Absolute capacitive sensing using sensor electrode pre-emphasis

摘要

A processing system comprises a sensor module and a determination module. The sensor module is configured to drive a modulated signal on to a sensor electrode to achieve a target voltage on the sensor electrode during a first portion of a sensing cycle, wherein the modulated signal comprises a first voltage that is beyond a level of the target voltage and which is driven for a first period of time and a second voltage that is at the target voltage and which is driven for a second period of time that follows the first period of time. The determination module is configured to determine an absolute capacitance of the sensor electrode during the first portion of the sensing cycle after driving the second voltage.