A Delta Sigma analogue to digital converter (ADC) is a semiconductor device that samples a target signal by large factors and filters out the chosen signal type. the resulting signal is then fed back and subtracted from the input to the filter.
The construction of a delta-sigma ADC involves a core modulator, a 1-bit analogue part that is very simple and a complex digital part. This type of ADC relies upon noise shaping and oversampling to achieve high-resolution conversion. The modulator has the responsibility for digitising the analogue input signal and reducing noise.
A digital filter follows the ADC which reduces the sampling rate, filters off unwanted noise signal and increases the resolution of the output (sigma-delta modulation, also called delta-sigma modulation).