Operating overdrive voltage and equal early voltages

Question

Response to the following problem:

(a) Sketch the circuit of a current-mirror-loaded MOS differential amplifier in which the input transistors are cascoded and a cascode current mirror is used for the load

(b) Show that if all transistors are operated at an overdrive voltage VOV and have Equal Early voltages /VA /, the gain is given by

A_d=2(V_A/V_ov)²

Evaluate the gain for V_ov=0.20V and V_A=10V.