| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an apparatus capable of generating a smooth spread spectrum clock, while suppressing increase in circuit scale. <P>SOLUTION: A spread spectrum clock generating apparatus comprises: a phase interpolator (4) which receives clock signal from a clock input terminal (1) and control signal (up signal 6 or down signal 7), adjusts the phase of an output clock signal according to the control signal and outputs it, and a control circuit (60) which receives and counts the clock signal that enters from the clock input terminal and outputs the control signal (up signal 6 or down signal 7) for varying the phase of the output clock signal, based upon the result of the count to the phase interpolator (4). The phase of the output clock signal from the phase interpolator (4) varies with time and is frequency-modulated within a prescribed frequency range. Changeover is performed, without accompanying sudden fluctuations in the frequency, with respect to frequency-modulation start signal and a frequency-modulation stop signal that enter from an SSC control terminal (8). <P>COPYRIGHT: (C)2006,JPO&NCIPI |
