| 摘要 |
PURPOSE:To recover a state of a frequency condition that an oscillated frequency of a VCO is smaller than a frequency of an oscillator caused tentatively to a normal state, to eliminate a restriction condition of an oscillated frequency range of the VCO and to realize the PLL oscillating circuit used without hindrance at an oscillated frequency at which the oscillated frequency of the VCO is close to the frequency oscillated from the oscillator. CONSTITUTION:This oscillating circuit is provided with a frequency comparator 10 comparing a difference between an oscillated frequency fvco of a VCO 50 and a frequency f54 of an oscillator 54 to detect an abnormal oscillating frequency state and with a phase comparator 20 with a controller receiving a signal from the frequency comparator 10 and generating a signal used to restore phase comparison output signals 20a, 20b in a state of fvco<f54 or fvco>f54 in the abnormal oscillating frequency state forcibly in a direction of fvco>f54 or fvco<f54. |
