| 摘要 |
PURPOSE:To reduce the opportunity of production of a frequency difference and a phase difference before and after input interruption by devising the circuit such that an oscillating output keeping a phase in the normal state just before the interruption on the occurrence of a reference input signal. CONSTITUTION:A delay circuit 12 delays a phase control signal fed from a 1st frequency divider 3 by a multiple of (n) of a phase comparison period in a phase comparator circuit 6. A suppression circuit 14 delays an output signal of the delay circuit 12, that is, the phase control signal from the frequency divider 3 by a time nT to control the phase of a 3rd frequency divider 10. Then the suppression circuit 14 prevents a phase control signal from being given to the frequency divider 10 from the frequency divider 3 before any fluctuation incident within a time nT when a reference signal is interrupted gives any effect on the phase of the frequency division signal from the frequency divider 10. Moreover, a selection circuit 5 selects a frequency division output signal from the frequency divider 10 to be fed to the phase comparator circuit 6 and a control voltage is kept at the interruption of the input. |
