Western Digital Technologies, Inc.

Hitachi Global Storage Technologies Netherlands B.v.

Hgst Netherlands, B.v.

Xinzhi Xing

John Thomas Contreras

Michael Alex

Manfred Ernst Schabes

Satya Prakash Arya

Albert John Wallash

Nobumasa Nishiyama

Antonio Ciccomancini Scogna

Yimin Hsu

Joey Martin Poss

Sukumar Rajauria

Tatemi Ido

Rehan Ahmed Zakai

Ronald G Parkinen

Hui He

Jack Nguyen

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.

Dark laser heating by positive pulse biasing in heat assisted magnetic recording

Disclosed herein are dual-spiral common-mode filters, printed circuit boards (PCBs) comprising such dual-spiral common-mode filters, and devices comprising such dual-spiral common-mode filters and PCBs. A dual-spiral common-mode filter is patterned into the reference plane of a PCB. The dual-spiral common-mode filter comprises a first spiral portion connected to a second spiral portion. The spiral portions may be substantially identical, or mirror images of each other, or different from each other. One or more signal traces in a signal trace layer of the PCB pass over the dual-spiral common-mode filter. The disclosed dual-spiral common-mode filters can replace both conventional patterned ground structure (PGS) filters used for radio-frequency interference mitigation and the cutouts often used in the reference plane of a PCB to mitigate impedance mismatches due to DC blocking capacitors. Also disclosed herein are methods of making PCBs that include dual-spiral common-mode filters.

Dual-spiral common-mode filter

A semiconductor device is disclosed including a wire bonded die stack where the bond wires skip dies in the die stack to provide bond wires having a long length. In one example, the semiconductor dies are stacked on top of each other with offsets along two orthogonal axes so that the dies include odd numbered dies interspersed and staggered with respect to even numbered dies only one of the axes. Wire bonds may be formed between the odd numbered dies, skipping the even numbered dies, and wire bonds may be formed between the even numbered dies, skipping the odd numbered dies. The long length of the bond wires increases an inductance of the wire bonds relative to parasitic capacitance of the semiconductor dies, thereby increasing signal path bandwidth of the semiconductor device.

Semiconductor device with die-skipping wire bonds

Technology for improved data detection using machine learning may include a method in which an analog read signal comprising data read from a non-transitory storage medium of the data storage device is received. The analog read signal is processed into a plurality of digital samples. A digital sample from the plurality of digital samples is classified into a category from a plurality of categories using a machine learning algorithm for at least some of the plurality of digital samples. The plurality of digital samples is then decoded based on at least some of the predicted categories.

Machine learning-based read channel data detection

Disclosed herein are multi-layer metal circuits, such as printed circuit boards (PCBs), with single-sided, partially-shielded, or fully-shielded via-less common-mode filters. The multi-layer metal circuits comprise at least one shield layer, at least one signal trace, and at least one reference layer (e.g., ground). The reference layer comprises a pattern of the via-less common-mode filter. The pattern may comprise, for example, a single piece-wise linear segment, or two or more disjoint and non-intersecting segments (which may be strictly linear or piece-wise linear). The reference layer is electrically isolated from the shield layer, and thus the via-less common-mode filters do not require vias. In addition to being used in PCBs, the disclosed multi-layer metal circuits may also be used in other applications, such as integrated circuits (e.g., implemented in semiconductor chips).

Via-less patterned ground structure common-mode filter

Disclosed herein are printed circuit boards with at least one signal trace situated over or under a reference plane. The reference plane includes a broadband common-mode filter that comprises looping and parallel structures etched into the reference plane. The looping structure includes an even number of side arms, and the parallel structure comprises an even number of interior arms, wherein each of the side arms extends toward the parallel structure, and each of the interior arms extends toward the looping structure. The at least one signal trace is substantially parallel to the side arms and to the interior arms, and is situated between a first half of the even number of side arms and a second half of the even number of side arms and between a first half of the even number of interior arms and a second half of the even number of interior arms.

Compact broadband common-mode filter

Disclosed herein are printed circuit boards with embedded solenoid filters through which signal traces pass to filter unwanted noise and electromagnetic interference. A printed circuit board comprises a least three layers, a solenoid embedded within the at least three layers, and at least one trace extending through the solenoid. The insertion loss characteristics of the solenoid filter can be tuned by modifying the number of turns in the solenoid(s) and the width of the solenoid(s). The solenoid filter may comprise multiple solenoids connected in series, with adjacent solenoids having opposite wind directions. Surface components may be included on the board to tune the insertion loss further.

