REALIZATION OF DIRECT-FORM IIR FILTERS USING DELTA OPERATOR

摘要

The use of the delta operator in the realizations of digital filters has recently gained interest due to its good finite-word-length performance under fast sampling. In this paper we consider the cascaded realization of IIR digital filters using second order direct form delta structure as basic unit. We focused on the stability and .the roundoff noise performance of the filter, specially the effect of the inverse delta operator. To increase the stability we proposed the use of Local Nonlinear Feedback Loop (LNFL) in the hardware implementation of the inverse delta operator. The simulation of the different systems showed large improvement in the stability of the system using the LNFL technique. The results showed that using LNFL with unity delta parameter results in more stable system than using optimum value for the delta parameter.