Patent ID: 7355379

Claim:
A phase difference detecting method comprising: inputting a first input signal and a second input signal, which are identical in frequency to each other and are different in phase from each other; generating a first generated signal and a second generated signal, which are identical in frequency and different by a first reference phase difference from the first input signal, on the basis of the first input signal; generating a third generated signal and a fourth generated signal, which are identical in frequency and are different by a second reference phase difference from the second input signal, on the basis of the second input signal; mixing the first generated signal and the third generated signal to detect relative phase difference between the first generated signal and the third generated signal, as a first relative phase difference; mixing the second generated signal and the fourth generated signal to detect relative phase difference between the second generated signal and the fourth generated signal, as a second relative phase difference; and referring to a relationship prepared in advance among the first relative phase difference, the second relative phase difference, and a true phase difference between the first input signal and the second input signal, to detect the true difference.