Seagate Technology Incorporated

Todd Michael Lammers

Robert Matousek

Tim Rausch

Jon David Trantham

Declan Macken

Thomas Lee Schick

Mourad Benakli

Kirill A Rivkin

Karim Tatah

Ralph William Cross

Andrei Dorobantu

Tyler Lenn Perry

Edward Charles Gage

Bruce Douglas Buch

Jianhua Xue

Housan Dakroub

Alfredo Sam Chu

Joshua Ward Christensen

Javier Ignacio Guzman

Andrew Thomas Jaeb

Xiong Liu

Kaizhong Gao

Wenzhong Zhu

Kevin Arthur Gomez

Mark Anthony Gubbins

Michael Thomas Johnson

William Michael Radich

Jason Charles Jury

Quan Li

Erik Jon Hutchinson

Andrew Robert Motzko

John Wolf

Ian James Gilbert

Anil Junuthula Reddy

Aditya Jain

Peng Peng

John Wayne Shaw, Ii

Beng Theam Ko

Chau Chin Low

Michael R Montemorra

Kent Edward Bodurtha

Matthew S Graeff

Jacob Charles Matousek

Abdelkrim Tatah

Apparatus and method for transferring data in a data storage system, such as but not limited to a hard disc drive (HDD). An optical link is provided between an analog front end (AFE) of a data storage device controller circuit (SOC) and a preamplifier/driver circuit (preamp) mounted to a rotary actuator to transfer an analog domain signal. A selected component is extracted from the signal using a modulation element such as a micro-resonance ring (MRR) or a Mach-Zehnder Interferometer Modulation (MZM) device. The extracted component is forwarded to a processing circuit to facilitate a transfer of data between a local memory and a non-volatile memory (NVM). The optical link includes a flexible portion in a flex circuit affixed to the rotary actuator and which supports the preamp. Multiplexed read, write, and power control signals are concurrently transmitted via the optical link. The link can concurrently service multiple head-disc assemblies (HDAs).

Analog optical link for a moveable actuator in a data storage system

Two or more different recording currents are applied to a write coil of a recording head. A first of the two or more currents is a positive current and a second of the two or more currents is a negative current. In response to the application of the two or more different recording currents, a data stream is recorded to regions of a moving continuous magnetic recording medium such that each region has three or more magnetic states. The three or more magnetic states can be read from the continuous magnetic recording medium via a magnetic read transducer to recover the data stream.

Method and apparatus for magnetically recording data with three or more states per unit of data

An apparatus includes a slider configured for heat-assisted magnetic recording, the slider comprising an air bearing surface (ABS), a writer, a reader, and a plurality of electrical bond-pads. The apparatus also includes a first component situated at the ABS of the slider proximate the reader and operatively coupled to a first pair of the plurality of electrical bond-pads, the first component being a thermocouple configured to sense for a thermal aspect of a magnetic recording medium surface. According to aspects of the invention, the slider is configured to share at least one bond-pad by operatively coupling a second pair of the plurality of electrical bond-pads to a second component, and the slider is configured to selectively utilize the thermocouple and the second component.

Bond-pad sharing for head-level thermocouple

A slider configured for heat-assisted magnetic recording includes a laser diode optically coupled to a waveguide of the slider. A power supply is coupled to the laser diode. A preamplifier is coupled to the power supply. The preamplifier is configured to monitor a forward voltage across the laser diode while operating the laser diode at a constant current during a write operation, detect a change in the forward voltage indicative of laser power instability, and generate a signal in response to detecting the forward voltage change.

Sensorless monitoring of laser power instability in a heat-assisted magnetic recording head

Systems and methods of laser bias calibration are presented. A preamplifier circuit may include a laser voltage monitor circuit and a laser bias control circuit configured to automatically adjust an output laser bias threshold voltage based on a monitored laser voltage. The laser bias control circuit may include a first differentiator circuit, a second differentiator circuit, and a threshold detection circuit. The preamplifier circuit may be utilized in a heat assisted magnetic recording device.

