Self-capacitive touch sensing circuit and noise suppressing method applied to self-capacitive touch panel

摘要

A self-capacitive touch sensing circuit including an operational amplifier, an internal capacitor, a first switch and a second switch is disclosed. A first input terminal and a second input terminal of operational amplifier are coupled to a capacitor and ground respectively and an output terminal of operational amplifier outputs an output voltage. The internal capacitor is coupled between the output terminal and first input terminal of operational amplifier. One terminal of first switch is coupled to a first external charging voltage and another terminal of first switch is coupled between the capacitor and the first input terminal. The first external charging voltage is higher than the second external charging voltage. The first switch and second switch are switched according to a specific order, so that the first external charging voltage or second external charging voltage will charge the capacitor.