| 摘要 |
PURPOSE:To increase the possibility of establishing phase locking sufficiently even in an input signal with a short consecution time by multiplying a signal frequency in an input signal consecutive time by a number of gradual multiple. CONSTITUTION:A frequency multiplier circuit 100 outputs an output signal S100 multiplying a frequency of an input signal S1 by a predetermined gradual multiple number N. A phase lock detection circuit 300 compares the output signal S100 of a frequency gradual multiple circuit 100 with a frequency signal S200 of a phase locked loop circuit 200 and the phase locked loop circuit 200 detects whether or not the state is in the phase lock establishing state to detect a frequency component of 1/N component included in the input signal S1. Thus, since the signal period number in an input signal consecutive time is multiplied by the number of gradual multiple, the possibility of establishing the phase lock sufficiently is increased even in the input signal with a short consecutive time and the signal detection capability of the signal detection circuit is considerably improved.
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