Design of narrow transition band variable bandwidth digital filter

Abstract

This study presents a novel implementation technique for linear phase variable bandwidth finite impulse response (FIR) filters with a noticeable reduction in transition bandwidth as well as hardware complexity. In this proposition, concept of Farrow structure based design technique is effectively utilised; whereas the fixed sub-filters are constructed from a generalised interpolated bandpass method based low-pass FIR filter by means of different techniques such as interpolation, up-sampling and masking. Simulation results have shown the frequency response characteristics of several variable bandwidth FIR filters, designed with the help of the proposed architecture. Simulation results have shown a drastic reduction of transition bandwidth resulting from the proposed variable bandwidth FIR filters of up to ∼70-80%, when compared with other state-of-the-art filtering techniques, with a significant reduction in hardware complexity of up to ∼50%.