The Design of Reactive Equilizers

N MOST broad-band communication systems, the problems of loss equalization and distortion correction are fundamental. Of the various types of electrical networks which are found useful as equalizers and compensators, the most frequently employed are the so-called constant resistance networks. In particular, they are of three usual types, as indicated in Fig. 1. In all cases, the relationship ZiZ 2 = R 2 , which is always possible to fulfill if Zi and Z 2 are built up of resistive and reactive components in the wellknown manner, provides the means of altering the transmission properties of the circuit without affecting its impedance. 1 Methods are also available which extend the problem to more complicated configurations having these constant resistance properties. However, in some applications, where signalto-noise ratio considerations are of importance, the resistive elements included as components of Zi and Z 2 in these circuits place a limitation on the final performance of the system. Hence, the satisfactory transmission and impedance matching properties of these circuits are purchased at the expense of a substantially increased noise level. As a consequence of this limitation on the performance of standard constant resistance equalizers, recent work