A second intercept point (IP2) calibrator and a method for calibrating IP2 are disclosed. The IP2 calibrator and the method for calibrating IP2 remove any direct current (DC) offset by comparing a common-mode reference voltage with the common-mode voltage measured between a first output terminal and a second output terminal of a mixer, and calibrates the IP2 of the mixer by comparing the common-mode voltage with a calibration reference voltage. The calibration reference voltage is independent of the common-mode reference voltage and may be a quantized variable voltage generated according to digital control code.