| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a method and apparatus for detecting a frequency level of a spread spectrum clock in which, for a spread spectrum clock having a frequency modulated over a plurality of frequency levels in a fixed modulation cycle, the frequency level of the spread spectrum clock is detected. <P>SOLUTION: A pulse generating circuit 48 generates a pulse at fixed period intervals by comparing a countable value of a reference clock with a value stored in a setting register 46. An SSC count value obtained by counting the number of spread spectrum clocks SSC_CLK for the fixed period is held in a counter buffer 51 and compared with various thresholds stored in a setting register 53 via a comparator circuit 55, and thereby a frequency level of the spread spectrum clock SSC_CLK at that time point is detected. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
