transmitting configuration data to a data storage device of the preamplifier circuit by a read line

Abstract

The invention is entitled "Data storage device for transferring configuration data to a preamplifier circuit through a read line". The invention discloses a data storage device comprising a head actuated over a magnetic medium, wherein the head comprises a write element and a first read element. A preamplifier circuit comprising an interface comprises at least a write line associated with the write element of the head and a first read line associated with the first read element of the head. A first read signal is received from the preamplifier circuit through the first read line during a read operation, and configuration data is transferred to the preamplifier circuit through the first read line during a write operation.

Description

BACKGROUND

[0001] Data storage devices such as disk drives include a magnetic disk and a head connected to a distal end of an actuator arm that is rotated about a pivot by a voice coil motor (VCM) to position the head radially over the disk. The disk includes a plurality of radially spaced concentric tracks for recording user data sectors and servo sectors. The servo sectors include head positioning information (e.g., track addresses) that is read by the head and processed by a servo control system to control the actuator arm as it tracks from track to track.

[0002] Disk drives typically include multiple disks each having a top surface and a bottom surface that are accessed by respective heads. That is, the VCM typically rotates multiple actuator arms about a pivot so as to simultaneously position multiple heads over respective disk surfaces based on servo data recorded on each disk surface. Figure 1 A prior art disk format 2 is shown that includes a plurality of servo tracks 4 defined by servo sectors 6 recorded around the circumference of each servo track. N Each servo sector 6 i includes a preamble 8 for storing a periodic pattern that allows proper gain adjustment and timing synchronization of the read signal and a sync mark 10 for storing a special pattern used for symbol synchronization to a servo data field 12. The servo data field 12 stores coarse head positioning information, such as a servo track address, used to position the head over a target data track during a track seeking operation. Each servo sector 6 i also includes a servo burst set 14 (e.g., N servo bursts and Q servo bursts) that are recorded at predetermined phases relative to each other and to the servo track centerline. The phase-based servo bursts 14 provide fine head position information used for centerline tracking while accessing data tracks during write / read operations. A position error signal (PES) is generated by reading the servo bursts 14, where the PES represents a measured position of the head relative to the centerline of a target servo track. The servo controller processes the PES to generate a control signal applied to the head actuator (e.g., voice coil motor) so as to radially actuate the head over the disk in a direction that reduces the PES.

[0003] Data is typically written to a disk by modulating a write current in an inductive coil (write coil) to record magnetic transitions onto the disk surface in a process known as saturation recording. During a readback, the magnetic transitions are sensed by a read element (e.g., a magnetoresistive element), and the resulting read signal is demodulated by a suitable read channel. Heat assisted magnetic recording (HAMR) is a recent development that improves the quality of the written data by heating the disk surface during a write operation to reduce the coercivity of the magnetic media, thereby enabling the magnetic field generated by the write coil to more easily magnetize the disk surface. Any suitable technique can be employed to heat the surface of the disk in HAMR recording, such as by fabricating a laser diode and a near-field transducer (NFT) with other write components of the head. Microwave assisted magnetic recording (MAMR) is also a recent development that improves the quality of the written data by using a spin torque oscillator (STO) to apply a high frequency assist magnetic field to the media at a resonant frequency close to the magnetic grains, thereby enabling the magnetic field generated by the write coil to more easily magnetize the disk surface. BRIEF DESCRIPTION OF DRAWINGS

[0004] Figure 1 A prior art disk format is shown that includes a plurality of servo tracks defined by servo sectors.

[0005] Figure 2A A data storage device in the form of a disk drive is shown according to an embodiment, including a head actuated over a disk and a preamplifier circuit including an interface having at least a write line associated with a write element of the head and a first read line associated with a first read element of the head.

[0006] Figure 2B A flowchart according to an embodiment in which a first read signal is received from the preamplifier during a read operation over the first read line and configuration data is transmitted to the preamplifier during a write operation over the first read line.

[0007] Figure 2C A preamplifier circuit according to an embodiment is shown, including an output amplifier configured to transmit a first read signal to a control circuit over a first read line and an input amplifier configured to receive configuration data from the control circuit over the first read line.

