Abstract: 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).

Abstract: 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).

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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).

Abstract: 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.

Abstract: An apparatus includes a slider of a heat-assisted magnetic recording head. The slider comprises an air bearing surface, a substrate, and a plurality of electrical bond pads coupled to bias sources. A writer is positioned proximate the substrate. The writer comprises write coils coupled between first and second bond pads. At least one heater is coupled between the first and second bond pads. The at least one heater is disposed within the writer and is configured to thermally actuate the air bearing surface of the writer. A reader is disposed on the slider such that the writer is between the substrate and the reader. Write induced protrusion of the air bearing surface of the writer is moderated by stiffness of the substrate proximate the writer.

Abstract: 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.

Abstract: Before writing to a heat-assisted magnetic recording medium, a current of a laser is modulated about a default threshold current level. 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 bias current for subsequent activation of the laser is adjusted based on the modulation level of the optical power sensor.

Abstract: First and second signal patterns are used to write corresponding portions of first and second adjacent tracks to a magnetic storage medium. A characteristic of the first signal pattern is changed based on the second signal pattern, the changing of the characteristic reducing an adjacent track interference affecting the second track.