SIGMA-DELTA IIR FILTER REALIZATION USING THIRD-ORDER REMODULATORS
Aristodimos Pneumatikakis, Anthony George Constantinides, T. Deliyannis, V. Anastassopoulos · Journal of Circuits Systems and Computers · 1998
In general, Sigma-Delta (ΣΔ) IIR filters are realized using cascades of second-order sections. The existing biquadratic structures do not exploit the high signal-to-noise ratio (SNR) of the higher-order ΣΔ modulators. A second-order IIR structure which achieves this high SNR is proposed. For this purpose a third-order ΣΔ remodulator, necessary to provide the ΣΔ output samples and eliminate the multipliers, is incorporated into the filter structure. The performance of the proposed biquadratic section is investigated and compared to existing counterparts. A cascade of three such sections is used to implement a sixth-order IIR filter.