Patent ID: 8547115

Claim:
A capacitance sensing circuit, comprising: a first sensing channel sensing a capacitance under test or a reference capacitance; a second sensing channel sensing the capacitance under test or the reference capacitance; and a difference comparing unit having a first input terminal and a second input terminal, the first input terminal receiving an output of the first sensing channel, the second input terminal receiving an output of the second sensing channel, and the difference comparing unit outputting a first difference according to the capacitance under test and the reference capacitance, wherein during at least one first period of a sensing period, the first sensing channel senses the capacitance under test, and the second sensing channel senses the reference capacitance, and during at least one second period of the sensing period, the first sensing channel senses the reference capacitance, and the second sensing channel senses the capacitance under test.