On the sensitivity of lattice wave digital filters versus block-optimal state-space structures

This paper describes a study comparing, in terms of sensitivity, IIR filters produced by second order structures connected in parallel and in cascade, and Lattice Wave Digital Filters (LWDF). Simulation programs have been used(“sen-iir” for IIR filters and “sen-cel” for LWDF), from which the filter coefficient derives the multiparametric sensitivity curve in relation to frequency to obtain more satisfactory results. For IIR filters optimal sections have been used as they have been shown to possess less roundoff noise (and consequently less sensitivity) than direct sections. Furthermore, these second order sections are reached internally via state variables. Part of the theoretical phase in the programs required for obtaining the sensitivity graphs has been included, obtained both from IIR filters in state variables and LWDF