A digital-to-analog converter has an output. An analog-to-digital converter senses a voltage at the output of the digital-to-analog converter and generates a digital voltage signal. A source mismatch estimator processes the digital voltage signal to output an error signal indicative of current source mismatch within the digital-to-analog converter. An error code generator generates a digital calibration signal from the error signal. The digital calibration signal is converted by a redundancy digital-to-analog converter to an analog compensation signal for application to the output of analog-to-digital converter to nullify effects of the current source mismatch.