3. Consider the following differential amplifier. R Vin1 O HE O+ Vout -O M VDD Vbias 0- M R R ww GND RL Vinz Assume all transistors are operating in saturation region and 2-y-0, VDD-3 V, VTH(NMOS)=0.5 V, nCox-1 mA/V, R=100 S2, (W/L)=(W/L)2=16 and (W/L)o-32. Also, assume that the Vbias 0.75 V and the circuit is symmetric. a) What should the value of R be if the magnitude of the differential voltage gain of the circuit is 4 V/V b) For the circuit to operate properly (i.e., all transistors operate in their saturation region), what are the minimum and maximum values of the input common-mode voltage (i.e., input DC voltage)