Patent ID: 8681110

Claim:
A sensing circuit for use with a receiving electrode of a capacitive touch panel, a mutual capacitance having a first terminal connected to a driving electrode of the capacitive touch panel and having a second terminal connected to the receiving electrode, the driving electrode receiving a driving signal, the sensing circuit comprising: an operation amplifier having a positive input terminal, a negative input terminal and an output terminal, wherein a reference voltage is inputted into the positive input terminal of the operation amplifier; a first switch having a first terminal connected to the receiving electrode and the second terminal of the mutual capacitance and having a second terminal connected to the negative input terminal of the operation amplifier; a second switch connected between the negative input terminal and the output terminal of the operation amplifier; a feedback capacitor; a third switch having a first terminal connected to the negative input terminal of the operation amplifier and a second terminal connected to a first terminal of the feedback capacitor; a fourth switch having a first terminal connected to a second terminal of the feedback capacitor and a second terminal connected to the output terminal of the operation amplifier; a fifth switch connected between the second terminal of the feedback capacitor and the negative input terminal of the operation amplifier; a sixth switch connected between the first terminal of the feedback capacitor and the output terminal of the operation amplifier; and a sensing circuit output terminal; wherein the driving signal generates at least one pulse during a driving cycle, at a time of a rising edge of the pulse, the first switch, the third switch and the fourth switch are controlled to be in a close state, but the second switch, the fifth switch and the sixth switch are controlled to be in an open state; at a time of a falling edge of the pulse, the first switch, the fifth switch and the six switch are controlled to be in a close state, but the second switch, the third switch and the fourth switch are controlled to be in an open state, and the feedback capacitor is charged in a first charging direction; wherein said sensing circuit output terminal directly connects to said second switch, said forth switch, and sixth switch; and wherein said third switch and said forth switch change states synchronously, and said fifth switch and said sixth switch change states synchronously.