| 摘要 |
PURPOSE:To reduce a channel changeover time by eliminating a phase error at the mode change. CONSTITUTION:A frequency division ratio setting circuit 17 increases gradually a 1st frequency division ratio M up to a ratio Mo in multi-stage stepwise in the case of channel changeover and gradually increases a 2nd frequency division ratio N in each stage so as to be closest to a desired frequency, where Mo and No are 1st and 2nd frequency division ratios to generate a channel frequency. In this case, the 1st and 2nd frequency division ratios N, M are switched by allowing the frequency division ratio setting circuit 17 to reference a phase synchronizing signal LD from a phase synchronization monitor section 13d and to input the 1st and 2nd frequency division ratios in a next stage to 1st and 2nd variable frequency dividers 12,16 respectively and an output signal frequency Fout of a frequency synthesizer is made coincident with a desired channel frequency by inputting the 1st and 2nd frequency division ratios No, Mo to the 1st and 2nd variable frequency dividers 12,16 finally. |
