| 摘要 |
PURPOSE:To make the output frequency to follow quickly the frequency of a reference signal. CONSTITUTION:The output voltage is increased in an input period of a 1st voltage signal (H) which is inputted from a phase comparing part 2 in response to the phase difference between the input and output signals. The increase and decrease of the output voltage are discontinued in an input period of a 2nd voltage signal (Z). Then the output voltage is reduced in an input period of a 3rd voltage signal (L). The reduced output voltage is applied to a filter LPF and smoothed there. This smoothed voltage is converted into a signal which is synchronized with the frequency of a reference signal. In such a constitution, the output voltage is linearly changed and therefore the cutoff frequency of the LPF can be set at a high level. Therefore the response speed of a synthesizer is improved when the output frequency is synchronized with the reference frequency. |
