Abstract: A disk drive is disclosed comprising a head actuated over a disk having a plurality of tracks, wherein each track comprises a plurality of data sectors and a plurality of servo sectors. The disk drive further comprises control circuitry including a read channel. The control circuitry configures a power mode of the read channel into a no-op mode, and when the head approaches a servo sector, configures the power mode into a servo mode. After configuring the power mode into the servo mode, the control circuitry waits for a pre-servo gate period, and after the pre-servo gate period, enables a servo gate to read the servo sector. After reading the servo sector, the control circuitry disables the servo gate and waits for a post-servo gate period. After the post-servo gate period, the control circuitry configure the power mode into the no-op mode.

Abstract: A method of manufacturing a flex circuit is disclosed for a disk drive comprising a disk, a head actuated radially over the disk, and control circuitry. The flex circuit is for electrically coupling the head to the control circuitry and comprises a substrate. An electrical coating applied to a first side of the substrate is etched to form a first electrical lead. The first side of the substrate is irradiated with radiation such that the first electrical lead masks the radiation from passing through the substrate to prevent curing of a photoresist applied to the second side of the substrate to form an uncured photoresist and a cured photoresist on the second side of the substrate. The uncured photoresist is removed from the second side of the substrate to form a groove, and the groove is filled with electrically conductive material to form the second electrical lead.

Abstract: A disk drive is disclosed comprising a servo control system operable to actuate a head over a disk. A sensor signal is filtered with a first filter comprising a frequency response, and the filtered sensor signal is filtered to generate a compensated sensor signal. An error signal is filtered with a second filter comprising the frequency response, and an adaptation control signal is generated based on the compensated sensor signal and the filtered error signal. An adaptive filter is adapted in response to the adaptation control signal, wherein the adaptive filter filters the sensor signal to generate feed-forward compensation values. The feed-forward compensation values are applied to the servo control system to compensate for the disturbance. A disturbance signal that represents the disturbance is generated, and the frequency response of the first and second filters is optimized based on the sensor signal and the disturbance signal.

Abstract: A disk drive is disclosed comprising a disk comprising a plurality of servo tracks defined by servo sectors recorded around the circumference of the disk at a servo sampling frequency, and a servo control system operable to actuate a head over the disk by generating a control signal applied to an actuator. A first sinusoid is injected into the servo control system and a first DC component (dc1) is measured in the control signal. A second sinusoid is injected into the servo control system and a second DC component (dc2) is measured in the control signal, wherein the second sinusoid comprises a phase offset from the first sinusoid. A resonance mode of the servo control system is measured based on dc1 and dc2.

Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of tracks, wherein each track comprises a plurality of data sectors. A test pattern is written to at least one data sector in at least one track, and the test pattern is read from the disk to generate a noisy read signal comprising added noise. An estimated data sequence is detected from the noisy read signal, and an amplitude of the added noise is increased until a failure detection metric reaches a metric threshold. A failure threshold is generated based on the amplitude of the added noise when the failure detection metric reaches the metric threshold, and a failure condition of the disk drive is predicted based on the failure threshold.

Abstract: A disk drive is disclosed comprising a disk having a plurality of data tracks defined by servo sectors, where each data track comprises a plurality of data sectors, and each servo sector comprises a servo preamble and servo data. The disk drive further comprises a head comprising a read element and a write element, and a servo read channel comprising an analog front end and a timing recovery circuit. During an access operation, data preceding the servo preamble of a first servo sector in the first data track is read in order to initialize the analog front end of the servo read channel. At least part of the servo preamble is read to initialize the timing recovery circuit of the servo read channel, and at least part of the servo data of the servo sector is read using the timing recovery circuit.

Abstract: A disk drive is disclosed comprising a disk comprising tracks defined by servo sectors, a head, and control circuitry comprising a servo control system operable to actuate the head over the disk in response to the servo sectors. The head is loaded over the disk during a load operation, and a radial velocity of the head is determined during the load operation. A target track is generated based on the determined radial velocity of the head, and the servo control system seeks the head to the target track.