Tdk Corporation

Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Electric Corporation

Masatoshi Nakayama

Kunihiro Ueda

Yuichi Kubota

Haruyuki Morita

Masanori Shibahara

Kenichi Horiguchi

Yukio Ikeda

Kenji Yokoyama

Fumio Maruta

Masahiro Nakano

Yasufumi Takasugi

Toru Shimozawa

Kazuhisa Yamauchi

Keiko Tsuchiya

Tsukimi Endo

Koji Kobayashi

Yuji Sakai

Tomokazu Hamada

Haruyasu Senda

Masatoshi Okamura

Mitsuru Takai

Shigeo Kurose

Toshiaki Izumi

Satoru Ishizaka

Hifumi Noto

Satoshi Kunugi

Akira Inoue

Hiroshi Tanabe

Jiro Yoshinari

Hideki Hirata

Kazumasa Fukuda

Teruyuki Shimura

Yasumichi Tokuoka

Tadashi Takagi

Toshihiko Ishida

Koichi Yajima

Akira Ohta

Kenji Nakaya

Kazutomi Mori

Tsuneo Kuwahara

Kazuhiro Iyomasa

Yasuhiro Onaka

Hiromichi Kanazawa

Izumi Ikeo

Yoshihiro Hamamatsu

Junichi Nagano

Takatoshi Ooyama

Michihiro Nemoto

Kiyoshi Yazu

Kazuyuki Totani

Provided is a low distortion amplifier which can satisfy both securement of a setting space in a vicinity of a transistor and low impedance. The low distortion amplifier includes a short stub having a leading end thereof short-circuited with a high-frequency short-circuit element and a low-frequency short-circuit element, in which the short stub is connected to a vicinity of at least one of a gate terminal and a drain terminal of the transistor, and includes a plurality of branched lines, the plurality of branched lines each having a leading end thereof short-circuited with the high-frequency short-circuit element and the low-frequency short-circuit element.

Low distortion amplifier and Doherty amplifier using low distortion amplifier

A directional coupler capable of improving a directionality of a directional coupler body including four terminals. The directional coupler includes a directional coupler body including the four terminals of an input port, an output port, a coupling port, and an isolation port; and a combiner for combining powers of an output signal of the coupling port and an output signal of the isolation port of the directional coupler body; and a directionality improving circuit for amplifying or attenuating at least one of the output signal of the coupling port and the output signal of the isolation port before outputting the same, and the combiner combines powers of the output signals amplified or attenuated by the directionality improving circuit.

Directional coupler

Provided is a high frequency amplifier including two amplifying elements of different element sizes connected in parallel and switching the amplifying elements in accordance with a level of output power. In particular, the high frequency amplifier includes an output matching circuit for matching to characteristic impedance (50 ohms) both when the output power is high and low, and increasing impedance when the turned-off amplifying element is viewed from a connection node on an output side of the two amplifying elements. Consequently, characteristics such as high output power and high efficiency can be achieved and it is possible to prevent an amplified high frequency signal from passing around to a matching circuit on a turned-off amplifying element side.

High frequency amplifier

When an input signal level is small, the electrical length of a phase lineand the electrical length of a phase lineare set in such a manner that the impedance seen by looking into the output side from an impedance reference pointat the output side of a carrier amplifierbecomes 2R+&#x3b1; (where R is a load resistance and &#x3b1; is positive), and the electrical length of a phase lineis set at a difference between the electrical length of the phase lineand the electrical length of the phase line

High efficiency amplifier

A linearizer changes a gain characteristic to a valley characteristic in which a gain reduces and then increases. The linearizer includes: a signal path in which an RF signal input terminal an input side bias blocking capacitor, a diode pair, including diodes having opposite polarities to each other, an output side bias blocking capacitor and an RF signal output terminal in series in the stated order; a bias circuit in which a resistor is provided between and a signal path formed between the input side bias blocking capacitor and the diode pair and a bias terminal; an RF short-circuiting capacitor whose one end is connected with the bias circuit between the bias terminal and the resistor and whose other end is grounded; and a DC feed inductor whose one end is connected with the signal path between the diode pair and the output side bias blocking capacitor and whose other end is grounded.

Linearizer

A method of producing a protective film on recording media including forming a protective film on at least the surface facing a recording medium, said protective film having the composition represented by the formula: SiCHON, where X=3-26, Y=0.5-13, Z=0.5-6 and W=0-6, in terms of atomic ratio, having a film thickness of 1-3 nm and having a refractive index of 2.0 or more.

