| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce unwanted side band waves. <P>SOLUTION: A VCO 27 and an N-multiplier 28 are provided in an oscillation and multiplication part 25 constituting a phase synchronizing loop with a phase comparator 23, a loop filter 24 and a frequency divider 26. By performing phase synchronizing loop operation to unwanted side band wave components simultaneously with a main oscillation signal wave like this, the level of the unwanted side band (spurious) waves is suppressed nearly by 20*log<SB>10</SB>N dB by the signal selecting effect of the phase synchronizing loop compared with the level in the case of simply multiplying by N (taking out the N-th order harmonic from the VCO). The pass band characteristics of the main oscillation signal wave is narrowed by the signal selecting effect, and the appearing range of the unwanted side band waves is also narrowed with it. Thus, the unwanted side band waves are reduced. <P>COPYRIGHT: (C)2003,JPO |
