CAPACITIVE SENSING SYSTEM, AND SENSING CIRCUIT AND SENSING METHOD FOR CAPACITIVE TOUCH SCREEN

摘要

A sensing circuit for a capacitive touch screen, a capacitive sensing system, and a sensing method for the capacitive touch screen. The sensing circuit comprises a first conversion circuit (222), a first current mirror circuit (225), and a second conversion circuit (226). The first conversion circuit (222) is coupled to a sensing node (110) of the capacitive touch screen, and is used for converting charge accumulated by the sensing node into a first current according to a first input voltage. The first current mirror circuit (225) is coupled to the first conversion circuit (222) and used for generating a second current according to the first current, wherein the second current is a copy or multiple of the first current. The second conversion circuit (226) is coupled to the current mirror circuit (225), and is used for generating an output voltage in response to at least the second current. The sensing circuit can greatly increase the contribution from the capacitance value change of the sensing node in a voltage change range of the output voltage.