Methods for producing a protective film on recording media

A protective thin-film for a magnetic head is produced by a method comprising vapor-depositing from an atmosphere containing Si, C and H under an operating pressure of less than 0.05 Torr while applying a negative bias voltage of less than &#x2212;400 V but greater than &#x2212;1000 V to a magnetic head, a protective thin film on at least the surface of the head facing a recording medium, the protective film containing Si, C and H in amounts of 3-9 at %, 61-81 at % and 16-30 at %, respectively, having a thickness of 1-3 nm and having a refractive index of 2.0 or more.

Method for producing a protective thin film for a magnetic head

A method of producing a wear-resistant protective film for a thermal head comprises depositing a wear-resistant protective film by sputtering on a thermal head which includes a substrate, and a heat-developing layer and a pair of electrodes formed on either the substrate or a heat-regenerative layer formed thereon. A layer of the wear resistant protective film is formed under a RF larger bias and another layer without a bias or with a smaller bias. Good step coverage is obtained by the RF sputter layer of the wear-resistant and the protective film prevents the intrusion of water that can cause cracking, and the layer formed under no or smaller bias reduces internal stresses and inhibits the development of cracks due to internal stresses as well as the cracking by RF sputtering.

Thermal head having wear-resistant protective film

A magnetoresistive thin-film magnetic head with high corrosion resistance for recording medium having massive capacity is provided by providing a protective film having a thickness of 40 &#x212b; or less. Since the distance between the head and the medium is remarkably reduced, the film is suitable for a recording medium having high-packing density. The magnetoresistive type thin-film magnetic head is provided, wherein the following layers are formed on at least the surface of the head facing a recording medium: (A) a lower layer composed of a thin film having the composition represented by the formula selected from the group consisting of:

Thin-film magnetic head, method for producing the same and magnetic disk device using the same

A dividerfor dividing and distributing a high-frequency signal input from an input terminalto two output sides, a main amplifying unit, connected to one output side of the divider, for amplifying one high-frequency signal output from the divider, a subsidiary amplifying unit, connected to the other output side of the divider, for performing no operation in case of a low instantaneous electric power of the other high-frequency signal output from the dividerand amplifying the other high-frequency signal in case of a high instantaneous electric power of the other high-frequency signal and a circulatorfor injecting the high-frequency signal amplified in the subsidiary amplifying unitinto the output side of the main amplifying unitand injecting the high-frequency signal amplified in the main amplifying unitinto an output terminalare arranged.

High-frequency amplifier, feed-forward amplifier and distortion compensating amplifier

A fluid dynamic bearing has a shaft ( ) fitted in a sleeve ( ) for rotation, with a fluid filled therebetween. The shaft ( ) and/or sleeve ( ) is formed with a pattern consisting of grooves ( ) and lands for generating a pressure distribution in the fluid and then covered with a diamond-like carbon film ( ) over the surface of the grooves and the surface of the lands.

Fluid dynamic bearing

A feedforward amplifier combines an input signal combined by a first error rejection loop with an error component and a first pilot signal detected by a second error detection loop, thereby canceling out the error component and the first pilot signal residual in the input signal.

Feedforward amplifier

Method of producing protected thermal head

A feedforward amplifier combines an input signal delayed by a delay circuit with an output signal by a combiner; down-converts the output of the combiner to a low frequency by a frequency converter; extracts a distortion component from the output of the frequency converter; measures the distortion component by a power detector; and controls a second vector regulator of a distortion canceling loop by a controller such that the distortion component measured becomes minimum.

Conventional distortion compensation circuits have addressed the problem that their distortion compensation amount is greatly reduced at levels other than the designed power level. The present invention provides a distortion compensation circuit that comprises: a vector adjuster; a linearizer; a linear signal extraction path for extracting part of an input signal from the input side of the vector adjuster; a nonlinear signal extraction path for extracting part of an output signal from the output side of the amplifier; a level detector for detecting a combined power level of the signals from the linear signal extraction path and the nonlinear signal extraction path; and a control circuit for adjusting a bias of the linearizer in accordance with the detected combined power level, electrically adjusting the linearizer so that the power detected by the level detector is minimized, and adjusting the vector adjuster so that the power detected by the level detector is minimized every time the linearizer is adjusted. As a result, the distortion compensation circuit of the present invention can optimize distortion compensation at all times independently of the average power changes of the input signal, the secular changes of the amplifier and the state changes of the amplifier caused by temperature changes.

Distortion compensation circuit

Growing community of inventors

Tokyo, Japan

Masatoshi Nakayama