Switched-capacitor sigma-delta analog-to-digital converter with input voltage overload protection

An analog-to-digital converter comprising:

• an integrator having an input and an output and an integrator capacitor connected between the input and output;
• a switched-capacitor input circuit including at least one input capacitor, at least one input sampling switch operable to connect the input capacitor to be charged by an input voltage during each of first and second non-overlapping time intervals, and at least one input transfer switch operable to connect the input capacitor to transfer charge to the integrator capacitor during one of the first and second time intervals;
• and
• a switched-capacitor feedback circuit, connected in a feedback path between the input and the output of the integrator, including at least one feedback capacitor, at least one feedback sampling switch operable to connect the feedback capacitor to be charged by a feedback reference voltage during each of the first and second time intervals, and at least one feedback transfer switch operable to connect the feedback capacitor to transfer charge to the integrator capacitor during each of the first and second time intervals.

A method for converting an analog input signal to digital output samples comprising the steps of:

• charging an input capacitor by the input signal during each of first and second non-overlapping time intervals;
• transferring charge from the input capacitor to an integrator capacitor during one of the first and second time intervals;
• charging a feedback capacitor by a feedback reference voltage during each of the first and second time intervals;
• and
• transferring charge from the feedback capacitor to the integrator capacitor during each of the first and second time intervals.

An analog-to-digital converter comprising:

• an integrator having an input and an output;
• a switched-capacitor input circuit including at least one input capacitor, the input capacitor to be charged by an input voltage during at least one of a plurality of time intervals, and to transfer charge to the integrator during not all of the plurality of intervals;
• and
• a switched-capacitor feedback circuit, connected in a feedback path between the input and the output of the integrator, including at least one feedback capacitor, to be charged by a feedback reference voltage during at least one of the plurality of intervals and to transfer charge to the integrator during each of the plurality of intervals.