For vdd =1.3 vand using iref =100 μa, it is required to design the circuit of fig. 8.1 to obtain an output current whose nominal value is 100 μa. find r if q1 and q2 are matched with channel lengths of 0.5 μm, channel widths of 5 μm, vt = 0.4 v, and k n = 500 μa/v2. what is the lowest possible value of vo? assuming that for this process technology the early voltage v a =5 v/μm, find the output resistance of the current source. also, find the change in output current resulting from a +0.5-v change in vo.