| 摘要 |
PURPOSE:To prevent spurious radiation with a comparatively simple circuit constitution by providing a signal suppressing circuit means eliminating a frequency component being (n)-fold of the frequency of an input signal, and further, as required, 1/n-fold between a low pass filter and a voltage controlled oscillation circuit VCO. CONSTITUTION:The signal suppression circuit 3a composed of an adder circuit 32 and a delay circuit 31 whose delay time (tau) is 1/2fr is provided on a post- stage of a phase comparator 11 and a low pass filter 12, and its output signal is applied to the VCO 14. A frequency divider 15 is connected between the VCO 14 and the phase comparator 11. The input frequency 10MHz is FM- modulated by the VCO 14 to become an output signal SOUT in a frequency of 360MHz. On the other hand, a spurious component is outputted at a position deviated by 10MHz at both sides of the frequency of 360MHz, but it is removed. |
