Patent ID: 8421774

Claim:
A sensing circuit for a capacitive touch panel, connected with a receiving electrode of the capacitive touch panel, wherein a mutual capacitance is existed between a driving electrode of the capacitive touch panel and the receiving electrode, and the driving electrode receives a driving signal, the sensing circuit comprising: a first switch, having a first end connected with the receiving electrode; a second switch, having a first end connected with the receiving electrode; a third switch, having a first end connected with a second end of the first switch; a feedback capacitor, having a first end connected with the second end of the first switch; a fourth switch, having a first end connected with a second end of the feedback capacitor; and an operation amplifier, having a positive input terminal connected with a ground terminal, a negative input terminal connected with the first end of the fourth switch, and an output terminal connected with a second end of the second switch, a second end of the third switch and a second end of the fourth switch, wherein a driving cycle of the driving signal includes N sub-driving cycles, when the sensing circuit is operated during high-level time intervals of the N sub-driving cycles, the first switch and the fourth switch are in the close state, and the second switch and the third switch are in the open state, otherwise, when the sensing circuit is operated during low-level time intervals of the N sub-driving cycles, the first switch and the fourth switch are in the open state, and the second switch and the third switch are in the close state, then an output voltage is generated from the output terminal of the operation amplifier during the low-level time interval of the N th sub-driving cycle, where N is an integer.