A method for operating an analog-digital converter including a number of charging units, each comprising a switchable capacitor and an associated reference potential source, includes evaluating a comparison potential in successive decision steps to obtain a comparison result; and successively switching one of the charging units following a previous one of the decision steps, wherein, depending on the obtained comparison result, the comparison potential is changed by the one respective charging unit by connecting the associated reference potential source to the switchable capacitor, wherein in two of the successive switching steps different reference potentials are applied to the switchable capacitor.