Efficient calibration of errors in multi-stage analog-to-digital converter

A digitally assisted method for calibrating an analog-to-digital converter having multiple stages of analog-to-digital conversion, the method comprising:

• measuring, by dedicated circuitry, one or more characteristics associated with the analog-to-digital converter, wherein the multiple stages generate respective output codes and respective residue signals;
• computing, by digital circuitry on-chip with the analog-to-digital converter, correction terms to be used for correcting residue signals of the multiple stages based on the measured errors, wherein computing correction terms used for a given stage takes into account a characteristic(s) measured for one or more earlier stages;
• and
• writing, by the digital circuitry, the correction terms to separate look up tables provided for each residue signal to be corrected, wherein each look up table is indexed by output codes of a respective stage.

An apparatus comprising:

• cascaded means having stages for generating respective output codes and respective residue signals;
• storage means for storing correction terms selectable by a respective output code;
• means for correcting respective residue signals based on selected correction terms;
• and
• means on-chip with the cascaded means for updating correction terms in the storage means based on measured characteristics, wherein updating the correction terms used for a given stage of the cascaded means takes into account the measured characteristics for the given stage of the cascaded means and one or more earlier stage(s) of the cascaded means.

A multi-stage converter with digitally assisted calibration, the multi-stage converter comprising:

• converter stages in cascade;
• one or more memory elements for storing correction terms;
• circuitry for adjusting a particular converter stage based on a selected correction term;
• and
• digital circuitry for computing the correction terms in the one or more memory elements, wherein computing correction terms used for a given converter stage takes into account a characteristic of the given converter stage and characteristic(s) of one or more earlier converter stages.