Self calibration segmented digital-to-analog converter

A method of self calibration for a segmented digital-to-analog converter, wherein the segmented digital-to-analog converter converts a digital input code to an analog output equal to the sum of an analog output and an analog calibration factor, further wherein the digital input code has an associated segment, and wherein a particular digital input code received by the segmented digital to analog converter produces an equivalent analog output, the method comprising the steps of:

• determining a trim value for each segment of a segmented digital to analog converter by comparing each segment to the same reference value and using the difference between the reference value and a given segment to determine the trim value for the given segment;
• storing the trim values in memory;
• summing a plurality of trim values to produce a digital calibration factor associated with each given digital input signal, wherein the plurality of trim values are the trim values for a plurality of segments preselected to be enabled by the given digital input signal;
• and
• storing each digital calibration factor in memory at an address corresponding to the digital input signal.