| 摘要 |
PURPOSE:To make the frequency dividing ratio variable by inserting a varactor diode into a closed loop feeding back the own mixer output via a delay circuit. CONSTITUTION:When a signal of a frequency f0 is inputted to an input terminal 1, a signal of a frequency mf0/(m+1) (m is an integer) being one of the frequency components of the input signal is outputted from a mixer 2, and fed back gain to the mixer 2 via a feedback loop comprising delay lines 3, 11, amplifiers 4, 13 and a varactor diode 8. The feedback signal and the input signal are mixed by the mixer 2 and a signal of a frequency f0 + or -mf0/(m+1) is outputted and in setting the natural frequency of said feedback loop near the frequency f0/(m+1), only the frequency component of f0-mf0/(m+1)=f0/(m+1) is extracted from a terminal 12. Since said natural frequency is made variable by the capacitance change in the varactor diode 8, the frequency division ratio is made variable by the varactor diode 8.
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