12.14 DESIGN OF FIR FILTERS
FIR filters can be designed by Fourier series method or by Numerical analysis methods. To reduce Gibb’s oscillations we use window functions. We will concentrate only on the Fourier series method.
12.14.1 Fourier Series Method for Design of FIR Filters
The frequency response of any FIR filter is a periodic function of ω having sampling frequency ωs which can be expressed by Fourier series. The frequency response of FIR filter is nothing but the DTFT of impulse response h(nTs) and we can write
Let us put in Eq. (12.182) ...