| 摘要 |
PURPOSE:To attain a phase locked loop state in a short time by holding a sweep voltage by the output control signal of a low pass filter and adding a properly set fixed voltage. CONSTITUTION:If a phase locked loop state is stepped out beyond the band width of a low pass filter 6, the holding state of a holding circuit 8 is released. The output voltage of the holding circuit 8 released from the holding state becomes the sweep voltage, and the output signal frequency of a voltage controlled oscillator 5 is changed to change the output signal frequency of a frequency converter 1. When the output signal frequency of a frequency phase comparator 2 enters within the band width of a low pass filter 6, the low pass filter 6 changes the output signal, and the holding circuit 8 is set to the holding state to hold the output voltage at this time. Next, the output voltage from a fixed voltage generator 9 is added by an adder 11. An approximately required output frequency is obtained by this operation. |
