| 摘要 |
PURPOSE:To obtain an optional highly stable oscillating frequency by using a high stable crystal oscillator as a reference oscillator so as to form a PLL and setting properly the frequency dividing ratio of the reference oscillator and of a voltage controlled oscillator. CONSTITUTION:The highly stable crystal oscillator 1, programmable dividers 2, 6, a phase comparator 3, an LPF6 and a voltage controlled oscillator VCXO5 form a PLL. Then the frequency dividing ratio of the dividers 2, 6 frequency dividing respectively the output frequency of the oscillator 1 and the VCXO5 is set in response to the input data from an external memory reader 11. Thus, an optional highly stable oscillating frequency is obtained as an output of the VCXO5 by setting properly the frequency dividing ratio of the divider 2, 6. |
