PURPOSE: To stabilize a VCO frequency, by subjecting phase detection to an output obtained by frequency-dividing the outputs of the 1st and 2nd oscillators and then applying this output as the control voltage of either one of the two oscillators consisting of the VCO.

CONSTITUTION: An output 2 of the 1st oscillator 1 which has an integer-fold value compared with the horizontal frequency of a TV signal is divided into 1/2 in frequency by a frequency divider. Thus a horizontal clock pulse is generated. On the other hand, the output 2 is divided into 644 parts by a frequency divider 5 and an output 6 is used to the input of one side of a phase detector 7. The 2nd oscillator 8 produces the secondary carrier wave. An output 9 is divided into 1/648 in frequency by a frequency divider 10, and an output 11 is used to the input of the other side of the detector 7. An output 12 is fed to the oscillator 8 in the form of the oscillating frequency control voltage 14 via a low pass filter 13. Thus the oscillating frequency of the oscillator 8 is stabilized.