Determining Io/Iref

Question

I'm asked to find the ratio \$I_o/I_{ref}\$ in the attachment which follows. Normally, due to the current mirror, I'd claim that the ratio should be 1. However, as it's also given in this section that \$V_o=3V_{GS}\$ and that \$\lambda\$ is given, I presume the answer would not be 1 and that channel modulation must be taken into account. Is there a formula to be used here to determine \$V_o\$ using \$V_A\$ perhaps, or is it more straightforward, namely via finding the current through the load:

\$I=k(V_{ov})^2(1+\lambda V_{DS})\$

Answer 1

Since the output is explicitly stated as 3Vgs, each left-hand NMOS has the same operating point as the right-hand side NMOS. So the output current must be Iref.