Unstable IIR-Like Filter Blocks for Generating Linear-Phase FIR Filters: A Noise Analysis

The authors have recently proposed two alternative techniques for generating narrow transition band linear-phase FIR filters. The implementation of both designs requires a set of demultiplexers and IIR filters, which accounts for the efficiency of the designs. On the other hand, since the demultiplexers and the IIR filters go through an activation-deactivation cycle at different time slots, the noise analysis for the structure becomes extremely complex. This study aims to derive closed form formulae for the roundoff noise generated in the proposed structures.