Embodiments of the present invention provide a time-to-digital converter, where the time-to-digital converter includes a delay unit, a first sampling unit, and a second sampling unit. The delay unit is connected to the first sampling unit and is configured to receive a first clock signal and delay the first clock signal; the first sampling unit is configured to perform sampling on the first clock signal and generate a first phase signal, so that a first phase-locked module adjusts a frequency of the first clock signal; the delay unit is further connected to the second sampling unit and is configured to receive a frequency-adjusted first clock signal and delay the frequency-adjusted first clock signal; and the second sampling unit is configured to perform sampling on the frequency-adjusted first clock signal and generate a second phase signal.