Question

Here the source labeled VDD is the power supply. Although the source follower has no voltage gain (actually a small loss) it has power gain: it presents a very high resistance to the signal source so it takes no power from the source, but it can drive a low resistance load. Also, because of feedback, which we will learn about later, the source follower is close to linear. In this problem we will investigate the large-signal characteristics of a source follower. As usual, the MOSFET is set up to operate in the saturated region. Write an algebraic expression for iDS in terms of K, vIN, vOUT,