Abstract: According to one embodiment, a class-D amplifier including: a PWM modulator that outputs a PWM modulation signal in response to an input signal; and a drive circuit that amplifies the PWM modulation signal, and supplies it to an output end. The drive circuit includes: a first output transistor whose main current path is connected between a power source supplying end and the output end; a second output transistor having a size larger than a size of the first output transistor; and a resistance element that is connected between the main current path of the first output transistor and the output end.

Abstract: A disk device includes a housing having a sidewall, the side wall having a first through-hole; a magnetic disk rotatably disposed in the housing and surrounded by the sidewall in a radial direction; a flexible printed circuit electrically connected to the magnetic disk; an insulator closing the first through-hole; a wireless communication device having a first communication antenna inside the housing; and a control board electrically connected to the flexible printed circuit. The control board is supplied with power from outside of the housing via a first connector, and is configured to receive a write command or a read command via the first communication antenna.

Abstract: According to one embodiment, a semiconductor device includes first to third electrodes, first to third nitride regions, and first and second insulating films. The first nitride region includes Alx1Ga1?x1N, and includes first and second partial regions, a third partial region between the first and second partial regions, a fourth partial region between the first and third partial regions, and a fifth partial region between the third and second partial regions. The first nitride region includes first to fifth partial regions. The second nitride region includes Alx2Ga1?x2N, and sixth and seventh partial regions. At least a portion of the third electrode is between the sixth and seventh partial regions. The first insulating film includes silicon and oxygen and includes first and second insulating regions. The third nitride region includes Alx3Ga1?x3N, and first to seventh portions. The second insulating film includes silicon and oxygen and includes third to seventh insulating regions.

Abstract: A semiconductor device includes a semiconductor body, an electrode provided on a surface of the semiconductor body. The semiconductor body includes a first semiconductor layer and a second semiconductor layer provided between the first semiconductor layer and the second electrode. The second semiconductor layer includes first and second regions arranged along the surface of the semiconductor body. The first region has a surface contacting the electrode, and the second region includes second conductivity type impurities with a concentration lower than a concentration of the second conductivity type impurities at the surface of the first region. The second semiconductor layer has a first concentration of second conductivity type impurities at a first position in the second region, and a second concentration of second conductivity type impurities at a second position between the first position and the electrode, the second concentration being lower than the first concentration.

Abstract: An electronic device includes a substrate, a first insulating film on the substrate, a second insulating film on the first insulating film, first and second coils respectively in the first and second insulating films, first and second terminals, and first and second connection conductors. The first and second insulating films contact each other so that the first and second coils are magnetically coupled. The first insulating film includes a first non-contact portion not contacting the second insulating film. One of the first and second insulating films includes a second non-contact portion not contacting the first or second insulating film. The first terminal is provided on the first non-contact portion and electrically connected to the first coil. The second terminal is provided on the second non-contact portion and electrically connected to the second coil. The first and second connection conductors are connected to the first and second terminals, respectively.

Abstract: According to one embodiment, a magnetic head includes a first magnetic pole, a second magnetic pole, and a stacked body provided between the first and second magnetic poles. The stacked body includes first to fourth magnetic layers, and first to fifth non-magnetic layers. The second non-magnetic layer is in contact with the second and first magnetic layers. The third non-magnetic layer is in contact with the third and second magnetic layers. The fourth non-magnetic layer is in contact with the fourth and third magnetic layers. A fourth thickness of the fourth magnetic layer along a first direction from the first magnetic pole to the second magnetic pole is not less than 0.5 times and not more than 1.6 times a first thickness of the first magnetic layer along the first direction. A second thickness of the second magnetic layer along the first direction is less than the first thickness.

Abstract: According to one embodiment, a disk device includes a first actuator assembly and a second actuator assembly which are respectively supported by a first bearing unit and a second bearing unit to be rotatable about a support shaft. The first bearing unit includes a first sleeve and a ball bearing. The second bearing unit includes a second sleeve and a ball bearing. The first sleeve includes a first end surface opposed to the second sleeve and an annular first step projecting from the first end surface, and the second sleeve includes a second end surface opposed to the first step with a gap and an annular second step projecting from the second end surface. The second step is opposed to the first step and the first end surface with a gap.

Abstract: According to one embodiment, a first storage area and a second storage area in which a plurality of tracks are set are provided in a radial direction of a magnetic disk. A plurality of post codes corresponding to the second storage area is stored in the first storage area. A controller controls first processing of reading a plurality of post codes from the first storage area and writing the plurality of read post codes in servo area of the second storage area. In the first processing, the controller controls both second processing and third processing in a state where a write head is located on a first track. The second processing is processing of writing a post code among the plurality of read post codes in a servo area. The third processing is processing of writing user data in a data area or reading user data from a data area.

Abstract: According to one embodiment, a magnetic disk device includes a rotatable disk-shaped recording medium, a magnetic head including a write head having a main magnetic pole that applies a recording magnetic field to the recording medium, an assist element that assists magnetic recording by the main magnetic pole, and a plurality of thermal actuators that control a head gradient with respect to the recording medium, and a controller which includes a detection unit configured to detect deterioration of the magnetic head, and changes a head gradient of the magnetic head by the thermal actuator according to the detected deterioration.

