An electronic device is operable to determine a touch input applied to a capacitive touch panel system thereof so as to account for time-varying noise affecting the touch panel system. The electronic device includes the touch panel system, an analog-to-digital conversion (ADC) unit, and a processing unit. The processing unit is operable to: receive digital signal values from the ADC unit representing capacitances detected by sensing points of the touch panel system; adjust at least one of the digital signal values based at least on a time-varying noise to produce at least one noise-adjusted value; and determine the touch input based on the at least one noise-adjusted value. In one embodiment, the electronic device determines the time-varying noise prior to adjusting the digital signal values. In another embodiment, the time-varying noise is produced by a display panel of a touchscreen display that also includes the touch panel system.