4. (30%) Figure 4 shows a MOSFET transistor M that makes a constant current source for a 20-kΩ
load. The body terminal and source terminal of MOSFET M are tied together. Assume that = 15 V,
and the transistor M has the device parameters: WIL = 80, = 50 μA/V2,=0.7 V,λ =
0.1. Suppose we want to have ID = 0.5 mA.
(c) (10%) Suppose the 15V supply voltage has 1% variations on it (i.e.,△ =± 0.15V). Estimate the percentage change in current Io. Notefor M in saturation.
(b) (10%) Determine the minimum allowed that still assures that M works properly as a constant current source.