A clock generator for generating a target clock signal, comprising: a control circuit, receiving a reference clock signal, and for generating a clock enable signal and a delay selecting signal according to the reference clock signal; a delay module, coupled to the control circuit, for delaying the reference clock signal according to the delay selecting signal to generate a delayed reference clock signal; and a clock gating unit, coupled to the delay module and the control circuit, for receiving the delayed reference clock signal and the clock enable signal, and for passing the delayed reference clock signal according to the clock enable signal, to generate the target clock signal.