Adaptive compensation of analog circuit imperfections for cascaded delta-sigma analog-to-digital converters

The performance of cascaded delta-sigma analog-to-digital converters is limited by noise leakage caused by analog circuit imperfections in its switched-capacitor implementation, such as finite opamp gain, nonlinear settling and capacitance ratio error. The adaptive algorithm and structure proposed in this paper can compensate the effects of these imperfections using digital filtering. Experimental results show that after the compensation the performance of a 2-0 cascaded delta-sigma analog-to-digital converters is improved by about 12 dB in signal-to-noise-and-distortion ratio for an oversampling ratio of 4, and by about 9 dB for a ratio of 8.