| 摘要 |
A shift amount measuring apparatus for measuring a phase shift amount of a signal under measurement which is input thereto includes a PLL circuit that generates a strobe signal which is synchronized with a reference signal, a CDR circuit that inputs, into the PLL circuit, a control signal which has a level determined in accordance with a difference in phase between the signal under measurement and the strobe signal, so as to achieve a predetermined difference in phase between the signal under measurement and the strobe signal, and a measuring circuit that, before and after the signal under measurement is phase-shifted, measures a value of the control signal when the predetermined difference in phase is achieved between the signal under measurement and the strobe signal, and calculates the phase shift amount of the signal under measurement based on a difference between the measured levels of the control signal.
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