| 摘要 |
PURPOSE:To shorten a control time till the output of a voltage controlled oscillator reaches an objective frequency and to reduce power consumption. CONSTITUTION:This circuit consists of a VCO 11, a 1st frequency divider 12 frequency-dividing the output of the VCO, a reference oscillator 15, a 2nd frequency divider 14 frequency-dividing the output of the frequency oscillator, and a CPU 13 detecting the frequency difference of the output of 1st and 2nd frequency dividers and controlling the oscillating frequency of the VCO based on the frequency difference. The CPU resets and releases the reset of the 1st and 2nd frequency dividers simultaneously and the times of output change of each frequency divider are compared after reset release to obtain a frequency difference, the oscillating frequency of the VCO is controlled accordingly and the operations of the 1st and 2nd frequency dividers are tentatively stopped simultaneously. |
