Lsi Corporation

Avago Technologies General IP (singapore) Pte. Ltd.

Avago Technologies International Sales Pte. Limited

Jason S Goldberg

Boris Livshitz

Ross Wilson

Anamul Hoque

Jeffrey Paul Grundvig

Paul Mazur

Erich Franz Haratsch

Ming Jin

Travis Roger Oenning

David W Kelly

Scott M Dziak

David Matthew Springberg

Haotian Zhang

Cameron Carroll Rabe

Jeffrey A Gleason

Edwin X Li

Kurt J Worrell

Ross S Wilson

An apparatus for measuring cross-talk in an array reader magnetic storage system includes an array reader with multiple read heads operable to read data from a magnetic storage medium, a first preamplifier connected to a first read head, a second preamplifier connected to a second read head, and a cross-talk measurement circuit connected to the first preamplifier and to the second preamplifier, operable to measure cross-talk between a first signal from the first read head and a second signal from the second read head.

Cross-talk measurement in array reader magnetic recording system

Aspects of the disclosure pertain to a system and method for providing controllable steady state current waveshaping in a preamplifier of a data storage system (e.g., hard disk drive). The preamplifier provides an output including a write current waveform having a steady state current level that is controllable via the write block circuitry of the preamplifier. This enhances the ability of the waveform to promote improved on-track and off-track write performance.

System and method for providing controllable steady state current waveshaping in a hard disk drive (HDD) preamplifier

Individual magneto-resistive read elements are connected to the pre-amplifier through a multi-conductor transmission line; one side of each magneto-resistive read element is taken to a single common lead which is also received in the read pre-amplifier. Amplification and bias control are performed by the read pre-amplifier. A low-noise input stage amplifier configuration accommodates a shared common lead in a multi-head environment. Means for independently biasing the magneto-resistive read elements are also provided. Feedback loops are employed to regulate the operating points of the input stages, and to set the potential of the common head terminal. Two-dimensional magnetic recording system testability is enhanced by ability to multiplex any head to a single system output.

Pre-amplifier input stage for multi-element magneto-resistive heads

A hard disk drive or other storage device comprises a storage medium, a write head configured to write data to the storage medium, and control circuitry coupled to the write head. The control circuitry comprises degauss circuitry coupled to or otherwise associated with one or more write drivers. The degauss circuitry is configured to generate an asymmetric degauss signal to be applied to the write head. The asymmetric degauss signal has a waveform with upper and lower decay envelopes that are asymmetric about a specified degauss current level, such as a substantially zero current level.

Storage device having degauss circuitry configured for generating degauss signal with asymmetric decay envelopes

A contact event between a sensing device and a storage medium is detected by receiving a signal indicating a physical proximity between the sensing device and the storage medium; generating a plurality of frequency bin outputs; comparing one or more frequency bin outputs to a corresponding first level threshold to yield a corresponding comparator output; summing the comparator output with at least one prior instance of the comparator output to yield an aggregated value; comparing the aggregated value to an aggregate threshold to yield an aggregate output; and generating a contact event output if one or more of a first group of the plurality of frequency bin outputs has an associated aggregate output set to a predefined binary value and a predefined minimum number of a second group of the plurality of frequency bin outputs has an associated aggregate output set to a predefined binary value.

Systems and methods for medium proximity detection in a read channel

An apparatus comprising a preamplifier, a channel, and a controller. The preamplifier may be configured to read/write data to a drive with a read/write head, in response to (i) a plurality of digital control signals multiplexed to be sent/received over a first bus and (ii) one or more analog data signals sent/received over a second bus. The channel may be configured to (i) connect to the first and second bus, and (ii) send/receive the plurality of digital control signals through (a) a plurality of interconnects and (b) the first bus. The controller may be configured to send/receive the digital control signals over the interconnects. The apparatus may be configured to (i) read/write the analog data signals to the drive and (ii) generate the digital control signals, in response to one or more input/output requests received from a drive interface.

Preamplifier-to-channel communication in a storage device

A hard disk drive or other disk-based storage device comprises a storage disk, a write head configured to write data to the disk, and control circuitry coupled to the write head. The control circuitry comprises a write driver and degauss circuitry associated with the write driver. The degauss circuitry is configured to control a degauss signal waveform to be applied to the write head by the write driver, and comprises separate amplitude envelope control mechanisms for steady state and overshoot portions of the degauss signal waveform. The separate amplitude envelope control mechanisms may comprise, for example, separate steady state and overshoot controllers for controlling the amplitude envelope decay rates of the respective steady state and overshoot portions of the degauss signal waveform over the plurality of pulses.

Storage device having degauss circuitry with separate control of degauss signal steady state and overshoot portions

A hard disk drive or other disk-based storage device comprises a storage disk, a read/write head configured to read data from and write data to the disk, and control circuitry coupled to or otherwise associated with the read/write head. The control circuitry comprises a write driver configured to generate a write signal for data to be written to the storage disk, and a multiple-slope transition controller associated with the write driver and configured to control a data transition in the write signal such that the data transition comprises at least two different segments each having a different slope, with the transition controller comprising separate slope control mechanisms for each of the segments. By way of example, the data transition may comprise a dual-slope transition having first and second segments arranged sequentially between a start point and an end point of the data transition.

Storage device having write signal with multiple-slope data transition

A hard disk drive or other disk-based storage device comprises a storage disk, a read/write head configured to read data from and write data to the storage disk, and control circuitry coupled to the read/write head and configured to process data received from and supplied to the read/write head and to control positioning of the read/write head relative to the storage disk. The control circuitry is further configured to adjust at least one parameter of a write signal for a target bit to be written to the storage disk based on respective magnetization polarities of one or more adjacent bits previously written to the storage disk.

Disk-based storage device having write signal compensation for magnetization polarity of adjacent bits

Various embodiments of the present invention provide systems and methods for detecting contact. For example, a method for detecting head contact is disclosed that includes: receiving an interface signal operable to indicate a physical contact between a sensing device and a storage medium; band pass filtering a data set derived from the interface signal to yield a band pass filtered output; comparing the band pass filtered output to a level threshold to yield a comparator output; summing the comparator output with at least one prior instance of the comparator output to yield an aggregated value; and comparing the aggregated value to an aggregate threshold to yield a contact output.

Systems and methods for medium contact detection

A circuit for use with a memory storage device including a magnetic storage medium and a write head operative to subject the magnetic storage medium to a magnetic field in response to an application of current to the write head, includes a write circuit operative to generate a write current supplied to the write head. The write current is characterized by a current waveform that reverses polarity in accordance with data to be stored on the magnetic medium. The circuit for use with the memory storage device further includes a degauss circuit operative to generate a degaussing current supplied to the write head. The degaussing current is characterized by a current waveform that oscillates between opposite polarities with an amplitude and a frequency that change over time.

Magnetic storage device with chirped write head degaussing waveform

Various embodiments of the present invention provide apparatuses, systems and methods for heat assisted magnetic recording. For example, an apparatus is disclosed that includes a signal generator operable to generate laser trigger pulses at the transition rate of the magnetic write data signal, a variable delay element operable to control an alignment between the laser pulse control signal and the magnetic write data signal, a phase difference detector operable to control the variable delay element, a triggerable pulse generator circuit operable to generate a laser pulse control signal based on the laser trigger pulses, a magnetic write head operable to record data to a magnetic storage medium under control of the magnetic write data signal, and a laser diode operable to heat the magnetic storage medium under control of the laser pulse control signal.

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Saint Paul, MN, United States of America

Jason S Goldberg