ABSTRACT
This chapter discusses the elements of insertion loss filter design. In this method, the available gain of the filter is chosen, subject only to clearly stated and not overly onerous constraints. The Darlington synthesis is then employed to design the lossless filter and, when it is inserted between real resistors, the prescribed transducer gain is realized. A major advantage of the procedure is the wide flexibility that is made available in the choice of transfer functions, and the fact that constant resistance loads are employed. The insertion loss technique supplanted an earlier approach, the method of image parameters. A finite number of cascaded identical lossless sections, when terminated by the correct frequency varying irrational image impedances, have a passband over which the signal propagates, and a cutoff region, where the image impedance becomes imaginary. Before discussing the problem of concrete realization of filters, authors consider the ideal conditions under which the information contained in a filtered signal is completely preserved.
