Seagate Technology Incorporated

Robert Matousek

Todd Michael Lammers

Thomas Lee Schick

Jon David Trantham

Timothy Ted Walker

Tim Rausch

Alfredo Sam Chu

Michael Henry Lennard

Wenzhong Zhu

William Michael Radich

John Edward Moon

Paul Francis Kusbel

Paul William Burnett

Anish A Ukani

Matthew Chad Burton

Shawn Alan Wakefield

Dale Thomas Riley

Kevin David Powers

Ronald L Delamarter

Raymond Dean Nicholson

Kent Dillin

Abdelkrim Tatah

Sunil Anuprasad Patel

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

A compact printed circuit board assembly includes a printed circuit board (PCB) and a preamplifier subassembly. The preamplifier subassembly includes a preamplifier and an insulating endcap abutting one another and arranged in a plane parallel to the PCB. An electrical via formed within the first insulating endcap provides an electrical connection between a decoupling capacitor and the PCB to reduce noise detectable in current flowing between the preamplifier and a current source.

Compact printed circuit board assembly with insulating endcap via

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

A preamplifier circuit can include a control line dedicated to receive a control signal that corresponds to indicating a specific register of the preamplifier circuit, which can allow the preamplifier to switch between utilizing two or more registers to control a current output of the preamplifier circuit. The preamplifier circuit may also have a serial input to program multiple registers of the preamplifier circuit in a serial fashion. In some embodiments, the current output may be a laser bias current. The preamplifier may adjust an output current that drives a laser emitter based on a control signal indicating which specific registers controls the output current. Further, a controller, such as a system-on-chip controller, may selectively vary the control signal to affect the current output of the preamplifier circuit. These systems and methods may be particularly useful for lasers and heat-assisted magnetic recording (HAMR).

Laser bias current control

Systems and methods of digital automatic power control are presented. A preamplifier circuit may include a digital-to-analog converter (DAC) circuit to sample a power signal, such as a from a laser power monitor. The preamplifier may store the sample in an internal preamplifier memory. The sample may be utilized to update a current output of the preamplifier that affects the power signal. These systems and methods may be particularly useful for lasers and heat-assisted magnetic recording (HAMR), which may be utilized during a read mode or a write mode of a HAMR data storage device.

Digital automatic power control

Methods, apparatuses, and systems for allowing a single-die preamp to act as two or more virtual preamps for reading or writing data through multiple heads or elements concurrently. A selection register of a preamplifier is set to enable access to a primary register map. Values of registers in the primary register map are set to program a primary preamp channel for performing read or write operations to a first head. The selection register is then set to enable access to a secondary register map, and values of registers in the secondary register map are set to program a secondary preamp channel for performing read or write operations to a second head. Read or write operations can be performed to the first head through the primary preamp channel at a same time that read or write operations are performed to the second head through the second preamp channel.

Multiple virtual preamps in a single die

The present application discloses detecting an asperity on a storage media surface using two amplitude threshold crossings of an asperity detection signal within a preset timing window. The present application further discloses a temperature-dependent resistive asperity sensor and a preamplifier that correlates a resistance change at the asperity sensor within a preset timing window to detect an asperity on a storage media surface. The asperity may be one or both of a void in the storage media surface and a protrusion from the storage media surface.

Storage media asperity characterization

A data storage apparatus includes a controller capable of being coupled to a read/write head. The controller is configured to receive a fault signal from a sensor of the read/write head. The sensor indicates whether an energy source used to heat the recording medium is malfunctioning during a write operation. In response to the fault signal, the controller takes remedial action to protect the data associated with the write operation.

HAMR drive fault detection system

Method and apparatus for decoding data, such as from a rotatable magnetic recording medium. In accordance with some embodiments, a plurality of sensors is provided, with each sensor configured to generate a sense signal from an adjacent pattern. A processing circuit is configured to decode data from the adjacent pattern using the generated sense signals.

Multi-sensor data transducer

An apparatus and associated method is presently disclosed for a control circuitry capable of managing a heat source used in data storage applications. Various embodiments of the present invention are generally directed to a heat source directed at a data storage medium with a synchronization signal and a serial interface that are each selectively activated via a demultiplexed write gate signal. The selective activation allows for pulsed operation of the heat source resulting in reduced duty cycle and temperature during a write operation.

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Berthoud, CO, United States of America

Robert Matousek