A novel approach to the design and synthesis of general-order Bode-type variable-amplitude active-RC equalizers

This paper presents a novel approach to the exact design and synthesis of general-order active-RC Bode-type variable-amplitude (VA) equalizers. The proposed design approach is based on, (a) the realization of the VA equalizer transfer function as the input-pair transmittance of a two-pair signal-flow network having the shaping transfer function as its output-pair terminating transmittance, and (b) the realization of the output-pair terminating transmittance in terms of a singly-terminated positive-real impedance function. The resulting VA active-RC equalizers permit the continuous variation of the equalizer transfer function from the shaping transfer function to its inverse through the use of a single positive variable resistor only.. In addition, they exhibit the important practical feature that a geometrically symmetric change in the value of the variable resistor causes a corresponding arithmetically symmetric change in the logarithmic magnitude-frequency response of the equalizer. An application example is given to illustrate the main results.