ABSTRACT
Higher-order filter functions have to be realized in order to satisfy the stringent selectivity requirements in telecommunication systems, special instrumentation, and many other applications. To realize high-order filter functions, two main approaches have been found most useful in practice. The first is to cascade second-order stages without feedback or through the application of negative feedback. The second is to use combinations of active and passive components in order to simulate either the inductances or the operation of a high-order LC ladder. Yet another approach, the use of just one opamp embedded in an RC network in order to realize the high-order function, although possible, has been dropped for reasons of high sensitivity. The realization of a high-order function can be achieved by a number of methods. The design of cascade of biquartics filter has been optimized in the case of high-order geometrically symmetric bandpass filters with zeros at the origin and infinity.
