The synthesis of a high order digital bandpass filters with tunable centre frequency and bandwidth

In this paper, described tunable digital bandpass filters whereby the centre frequency and bandwidth can be independently related to the multiplier coefficients, which permit simple frequency response adjustment by varying the coefficients values. The bandpass filters proposed here have a cascade form and are composed of several second-order recursive bandpass sections with identical characteristics. The methods for the direct compulation of the number of second-order filters in the cascade form, adjustable parameters and designing filter bank are shown in this paper. The design equations strale the true parametric tuning ability of the circuit. By cascading a few such circuits, a complete parametrically adjustable digital frequency responsed equalizer may be realized. It does not require precomputing the multiplier coefficient values for all designed equalizer settings.