On the performance of an oversampled analog to digital converter with digital requantizer in feedback path

Conventional delta-sigma converters limit the complexity of the feedback DAC to a precision single bit which in turn leads to the use of a 1-bit ADC in the feedforward path. A spectrally controlled requantization between the output of the multibit ADC and the input to the 1-bit DAC can be performed with an oversampled digital sigma-delta loop in the feedback path of the analog sigma-delta loop. This paper we describes and reports on the hardware implementation of an enhanced performance delta-sigma loop modified to use a multibit ADC in the feedforward path along with a 1-bit DAC in the feedback path