PURPOSE: To obtain a signal having a phase the same as that of a frequency of a frequency component of a data pulse without jitter by making a frequency component of the data pulse included in an input data signal coincident with a center frequency of an N pass filter.

CONSTITUTION: Since there is a shift between a phase of a data signal and a phase of an output signal of a voltage controlled oscillator 10, the relation between a charging voltage V4 of a capacitor C4 and a charging voltage V8 of a capacitor C8 is V4>V8, a comparator 12 compares the voltages so as to output a voltage of ground potential. Thus, the oscillator 10 is controlled in a direction decreasing the oscillated frequency, an phase of an output signal of a switching signal generator 1 is changed and the switch timing of switches S4, S8 is changed. When the relation is V8>V4 conversely, the comparator 12 outputs a voltage of a power supply level. Thus, the oscillating frequency of the oscillator 10 is increased and the timing of the switches S4, S8 is changed. Then the relation of V4=V8 is established in the oscillating frequency of the oscillator 10 in this way and the frequency is fixed to a point coincident with the phase of a data signal.