| 摘要 |
PURPOSE:To provide a frequency variable range exceeding a half of the frequency of a reference frequency signal by using a frequency synthesizer as a generating source of the reference frequency signal. CONSTITUTION:A frequency set signal generator 2 generates a digital signal 107 in response to the setting value of a frequency F so that a frequency synthesizer 3 generates frequencies f0, f1, f2- satisfying the relation formula of fn=(Mo+mn)fs, where f0 is a frequency of a reference frequency signal 101 applying phase lock to the minimum value of the required variable range of the frequency F, fs is a desired change step frequency of the frequency F and Mo= fo/fx, (m) is a positive integer and (n) is 0 or a positive integer. Further, a digital signal 108 sets the step-down order Mn of a frequency divider 5 as Mn= Mo+mn. Further, a digital signal 109 sets the step-down order Nn of a frequency divider 6 so as to attain a desired frequency F. In selecting the frequency fn and the step-downorders Mn, Nn in this way, the frequency F is varied in a prescribed step frequency is over a frequency width exceeding the limit of 1/2 fn. |
