A Design of Two Sub-Stage Square-Root Nyquist Matched Filter

A pair of matched filters whose cascade response satisfies the Nyquist criterion can guarantee the inter-symbol interference (ISI)-free transmission for band-limited communication systems. For a linear phase finite impulse response square root Nyquist filter, it is necessary to strike a balance between the stop-band attenuation (SBA) and ISI performance. This paper proposes a novel approach for obtaining the square root Nyquist filter by adopting two sub-stage cascade filters group, which is known as the compensated half-band (HB) filter group (CHFG). The first sub-stage of the CHFG is a HB filter which can guarantee the required SBA performance on low computational complexity; whereas, the second substage is an ISI compensation filter to ensure that the cascaded response of two CHFGs satisfies the Nyquist criterion. Theoretical analysis and experimental results show that the proposed CHFG can either achieve better SBA/ISI performance or reduce the computational complexity.