A delay-locked loop includes a phase detector, a shift register, a digital low pass filter, a digital to analog converter, a bias circuit, and a delay circuit. The phase detector generates a lagging signal and a leading signal corresponding to a phase difference between an input clock signal and a feedback clock signal. The shift register outputs a digital data according to the lagging signal and the leading signal. The digital low pass filter generates a selecting signal according to the digital data. The bias circuit generates a first control voltage and a second control voltage in response to the bias voltage converted from the selecting signal. The delay circuit generates the feedback clock signal corresponding to the first control voltage and the second control voltage.