Patent ID: 7199959
Filing Date: 2007-04-03
Classification: G11B

Abstract:
1. A servo writer for writing servo sectors onto a disk responsive to a reference digital clock signal and for compensating for repeatable timing errors associated with the reference digital clock signal, the servo writer comprising: a direct digital synthesizer (DDS) to form a phase and frequency adjustable continuous wave signal based upon the reference digital clock signal; a phase lock loop (PLL) coupled to the DDS, the PLL to measure repeatable timing errors associated with the phase and frequency adjustable continuous wave signal and to generate an output clock signal that is used to clock the writing of servo sectors onto the disk; and a digital control system coupled to the DDS and the PLL, the digital control system to calculate repeatable error compensation adjustment values based on the repeatable timing errors measured using the PLL; wherein the repeatable error compensation adjustment values are applied to the DDS such that the DDS compensates for the repeatable timing errors and the output clock signal used to clock the writing of servo sectors onto the disk includes minimal repeatable timing errors.