| 摘要 |
A phase-acquisition (PA) loop for a read channel comprises an accumulator, a comparator, and a filter. The accumulator holds an acquired phase-correction value corresponding to a difference between a phase of a sample clock and a phase of data carried by a read signal, and provides the acquired phase-correction value to a circuit that modifies the read signal to compensate for the phase difference. The comparator receives a reference phase-correction value that also corresponds to the difference between the phases of the sample clock and the data, and generates an error signal that is related to a difference between the reference and acquired phase-correction values. And the filter causes the acquired phase-correction value to have a predetermined relationship to the reference phase-correction value. Because such a PA loop may require significantly fewer samples of a read-signal preamble than prior PA loops requires to acquire the phase between a sample clock and data carried by a read signal, such a PA loop may allow one to significantly reduce the length of the preamble.
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