[0008] Figure 3 An embodiment is shown in which the head includes a first read element and a second read element configured for two-dimensional magnetic recording (TDMR) and the configuration data is transmitted during a write operation over corresponding first and second read lines.

[0009] Figure 4Embodiments are shown in which configuration data configures write parameters, such as data-dependent overshoot amplitude (OSA) of write current applied to write coil, during write operations.

[0010] Figure 5A and Figure 5B Embodiments are shown in which configuration data configures write parameters, such as data-dependent write current amplitude (Iw) and overshoot amplitude (OSA), during write operations.

[0011] Figure 6 Embodiments are shown in which configuration data can be transmitted over two read lines using suitable M-ary signaling (e.g., M-ary pulse amplitude modulation) that increases resolution of the configuration data to five bits. DETAILED DESCRIPTION

[0012] Figure 2A Data storage devices in the form of disk drives according to embodiments are shown that include a head 16 actuated over a disk 18, where the head 16 includes a write element 20 and a first read element 22A Figure 2C ). While disk drives are used herein as illustrative examples, various embodiments of the present invention can be applied to and / or include other types of data storage devices having magnetic media, such as tape drives. The disk drive also includes a preamplifier circuit 24 that includes an interface having at least a write line 26 associated with the write element 20 of the head 16 and a first read line 28 associated with the first read element 22A of the head 16. A control circuit 30 is configured to execute Figure 2B a flowchart of FIG. 1, where a first read signal is received from the preamplifier over the first read line during read operations (block 32) and configuration data is transmitted to the preamplifier over the first read line during write operations (block 34).

[0013] Fidelity of magnetic transitions written onto the magnetic media, including degradation of adjacent data tracks due to adjacent track interference (ATI) when writing to a target data track, can depend on a plurality of write parameters configured for the head. For example, write parameters can include parameters of write current (Iw) applied to a write coil of the head, including amplitude of the write current, overshoot amplitude (OSA) of the write current, and overshoot duration (OSD) of the write current. In one embodiment, write parameters can be boosted (i.e., write boosting) according to a pattern of magnetic transitions being written to the magnetic media. For example, write current OSA can be boosted when writing high frequency patterns of magnetic transitions to fully saturate the magnetic media, while write current OSA can not be boosted when writing lower frequency patterns of magnetic transitions, while boosting write current amplitude and / or OSD to reduce ATI.

[0014] Conventionally, during a write operation, one or more write parameters are dynamically adjusted within the preamplifier circuitry by including circuitry within the preamplifier to detect the specific data pattern being written, and then the write parameters are adjusted accordingly. However, the complexity of the data correlation detection circuitry within the preamplifier circuitry is typically limited by the manufacturing process employed in implementing the signal processing circuitry required for the write / read operation. Therefore, in one embodiment, the data correlation detection circuitry in... Figure 2A The control circuit 30 is implemented within the data, and is typically fabricated with a much higher transistor density to facilitate buffering of the write data and more complex data pattern detection algorithms. The control circuit 30 then transmits configuration data to the preamplifier circuit 24 during the write operation to configure one or more write parameters to optimal settings corresponding to different data patterns written to the magnetic medium. In one embodiment, to reduce the number of transmission lines connecting the preamplifier circuit 24 to the control circuit 30, the configuration data for configuring one or more write parameters during the write operation is transmitted from the control circuit 30 to the preamplifier circuit 24 via one or more read lines. That is, since the read lines are typically unused during the write operation, in one embodiment, the read lines are used to transmit data-related configuration data from the control circuit 30 to the preamplifier circuit 24, thereby eliminating the need for additional transmission lines that would otherwise be required to transmit configuration data.

