Estimation of Delta–Sigma Converter Spectrum

Effects of the windowing process, widely investigated by the scientific literature for narrow–band components embedded in white noise, is not sufficiently detailed when signals are corrupted by colored noise. Such a phenomenon can heavily affect the spectral parameters estimation of the noisy signal. In this paper effects of the windowing on the output of analog–to–digital converters with ∆Σ topology, which present a spectrally shaped quantization noise, is analyzed. In particular, the spectral leakage of both narrow– and wide– band components is investigated and a criterion for choosing the most appropriate window for any given modulator resolution is given. The proposed analysis validates the use of the Hanning sequence as the optimum two term cosine window to be employed for characterizing low order ∆Σ modulators.