Ultra-selective lowpass linear-phase FIR filter function

A new ultra-selective lowpass finite impulse response (FIR) filter function is proposed. First, a new difference equation with all coefficients equals one, and the general structure of the corresponding linear-phase lowpass digital filter is given. Then, the high economical realisation with only four adders and without multipliers, for any filter order is presented. The concrete example of the proposed filter, compared to the already existing filters, demonstrates a higher selectivity, lower passband and circuit of lower complexity.