the invention concerns a method for compensating the non - linearity of a sigma - delta analog - to - digital converter with quantization at n levels comprising a digital - to - analog converter . the method comprises a calibrating step which consists in transforming the multibit sigma - delta analog - to - digital converter into a sigma - delta analog - to - digital converter with quantization at three levels , then at two levels . the correction values of each level to be corrected are accurately measured . the method also comprises a normal functioning phase which consists , when the sigma - delta an analog - to - digital converter is operating with quantization at n levels , in producing an instantaneous correction of errors of the analog - to - digital converter using said correction values .