| 摘要 |
PURPOSE:To make possible the fine rate adjustment without making unstable the oscillation of crystal by providing control means which have plural pieces of reactance elements provided to a crystal oscillator and open and close selectively plural switches. CONSTITUTION:The oscillation frequency of the crystal oscillator 1 is changed by opening and closing of a switching transistor (SWT)3 provided together with a capacitor (C)2. The output of the oscillator 1 is frequency-divided 4 to forma reference signal and one F1 of the signals to determine the resolving power of the reference signal and the rate adjustment. A clock means 5 forms a signal F2 to determine the period of the rate adjustment by receiving the reference signal from the means 4. A means 6 for calculating the rate adjustment width calculates the rate adjustment width and a means 7 for calculating the rate adjustment quantity calculates the total rate adjustment quantity. A logical regulator 9 changes the frequency dividing ratio from the data from the means 6, 7. A SWT control means 8 selects the C to be connected to the SWT3 from the rate adjustment quantity and the F1, F2 and forms the timing signal to open and close the SWT3. A plurality of C for the rate adjustment are provided in addition to the logical regulation in the above-mentioned manner, by which the rate adjustment to the fine region is made possible.
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