Synthesis and pipelining of ladder wave digital filters

Abstract

In conventional digital-domain ladder wave digital filter (WDF) design approaches, pole-zero cancellation of a reflection function is performed each time an adaptor parameter is calculated. In this brief, a new ladder WDF synthesis method in the digital domain is proposed. In this approach, adaptor combinations realizing a complex conjugate transmission zero pair are regarded as one module and pole-zero cancellation is performed after all the parameters in the module are calculated. By this approach, the number of pole-zero cancellations is reduced by 66% compared with that of the conventional methods, which not only reduces numerical error accumulation during the filter synthesis, but also simplifies the filter-synthesis procedures. Also, a ladder WDF pipeline method is proposed, which reduces the hardware overhead of the pipelined filter by about 33%-50% compared with that of the previous pipeline method.