| 摘要 |
An oscillator ( 30 ) supplies a high frequency signal (S) to a frequency divider ( 31 ) . A phase comparator ( 32 ) produces a signal measuring phase difference between the divided frequency signal (QA) and a reference signal. A low-pass filter ( 34 ) controls the oscillator on the basis of the measurement signal. A measurement window, of duration defined by counting cycles of the high frequency signal, is generated in response to each active edge of the divided frequency signal. The measurement signal is activated during the measurement window so that it comprises, when an active edge of the reference signal falls within the window, a first pulse between the start of the window and this edge and a second pulse, opposite to the first, between this edge and the end of the window.
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