Time-to-digital converter

Abstract

A TDC circuit having a small scale circuit and high resolution is disclosed, which is a time-to-digital converter that detects a phase with respect to a reference clock of a signal to be measured, comprising a first delay line in which a plurality of first delay elements with a first delay amount is connected in series, a second delay line group that is connected to a plurality of connection nodes of the first delay line or an input node in the first stage and in which at least one or more second delay elements with a second delay amount different from the first delay amount are connected in series, a plurality of judgment circuits that judge whether the changing edge of the signal to be measured is advanced or delayed with respect to the changing edges of a delayed clock output from the first delay element and the second delay element, and an operation circuit that calculates a phase with respect to the reference clock of the changing edge of the signal to be measured from the judgment results, wherein a difference between the first delay amount and the second delay amount is smaller than the first delay amount and the second delay amount.