Hitachi, Ltd.

Director-general of the Agency of Industrial Science and Technology

Minoru Nagata

Takahiro Okabe

Tohru Nakamura

Kenji Kaneko

Takao Miyazaki

Satoshi Tanaka

Nobuo Kotera

Hirotoshi Tanaka

Taizo Kinoshita

Kazuo Nakazato

Masaharu Kubo

Tomoyuki Watanabe

Isao Yoshida

Toshiaki Masuhara

Kiichi Yamashita

Yutaka Okada

Nobuo Hamamoto

Tadashi Onishi

Susumu Takahashi

Yuichiro Nakaya

Tokuo Kure

Masao Kawamura

Masanori Maruyama

Kenichi Mizuishi

Yukio Fujii

Ichiro Imaizumi

Takeaki Okabe

Masahiko Ogirima

Toru Toyabe

Shikayuki Ochi

Tatsundo Suzuki

Masatoshi Matsuda

Yosuke Tyojamori

Katsutaka Kimura

Toshio Sasaki

Yoshio Sakai

Naoki Yamamoto

Osamu Minato

Nobuyoshi Natsuaki

Wasao Takasugi

Masatoshi Ohtake

Katsuro Sasaki

Naoki Ozawa

Hideaki Kato

Hisao Katto

Makoto Furihata

Yasunobu Kosa

Hidehito Obayashi

Kiyoshi Aiki

Norikazu Hashimoto

Yokichi Itoh

Setsuo Ogura

Kazuhiro Kondo

Mineo Katsueda

Kazutoshi Ashikawa

Yasushi Hatta

Mitsuo Ito

Isamu Orita

Masaru Takeuchi

Mitsuya Sato

Norio Anzai

Shigeo Ohtaka

Masatomo Furumi

Hiroshi Kishida

Hidefumi Ito

Hisashi Horikoshi

Takashi Agatsuma

Takanori Nishimura

Shojiro Sugaki, Deceased

Kikuo Watanabe

Keikichi Moriwaki

In a digital information system for realizing the sale of information or the like having a commercial value in the form of a digital signal, and an audio processor, and signal processor suitably used with the system, when a digital signal is received/delivered, a digital signal source is connected directly to a player for receiving and storing a specified information, which is reproduced by the player independently. A voice interval of a digital audio signal is processed to realize the slow and fast playback. The system includes a data compressor and a data extender of simple configuration. The value of the digital signal received/delivered can be exhibited directly. A selling system is constructed easily, and the player is simple in configuration and easy to operate by anyone. The fast and slow playback are possible without deteriorating the sound quality, and ripples can be greatly reduced against the digital input signal, thereby making possible a faithful data compression of an acoustic signal or the like by a simple configuration. The self-diagnosis function permits the use of a defective memory chip, thereby leading to a very economical system.

Digital information system, digital audio signal processor and signal converter

The electric power consumption by a terminal used for communication of multimedia information is controlled by changing the quality of transmitted information. The terminal is provided with input means (101, 102, 106 and 107) through which such information as images and sounds is inputted, channel control sections (123 and 124) which output the input information to channels and receive information from the channels, output means (103, 104, 108, 109 and 105) which output the information received from the channels in the form of images, sounds, etc., a codec means (110) which is provided between the input and output means and the control sections, encodes the input information in one of multiple encoding modes in which electric power is differently consumed, and decodes the information inputted from the channels, and a control section (133) which controls the selection of the encoding mode. This terminal can continue information communication for a required period of time at minimum power consumption at the sacrifice of the quality of transmitted information. Therefore, either the power consumption or quality of information can be adequately selected according to the transmission.

Portable terminal apparatus for multimedia communication

A radio paging system with voice transfer function for transmitting a voice message input from an ordinary push-button telephone set to a small-sized receive-only unsophisticated radio pager. A paging station is provided to transmit by radio the message from a telephone network to the radio pager as follows: voice information constituting the message is first converted from analog to digital format, compressed, stored in memory, and scrambled by a privacy function part for transmission. The radio pager in turn demodulates the received information, stores it in memory, retrieves a necessary message therefrom as designated, descrambles the designated message from scrambled state, expands the message from compressed state, and outputs the message as an audible output. In this manner, the user carrying the radio pager is able to get the message from the caller without the risk of being tapped by a third party.

Radio paging system with voice transfer function and radio pager

A semiconductor circuit including first and second FET's for delivering an output signal without being affected by a change in threshold voltage of the FET's is disclosed. According to one practical form of the semiconductor circuit, the drain-source current path of an additional FET whose gate and source are shorted to each other, is connected in parallel to the drain-source current path of the first FET whose gate and drain are shorted to each other, to make the voltage-current characteristic of the second FET agree with that of the parallel combination of the first and additional FET's. According to another practical form of the semiconductor circuit, a voltage dividing circuit is connected in parallel to the drain-source current path of the first FET, and a divided output voltage from the voltage dividing circuit is applied between the gate and source of each of the first and second FET's.

Current mirror circuit employing depletion mode FETs

A method of manufacturing a bipolar transistor semiconductor device wherein the active regions of a transistor are formed in an opening provided in an insulating film, electrodes are led out by a polycrystalline silicon film formed on the insulating film, and the upper surfaces of the emitter and base electrodes and the exposed surface of the insulating film are substantially even.

