An active stylus includes an electrode, a recycling capacitor, a first switch, a power source, and a second switch. The first switch is coupled between the recycling capacitor and the electrode. The second switch is coupled between the power source and the electrode. In a first phase, the second switch is turned on, the power source provides a current or a voltage for the electrode and the first switch is turned off. In a second phase, the second switch is turned off and the first switch is turned on. Alternatively, the recycling capacitor may be replaced with an electrode.