Input offset compensation for a comparator circuit

An offset-compensation system, comprising:

• a comparator including:
• a first input terminal configured to receive a first input signal;
• a second input terminal configured to receive a second input signal;
• an input stage including a first transistor and a second transistor configured together as a differential pair;
• an output stage coupled to the input stage and configured to generate a comparator-output signal;
• and
• a chopper circuit configured to alternate an input polarity of the input stage and an output polarity of the output stage during a first phase and a second phase;
• a counter circuit coupled to receive the comparator-output signal and a clock signal, the counter circuit configured to generate a first count during the first phase and to generate a second count during the second phase based on the comparator-output signal and the clock signal;
• and
• a compensation circuit configured to generate an offset-compensation signal based on the first count and the second count;
• and
• wherein the comparator further includes an offset controller configured to adjust an input offset of the comparator based on the offset-compensation signal.

A method, comprising:

• receiving a first input signal at a first input terminal of a comparator;
• receiving a second input signal at a second input terminal of the comparator;
• alternating an input polarity of an input stage of the comparator during a first phase and a second phase;
• generating a first count corresponding to the first phase based on a comparator-output signal and a clock signal;
• generating a second count corresponding to the second phase based on the comparator-output signal and the clock signal;
• and
• compensating for an input offset of the comparator based on the first count and the second count.