I have a specific transistor which is 5 fingers and I made it 7 for the dummy and the dummy is shared in drain with the transistor and the drain of the transistor is connected to something "live" so I am stuck at this point.
Is there another way to make the dummy in this case?
Maybe go to N+1 fingers, and N/(N+1) W? Or N-1, N/(N-1)?
Of course if you care about dummies you probably are
matching the W, L to some number of other FETs and this
could ripple outward....
But you want to be able to put source at both ends of the
rack so your dummy can be S-G-S tied off. Odd numbers
of fingers don't work out so well for that.
You shouldn't have any problem tying off the gate of dummy transistors to the appropriate supply to turn them off. Connecting the source is optionable.