| 摘要 |
PROBLEM TO BE SOLVED: To maintain phase difference noise characteristics which are similar to conventional ones and obtain a high output level with low power consumption by taking out only the basic frequency component of a voltage-controlled oscillator output, and passing only a frequency component which is N times as high as the basic frequency of the output side of the frequency synthesizer. SOLUTION: A reference oscillator 1 oscillates a highly stable oscillation frequency fr. A voltage-controlled oscillator 4 oscillates a frequency fo which is 1/N time as high as a desired oscillation frequency as its basic frequency and outputs higher harmonics (2fo, 3fo...) at the same time. A band-pass filter 6 passes the frequency fo selectively. A frequency divider 5 divides the oscillation frequency fo by M so as to match the oscillation frequency fr. A phase comparator 2 compares the phases of the output of the reference oscillator 1 and frequency divider 5 with each other to detect the phase difference. A low-pass filter 3 removes unwanted higher harmonic components included in the output of the phase comparator 2. A band-pass filter 8 extracts only an Nth higher harmonic component (N×fo).
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