| 摘要 |
PURPOSE:To relieve the adverse effect given from a spurious output in the vicinity of a carrier by selecting a local oscillating output of a local oscillator to an integral number of multiple of a reference frequency being an input to a phase comparator of a PLL. CONSTITUTION:Part of an output f0 of a voltage controlled oscillator 11 is mixed by a mixer 12, and a local oscillating frequency fL of an output of a local oscillator 2 for mixing-down to frequency-divide the frequency into 1/N is selected to an integral number of multiple of a reference frequency f0 being an input of a phase comparator 15. Thus, a spurious output level due to a harmonic of the reference frequency fC being the input of the phase comparator 15 is minimized. Thus, the adverse effect given from a spurious output in the vicinity of a carrier is reduced without losing the output carrier spectrum characteristic and its stability. |
