1. A method of self-calibration of a successive approximation register-analog to digital (SAR-A/D) converter comprising an N-bit digital-to-analog converter for outputting an N-bit output code, the digital-to-analog converter comprising a first subconverter having a plurality (N Th ) of thermometer elements and a second subconverter having a plurality of binary-weighted elements N Bin , the output code defined by a thermometer scale having a number of levels equal to N Th , the method comprising: measuring, for each thermometer element of the plurality of thermometer elements, an error value; determining a mean value of the error values; dividing the plurality of thermometer elements into a first subset (X) and a second subset (Y), each containing an identical number of elements (x, y) equal to N Th /2, wherein the first subset (X) comprises the thermometer elements whose error values are closer to the mean value when a sum of the error values of thermometer elements of the first subset (X) is not more than the error value of the thermometer element farthest from the mean value of the first subset (X), and the second subset (Y) comprises the thermometer elements of the plurality of thermometer elements that are not contained in the first subset (X); generating the thermometer scale, wherein each level m i of the thermometer scale, with i ranging from 0 to N Th /2, is an incremental sum of each error value of the first subset (X), each further level m i of the thermometer scale, with i ranging from (N Th /2)+1 to N Th , is the sum of the values of the second subset (Y) plus the incremental sum of the values of the first subset (X); and generating the output code according to the thermometer scale.