摘要 |
<p>In a second system that generates a clock signal that is synchronized with a first system, a control voltage value that controls the second oscillator such that the second system is synchronized with the first system is monitored according to the phase difference between a reference signal that is generated using the output of a first oscillator in the first system and the output of a second oscillator, whereby frequency fluctuation that occurs due to age deterioration of the first oscillator is detected.</p> |