| 摘要 |
PROBLEM TO BE SOLVED: To provide a phase locked loop circuit that can reduce a phase lock time without causing a frequency jump at start of phase locking. SOLUTION: The phase locked loop circuit for generating an output signal phase-locked to a reference input signal is provided with a phase comparator that compares a phase of the reference input signal with a phase of a signal resulting from frequency-dividing the output signal, a low pass filter that smoothes an output signal of the phase comparator, a voltage-controlled oscillator that outputs an output signal with an oscillated frequency corresponding to a voltage smoothed by the low pass filter, a frequency divider that frequency- divides an output signal of the voltage-controlled oscillator, and a control circuit that generates an enable signal on the basis of the reference input signal and an operation start signal and supplies them to the frequency divider.
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