Repeat Problem 7.92 with a 5 MΩ resistor placed across the 400 nF feedback capacitor. There is no energy stored in the capacitors in the circuit shown in Fig. P 7.94 at the instant the two switches close. Assume the op amp is ideal.
 a) Find vo as a function of va, vb, R, and C.
 b) On the basis of the result obtained in (a), describe the operation of the circuit.
 c) How long will it take to saturate the amplifier if va = 40 mV; vb = 15 mV; R = 50 kΩ; C = 10 nF; and VCC = 6 V?