| 摘要 |
<p>A clock pulse generator which has the frequency of its output automatically controlled by comparison of the generated clock pulses with an external reference signal comprises an input for receiving the reference signal, a voltage controlled oscillator for generating the clock pulses, a counter for frequency-dividing the clock pulses to obtain a comparing signal having substantially the same frequency as the external reference signal, a phase comparator for comparing the phase of the comparing signal with the phase of the external reference signal and providing the control voltage for the oscillator in response to a detected phase difference therebetween, and an inhibiting circuit for inhibiting the control voltage whenever the phase of the external reference signal is outside a predetermined range with respect to the comparing signal.</p> |
