Hitachi, Ltd.

Other

Yasushi Hatta

Hiroyuki Tanaka

Katsuyoshi Washio

Kiichi Yamashita

Ryoji Takeyari

Toru Masuda

Nobuo Kotera

Hirotoshi Tanaka

Kenichi Ohhata

Keiichi Kitamura

Satoshi Tanaka

Yasushi Takahashi

Takehisa Hayashi

Minoru Nagata

Kazumichi Mitsusada

Tatsuya Kouketsu

Kyosuke Ishikawa

An optical receiver generates a voltage signal having a predetermined swing from a current signal, and feeds the voltage signal to a decision circuit. An optical receiving element receives the input optical signal, converts the optical signal to a current signal, and provides the current signal to a preamplifier, which converts the input current signal into a voltage signal. The voltage signal is input to an amplifier having a limiting function, which linearly amplifies the voltage signal when the swing of the voltage signal is smaller than a predetermined value, and limitedly amplifies the voltage signal when the voltage signal is greater than the predetermined value. An automatic-gain-control amplifier receives the output from the amplifier with the limiting function, and amplifies the input voltage signal to a voltage signal having a constant swing. The decision circuit receives the output of the automatic-gain-control amplifier and decides the binary nature of the voltage, and thus of the input optical signal.

Optical receiver

A semiconductor integrated circuit device of a type wherein loads for source follower amplifiers FETs whose gates receive an amplified signal produced from a differential amplifier section and whose each source generates an output signal, comprise first load FETs whose each gate area is small and second load FETs which are respectively series-connected with the first load FETs, whose each gate length is relatively long and each of which has small drain conductance.

Semiconductor integrated circuit device

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 logic circuit made up of FET's is disclosed in which an output interface circuit is formed of a source follower circuit including a signal transmitting FET and a constant-current supplying FET, and a ratio of the gate width of the signal transmitting FET to the gate width of the constant-current supplying FET is set so that the high and low levels of the output signal of the logic circuit are independent of the threshold voltage of the FET's.

MESFET circuit with threshold-compensated source-follower output

Disclosed is a semiconductor integrated circuit device forming MESFETs by use of a semi-insulator GaAs substrate which prevents destruction of an electrostatic destruction protect circuit and a Schottky junction of an internal circuit by causing a part of electrostatic energy, which is applied to external terminals, to flow from a semiconductor region connected to the external terminals into another semiconductor region which is formed in the vicinity of the semiconductor region described above and to which a predetermined fixed potential is applied.

Semiconductor integrated circuit device having semi-insulator substrate

Growing community of inventors

Kodaira, Japan

Yasushi Hatta