[0015] Any suitable interface circuitry can be used to transmit the read signal from the preamplifier circuit 24 to the control circuit 30 during a read operation, and to receive configuration data from the control circuit 30 during a write operation. Figure 2CIn embodiments, the preamplifier circuit 24 includes an output amplifier 36 coupled to the appropriate read element 22A and configured to transmit a read signal through the read line 28 during a read operation. The preamplifier circuit 24 also includes an input amplifier 38 configured to receive configuration data through the read line 28 during a write operation, where the configuration data is processed by the write control circuit 40 to configure one or more data-dependent write parameters during the write operation. That is, when write data is transmitted through the write line 26, corresponding configuration data is simultaneously transmitted through the read line 28 and processed by the write control circuit 40, which makes corresponding adjustments to the write parameters (e.g., by adjusting the operation of a write amplifier 42). In one embodiment, the preamplifier circuit 24 includes appropriate circuitry for enabling / disabling the input amplifier 38 or the output amplifier 36 depending on the mode of operation (i.e., a write or read operation). For example, the preamplifier circuit 24 can include appropriate switches (not shown) for connecting / disconnecting the input amplifier 38 or the output amplifier 36 from the read line 28. In another embodiment, the input amplifier 38 and the output amplifier 36 can be implemented with appropriate tri-state circuitry to enable / disable the amplifiers depending on the mode of operation. The interface of the preamplifier circuit 24 can include additional transmission lines (not shown in FIG. 1), such as a read / write enable line, a mode line, or a serial input / output (SIO) for transmitting other configuration data, such as head selection circuitry in a multi-head disk drive. Figure 2C

[0016] Figure 3 Embodiments are shown in which the head 16 can include a first read element 22A and a second read element 22B configured to implement a two-dimensional magnetic recording (TDMR) read operation. For example, in one embodiment, the read elements 22A and 22B can be radially offset as the head reads a target data track, where the resulting read signals (transmitted through the read lines 28A and 28B) can be processed by the control circuit 30 using any suitable TDMR signal processing to improve the accuracy of the read operation. During a write operation, configuration data (e.g., data-dependent write parameter settings) can be transmitted to the preamplifier circuit 24 through both the first read line 28A and the second read line 28B, thereby increasing the resolution of the configuration data. For example, in one embodiment, the configuration data can be transmitted using 2-bit binary signaling such that the configuration data can assume one of four values during a bit cell of the write operation. Figure 4 ​An example embodiment is shown in which the overshoot amplitude (OSA) of the write current is configured using 2-bit binary signaling received over first and second read lines 28A and 28B. In this embodiment, the write / read enable signal is high during read operations when read signals from the read elements can be transmitted over the first and second read lines 28A and 28B to the control circuit 30. During write operations, the 2-bit configuration data is represented by a first dynamic waveform shaping signal (DWS 0) and a second dynamic waveform shaping signal (DWS 1) that are configured based on the data pattern being written. In this example, the 2-bit DWS lines configure the OSA write parameter to one of three different levels depending on the data pattern being written (e.g., 1T, 2T, 3T, or 4T data pattern) as shown by the write current signal of Figure 4 . That is, in this embodiment, the control circuit 30 detects the data pattern being written and then configures the 2-bit DWS signals over the first and second read lines 22A and 22B to optimize the OSA write parameter depending on the data pattern being written.

[0017] Figure 5A An example embodiment is shown in which the write current amplitude (Iw) and overshoot amplitude (OSA) can be configured using 2-bit binary signaling received over first and second read lines 28A and 28B. Figure 5A The top line represents the digital data being written to the magnetic media, which is encoded into a corresponding non-return-to-zero (NRZ) signal. In the example of Figure 5A , the 2-bit DWS signals configure a high OSA for 1T data pattern, a normal OSA and Iw for 2T data pattern, and no OSA and low Iw for 4T data pattern. Figure 5B A table is shown that illustrates all possible 5-bit data patterns that can be written according to the embodiment that uses 2-bit binary signaling to transmit configuration data, as well as the corresponding write parameter settings for Iw and OSA.

[0018] In another embodiment, the DWS signals can be modulated using any suitable M-ary (M-ary) signaling technique (e.g., M-ary pulse amplitude modulation (PAM)) in order to increase the resolution of the configuration data. For example, in one embodiment, the resolution of the configuration data can be increased from 2-bit to 5-bit using PAM signaling such that Figure 5B each five-bit pattern shown in the table of Figure 6 An example of this embodiment is shown in which the write current amplitude (Iw) and overshoot amplitude (OSA) can be adjusted to custom amplitudes at each bit cell of the data sequence by transmitting a DWS signal having one of six unique levels, thereby enabling 5-bit signaling of the configuration data.

