Disk apparatus having a data reproducing system using a digital PLL

摘要

A first D/A converter having a fine frequency resolution and second D/A converter having a rough frequency resolution are used in combination for frequency control and phase control, and a wide operational frequency range in reproduction can be covered with high accuracy by incorporating a digital PLL circuit. The dynamic ranges of the first and second D/A converters are so controlled as to be subject to addition and subtraction at a time having no problem for data reproduction. Therefore, the frequency adjustment can be rapidly performed in the frequency control and the clock continuously locked to the data can be obtained by the phase control, thereby remarkably reducing the seek time.