Circuits, Systems, and Signal Processing

, Volume 32, Issue 4, pp 1523-1536

First online:

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

  • Madhab Chandra TripathyAffiliated withDepartment of Electrical Engineering, Indian Institute of Technology
  • , Karabi BiswasAffiliated withDepartment of Electrical Engineering, Indian Institute of Technology Email author 
  • , Siddhartha SenAffiliated withDepartment of Electrical Engineering, Indian Institute of Technology

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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 α and β (0<α, β≤1). 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 (α and β) 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.


Fractional order capacitor KHN biquad filter Constant phase angle Domino ladder circuit Fractional order filter