Strategic SC filter design based on a comparative study of various S- to Z-mappings

A systematic switched-capacitor (SC) filter design method that satisfies a set of frequency specifications and whose implementation requires less total capacitance than the conventional design using bilinear mapping is presented. The design approach is based on the following: (i) a prewarping scheme for different mappings of the 1/s and 1/s² terms of each biquadratic factor forming the transfer function; (ii) strategic addition of zeros at z =-1; (iii) iterative modification of the frequency responses rendering different transfer functions that eventually satisfy the original frequency design specifications. A detailed algorithm is discussed together with examples showing the attractive properties of the proposed method