Method and apparatus for oscillation recovery in a delta-sigma A/D converter

An integrator stage of an analog-to-digital modulator circuit, the integrator stage comprising:

• an amplifier having an inverting input, a non-inverting input, an inverting output and a non-inverting output;
• a first integrating capacitor coupled between the inverting input and the non-inverting output;
• a second integrating capacitor coupled between the non-inverting input and the inverting output;
• a first restore switch coupled between the inverting input and the non-inverting input;
• and
• a second restore switch coupled between the inverting output and the non-inverting output.

An analog-to-digital converter modulator circuit comprising:

• an input conductor;
• an output conductor;
• a summing junction configured to sum a signal on the input conductor with a sample of a signal on the output conductor carried by a feedback conductor, and to generate an output signal;
• a plurality of integrator stages coupled between the input and the output, each stage having:
• an operational amplifier comprising:
• a first restore switch coupled between an inverting input and a non-inverting input;
• and
• a second restore switch coupled between an inverting output and a non-inverting output;
• a first integrating capacitor coupled between the inverting input and non-inverting output;
• and
• a second integrating capacitor coupled between the non-inverting input and inverting output;
• converter circuitry configured to receive an analog output from a last of the plurality of integrator stages and convert the analog output to a digital output on the output conductor;
• and
• monitoring circuitry coupled to a portion of the modulator circuit and configured to monitor at least one circuit operating characteristic and generate a restore signal for activating each of the first and second restore switches.