Abstract: Example servo interface circuitry, data storage devices, and methods to provide parallel self-servo write in a data storage device are described. The data storage device may include servo control circuitry that includes at least three digital-analog converters to provide control signals to the voice control motor (VCM) and arm actuators (e.g., micro actuators and milli actuators) of the data storage device. In data read/write mode, one actuator control signal controls the milli actuator for the target arm/head and another actuator control signal controls the micro actuator for the target arm/head. In self-servo write mode, one actuator control signal controls the micro actuator for one target arm/head and the other actuator control signal controls the micro actuator for another target arm/head for parallel self-servo writing.

Abstract: Example circuits, data storage devices, and methods to provide parallel self-servo write in a data storage device are described. The data storage device may include multiple heads actuated over respective surfaces of storage media and at least two preamplifiers and read paths to a channel circuit. Control circuitry may select heads connected through different preamplifiers for parallel self-servo write and receive read signals from the selected heads in parallel. These read signals, which may be based on self-servo write reference spirals previously written to the storage media, may be used to determine respective position error signals for the two heads and control their respective positions with corresponding control signals to a shared voice control motor and respective micro and/or milli actuators on the arms supporting the heads.

Abstract: Example storage preamplifier circuits, data storage devices, and methods for parallel self-servo write are described. The data storage device may include a pair of preamplifier circuits electrically connected to respective banks of read heads actuated over a storage media surfaces. In read/write operation, each preamplifier circuit may selectively and sequentially provide read signals from a selected head to a pair of read channel interfaces. In self-servo write operation, each preamplifier circuit may selectively and in parallel provide read signals from a selected head in their corresponding banks of read heads to the pair of read channel interfaces. For example, the pair of read channel interfaces for two-dimensional magnetic recording may receive read signals from one read sensor in a head in the first bank of heads and another read sensor for another head in the second bank of heads.

Abstract: Various illustrative aspects are directed to a data storage device comprising a disk, a read/write head configured to read data from and write data to the disk, a laser diode (LD) coupled to a near field transducer (NFT) configured to heat an area of the disk near the read/write head, an asymmetric LD driver configured to drive the LD, and one or more processing devices configured to: preheat the LD to a target temperature, wherein the preheating comprises: generating at least one bias pulse conforming to one or more tunable parameters, based at least in part on the target temperature; and applying, using the asymmetric LD driver, the at least one bias pulse to the LD such that no optical response is produced by the LD; and initiate a write operation for writing data to the disk.

Abstract: Example control circuitry, data storage devices, and methods for determining wedge repeatable runout correction values for interleaved servo patterns in a data storage device are described. The data storage device may include multiple heads actuated over different surfaces of a data storage device and receive read signals from two different heads over two different surfaces in parallel. The servo wedges of the two surfaces may be offset to enable parallel learning of wedge repeatable runout correction values.

Abstract: Various illustrative aspects are directed to a data storage device comprising a storage medium and a head configured to access the storage medium. The head comprises a first write assist element and a second write assist element. Control circuitry for driving the head is configured to apply a first write assist current Im that is synchronized to a write data current Iw to the first write assist element; and to apply a second DC write assist current Imdc to the second write assist element.

Abstract: Various illustrative aspects are directed to a data storage device comprising a disk, a read/write head configured to read data from and write data to the disk, a laser diode (LD) coupled to a near field transducer (NFT) configured to heat an area of the disk near the read/write head, an asymmetric LD driver configured to drive the LD, and one or more processing devices configured to: preheat the LD to a target temperature, wherein the preheating comprises: generating at least one bias pulse conforming to one or more tunable parameters, based at least in part on the target temperature; and applying, using the asymmetric LD driver, the at least one bias pulse to the LD such that no optical response is produced by the LD; and initiate a write operation for writing data to the disk.

Abstract: A data storage device comprises a first resistive temperature detector (RTD) and a second RTD coupled to a first voltage source. A tuning bridge coupled between the first and second RTDs and a second voltage source reduces offset between a first bias voltage across the first RTD and a second bias voltage across the second RTD. A low noise amplifier (LNA) receives the first and second bias voltages as a differential bias voltage. A modulator coupled between the first and second RTDs and the LNA modulates the differential bias voltage.

Abstract: A data storage device comprises a first resistive temperature detector (RTD) and a second RTD coupled to a first voltage source. A tuning bridge coupled between the first and second RTDs and a second voltage source reduces offset between a first bias voltage across the first RTD and a second bias voltage across the second RTD. A low noise amplifier (LNA) receives the first and second bias voltages as a differential bias voltage. A modulator coupled between the first and second RTDs and the LNA modulates the differential bias voltage.

Abstract: Various illustrative aspects are directed to a data storage device comprising a disk, a read/write head configured to read data from and write data to the disk, a laser diode (LD) coupled to a nearfield transducer configured to heat an area of the disk near the read/write head, a first resistive temperature detector (RTD), a second RTD, and one or more processing devices configured to: apply a laser bias to the LD during a write operation; obtain a plurality of differential signal measurements, based at least in part on a plurality of measurements from each of the first and second RTDs; and adjust the laser bias applied to the LD, based at least in part on comparing the plurality of differential signal measurements to a target value for the differential signal.

