Design of general-order Bode-type variable-amplitude digital equalizers

The conventional design of Bode-type variable-amplitude digital equalizers is based on the realization of an overall magnitude-frequency response which can be varied from that of a shaping transfer function to its inverse by varying a single variable multiplier over a specified range of values, where the latter range of multiplier values is strongly dependent on the choice of the shaping transfer function. This paper presents a novel approach to the design of arbitrary-order Bode-type variable-amplitude digital equalizers which eliminates the dependence between the range of variable multiplier values and the shaping transfer function. The salient feature of this approach is that it leads to a substantial simplification in the realizability conditions associated with the digital equalizer, and, in turn, leads to a reduction in the cost of the corresponding hardware implementation of the digital equalizer. Moreover, it narrows the variable multiplier values to an effective range which is devoid of impractically large extreme values. The proposed technique is illustrated through its application to the design of a new fourth-order Bode-type variable-amplitude digital equalizer.