| 摘要 |
PURPOSE:To attain fast lockup and stable ripple elimination by supplying a control voltage to a voltage controlled oscillator circuit or a filter circuit in revising a frequency divider ratio of a programmable frequency divider. CONSTITUTION:An oscillated output of a VCO 4 is frequency-divided by the programmable frequency divided 5 and the phase of its frequency division output and the phase of an oscillated output from a reference oscillation circuit 1 are compared by a phase comparator circuit 2. An output of the phase comparator circuit 2 is given to the VCO 4 via a filter circuit 3. In revising the frequency division ratio of the programmable frequency divide 5, a control voltage from a control voltage supply circuit 7 is fed to the filter circuit 3 by a control circuit 6 to set the oscillation output of the VCO 4 in the vicinity of a desired frequency. |
