Improved performance of multi-bit delta-sigma analog to digital converters via requantization

System performance of an oversampled analog to digital converter (ADC) with feedback noise shaping is limited by the precision of the digital to analog converter (DAC) in the feedback path as well as by the number of integrators in the loop(s). Standard designs avoid the DAC precision problem by restricting the ADC and DAC to a single bit, while stability and matching considerations limit systems to three loops. This limit in turn defines the oversample ratio for a given effective bandwidth and noise performance. A simple modification to the oversampled ADC which avoids these limitations via requantization in the feedback path of the original delta-sigma loop structure is presented.<
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