Self-calibration circuit for delta-sigma modulators, corresponding device and method

A system, comprising:

• a sensor;
• a delta-sigma modulator coupled to the sensor, the delta-sigma modulator having:
• a quantizer;
• a signal propagation path including a plurality of cascaded integrators coupled between the sensor and the quantizer;
• and
• a feedback network including a plurality of digital-to-analog converters, wherein in a quantizing mode of operation,
• each of the plurality of digital-to-analog converters of the feedback network is coupled between an output of the quantizer and a respective integrator of the plurality of cascaded integrators;
• and
• the delta-sigma modulator generates a digital signal at an output of the quantizer based on an analog input signal received from the sensor;
• and
• calibration circuitry coupled to the output of the quantizer, wherein in a calibration mode of operation,
• a first digital-to-analog converter of the plurality of digital-to-analog converters of the feedback network receives a signal including a periodic alternated digital sequence, the first digital-to-analog converter being coupled to a first integrator of the plurality of cascaded integrators;
• integrators of the plurality of cascaded integrators other than the first integrator operate in a gain mode of operation;
• the delta-sigma modulator generates a digital test signal at an output of the quantizer based on the signal including the periodic alternated digital sequence;
• and
• the calibration circuitry generates an integrator calibration signal based on the digital test signal and a reference digital word.

A method, comprising:

• operating a delta-sigma modulator having calibration circuitry in a calibration mode of operation, generating an integrator calibration signal;
• calibrating the delta-sigma modulator based on the integrator calibration signal;
• and
• operating the calibrated delta-sigma modulator in a quantizing mode of operation, wherein,
• the delta-sigma modulator includes:
• an input node;
• a quantizer;
• a signal propagation path including a plurality of cascaded integrators coupled between the input node and the quantizer;
• and
• a feedback network including a plurality of digital-to-analog converters,
• in the calibration mode of operation,
• the calibration circuitry is coupled to an output of the quantizer;
• a first digital-to-analog converter of the plurality of digital-to-analog converters of the feedback network receives a signal including a periodic alternated digital sequence, the first digital-to-analog converter being coupled to a first integrator of the plurality of cascaded integrators;
• integrators of the plurality of cascaded integrators other than the first integrator operate in a gain mode of operation;
• the delta-sigma modulator generates a digital test signal at an output of the quantizer based on the signal including the periodic alternated digital sequence;
• and
• the calibration circuitry generates the integrator calibration signal based on the digital test signal and a reference digital word, and
• in the quantizing mode of operation,
• each of the plurality of digital-to-analog converters of the feedback network is coupled between an output of the quantizer and a respective integrator of the plurality of cascaded integrators;
• and
• the delta-sigma modulator generates a digital signal at an output of the quantizer based on an analog input signal received at the input node.

A non-transitory computer-readable medium having contents which configure a delta-sigma modulator having calibration circuitry to perform a method, the method comprising:

• operating the delta-sigma modulator in a calibration mode of operation, generating an integrator calibration signal;
• calibrating the delta-sigma modulator based on the integrator calibration signal;
• and
• operating the calibrated delta-sigma modulator in a quantizing mode of operation, wherein,
• the delta-sigma modulator includes:
• an input node;
• a quantizer;
• a signal propagation path including a plurality of cascaded integrators coupled between the input node and the quantizer;
• and
• a feedback network including a plurality of digital-to-analog converters,
• in the calibration mode of operation,
• the calibration circuitry is coupled to an output of the quantizer;
• a first digital-to-analog converter of the plurality of digital-to-analog converters of the feedback network receives a signal including a periodic alternated digital sequence, the first digital-to-analog converter being coupled to a first integrator of the plurality of cascaded integrators;
• integrators of the plurality of cascaded integrators other than the first integrator operate in a gain mode of operation;
• the delta-sigma modulator generates a digital test signal at an output of the quantizer based on the signal including the periodic alternated digital sequence;
• and
• the calibration circuitry generates the integrator calibration signal based on the digital test signal and a reference digital word, and
• in the quantizing mode of operation,
• each of the plurality of digital-to-analog converters of the feedback network is coupled between an output of the quantizer and a respective integrator of the plurality of cascaded integrators;
• and
• the delta-sigma modulator generates a digital signal at an output of the quantizer based on an analog input signal received at the input node.