| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a frequency switching device capable of preventing increase in circuit scale and preventing system malfunction when a frequency is switched during operation. <P>SOLUTION: The frequency switcher 5 is provided with a phase frequency comparator 10, a charge pump circuit 11, an LPF circuit 12, a VCO circuit 13, a counter circuit 14, and a control section 8 for controlling the operation of the counter circuit 14. The control section 8 is provided with a multiplication number changing section 16 and a change permission determining section 15. The change permission determining section 15 determines whether or not the multiplication number should be changed to a target multiplication number on the basis of a counter value of the counter circuit 14. For example, when the counter value becomes a reference value not more than the target multiplication number (e.g. counter value zero), the section 15 permits to change the multiplication number. <P>COPYRIGHT: (C)2008,JPO&INPIT |
