Design and analysis of delta-sigma based IIR filters

Design techniques for IIR filters operating on oversampled delta-sigma (ΔΣ) modulated signals are presented. It is shown that ΔΣ-based IIR filters can be efficiently realized by eliminating all multibit multipliers through the use of remodulating internal filter states. Noise results are presented showing that linear noise analysis gives excellent predictions of the noise performance over the frequency band of interest. It is also shown that latency and computational complexity can be reduced in some VLSI applications where digital representations of analog signals exist using oversampled ΔΣ converters