Figure 118 $\left(R_{1}, R_{2}\right)$ Each of the Four MOS Transistors Is Operating at with Negative

Figure 11.8.1
Figure 11.8.1 shows a MOS current-mirrorloaded differential amplifier with negative feedback applied through a voltage divider $\left(R_{1}, R_{2}\right)$ . Each of the four MOS transistors is operating at an overdrive voltage $\left|V_{O V}\right|=0.2 \mathrm{~V}$ and has an Early voltage $\left|V_{A}\right|=20 \mathrm{~V}$ .
(a) Find expressions for $\beta$ and for the ideal value of the closed-loop gain $V_{o} / V_{s}$ . Hence, find the value of $\beta$ and the ideal value of $V_{o} / V_{S}$ .
(b) Give the $A$ circuit and expressions for $A$ and $R_{O}$ . Hence, find the values of the open-loop gain $A$ and the open-loop output resistances $R_{O}$ .
(c) Find the value of the closed-loop gain $A_{f} \equiv$ $V_{o} / V_{S}$ . Compare to the ideal value found in (a).
(d) Find the value of the output resistance $R_{\text {out }}$ .