TrueTrack/sup TM/ servo technology for high TPI disk drives

The performance of a high track density disk drive is critically limited by positioning errors induced by disk shift, spindle vibration and disk warp-based servomechanics. The spectrally rich error components can be compensated for by high-gain digital filters. The filters augment the basic function of a conventional controller. Using a novel method for initializing filters, precision tracking is achieved without compromising the settle out performance of a disk drive. An autonomous filter state propagation method during seek is shown to simplify the implementation process. A silicon servo chip has been designed to incorporate the key functions of the algorithm.