Comparator, analog to digital converter, and offset cancellation method thereof

An analog-to-digital converter, comprising:

• a plurality of comparator circuits configured to generate a plurality of decision signals according to an input signal;
• an offset calculation circuit configured to calculate an offset of the plurality of comparator circuits according to the plurality of decision signals to generate a plurality sets of control signals;
• a hybrid offset voltage generation circuit configured to select a first reference voltage and a second reference voltage from a plurality of reference voltages according to the plurality sets of control signals and utilize the first reference voltage and the second reference voltage to perform a charge transfer operation to generate a plurality sets of calibration voltages;
• and
• a plurality of offset cancellation circuits configured to cancel the offset according to the plurality sets of calibration voltages.

An offset cancellation method, comprising:

• generating, by a comparator circuit, a decision signal according to an input signal;
• calculating an offset of the comparator circuit according to the decision signal to generate a plurality of control signals;
• selecting a first reference voltage and a second reference voltage from a plurality of reference voltages according to the plurality of control signals, in order to utilize the first reference voltage and the second reference voltage to perform a charge transfer operation to generate a plurality of calibration voltages;
• and
• cancelling the offset of the comparator circuit according to the plurality of calibration voltages.