US Patent 7545295 Self-calibrating digital-to-analog converter and method thereof

A digital-to-analog converter improves differential non-linearity by performing a calibration of at least one weighted cell in response to a calibration command. The digital-to-analog converter includes a group of weighted cells, a tunable cell having a tunable weight controlled by a tuning word, and a calibration cell to generate a combined output signal in response to a digital input word, the calibration command, and a calibration sequence. The digital-to-analog converter also includes a calibration circuit configured to sample and subsequently process the combined output signal to establish the tuning word in accordance with the calibration command and the calibration sequence.