Method of manufacturing a bipolar transistor

Disclosed is a process for making a bipolar transistor which comprises an n-type Si semiconductor body having a convex portion, an insulation film covering the surface of the semiconductor body other than the convex portion, and a p-type polycrystalline Si layer formed on the insulation film. A p-type region formed in the convex portion serves as an intrinsic base region, the polycrystalline Si layer serves as an extrinic base region, an n-type region formed in the intrinsic base region serves as an emitter region, and the body serves as a collector region.

Process for making polysilicon contacts to IC mesas

A radiation-hardened semiconductor device including a bipolar transistor is disclosed in which a highly-doped layer equal in conductivity type to and larger in impurity concentration than the base region of the transistor is formed in that portion of the surface of the base region which exists beneath an insulating film, to prevent minority carriers injected into the base region, from reaching the above-mentioned surface portion. Thus, the injected minority carriers can reach a collector region without being extinguished by the recombination at the surface of the base region.

Radiation-hardened semiconductor device with surface layer

A bipolar transistor comprises an n-type Si semiconductor body having a convex portion, an insulation film covering the surface of the semiconductor body other than the convex portion, and a p-type polycrystalline Si layer formed on the insulation film. A p-type region formed in the convex portion serves as an intrinsic base region, the polycrystalline Si layer serves as an extrinsic base region, an n-type region formed in the intrinsic base region serves as an emitter region, and the body serves as a collector region.

Polysilon contacts to IC mesas

A wide-band and high-gain differential amplifier adapted to amplifying transmitted optical signals of the GHz band is constituted by GaAs MESFET's. Two MESFET's Q1 and Q2 are differentially connected to each other. Drains of Q1 and Q2 are connected to load resistances R.sub.L and R.sub.L via a source-drain path of other MESFET's Q3 and Q4 whose gates are grounded in AC-wise. Current by-passing means 4, 4 are connected to the sources of other MESFET's Q3, Q4. DC bias currents of the differential pair of MESFET's Q1, Q2 are set to relatively large values to increase the mutual conductance gm of the differential pair of MESFET's Q1, Q2. Despite a large DC bias current, the current by-passing means 4, 4 decrease the DC voltage drops across the load resistances R.sub.L, R.sub.L, and enable the differntial amplifier to operate on a low power source voltage.

Amplifying circuit

A semiconductor device is constructed so that an insulation film is provided in regions other than a protruding portion of a substrate. A polycrystalline silicon layer and a metal silicide layer are formed over said insulation film to provide a multi-layer structure, and a take-out portion for at least one of the emitter, base, and collector members of a bipolar transistor provided in the mesa region is constituted by a film of this multi-layer structure. By virtue of the use of metal silicide together with the polycrystalline silicon, a very low resistance is achieved which enhances the device's operating speed. Further, the metal silicide is separated from the protruding portion of the substrate by a portion of the polycrystalline silicon to provide a smooth interface with the substrate. This smooth interface significantly reduces crystal defects in the single crystal substrate.

Semiconductor device

This invention relates to a threshold voltage detection circuit for detecting the threshold voltage of field effect transistors (FETs) and to a semiconductor circuit capable of a stable operation irrespective of the fluctuation of the threshold voltage by utilizing this threshold voltage detection circuit. The source-drain path of first FET is connected in series with that of second FET having substantially the same threshold voltage as that of the first FET and the conductances of these first and second FETs are set to a predetermined ratio to generate a voltage drop associated with the threshold voltage in the first FET. This voltage drop can be used for detecting the threshold voltage and for level-shifting. The output of the series connection of the first and second FETs is applied to the gate of a constant current FET having the same threshold voltage as that of the first and second FETs and the drain current of the constant current FET can thus be set irrespective of the fluctuation of the threshold voltage.

Threshold voltage fluctuation compensation circuit for FETS

A constant voltage circuit according to this invention comprises first means attenuating or dividing fluctuating voltage and an amplifying FET, to the gate of which the output attenuated or divided by the first means is applied and whose drain is connected with the fluctuating voltage through load means. The attenuation ratio or division ratio of the first means, the mutual conductance of the amplifying FET and the impedance of the load means are so set that the voltage drop across the load means cancels the fluctuating amount of the fluctuating voltage. Consequently an output voltage, which is maintained substantially constant, is obtained at the drain of the amplifying FET, independently of fluctuations in the fluctuating voltage, and thus a constant voltage circuit can be obtained. A constant current circuit according to this invention utilizes the constant voltage circuit described above. The output voltage of the constant voltage circuit is supplied to the gate of the constant current FET. Consequently a current, which is maintained substantially constant, flows through the drain-source path of this constant current FET and thus a constant current circuit can be obtained.

Semiconductor circuit

A semiconductor device wherein the active regions of a transistor are formed in an opening provided in an insulating film, electrodes are led out by a polycrystalline silicon film formed on the insulating film, and the upper surfaces of the emitter and base electrodes and the exposed surface of the insulating film are substantially even.

Bipolar transistor with sidewall bare contact structure

Growing community of inventors

Kodaira, Japan

Minoru Nagata