Analog-to-digital converter with instability recovery circuit

An integrated circuit (IC) comprising:

• a delta-sigma modulator (DSM) including a number integrators, a first digital-to-analog converter (DAC), a second DAC, and a quantizer, wherein N is greater than one;
• and
• a control circuit configured to:
• in a first mode, operate the DSM as an Nth order modulator, so that the first DAC provides a first feedback signal responsive to an output of the quantizer, and so that outputs of the N integrators are responsive to the first feedback signal;
• in a second mode, operate the DSM as a first order modulator, so that the second DAC provides a second feedback signal responsive to the output of the quantizer, and so that an output of the quantizer is responsive to an output of a single one of the N integrators and to the second feedback signal and not to the first feedback signal;
• and
• switch from the first mode to the second mode responsive to an output of an integrator and a threshold.

A system comprising:

• a lowpass analog filter having an analog signal input and an output;
• a sampling circuit having an input and an output, the input of the sampling circuit coupled to the output of the lowpass analog filter;
• a first integrator having a first input, a second input, and an output, the first input of the first integrator coupled to the output of the sampling circuit;
• a first weighted summer having an first input, a second input, a third input, and an output, the first input of the first weighted summer coupled to the output of the sampling circuit, and the second input of the first weighted summer coupled to the output of the first integrator;
• a second integrator having an input and an output, the input of the second integrator coupled to the output of the first weighted summer;
• a second weighted summer having an input and an output, the input of the second weighted summer coupled to the output of the second integrator;
• a quantizer having an input and an output, the input of the quantizer coupled to the output of the second weighted summer;
• a first digital-to-analog converter (DAC) having an input and an output, the input of the first DAC coupled to the output of the quantizer and the output of the first DAC coupled to the second input of the first integrator;
• a second DAC having an input and an output, the input of the second DAC coupled to the output of the quantizer and the output of the second DAC coupled to the third input of the first weighted summer;
• a lowpass digital filter having an input and an output, the input of the lowpass digital filter coupled to the output of the quantizer.