(a) Using a simple (rπand gm) model for each of the two transistors in Figure 4.a, find the small-signal resistance between A and A '. Where = 16μA.

(b) Figure 4.b shows the circuit for determine the 741 op-amp output resistance when vo is positive and is conducting most of the current. Using the resistance of the network calculated in 4.(a) and neglecting the large output resistance of, find Ro when is sourcing an output current of 5mA. (10%,10%)