ADC having chopper offset cancellation

A circuit comprising:

• a differential amplifier circuit having positive and negative inputs and positive and negative outputs;
• a capacitive element across the differential inputs and outputs in an integrating configuration, the capacitive element including positive and negative differential components, each having a first end and a second end;
• and
• a chopper mechanism for providing offset cancellation for the circuit, the chopper mechanism including
• a first pair of cross-coupled switches including a first switch coupled between the first end of the capacitive element positive component and the negative input of the amplifier circuit and a second switch coupled between the first end of the capacitive element positive component and the positive input of the amplifier circuit;
• a second pair of cross-coupled switches including a third switch coupled between the second end of the capacitive element positive component and the positive output of the amplifier circuit and a fourth switch coupled between the second end of the capacitive element positive component and the negative output of the amplifier circuit,
• a third pair of cross-coupled switches including a fifth switch coupled between the first end of the capacitive element negative component and the negative input of the amplifier circuit and a sixth switch coupled between the first end of the capacitive element negative component and the positive input of the amplifier circuit;
• and
• a fourth pair of cross-coupled switches including a seventh switch coupled between the second end of the capacitive element negative component and the positive output of the amplifier circuit and an eighth switch coupled between the second end of the capacitive element negative component and the negative output of the amplifier circuit such that the cross-coupled switches enable swapping of the inputs and outputs of the amplifier circuit for canceling chopper offset.

An Analog-to-Digital Converter (ADC) circuit, comprising:

• a differential amplifier circuit;
• a differential capacitive element coupled across the amplifier circuit in an integrating feedback configuration;
• and
• an offset cancellation mechanism including input cross-coupled switches coupled between the differential capacitive element and the amplifier circuit inputs and output cross-coupled switches coupled between the differential capacitive element and the amplifier circuit outputs for swapping the amplifier circuit inputs and outputs to cancel chopper offset.

A method for canceling chopper offset, comprising:

• receiving a differential input signal;
• storing a signal level of the input signal;
• presenting a charge packet corresponding to the stored signal level to a differential amplifying circuit including an integrator feedback circuit;
• and
• chopping the charge packet between positive and negative inputs of the differential amplifying circuit such that chopper offset is canceled.