A Design Example of a Fractional-Order Kerwin-Huelsman-Newcomb Biquad Filter with Two Fractional Capacitors of Different Order

Design, realization and performance studies of continuous-time fractional order Kerwin-Huelsman-Newcomb (KHN) biquad filters have been presented. The filters are constructed using two fractional order capacitors (FC) of orders alpha and beta (0 <alpha, beta a parts per thousand currency sign1). The frequency responses of the filters, obtained experimentally have been compared with simulated results using MATLAB/SIMULINK and also with PSpice (Cadence PSD 14.2), where the fractional order capacitor is approximated by a domino ladder circuit. It has been observed that fractional order filters can give better performance in certain aspects compared to integer order filters. The effects of the exponents (alpha and beta) on bandwidth and stability of the realized filter have been examined. Sensitivity analysis of the realized fractional order filter has also been carried out to investigate the deviation of the performance due to the parameter variation.