Patent ID: 8476910

Claim:
A capacitive sensor with a calibration mechanism comprising: a set of sensing capacitors to generate a capacitance variation; a subtraction circuit comprising: a first capacitor array to generate offset-adjusting charges according to an initial offset of the sensing capacitors; and a second capacitor array to generate subtraction charges according to a sensitivity of the sensing capacitors, in which the subtraction charges is a fixed value; and an integration circuit comprising two input ends, wherein one of the two input ends is connected to the sensing capacitors and the subtraction circuit; wherein when during a sensing period, the integration circuit performs integration according to the capacitance variation and performs a cancellation of the effect of the initial offset according to the offset-adjusting charges to generate an integration output signal; when during a computing period, the integration output signal is continuously subtracted by the subtraction charges of the fixed value until the integration output signal is smaller then a reference voltage to generate a subtraction count.