METHOD OF SELF-CALIBRATING A SAR A/D CONVERTER AND SAR-A/D CONVERTER IMPLEMENTING SAID METHOD

摘要

The present disclosure relates to a method of self-calibration of a SAR-A/D converter, comprising a N bit -bit digital-to-analog converter (DAC) for outputting a N bit -bit output code, said digital-to-analog converter (DAC) comprising a first subconverter (C MSB ) having a plurality N Th of thermometer elements T j (1) and a second subconverter (C LSB ) having a plurality of binary-weighted elements N Bin , said output code being defined by a thermometer scale S Th having a number of levels equal to 2 NBitTh +1. The method is characterized in that it comprises the steps of: - measuring, for each thermometer element of said plurality N Th of thermometer elements T j , an error value; - determining a mean value (µ) of these values; - dividing said plurality N Th of thermometer elements T j into a first subset (X) and a second subset (Y) each containing an identical number of values (x, y), equal to N Th /2, wherein said first subset (X) comprises the thermometer elements T j whose values are closer to said mean value (µ) as long as the error of the sum of thermometer elements T j of the first subset (X) is not worse than the error value of the element farthest from said mean value (µ) of said first subset (X) and said second subset (Y) comprising all the remaining thermometer elements T j ; - generating said thermometer scale, on the assumption that: - each level m i of said thermometer scale S Th , with i ranging from 0 to N Th /2, will be the incremental sum of each value (x) of said first ordered subset X; - each further level m i of said thermometer scale S Th , with i ranging from N Th /2+1 to N Th , will be the sum of all the values (y) of said second subset Y plus the incremental sum of the elements (x) of the subset X in any order; - generating said output code (OUTPUT) according to said thermometer scale S Th .