[0019] In one embodiment, the write parameters configured during a write operation can include parameters of a write assist bias applied to a suitable write assist element, such as any suitable parameter of a bias applied to a laser in a heat assisted magnetic recording (HAMR), a bias applied to a spin torque oscillator (STO) in a microwave assisted magnetic recording (MAMR), or a bias applied to any other suitable material stack for energy assisted recording. In one embodiment, the parameters configured for the write assist element can be similar to the parameters configured for the write current (e.g., bias amplitude, OSA, OSD, etc.). In one embodiment, data dependent write parameters can be configured for both the write current and the write assist element in order to optimize fidelity of recorded magnetic transitions as described above.

[0020] Any suitable control circuitry can be employed to implement the flowcharts in the above-described embodiments, such as any suitable integrated circuit or circuits. For example, the control circuitry can be implemented within a read channel integrated circuit, or in a component separate from the read channel, such as a data storage controller, or some of the above-described operations can be performed by the read channel while other operations are performed by the data storage controller. In one embodiment, the read channel and data storage controller are implemented as separate integrated circuits, and in alternative embodiments they are fabricated as a single integrated circuit or system on a chip (SOC).

[0021] In one embodiment, the control circuitry includes a microprocessor that executes instructions operable to cause the microprocessor to perform the flowcharts described herein. The instructions can be stored in any computer-readable medium. In one embodiment, they are stored on a non-volatile semiconductor memory external to the microprocessor or integrated with the microprocessor in the SOC. In another embodiment, the instructions are stored on a magnetic disk and read into volatile semiconductor memory when the disk drive is powered on. In another embodiment, the control circuitry includes suitable logic circuitry, such as state machine circuitry. In some embodiments, at least some of the flowchart blocks can be implemented using analog circuitry (e.g., analog comparators, timers, etc.), and in other embodiments some of the blocks can be implemented using digital circuitry or a combination of analog / digital circuitry.

[0022] In various embodiments, the disk drive can include a magnetic disk drive, an optical disk drive, a hybrid disk drive, etc. Also, some embodiments can include an electronic device such as a computing device, a data server device, a media content storage device, etc., that includes a storage medium and / or control circuitry as described above.

[0023] The various features and processes described above can be used independently of one another or can be combined in various ways. All possible combinations and subcombinations are intended to fall within the scope of the present disclosure. Additionally, certain method, event, or process blocks can be omitted in some implementations. The methods and processes described herein are also not limited to any particular sequence or order, and the blocks or states related thereto can be performed in other sequences, or in other orders, that are appropriate for certain implementations. For example, tasks or events can be performed in an order other than that specifically disclosed, or multiple tasks or events can be combined in a single block or state. The example tasks or events can be performed in serial, in parallel, or in some other manner. Tasks or events can be added to or removed from the disclosed example embodiments. The example systems and components described herein can be configured differently than described. For example, elements can be added to, removed from, or rearranged compared to the disclosed example embodiments.

[0024] While certain example implementations have been described, these implementations have been presented by way of example only, and are not intended to limit the scope of the discoveries disclosed herein. Thus, none of the foregoing description should be interpreted as implying that any particular feature, characteristic, step, module, or block is essential or indispensable. Indeed, the novel methods and systems described herein can be embodied in a variety of other forms. In addition, various omissions, substitutions and changes in the form of the methods and systems described herein can be made without departing from the spirit of the disclosure disclosed herein.

Claims

1. A data storage device comprising: a magnetic medium; a magnetic head actuated over the magnetic medium, wherein the magnetic head comprises: a write element; a first read element; a second read element; and a preamplifier circuit comprising an interface, the interface comprising at least: a write line associated with the write element of the magnetic head; a first read line associated with the first read element of the magnetic head; and a second read line associated with the second read element of the magnetic head; and a control circuit configured to: receive, during a read operation, a first read signal from the preamplifier circuit over the first read line; receive, during the read operation, a second read signal from the preamplifier circuit over the second read line; and transmit, during a write operation, configuration data in the form of binary signaling to the preamplifier circuit over the first read line and the second read line.

