| 摘要 |
PURPOSE:To make it possible to detect a step-out state even if it is remarkable, by integrating a phase error signal and then by recognizing the step-out state when the integral value surpasses a prescribed value. CONSTITUTION:Phase comparator 1, charge pump 2 and voltage control oscillator 3 constitute a phase synchronizing circuit, which is additionally provided with integrating circuit 4 as a step-out detecting circuit and level slicing circuit 5. As the phase synchronizing circuit gets out of synchronism, the number of output pulses from phase comparator 1 increases and the pulse width also increases. As a result, charges accumulated in capacitor 7 increses and the potential of capacitor 7 rises. Then, when the potential exceeds reference voltage 10, comparing circuit 9 generates an output. Thus, the step-out state can be detected. |
