| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a clock generator which has a small additional circuit scale and is capable of executing the spectral diffusion of an oscillation frequency by easy control, and to provide its control method. <P>SOLUTION: The clock generator is provided with a phase-locked loop circuit in which an output clock signal PO is outputted from a voltage control oscillator (VCO) 14 through a charge pump circuit (CP) 12 and a loop filter (LF) 13 from a frequency phase comparator 11, and also, returned to the frequency phase comparator 11 via a frequency divider (DIV) 15. A phase difference between a reference clock signal R and a frequency division clock signal D is detected and locked to an oscillation frequency prescribed frequency of the output clock signal PO. A modulating signal M is outputted from a modulating pulse generator 1 regardless of the phase synchronization control of the phase-locked loop circuit and superimposed on a phase comparison signal P. Consequently, the oscillation frequency of the output clock signal PO is modulated. The output clock signal PO having prescribed spread spectrum characteristics can be obtained. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
