It's only a theoretical question; no particular circuit needed.
Some backstory: Suppose there are, say, two NMOS transistors with different W/L ratios in series. Further, suppose that both of them have their gate voltages equal, and their corresponding drain and source voltages. Neglect body and channel length modulation effects. Assume both are in saturation voltages.
The current in first NMOS: Id1= (W1/L1)* kn' *(Vgs - Vt)^2
The current in second NMOS: Id2= (W2/L2)* kn' * (Vgs - Vt)^2
All the terms in both the equations are equal except the W/L ratios.
My Question: When individually calculated, the drain currents of both the transistors are different. More specifically, the drain current is higher in the transistor with higher W/L ratio, and smaller in the other one. But, when both of them are in series, what would be the actual/total drain current in the circuit? Will the current be equal to Id1 or Id2 or something else?
I'm still posting a link of a random figure(ignore the PMOS circuit) for a better idea: http://ece-research.unm.edu/jimp/vlsi/misc/IMG00002.GIF