| 摘要 |
<p>A frequency synthesizer provided with a phase comparator (10) for comparing a feedback frequency with a reference frequency, a filter (12) connected to the phase comparator (10) and passing low frequencies, a voltage-controlled oscillator (14) connected to the filter (12), a multistage frequency converter (16) receiving the oscillation signal generated by the voltage-controlled oscillator (14), a frequency demultiplier for forming a feedback frequency by frequency-demultiplying the output of the multistage frequency converter (16). The multistage frequency converter (16) is constituted by connecting a plurality of frequency converters, which perform non-integer frequency-demultiplication, in series or in parallel with each other. Consequently the ratio of the frequency-demultiplication can be set arbitrarily and finely. Thereby, no matter how the output frequency of the frequency synthesizer changes, the feedback frequency inputted to the phase comparator can be set constant and high. Therefore, the reference frequency can be set as high as the feedback frequency too, independently of the spacing frequency between the output channels of the voltage-controlled oscillator (14), and the speed of ziehen effect can be made very high.</p> |
