Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Tetsuo Chato

Yuzo Shimizu

Hiroshi Yamaguchi

Toyoyuki Shimazaki

Hideo Fukuda

Masaki Taniguchi

Yasufumi Shirakawa

Kenji Imaizumi

Yousuke Kuroiwa

Katsuichi Ohsawa

Katuichi Ohsawa

The test circuit according to the present invention includes: a plurality of light-receiving elements; a plurality of amplifiers, each of which converts, into a voltage, a photoelectric current supplied from one of the light-receiving elements; and an electric current supplying unit which supplies an electric current to each of the light-receiving elements and each of the amplifiers. In this test circuit, the electric current supplying unit selectively supplies an electric current to a first group of light-receiving elements and to a second group of light-receiving elements, the first group of light-receiving elements including light-receiving elements, out of the plurality of light-receiving elements, which are neither vertically nor horizontally adjacent to each other, and the second group of light-receiving elements including light-receiving elements, out of the plurality of light-receiving elements, which are vertically or horizontally adjacent to the light-receiving elements of the first group of light-receiving elements.

Test circuit and test method that includes supplying a current to a plurality of light-receiving elements

An amplifier circuit according to the present invention includes: a first operational amplifier having a negative input terminal, a positive input terminal, and an output terminal; a photodiode connected to the negative input terminal; a first resistor inserted between the output terminal and the negative input terminal; and a second resistor inserted between the output terminal and the positive input terminal, in which the amplifier circuit outputs current from the output terminal via the second resistor.

Amplifier circuit and optical pickup device

The present invention provides a light-receiving amplifier circuit which includes a clipping circuit, can prevent an oscillation at the time of clipping operation, and can freely set clipping voltage. The light-receiving circuit of the present invention includes a photodiode, an operation amplifier, a conversion resistance connected between an output terminal and an inverting input terminal of the operation amplifier, and a clipping circuit which clips output voltage of the operation amplifier to a predetermined value. The clipping circuit includes a PNP transistor which detects a change in the output voltage of the operation amplifier and a voltage source connected to a base of the PNP transistor. Here, when the PNP transistor is turned ON along with an increase of an emitter potential of the NPN transistor which constitutes an output amplifier stage of the operation amplifier, voltage from the voltage source is applied to the base of the NPN transistor via the PNP transistor.

Light-receiving amplifier circuit and optical pick-up device using the same

The present invention is intended to prevent a light-emitting diode from emitting light continuously in the case when the level at an input terminal is fixed high because of software or the like and to avoid various problems, such as battery exhaustion and breakdown of the light-emitting diode, in PDAs, cellular phones, etc. For these purposes, a high-pass filterfor passing the high-frequency components of an optical transmission input signal having a pulse waveform and a binary circuitfor binarizing the output signal of the high-pass filterso as to be returned to a pulse waveform are provided in the preceding stage of a light-emitting device driving circuitfor driving a light-emitting diodefor optical transmission.

Optical transmitter

A semiconductor device includes the following: a semiconductor substrate of a first conduction type; an intrinsic semiconductor layer of the first conduction type formed on the semiconductor substrate; a first semiconductor layer of a second conduction type formed on the intrinsic semiconductor layer; a first impurity layer of the first conduction type formed in the first semiconductor layer of the second conduction type; and a bipolar transistor and a MIS transistor formed in the first semiconductor layer of the second conduction type. The laminated structure of the semiconductor substrate, the intrinsic semiconductor layer, and the first semiconductor layer provides a diode for photoelectric conversion. A first insulator layer and a second insulator layer are formed respectively in at least a portion below the bipolar transistor and the MIS transistor. The transistors are isolated from the semiconductor substrate by the insulator layers, so that the characteristics of the transistors can be adjusted independently of the diode.

Growing community of inventors

Osaka, Japan

Tetsuo Chato