| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a spread spectrum clock generating circuit where a spectrum can sufficiently be spread with a simple constitution. <P>SOLUTION: A spread spectrum clock generating circuit is provided with a frequency phase comparator 12 detecting a phase difference between a reference clock CLK and a generation clock CK, a charge pump 13 generating a charge/discharge signal in accordance with the detected phase difference, a loop filter 14 generating a difference signal corresponding to the charge/discharge signal, a spread spectrum modulation circuit 19 modulating the difference signal and generating a spread spectrum modulation signal and a clock generator 20 generating the clock CK of a frequency corresponding to a spread spectrum signal. The spread spectrum modulation circuit 19 generates the spread spectrum modulation signal whose amplitude changes to a plurality of different amplitudes. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
