FIR Filter Design based on All Phase Symmetric Frequency Sampling Method

All phase symmetric frequency sampling method is put forward in this paper, which can setup shift variable according to the cut-off frequency. This method exerts inverse phase-shifts on two sub-filters, constructs a compensation filter, and at last combines sub-filters with compensation filter to form the needed low-pass, band-pass filter and notch filter. The design method is simple with a specific concept, and resolves the difficult problem of controlling the cut-off frequency accurately without changing the length of the filter in the traditional window method and frequency sampling method