Western Digital Corporation

Ronald E Wilson

Karl M Lofgren

A phase-locked system for recovering data from a disk drive includes a phase detector for signalling the difference in phase between incoming delayed data pulses and a phase detection window clock signal. The phase detection window clock signal is derived from one output of an integrated-circuit window generator, driven by the output of a voltage-controlled oscillator whose frequency is controlled by the phase detector. The phase-locked loop is completed by comparing the phase detection window clock signal output of the window generator with the incoming delayed data pulses in the phase detector. Data detection window clock pulses, defining time windows in which the delayed data pulses are exactly centered, are produced at a second output of the window generator which has a line about which it is essentially symmetric, resulting in the two outputs of the window generator being exactly 180.degree. apart in phase from each other.

Data synchronizer with symmetric window generation

A phase-locked system for recovering data from a disk drive includes a phase detector for signalling the difference in phase between incoming delayed data pulses and a phase detection window clock signal. The phase detection window clock signal is derived from one output of a phase shifter driven by the output of a voltage-controlled oscillator whose frequency is controlled by the phase detector. The phase-locked loop is completed by comparing the phase detection window clock signal output of the phase shifter with the incoming delayed data pulses in the phase detector. Data detection window clock pulses, defining time windows in which the delayed data pulses are discerned, are produced at a second output of the phase shifter. The phase shifter produces a delay variable in precise increments over a wide range, causing a variable phase relationship between the time windows and the delayed data pulses that are to be discerned therein.

Disk drive data synchronizer with window shift synthesis

An integrated system for use in a disk drive system for the implementation of write precompensation for recording of data and read window margining for accelerated testing of the disk drive. Both functions are provided by a common delay-line circuitry. The output of the delay line circuit is applied to both window shifting and write precompensation. An on-board read detection error analysis can be performed after installation of the drive in a computer system in its final configuration. Actual read error tolerance based on the overall system in its actual operating condition can thus be obtained. Enhanced data recovery techniques are also facilitated.

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Lake Forest, CA, United States of America

Ronald E Wilson