The source follower amplifier provides lower output impedance and essentially unity gain. The circuit diagram is shown in Figure P2.20(a), and the small-signal model is shown in Figure P2.20(b). This circuit uses an FET and provides a gain of approximately unity. Assume that $R_2 \gg R_1$ for biasing purposes and that $R_g \gg R_2$. (a) Solve for the amplifier gain. (b) Solve for the gain when $g_n=2000 \mu \Omega$ and $R_s=10 \mathrm{k} \Omega$ where $R_5=R_1+R_2$. (c) Sketch a block diagram that represents the circuit equations.