New multibit delta-sigma modulator structure with reduced sensitivity to the D/A conversion error

A new structure is presented for multibit delta-sigma modulators, where the D/A conversion error as well as the A/D conversion error (the quantisation noise) is spectrally shaped. Thus the requirement on the accuracy of the D/A convertor is relaxed without sacrificing the advantages of using a multibit A/D convertor in delta-sigma modulators. The new structure also has a feature of design flexibility, for the choice of the noise shaping function does not have strong influence on the signal in the passband. Both analysis and simulation show that the new structure is relatively tolerant of analogue component inaccuracies