Laser bias calibration

Systems and methods for a providing a chirped current profile with an undershoot for a channel preamplifier are described. A method for writing bits in a magnetic recording disc may include applying an overshoot to a write current which is supplied to a magnetic writer of the magnetic recording disc and applying an undershoot to the write current after the overshoot is applied to at least partially de-saturate the magnetic writer. The method may also include writing a bit to the magnetic recording disc with the magnetic writer using the supplied write current. In some examples, the application of a short negative pulse after an overshoot portion of the write current waveform is delivered to the head during a write operation that writes the bit to the magnetic recording disc.

Chirped current profile with undershoot feature

In certain embodiments, an apparatus may comprise a first output driver connected to a first output via a first trace and a second output driver connected to a second output via a second trace. The first output driver may be configured to output a first drive signal to the first output to drive the first output and the first drive signal may cause first induced noise in the second trace. Further, the second output driver may be configured to output a second drive signal based on the first drive signal where the second drive signal may reduce the magnitude of the first induced noise at the second output.

Noise cancellation in multitransducer recording

A preamplifier may have a freeze bit that when set, puts the preamplifier in a static state, which prevents the preamplifier from implementing subsequent programming commands. The freeze state may continue until an unfreeze bit is programmed. In a multiple preamplifier system, preamplifiers can be differently and individually configured over a single interface. Preamplifiers may be released from the static state (frozen) by either programming the unfreeze bit (which can release all of the preamps) or by programming the freeze bit to a '0' state (releases the individual preamp). An inversion control circuit can allow inversion of a control signal to a preamplifier. The inversion control circuit may be enabled and disabled based on a physical conductive connection to a logic high voltage or a logic low voltage. One or more programmable control lines can determine whether the inversion function is activated when the inversion control circuit is enabled.

Individually programmable preamplifier

Systems and methods of laser bias calibration are presented. A preamplifier circuit may configure a laser current supplied to a laser emitter to be a first laser current of the plurality of laser currents during the writing of one or more first sectors. The preamplifier may further detect one or more gaps in a write power signal while the laser current of the laser emitter is configured to be the first laser current. In response to the detection of the one or more gaps in the write power signal, the preamplifier may configure the laser current supplied to the laser emitter to be a second laser current of the plurality of laser currents during the writing of one or more second sectors. The preamplifier circuit may be utilized in a heat assisted magnetic recording device.

Laser current calibration using preamplifier

Amplifiers, preamplifiers, and other circuits may have registers that are assigned to store data corresponding to certain functions. When the data stored in the registers are no longer needed, the registers may be assigned to store data corresponding to other functions, such as signal acquisition. The registers can be logically grouped into a virtual memory bank. The memory bank may store new data to a first register, and move data from the first register to a second register when new data arrives. In some embodiments, these registers and memory control circuit can be implemented within a preamplifier circuit.

Assignable registers on a preamp chip

Methods and apparatuses for detecting mode hopping in a laser diode or other optical energy source in heat-assisted magnetic recording. An output power of the laser diode or other optical energy source is measured and the output power is differentiated over time to determine a rate of change. If it is determined that the rate of change exceeds a threshold value, a fault signal is asserted indicating a potential mode hopping event.

Laser mode hopping detection for heat-assisted magnetic recording device

Before writing to a heat-assisted magnetic recording medium, a DC signal modulated with an AC signal is applied to a laser of a read/write head. A modulation level of an optical power sensor is measured, the optical power sensor being coupled to detect optical output of the laser in response to the modulated current. A target value of the DC signal that causes the modulation levels to reach a predetermined value between zero and a maximum value is determined and used to set a bias current for subsequent activation of the laser based.

Setting laser current based on modulation level of an optical power sensor measurement

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Lafayette, CO, United States of America

Todd Michael Lammers