Design and implementation of 270-Tap finite impulse response filter

Abstract

Filtering is processing of a time domain signal and hence results in changing the original spectral components. The process involves reducing or filtering out some of the unwanted input spectral contents, where it allows certain frequencies to pass while attenuating some other frequencies. Filters are basically of two types–analog and digital, where analog filter operates on continuous signal, while digital filter operates on discrete sample values. Digital filters are basically of two types, finite impulse response (FIR) and infinite impulse response (IIR) filters. FIR filter uses only present and past input samples and none of the past output values for obtaining the present output sample value. This paper is about the implementation of a 270-tap low-pass FIR filter. The paper implements a direct form of FIR filter with given passband, stop-band specifications using MATLAB and Verilog codes. Specifications of the FIR filter are passband frequency = 100 kHz, stop-band frequency = 500 kHz, passband attenuation = 0.01 dB, stop-band attenuation = 120 dB, sampling frequency = 20 MHz.