A portable device for receiving broadcast information is provided. A mixer down-converts a radio-frequency signal with a local oscillation clock to provide an intermediate frequency signal. A filter is arranged to filter the intermediate frequency signal. An analog-to-digital converter converts the filtered intermediate frequency signal into a digital signal according to a sampling rate. The broadcast information is obtained according to the digital signal. The local oscillation clock has a first frequency in a normal mode and a second frequency in a power-saving mode, and the second frequency is lower than the first frequency.