A phase-locked loop circuit for generating an output signal includes a phase frequency detector (PFD), a processing module, and a clock generator. The PFD is implemented for generating a plurality of indicating signals according to a first reference signal and a feedback signal, where the feedback signal is generated according to the output signal. The processing module is coupled to the PFD, and is implemented for generating a control signal according to the indicating signals and a plurality of clock signals, where the clock signals have an identical frequency but different phases. The clock generator is coupled to the processing module, and is implemented for generating the clock signals according to the control signal. The output signal is generated according to a specific clock signal selected from the clock signals.