| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a phase synchronization circuit for outputting an output signal of a stable frequency, and provide its control method and a communications device. Ž<P>SOLUTION: The phase synchronization circuit includes a voltage-controlled oscillation circuit, a comparison means, two or more sample/hold circuits, a switching means, and an abnormality detection means. The voltage-controlled oscillation circuit outputs a signal of a frequency according to a control voltage input, as an output signal. The comparison means compares the phase of the input signal with the phase of the output signal of the voltage-controlled oscillation circuit. The two or more sample/hold circuits hold voltage based on the phase comparison with to different timing, respectively. The switching means selects either of the two or more sample/hold circuits and inputs the output from the selected sample/hold circuit into the voltage-controlled oscillation circuit as the control voltage. The abnormality detection means detects abnormality in the input signal. The switching means selects the output of either of the two or more sample/hold circuits, based on the detection result of abnormality by the abnormality detection means. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž</p> |
