A charge pump used for producing at least a first output voltage and a second output voltage according to an input voltage is disclosed. The charge pump includes a pump unit, the first to fourth switches, a first output capacitor and a second output capacitor. During a first period, the input voltage and the first voltage, through the first end and the second end of the pump unit respectively, charge at least an internal capacitor. During a second period, the internal capacitor, based on the second voltage level of the first switch and though the second switch, provides the first output capacitor with charges for producing the first output voltage. Finally, during the third period, the internal capacitor, based on the third voltage level of the third switch and though the fourth switch, provides the second output capacitor with charges for producing the second output voltage.