analysis
5. Go to dcinfo (i dont remember exactly this but is similar to dcinfo) and click on particular transistor
you will find the range in which your transistor works in saturation..remember you have to keep the parameter variable
corresponding to which you want to see the operation of your transistor