2. The data storage device of claim 1, wherein the control circuit is further configured to: transmit, during the write operation, write data to the preamplifier circuit over the write line.

3. The data storage device of claim 2, wherein the configuration data configures at least one write parameter of the write operation.

4. The data storage device of claim 3, wherein the write parameter comprises at least one of: an amplitude of a write current, an overshoot amplitude of the write current, or an overshoot duration of the write current.

5. The data storage device of claim 3, wherein the write parameter comprises at least one of: an amplitude of a laser current, an overshoot amplitude of the laser current, or an overshoot duration of the laser current.

6. The data storage device of claim 3, wherein the write parameter comprises at least one of: an amplitude of a write assist bias, an overshoot amplitude of the write assist bias, or an overshoot duration of the write assist bias.

7. The data storage device of claim 6, wherein the configuration data configures the write parameter of the write operation to be one of at least five different modes.

8. The data storage device of claim 7, wherein the write parameter comprises at least one of: an amplitude of a write current, an overshoot amplitude of the write current, or an overshoot duration of the write current.

9. A data storage device comprising: a magnetic medium; a magnetic head actuated over the magnetic medium, wherein the magnetic head comprises a write element, a first read element, and a second read element; a preamplifier circuit, the preamplifier circuit comprising an interface, the interface comprising at least a write line associated with the write element of the magnetic head, a first read line associated with the first read element of the magnetic head, and a second read line associated with the second read element of the magnetic head; and a control circuit configured to: receive, during a read operation, a first read signal from the preamplifier circuit over the first read line; ​ receiving a second read signal from the preamplifier circuit through the second read line during the read operation; and transmitting configuration data in the form of binary signaling to the preamplifier circuit through the first read line and the second read line, wherein the configuration data is used to configure at least one write parameter of a write operation.

10. The data storage device of claim 9, wherein the write parameter comprises at least one of: an amplitude of a write current, an overshoot amplitude of the write current, or an overshoot duration of the write current.

11. The data storage device of claim 9, wherein the write parameter comprises at least one of: an amplitude of a write assist bias, an overshoot amplitude of the write assist bias, or an overshoot duration of the write assist bias.

12. The data storage device of claim 9, wherein the write parameter comprises at least one of: an amplitude of a laser current, an overshoot amplitude of the laser current, or an overshoot duration of the laser current.

13. The data storage device of claim 12, wherein the configuration data configures a write parameter of the write operation to be one of at least five different modes.

14. The data storage device of claim 13, wherein the write parameter comprises at least one of: an amplitude of a write current, an overshoot amplitude of the write current, or an overshoot duration of the write current.

15. A data storage device, comprising: a magnetic medium; a head actuated over the magnetic medium, wherein the head comprises a write element, a first read element, and a second read element; a preamplifier circuit comprising an interface comprising at least a write line associated with the write element of the head, a first read line associated with the first read element of the head, and a second read line associated with the second read element of the head; and means for receiving a first read signal from the preamplifier circuit through the first read line during a read operation; means for receiving a second read signal from the preamplifier circuit through the second read line during the read operation; means for transmitting configuration data in the form of binary signaling to the preamplifier circuit through the first read line and the second read line.

16. A preamplifier circuit, comprising: an interface comprising at least a write line associated with a write element of a head, a first read line associated with a first read element of the head, and a second read line associated with a second read element of the head; a first output amplifier configured to transmit a first read signal associated with the first read element through the first read line during a read operation; a second output amplifier configured to transmit a second read signal associated with the second read element through the second read line during the read operation; a first input amplifier configured to receive configuration data in binary signaling form over the first read line, wherein the configuration data is used to configure at least one write parameter of a write operation; and a second input amplifier configured to receive configuration data in binary signaling form over the second read line, wherein the configuration data is used to configure the at least one write parameter of the write operation.

17. The preamplifier circuit of claim 16, wherein the configuration data includes a write parameter comprising at least one of an amplitude of a write current, an overshoot amplitude of the write current, or an overshoot duration of the write current.

18. The preamplifier circuit of claim 16, wherein the configuration data configures a write parameter of the write operation to be one of at least five different modes.

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