| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a frequency monitor circuit, a clock supply device which can inexpensively be constructed, the maintenance of which is easy and a frequency monitor method. <P>SOLUTION: The clock supply device is provided with a data memory 9 that writes the highest digital value obtained by performing digital sampling of the highest frequency for fault judgment and the lowest digital value obtained by performing digital sampling of the lowest frequency for fault judgment and a digital value comparator circuit 10 that judges whether or not a phase comparison result digital signal 112 between the signal 110 obtained by dividing frequency of an input clock selected among a plurality of input clocks 101 to 10N and a signal 116 obtained by dividing frequency of an output clock of a voltage control oscillator 7 lies within the range between the highest digital value and the lowest digital value and when the phase comparison result digital signal 112 becomes out of the range, outputs an alarm signal 119. <P>COPYRIGHT: (C)2003,JPO |
