Optimal FIR filter for suppression of power line frequency component

In this paper a design technique for multiband FIR filter for DC and power line frequency component suppression is described. The digital filter has a linear phase characteristic and equiripple amplitude characteristic in the passband. The amplitude characteristic of this filter satisfies the alternation theorem and consequently has the lowest complexity in obtaining a prescribed maximum deviation in the passband and the fastest possible rate of attenuation near the cutoff frequency. In this sense this filter is optimal. Closed-form expressions for direct calculation of filter coefficients, cutoff frequency and maximal passband attenuation are derived.