Provided is a capacitive touch sensor which includes a flat panel display for displaying an image and a touch sensor panel positioned on the flat panel display or embedded in the flat panel display. The capacitive touch sensor may include: a driving clock generator configured to generate a plurality of time-periodic output signals by using a gate driver signal of the flat panel display, and apply the generated time-periodic output signals to the touch sensor panel and a receiver circuit unit; a driver configured to generate a driving signal of the touch sensor panel using a part of the output signals of the driving clock generator; and the receiver circuit unit configured to process noise contained in a signal received from the touch sensor panel, using the output signals.