Self-calibrated digital-to-analog converter

摘要

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.

主权项

1. A circuit, comprising:
a plurality of current source cells coupled to an output and each configured to generate an output current in response to digital-to-analog conversion of digital data, a sum of said output currents producing an output voltage; and a calibration circuit comprising:
a training code generator configured to generate first and second training codes for application to the plurality of current source cells as said digital data, the first and second training codes configured to isolate a selected one of the current source cells;an analog-to-digital converter configured to sample the output voltage in response to each of the first and second training codes and generate corresponding first and second digital voltage signals;a differencing circuit configured to determine a difference between the first and second digital voltage signals, said difference being indicative of mismatch in the selected one of the current source cells;an error code generator configured to generate a digital calibration signal in response to said difference and the digital data for digital-to-analog conversion by the plurality of current source cells; anda redundancy digital-to-analog converter configured to convert the digital calibration signal to an analog compensation signal for application to said output.