Abstract: A semiconductor device includes a semiconductor part having a first surface and a second surface opposite to the first surface, a first electrode on the first surface, a second electrode on the second surface, first to third control electrodes between the first electrode and the semiconductor part. The first to third control electrodes are biased independently from each other. The semiconductor part includes a first layer of a first-conductivity-type, a second layer of a second-conductivity-type, a third layer of the first-conductivity-type and the fourth layer of the second-conductivity-type. The second layer is provided between the first layer and the first electrode. The third layer is selectively provided between the second layer and the first electrode. The fourth layer is provided between the first layer and the second electrode. The second layer opposes the first to third control electrode with insulating films interposed.

Abstract: A phase correcting device includes a local oscillator that includes an all digital phase-locked loop configured to output a local oscillation signal, a first phase detector configured to detect a phase of the local oscillation signal to output the phase of the local oscillation signal, a reference phase device configured to generate a quasi-reference phase corresponding to a reference phase of the local oscillation signal to output the quasi-reference phase, based on a reference clock, a second phase detector configured to detect a fluctuation amount of a phase of the local oscillator, based on the phase detected by the first phase detector and the quasi-reference phase, and a correction circuit configured to correct the phase of the inputted signal by using a detection result of the second phase detector.

Abstract: A power-supply module according to the present embodiment comprises a capacitor and a switching circuit. The switching circuit comprises a plurality of switching elements, and is configured to charge the capacitor by using an input voltage with a combination of connection and disconnection of the switching elements, and output an output voltage that is different from the input voltage. The capacitor is a silicon capacitor, and each of the switching elements is a transistor.

Abstract: A switch circuit of an embodiment includes a radio-frequency switch and a level shifter circuit. The radio-frequency switch, which includes a first switch group and a second switch group each including a plurality of switches, switches transmission/reception of a radio-frequency signal. The level shifter circuit outputs a first signal for controlling ON/OFF of each switch of the first switch group and a second signal for controlling ON/OFF of each switch of the second switch group.

Abstract: According to one embodiment, a disk device includes a magnetic disk, a load beam, a flexure, a head unit, and a first restrictor. The load beam has a first face facing the magnetic disk. The flexure is attached to the first face. The head unit includes: a magnetic head attached to the flexure, configured to read and write information from and to the magnetic disk; and a heat-assister attached to the magnetic head, configured to heat the magnetic disk. The first restrictor is included in the head unit, configured to come in contact with at least one of the load beam and the flexure along with movement of the magnetic head away from the first face by a first distance.

Abstract: A sensor includes an avalanche photodiode (APD), a first resistor, a second resistor, and a rectification element. The first resistor is connected between a current output terminal of the APD and a first output terminal. The second resistor and the rectification element are connected in series between the current output terminal and a second output terminal. The rectification element is connected between the second resistor and the second output terminal.

Abstract: According to one embodiment, a magnetic disk device includes a disk including a first region with a first format efficiency and a second region with a second format efficiency lower than the first format efficiency, a head that writes data to the disk and reads data from the disk, and a controller that selects a first postcode to be written to the first region from a plurality of postcodes with different lengths and writes the first postcode to the first region, and selects a second postcode to be written to the second region from a plurality of postcodes with different lengths and writes the second postcode to the second region.

Abstract: According to one embodiment, a method for manufacturing a semiconductor member is disclosed. The method can include measuring a first mass of a semiconductor substrate including a first semiconductor layer of a first conductivity type. The method can include forming a first opening in an upper surface of the first semiconductor layer. The method can include measuring a second mass of the semiconductor substrate in which the first opening is formed. In addition, the method can include when forming a second semiconductor layer of a second conductivity type in the first opening, changing an impurity concentration of the second conductivity type in the second semiconductor layer according to a difference in mass between the first mass and the second mass.

Abstract: According to one embodiment, a suspension assembly includes a support plate, a wiring member disposed on the support plate, and a head supported on the support plate through the wiring member. The wiring member includes a distal end portion electrically connected to the head, a connection end portion extending outside the support plate, and a plurality of wirings extending between the distal end portion and the connection end portion. The connection end portion includes an opening with predetermined length and width and thirteen or more connection terminals disposed in the opening and arranged at intervals in a direction of the length. A percentage of an area of the opening occupied by areas of the thirteen or more connection terminals is 40% to 65% inclusive.

Abstract: A motor drive device of an embodiment includes a first drive circuit, a second drive circuit, a first detection circuit, a second detection circuit, a third detection circuit, a fourth detection circuit, and an output circuit. The first drive circuit drives a first phase of a motor. The second drive circuit drives a second phase of the motor. The first detection circuit detects a first anomaly of the first phase. The second detection circuit detects the first anomaly of the second phase. The third detection circuit detects a second anomaly of the first phase. The fourth detection circuit detects the second anomaly of the second phase. The output circuit outputs an occurred anomaly as a flag signal based on results of detection by the first to fourth detection circuits.

Abstract: According to one embodiment, among a plurality of magnetic heads, the larger the magnetic pole width of the magnetic pole of the magnetic head in the width direction of a recording track formed in a recording layer or the larger an area width of the magnetic head capable of reading the magnetic characteristics of an area of the recording layer on which magnetic recording has been carried out by means of the magnetic head, the farther is the magnetic head arranged outwardly from the vicinity of the center in the parallel arrangement direction of the magnetic disks.