| 摘要 |
<P>PROBLEM TO BE SOLVED: To accurately detect unlock that periodically occurs in a burst manner in a PLL circuit and to accurately determine a clock system to be a core of a digital signal circuit that can flexibly correspond even to a change in an ambient temperature and abnormality of a frequency to be reference of a carrier frequency of a radio part. <P>SOLUTION: This unlock detecting method in a PLL circuit performs sampling in a predetermined cycle, counts up by a counter in the case of unlock, compares a value counted up by the predetermined number of cycles with a predetermined threshold in a control part, and outputs an alarm signal when the value counted up exceeds the predetermined threshold. <P>COPYRIGHT: (C)2008,JPO&INPIT |
