PURPOSE: To eliminate frequency adjustment of a low frequency oscillation circuit by obtaining a reference time signal corrected with a high frequency oscillation circuit with the contents of a phase difference counter automatically converging to zero.

CONSTITUTION: An oscillation block 71 inputs an correction value CC to output a low frequency signal fL corrected with respect to a reference low frequency oscillation frequency fB and a division block 73 outputs a reference time signal fW and a sampling signal fS. A phase comparison block 72 receives a high frequency signal fH and the sampling signal fS as input and output a phase difference signal fP. A phase difference count block 74 receives the phase difference signal fP, a reference time TP and a high frequency deviation correction value Ch as input and outputs phase difference count CP. A correction value renewing block 75 receives the phase difference count CP as input and updates and outputs a correction value CC. Thus, with an intermittent updating of the correction value CC, the deviation block 72 provides the reference time signal fW constantly corrected with the correction value CC.