Closed-Form Design of Digital FIR Notch Filter Using Chebyshev Polynomial

Digital notch filter is a powerful tool to remove a sinusoidal or narrowband interference superimposed on a broadband signal. In this paper, the Chebyshev polynomial approximation method is employed to design linear phase FIR digital notch filter. Three main features of the proposed design are listed below: Firstly, the filter coefficients have closed-form solution without performing any optimization. Secondly, the notch filter has exact zero-gain response at the prescribed notch frequency. Thirdly, the 3-dB rejection bandwidth of notch filter can be adjusted by changing the filter order. Moreover, the power-line interference removal in electrocardiogram (ECG) signal is used to show the usefulness of the proposed notch filter.