A time-to-digital converter includes N stages of converting circuits, where N2, and N is an integer. Each stage of the converting circuit includes a first delayer and an arbiter; an output end of the first delayer in each stage of the converting circuit outputs a delayed signal of the stage of the converting circuit; and the arbiter in each stage of the converting circuit receives a sampling clock and the delayed signal of the stage of the converting circuit, and compares the sampling clock with the delayed signal to obtain an output signal of the stage of the converting circuit. The first delayer in each stage of the converting circuit includes at least one first delay cell circuit with a first time unit. The first delayer in any stage of the converting circuit includes a less number of first delay cell circuits than the first delayer in a next stage of the converting circuit.