| 摘要 |
PURPOSE:To present an alarm circuit highly reliable with an effect by drift and the like removed, by such functional method that, a pulse signal of constant width generated from the reference frequency signal to be the reference for the phase comparison, be compared with a phase difference output pulse width signal to obtain the alarm signal. CONSTITUTION:A phase comparator PC makes a comparison between the phases of reference frequency signal and controlled frequency signal, with its output pulse applied to a reference pulse generating circuit PG1, PG2 and a phase decision circuit P. A decision is made in the phase decision circuit P for whether the phase is leading or lagging, and a comparison is made with an output of the reference pulse generating circuit PG1, PG2 in a leading phase decision circuit P1 and lagging phase decision circuit P2. With a lagging or leading of the phase exceeding a reference value, an alarm signal arm is outputted through an OR circuit OR. |