Solenoid filter built into a printed circuit board

A method and apparatus is provided for extending a read bandwidth and increasing a high-frequency signal-to-noise ratio (SNR) of a front-end of a read path of a hard disk drive (HDD) by introducing a high impedance section at the front-end of the read path. The high impedance section may mitigate capacitive effects found at the front-end of the read path, thereby improving signal transfer by extending the read bandwidth.

Read path compensation for SNR and signal transfer

A perpendicular magnetic recording write head that a write pole, an electrically conductive coil coupled to the write pole for generating magnetic flux in the write pole in the presence of electrical write current, and a spin torque oscillator (STO) that injects auxiliary magnetic flux to the write pole in a direction generally orthogonal to the write pole to facilitate magnetization switching of the write pole. The STO comprises a stack of layers including electrodes, a pinned ferromagnetic layer having a fixed, a free ferromagnetic layer having a magnetization free to rotate, and a nonmagnetic spacer layer between the pinned and free layers. The free layer may be oriented either substantially orthogonal to the write pole or substantially parallel to the write pole, in which latter embodiment a flux guide may be located between the free layer and the write pole for directing the auxiliary magnetic flux from the free layer to the write pole.

Perpendicular magnetic recording write head with spin torque oscillator for fast switching of write pole magnetization

An integrated conductor/suspension structure for supporting and electrically connecting a write/read head in a hard disk drive and methods of making the conductor/suspension structure are provided. The integrated conductor/suspension structure may allow for an increased characteristic-impedance range, greater interference shielding and a reduction of signal loss that is contributed by a lossy conductive substrate. The suspension structure includes apertures formed therein that result in a reduction in the lossy material and its effect on the electrical signals. In addition, the conductor/suspension structure of the present invention provides shielding to reduce the interference from external electric fields.

Conductor suspension structure and electrical connection assembly for transmitting complementary signals in a hard disk drive

A perpendicular magnetic recording system has a write head with a main perpendicular write pole connected to a yoke with first and second electrical coils. The first coil is wrapped around the yoke on one side of the main pole, and the second coil is wrapped around the yoke on the other side of the main pole. The first end of each coil is connected to a respective terminal. The second ends of the two coils are connected together and connected to a common terminal. A lead-time circuit is connected between the common terminal and the first end of one of the coils. Immediately after the direction of write current is switched by the write driver, the lead-time circuit causes the current in one of the coils to lead the current in the other coil. The current displacement between the two coils creates a precession of the magnetic flux reversal, thereby reducing the switching time of the write head.

Perpendicular magnetic recording system with magnetic precession for fast switching of perpendicular write pole magnetization

A perpendicular magnetic recording system has a write head having a main helical coil (the write coil) and main pole (the write pole) that directs write flux in a direction perpendicular to the recording layer in the magnetic recording medium, and an auxiliary coil and auxiliary pole that injects magnetic flux into the write pole at an angle to the primary or perpendicular axis of the write pole. The auxiliary coil is preferably a helical coil wrapped around the auxiliary pole. The additional flux from the auxiliary pole, which is injected non-parallel to the primary magnetization of the write pole, exerts a relatively large torque on the magnetization of the write pole, thereby facilitating magnetization reversal of the write pole. Electrical circuitry is connected to the main coil and the auxiliary coil to generate the auxiliary flux simultaneous with the switching of the magnetization of the write pole.

Perpendicular magnetic recording system with helical write coil and auxiliary coil for fast switching of write pole magnetization

An apparatus and method for forming an opening in a base-metal layer of an electrical lead suspension (ELS) to increase the impedance. The method provides a base-metal layer having at least one opening. A dielectric layer above the base-metal layer is also provided, the dielectric layer covering a portion of the base-metal layer and at least one of the openings in the base-metal layer. A signal conductive layer is provided above dielectric layer. The signal conductive layer carries at least one solder pad portion, wherein the solder pad portion is aligned above the portion of the dielectric layer covering at least one of the openings in the base-metal layer. By aligning the at least one solder pad portion over the opening of the base-metal layer the solder pad to base-metal layer the impedance between the at least one solder pad portion and the base-metal layer is increased.

Method and apparatus for forming an opening in a base-metal layer of an electrical lead suspension (ELS) to increase the impedance

An apparatus and method for reducing heat absorption around solder pads on an electrical lead suspension (ELS). The method provides a base-metal layer having at least one opening. A dielectric layer is also provided above the base-metal layer, the dielectric layer covering a portion of the base-metal layer and at least one of the openings in the base-metal layer. A signal conductive layer is provided above dielectric layer. The signal conductive layer carries at least one solder pad portion, wherein the solder pad portion is placed above the portion of the dielectric layer such that the solder pad portion does not align with the at least one opening in the base-metal layer. In so doing, the heat absorption with respect to the base-metal layer is reduced.

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San Jose, CA, United States of America

Xinzhi Xing