Patent ID: 8793297

Claim:
A phase interpolator comprising: a plurality of testing selectors provided corresponding to a plurality of selectors, to each of which a plurality of testing input signals of different phases are input and each of which outputting any of the plurality of testing input signals according to a first control signal; a plurality of selectors to each of which a predetermined input signal of different phases and a testing input signal output from a corresponding testing selector are input and each of which outputting one of the input signal and the testing input signal output from the corresponding testing selector according to a second control signal; a plurality of mixers provided corresponding to the plurality of selectors, to each of which output of a corresponding selector is input and outputting an output signal in which signals to which weighting is added to output of the corresponding selectors are compounded according to a third control signal; an output circuit outputting the output signal output from the plurality of mixers; and a detection circuit detecting fluctuation in an amplitude of the output signal output from the plurality of mixers.