A differential amplifier circuit is shown in the figure below. In the circuit, VDD = +10 V, the current I provided by the current source is 2 mA and the internal source resistance is RSS = 50 kΩ. The transistor parameters are as follows: - All NMOS: μnCox = 100 μA/ V2, W/L = 10 μm/1.6 μm, Vtn = 0.7V, λnL = 0.10 μm/V - All PMOS: μpCox = 50 μA/V2, W/L = 10μm/1.6μm, Vtp = −0.8 V, λpL = 0.05 μm/V (1) Calculate the DC output voltage VO (ignore the channel length modulation effect of all transistors). (2) Under the differential mode operation (i.e., v1 = 1/2vd, v2 = -1/2vd ), calculate the differential mode small signal voltage gain Ad = vo/vd (include the channel length modulation effect of all transistors). Hint: please pay special attention to the connections of Q3 and Q4 transistors.