4. (30%) Figure 4 shows a MOSFET transistor M that makes a constant current source for a 20-kQ
load. The body terminal and source terminal of MOSFET M are tied together. Assume that VoD= 15 V,
and the transistor M has the device parameters: WIL = 80, MaCox = 50 HANV?, VTH =0.7 V,4 =
0.1. Suppose we want to have Ip = 0.5 mA.
Suppose the 15V supply voltage has 1% variations on it (i.e., AVoo =士 0.15V). Estimate the
percentage change in current Io. Note: I = 平(Vos-VH)(I+Nos)for M in saturation.