Sigma-delta analog-to-digital converter circuit with real time correction for digital-to-analog converter mismatch error

A circuit for estimating unit current element mismatch error in a digital to analog converter circuit, where unit current elements of the digital to analog converter circuit are actuated in response to bits of a thermometer coded signal generated in response to a quantization output signal, comprising:

• a correlation circuit configured to generate estimates of the unit current element mismatch error from a correlation of a first signal derived from the thermometer coded signal and a second signal derived from the quantization output signal;
• wherein said correlation circuit comprises:
• a first signal processing circuit configured to process the thermometer coded signal to generate a signal measure that is constant and independent of the thermometer code of thermometer coded signal;
• a second signal processing circuit configured to filter the signal measure to generate a filtered signal measure;
• and
• a third signal processing circuit configured to filter the quantization output signal to generate a filtered quantization output signal;
• wherein the correlation circuit functions to correlate the filtered signal measure and the filtered quantization output signal to generate the estimates of the unit current element mismatch error.

A system, comprising:

• a quantization circuit configured to generate a quantization output signal;
• a digital to analog converter (DAC) circuit including unit current elements that are actuated in response to bits of a thermometer coded signal generated in response to the quantization output signal;
• and
• an error estimation circuit configured to estimate unit current element mismatch error in the digital to analog converter circuit, wherein the error estimation circuit comprises:
• a correlation circuit having a first input that receives the thermometer coded signal and a second input that receives the quantization output signal, said correlation circuit configured to generate estimates of the unit current element mismatch error from a correlation of a first signal derived from the received thermometer coded signal and a second signal derived from the received quantization output signal.

A system, comprising:

• a quantization circuit configured to generate a quantization output signal;
• a digital to analog converter (DAC) circuit including unit current elements that are actuated in response to bits of a thermometer coded signal generated in response to the quantization output signal;
• an error estimation circuit configured to estimate unit current element mismatch error in the digital to analog converter circuit, wherein the error estimation circuit comprises:
• a correlation circuit configured to generate the estimates of the unit current element mismatch error from a correlation of a first signal derived from the thermometer coded signal and a second signal derived from the quantization output signal;
• and
• a replica DAC circuit that receives the quantization output signal and is configured to apply a correction for the unit current element mismatch error in response to the estimates of the unit current element mismatch error generated by the correlation circuit.

A system, comprising:

• a quantization circuit configured to generate a quantization output signal;
• a digital to analog converter (DAC) circuit including unit current elements that are actuated in response to bits of a thermometer coded signal generated in response to the quantization output signal;
• and
• an error estimation circuit configured to estimate unit current element mismatch error in the digital to analog converter circuit, wherein the error estimation circuit comprises:
• a correlation circuit configured to generate the estimates of the unit current element mismatch error from a correlation of a first signal derived from the thermometer coded signal and a second signal derived from the quantization output signal;
• wherein the correlation circuit comprises:
• a first signal processing circuit configured to process the thermometer coded signal to generate a signal measure that is constant and independent of the thermometer code of thermometer coded signal;
• a second signal processing circuit configured to filter the signal measure to generate a filtered signal measure;
• and
• a third signal processing circuit configured to filter the quantization output signal to generate a filtered quantization output signal;
• wherein the correlation circuit functions to correlate the filtered signal measure and the filtered quantization output signal to generate the estimates of the unit current element mismatch error.

A sigma-delta modulator, comprising:

• a differencing circuit having a first input configured to receive an input signal and a second input configured to receive a feedback signal and an output configured to generate a difference signal;
• a loop filter circuit configured to filter the difference signal and generate a change signal;
• a quantization circuit configured to sample the change signal at a sampling frequency rate, quantize the sampled change signal and generate a stream of code words;
• a digital-to-analog converter (DAC) circuit configured to generate the feedback signal by converting a thermometer coded signal generated in response to the stream of code words, wherein the DAC circuit has a non-ideal operation due to mismatch error;
• a replica DAC circuit that provides a digital replication of the DAC circuit, said digital replication comprising estimated error programming which accounts for the non-ideal operation of the DAC circuit due to mismatch error;
• and
• an error estimation circuit configured to generate the estimated error programming from a correlation of the thermometer coded signal and the stream of code words.