An analog-to-digital converter, ADC, configured to receive an analog signal as input and to provide an output digital value (DATA_OUT) representative of the analog signal, comprising: a first multiplexer configured to receive two or more reference signals (VREF1, VREF2) and to provide a selected reference signal; a sigma delta modulator configured to receive the selected reference signal and the analog signal and to provide pulse density modulation, PDM, streams representative of the analog signal received; a control circuit configured to cause the first multiplexer to select (i) in a first phase of a conversion, a first one of the reference signals as the selected reference signal and (ii) in each of one or more subsequent phases of the conversion, one of the other reference signals as the selected reference signal, the selected reference signal in each subsequent phase being different from any of the selected reference signal of earlier phases, such that the sigma delta modulator is configured to provide, (i) in the first phase of the conversion, a first PDM stream representing the most significant bits, MSBs, of the output digital value and (ii) in each of the one or more subsequent phases of the conversion, a corresponding additional PDM stream, representing the least significant bits, LSBs, of the output digital value, with each of the first and additional PDM streams corresponding to a different oversampling ratio, OSR, of the sigma delta modulator, the OSR being equal to 2 N, where N is the number of bits in the MSBs or respectively LSBs of the corresponding phase of the conversion; and a digital filter configured to combine the first PDM stream and the subsequent one or more additional PDM streams to provide the output digital value (DATA_OUT). a first multiplexer configured to receive two or more reference signals (VREF1, VREF2) and to provide a selected reference signal; a sigma delta modulator configured to receive the selected reference signal and the analog signal and to provide pulse density modulation, PDM, streams representative of the analog signal received; a control circuit configured to cause the first multiplexer to select (i) in a first phase of a conversion, a first one of the reference signals as the selected reference signal and (ii) in each of one or more subsequent phases of the conversion, one of the other reference signals as the selected reference signal, the selected reference signal in each subsequent phase being different from any of the selected reference signal of earlier phases, such that the sigma delta modulator is configured to provide, (i) in the first phase of the conversion, a first PDM stream representing the most significant bits, MSBs, of the output digital value and (ii) in each of the one or more subsequent phases of the conversion, a corresponding additional PDM stream, representing the least significant bits, LSBs, of the output digital value, with each of the first and additional PDM streams corresponding to a different oversampling ratio, OSR, of the sigma delta modulator, the OSR being equal to 2 N, where N is the number of bits in the MSBs or respectively LSBs of the corresponding phase of the conversion; and a digital filter configured to combine the first PDM stream and the subsequent one or more additional PDM streams to provide the output digital value (DATA_OUT).