As mentioned in the text, an important class of devices used in the implementation of fe...

As mentioned in the text, an important class of devices used in the implementation of feedback systems is the class of operational amplifiers. A model for such an amplifier is depicted in Figure P11.50(a). The amplifier's input is the difference

Between two voltages and the output voltage is an amplitude version of the input; that is

Consider an operational amplifier connection shown in Figure P11.50(b). In this figure, are impedances. (That is, each is the system function of an LTI system whose input is the current flowing through the impedance element and whose output is the voltage across the element.) Making the approximation that the input impedance of the operational amplifier is infinite and that its output impedance is zero, we obtain the following relationship between , and , the Laplace transforms of , respectively: