On ΣΔ signal processing remodulator complexity

There has recently been some interest in the emerging technique of Sigma Delta Signal Processing (SDSP) where direct processing of the bitstream is proposed as an alternative to the decimation-PCM processing-interpolation cycle required for DSP of ΣΔ converted signals. SDSP requires digital (re)modulation with a variety of wordlengths in the oversampled datastream; the prediction and control of the remodulator complexity is crucial in determining the relative value of SDSP in any given context. This paper addresses this issue in deriving a new method for reducing remodulator complexity and in obtaining its dependence on the datastream wordlength