TABLE OF CONTENTS In Chapter 1 we illustrated the means for obtaining filter transfer functions that meet given frequency or time-domain requirements. Given an appropriate circuit configuration, one then evaluates the circuit element values that yield the desired transfer function. This operation, referred to as network synthesis, implies two operations: (1) the selection of an appropriate active network configuration, and (2) the calculation of the element values. In Chapter 2 we described a number of simple operational amplifier building blocks for active filters. As shown in Chapters 4, 5, and 6, combinations of these active building blocks and passive components can be interconnected to provide a vast number of equivalent circuit configurations which are capable of realizing a given transfer function.
Given this difficult task of selecting a circuit configuration, it is valuable to identify criteria that can be used as a figure of merit for determining the goodness of a circuit configuration. One of the most important criteria for comparing equivalent circuit configurations and for establishing their practical utility in meeting desired requirements is sensitivity. In practice, real circuit components will deviate from their nominal design values (i.e., those computed in step 2 of the synthesis operation) due to manufacturing tolerances, environmental changes such as in temperature and humidity, and chemical changes which occur as the circuit ages. Furthemore, modeling inaccuracies such as the non ideal op amp characteristics discussed in Chapter 2 and such parasitics as capacitor losses can also cause a practical active and passive component to...
