An apparatus includes an integration circuit that integrates values of one of a data center and a data edge of input data, based on clock signals, a sampling circuit that samples another at the data center and a data edge of the input data, based on clock signals, a first determination circuit that determines a data value of an integration value of the integration circuit, a second determination circuit that determines a data value of a sampling value of the sampling circuit, a phase detection circuit that detects phase information of the input data, based on a data value determined by the first determination circuit and the second determination circuit, and a phase adjusting circuit that adjusts a phase of a reference clock so as to track a phase of the input data, in accordance with the phase information, so as to output as the clock signals.