Efficient determination of feedback DAC errors for digital correction in ΔΣ A/D converters

Feedback DAC errors in a ΔΣ analog to digital converter are determined by measuring the idle channel output and removing the DAC elements one by one. This method requires simple computation, does not add excess loop delay, and requires no reconfiguration of the ΔΣ modulator. The errors so determined can be used to correct the output codes in the digital domain or the DAC elements in the analog domain. This technique is a useful alternative to the popular dynamic element matching at high speeds as excess delay cannot be tolerated and at low oversampling ratios where DEM can result in tones. Simulation results indicate that the correction values can be obtained to an accuracy that is sufficient to reduce noise and distortion to nearly ideal levels.