| 摘要 |
PURPOSE:To facilitate to ensure the spurious characteristic at low noise by providing another phase locked loop having a higher comparison frequency, adding the frequency to a frequency of a fixed frequency phase locked oscillator in mixture to increase the frequency and applying multiplication in a way of microwave frequency synthesizer. CONSTITUTION:The frequency is multiplied in a 1st phase locked loop 21 to increase the comparison frequency of the loop in the frequency divider operating frequency range, a signal whose frequency varies in the unit frequency change width with respect to variable frequency division is extracted from the 1st phase locked loop and the result is used as the reference comparison and a 2nd phase locked loop 22 phase-locked in response to the frequency change is provided, the output is odded in mixture with the frequency of a fixed frequency phase locked oscillator 23 and then multiplied further. Through the constitution above, in selecting number of multiple in the phase locked loop and an output multiple number, even if the output multiple number is selected to a large value such as eight multiple so as to bring the frequency to the quasi-microwave band giving ease of constitution before the multiplier stage and comparatively small cable transmission loss, the loop comparison frequency is increased by the multiplication in the phase locked loop.
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