Disclosed is a low-power and high-resolution time-to-digital converter including: a coarse delay cell configured to delay a reference clock by a coarse delay time and output the reference clock; a rising-edge retimer configured to output a rising-edge retimed clock synchronized with the rising-edge of a DCO clock in response to the reference clock; a falling-edge retimer configured to output a falling-edge retimed clock synchronized with the falling-edge of the DCO clock; a firs sampler configured to latches output of the coarse delay cell in response to the rising-edge retimed clock and the falling-edge retimed clock; and a pseudo-thermometer code edge detector configured to detect a rising-edge fractional phase error between the reference clock and the rising-edge retimed clock as a coarse phase error from a signal output by the first sampler, and detect a falling-edge fractional phase error between the reference clock and the falling-edge retimed clock.