A voltage modulation circuit includes a charge pump circuit and a voltage detection circuit. The voltage detection circuit is coupled to the charge pump circuit. Herein, the charge pump circuit supports a plurality of power supply modes with different conversion rates and is configured to perform a power supply operation in a selected power supply mode of the power supply modes according to a control signal, to convert a power supply voltage into at least one output voltage, and to output a wake-up signal when switching of the selected power supply mode meets a specific condition. The voltage detection circuit is activated by the wake-up signal, and is configured to detect the output voltage and to suspend the power supply operation of the charge pump circuit according to a magnitude of the output voltage.