Patent ID: 8259196

Claim:
A comparator comprising: a signal input terminal; a reference signal terminal; a first capacitor connected between the signal input terminal and a signal line; a second capacitor connected between the reference signal terminal and a reference signal; a first switching transistor for calibration which is turned on and off to periodically charge the first capacitor with a voltage difference between a signal voltage and an operating point voltage of the comparator, the first switching transistor coupled between the first capacitor and an output signal node; and a second switching transistor for calibration which is turned on and off to periodically charge the second capacitor with a voltage difference between a reference signal voltage and the operating point voltage of the comparator, wherein an on-resistance of each of the first and second switching transistors when turned on when performing the charging is dynamically controlled by a control pulse having a limited amplitude, and the control pulse has an amplitude smaller than that of the operating point voltage but large enough to cause the first and second switching transistors to turn on.