Fuji Electric Co., Ltd.

Yoshio Tsuruta

Yoshinari Enomoto

Takashi Nishibe

Shotaro Yokoyama

An optical sensor circuit of the invention includes a photodiode, a reset switch, a capacitor for charge integration, an operational amplifier, reference voltage generating circuits connected to the operational amplifier via switches, and a reference voltage selecting circuit connected to the control input terminals of the respective switches. The reference voltage for defining the upper limit of the output range of the optical sensor circuit can be set at an appropriate value. Since the reference voltage is set at an appropriate value corresponding to the input range of an A/D converter due to this circuit configuration, a conversion error in the A/D converter is avoided, and the analog output of the optical sensor circuit is converted to a digital quantity while the resolution of the A/D converter is fully utilized.

Optical sensor circuit with output changing means

A photoelectric converting circuit having a photodiode generating a photoelectric current in accordance with the quantity of light, a first integrating circuit integrating the photoelectric current to convert it into a voltage, and a charge amplifier amplifying the change in the output voltage of the first integrating circuit. The charge amplifier is composed of a second integrating circuit and a coupling capacitance connected between the output of the first integrating circuit and the input of the second integrating circuit. The change in the output of the second integrating circuit is proportional to the ratio of the coupling capacitance to the integration capacitance of the second integrating circuit. This makes it possible to improve the sensitivity of the photoelectric converting circuit without reducing the value of the integration capacitance of the first integrating circuit.

Photoelectric converting circuit having an amplification factor

The present invention discloses a light-receiving element, and method for making same, for a charge storage light sensor having a first semiconductor later of a first conductive type with an element isolation region disposed thereon. The element isolation regions are formed to produce tilted edges embedded within the first semiconductor layer and to also produce an embedded region of a second conductive type. The embedded region is effective to collect the photoelectric current resulting from light exposure to the first semiconductor layer regions upon the application of a reverse bias potential to the embedded region.

Method of making a photodiode with reduced junction area

The present invention discloses a light-receiving element, and method for making same, for a charge storage light sensor having a first semiconductor layer of a first conductive type with an element isolation region disposed thereon. The element isolation regions are formed to produce tilted edges embedded within the first semiconductor layer and to also produce an embedded region of a second conductive type. The embedded region is effective to collect the photoelectric current resulting from light exposure to the first semiconductor layer regions upon the application of a reverse bias potential to the embedded region.

Semiconductor photodiode device with reduced junction area

A light sensor device which uses semiconductors, can assure linearity even with low light intensity, and has a fast response time provides a voltage output proportional to a photoelectric current obtained from the output of an operational amplifier by accumulating the photoelectric current from a photodiode using the operational amplifier and an integration capacitance connected in parallel to the operational amplifier.

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Matsumoto, Japan

Yoshio Tsuruta