Abstract: Various illustrative aspects are directed to a data storage device comprising a disk and a read/write head configured to read data from and write data to the disk. The read/write head comprises a write pole tip and a transducer configured near the write pole tip. One or more processing devices are mounted on or near the read/write head and generate an AC current that is applied to the transducer to cause the transducer to generate a high frequency auxiliary field that is applied to the disk. The one or more processing devices may be an RF source IC mounted on or near a slider on which the read/write head is integrated or mounted.

Abstract: Various illustrative aspects are directed to a data storage device comprising a slider with a resistive temperature detector (RTD) having a first resistance electrically connected to a first amplifier and a plurality of controlled current sources and switches, and one or more processing devices configured to: control the switches to generate an alternating-bias signal having a first clock frequency for biasing the first resistance, modulate an input signal of the first amplifier using the first clock frequency to generate a modulated signal, demodulate an amplified modulated signal at an output of a second amplifier using the first clock frequency to generate a resistance detection signal, the second amplifier coupled to the first amplifier, and process the resistance detection signal to determine the first resistance and/or a change in value of the first resistance.

Abstract: A data storage device may include one or more disks, an actuator arm assembly comprising one or more disk heads, at least one laser diode positioned inside a corresponding laser diode cavity, a preamplifier, and one or more processing devices. The one or more processing devices are configured to: generate a reverse bias; apply, using the preamplifier, the reverse bias to the at least one laser diode to preheat a corresponding laser diode cavity to a target temperature prior to a write operation; control transition of the preamplifier from applying the reverse bias to applying a forward bias to the at least one laser diode; and activate the at least one laser diode to begin the write operation.

Abstract: Various illustrative aspects are directed to a data storage device comprising a disk; a read/write head configured to read data from and write data to the disk; a laser diode configured to heat an area of the disk near the read/write head; and one or more processing devices configured to preheat the laser diode to a target temperature associated with a write operation, wherein the preheating comprises applying (e.g., using a preamplifier) at least one forward bias pulse to the laser diode, wherein a corresponding duration of the at least one forward bias pulse is shorter than a duration of a turn-on delay for the laser diode; and initiate a write operation for writing data to the disk, based at least in part on the preheating.

Abstract: Various illustrative aspects are directed to a data storage device comprising a disk and a read/write head configured to read data from and write data to the disk. The read/write head comprises a write pole tip and a transducer configured near the write pole tip. One or more processing devices are mounted on or near the read/write head and generate an AC current that is applied to the transducer to cause the transducer to generate a high frequency auxiliary field that is applied to the disk. The one or more processing devices may be an RF source IC mounted on or near a slider on which the read/write head is integrated or mounted.

Abstract: Various illustrative aspects are directed to a data storage device comprising a slider with a resistive temperature detector (RTD) having a first resistance electrically connected to a first amplifier and a plurality of controlled current sources and switches, and one or more processing devices configured to: control the switches to generate an alternating-bias signal having a first clock frequency for biasing the first resistance, modulate an input signal of the first amplifier using the first clock frequency to generate a modulated signal, demodulate an amplified modulated signal at an output of a second amplifier using the first clock frequency to generate a resistance detection signal, the second amplifier coupled to the first amplifier, and process the resistance detection signal to determine the first resistance and/or a change in value of the first resistance.

Abstract: A data storage device may include one or more disks, an actuator arm assembly comprising one or more disk heads, at least one laser diode positioned inside a corresponding laser diode cavity, a preamplifier, and one or more processing devices. The one or more processing devices are configured to: generate a reverse bias; apply, using the preamplifier, the reverse bias to the at least one laser diode to preheat a corresponding laser diode cavity to a target temperature prior to a write operation; control transition of the preamplifier from applying the reverse bias to applying a forward bias to the at least one laser diode; and activate the at least one laser diode to begin the write operation.

Abstract: A data storage device is disclosed comprising a head actuated over an energy assisted magnetic media comprising a plurality of data tracks, wherein each data track comprises a plurality of data sectors. A write operation to a first data sector is executed by applying a first current to a write coil of the head while the head is over a second data sector preceding the first data sector, wherein the first current comprises a first amplitude. A second current is applied to the write coil while the head is over the first data sector, wherein the second current comprises a second amplitude lower than the first amplitude.

Abstract: Various illustrative aspects are directed to a data storage device comprising a slider with a resistive temperature detector with a first resistance, a resistance detection circuit electrically coupled to the first resistance and comprising a low and high frequency path corresponding to a DC and AC mode, respectively, and one or more processing devices configured to: bias the first resistance with a voltage bias, where the first resistance is coupled to a first and second amplifier, control a pulse generator to add a bias pulse on the HF path to generate a HF resistance detection signal, where the second amplifier is biased using the voltage bias and the bias pulse, control a clock to chop a LF signal at the first amplifier on the LF path, demodulate the chopped LF signal to generate a LF resistance detection signal, and concurrently process the HF and LF resistance detection signals.

Abstract: Various illustrative aspects are directed to a data storage device comprising a storage medium and a head configured to access the storage medium. The head comprises a first write assist element and a second write assist element. Control circuitry for driving the head is configured to apply a first write assist current Im that is synchronized to a write data current Iw to the first write assist element; and to apply a second DC write assist current Imdc to the second write assist element.