Kabushiki Kaisha Toshiba

Canon Kabushiki Kaisha

Shigeyuki Sakura

Masayuki Sugizaki

Hiroshi Suzunaga

Miki Hidaka

Toyoaki Uo

Kazuhiro Shimada

Motoyasu Morinaga

Katsuji Kaminishi

Asako Ikeda

Hirofumi Kobayashi

Atsushi Iwata

Masaru Numano

Yukiko Takiba

Yuichi Tagami

Atsushi Namai

Hiroshi Shimomura

Takeshi Miyakawa

Kei Kasai

Yoshitaka Murasaka

Hisami Saito

Toshifumi Imamura

A light receiving circuit includes a light receiving element, a first transistor that includes a control terminal which is connected to the light receiving element through a first node, a first terminal and a second terminal, a first load circuit that is connected between a power supply potential and a second node connected to the second terminal, and outputs a voltage signal to a third node, wherein the voltage signal is based on a current signal in the light receiving element, a first feedback resistor that is connected between the first node and the third node, a first limiter circuit that is connected in parallel with the first feedback resistor, and limits an increase of voltage at both ends of the first feedback resistor, and a first circuit that is connected between the second node and the reference potential, includes a second transistor which is diode-connected.

Light receiving circuit and light coupling device

A light receiving circuit includes an inverting amplification circuit, a first light receiving element, a first circuit, and a charging circuit. The inverting amplification circuit includes an input terminal and an output terminal. The first light receiving element is connected between the input terminal and a reference potential terminal. The first circuit includes a first resistor, a second resistor, a third resistor and a capacitor. The first resistor second resistor connected through a connection point. The first resistor is connected between the input terminal and the connection point, and the second resistor connected between the output terminal and the connection point. The third resistor is connected between the connection point and connection node, and the capacitor is connected between the connection node and the reference potential terminal. The charging circuit connected between the power supply terminal and the connection node.

A light receiving circuit includes first, second, and third resistors, a photodiode that is connected in series with the first resistor between first and second potential lines, and a first MOS transistor of a first conductivity type having a source connected to a second node, a drain connected to an output, and a gate connected to a first node that is between the first resistor and the photodiode. The light receiving circuit also includes a capacitor which is connected in parallel to the second resistor between the first potential line and the second node. The third resistor is connected between the output and the second potential line.

Light receiving circuit

According to one embodiment, a photodiode includes a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type, a third semiconductor layer of the first conductivity type, and a film. The second semiconductor layer is provided in the first semiconductor layer. The third semiconductor layer is provided in the first semiconductor layer so as to surround the second semiconductor layer. Each of one ends of the second and third semiconductor layers is located at an upper surface of the first semiconductor layer. The first to third semiconductor layers include first to third impurity concentrations respectively. The second and third impurity concentrations are higher than the first impurity concentration. The film is provided above the third semiconductor layer, and blocks light to enter into a neighborhood of the third semiconductor layer.

Photodiode

According to an embodiment, a light-receiving circuit includes a MOSFET, a first light-receiving element and a second light-receiving element. The first light-receiving element controls a state of the MOSFET between ON state and OFF state by applying a voltage induced by a light signal between a gate of the MOSFET and a source of the MOSFET; and a second light-receiving element controls a threshold voltage of the MOSFET.

According to one embodiment, a light receiving circuit includes a light receiving element, a differential circuit, a fifth transistor, and first and second current sources. The differential circuit includes an amplifier and a bias circuit. The amplifier includes a first transistor, a second transistor, and a first feedback resistor. The amplifier is configured to convert a current from the light receiving element into a voltage. The bias circuit includes a third transistor, a fourth transistor, and a second feedback resistor. A reference voltage is supplied to a control electrode of the fourth transistor. The second and third transistors are included in a current mirror circuit. A fifth transistor has a control electrode connected to a connection point between the first and second transistors. A voltage signal switched to a high level or a low level according to a change of an optical signal is outputted.

A light receiving circuit includes a light receiving element, a transimpedance amplifier, a delay circuit and a comparator. The transimpedance amplifier is configured to convert the current signal into a first voltage. The comparator includes first to third current control elements each including first to third electrodes and configured to control current of the third electrode by voltage of the second electrode. The first voltage is inputted to the second electrode of the first current control element. Output voltage of the delay circuit is inputted to the second electrode of the second current control element. A second voltage is inputted to the second electrode of the third current control element. The comparator is configured to compare output current of the first current control element with sum of output current of the second current control element and output current of the third current control element.

Light receiving circuit and photocoupler

According to one embodiment, a light receiving circuit having a trans-impedance amplifier and an output circuit is provided. The trans-impedance amplifier includes a photodiode, a feedback resistor and a first transistor having a channel of a first conductive type. The photodiode converts an optical signal into an electrical signal. Ends of the feedback resistor are connected respectively to the photodiode and a node. A gate of the first transistor receives the electrical signal from the photodiode. A signal corresponding to a signal from a drain of the first transistor is output to the node. The output circuit includes a second transistor having a channel of the first conductive type, and generates an output signal from a drain of the second transistor. A gate of the second transistor is connected to the node.

A light receiving circuit includes a photodiode, a transimpedance amp having a feedback resistor, an electric current comparator and an automatic threshold control circuit that includes a current mirror circuit for forming a current according to the mirror effect. With this light receiving circuit, regardless of how powerful the input light signal is, low pulse width distortion characteristics can be achieved.

Light receiving circuit having an automatic threshold control circuit for forming and allowing electric current flowing between a second potential line and first and second connection points

According to one embodiment, an optical coupling device is provided. A first photodiode receives an optical signal generated by a light emitting element and converts the optical signal into a first electrical signal. A first inverting amplifier is provided with a first feedback resistor and a first operating amplifier connected in parallel with each other. The input end is connected to a cathode of the first photodiode. A first signal which is obtained by inverting the first electrical signal is output from the output end. A second inverting amplifier is provided with a second feedback resistor and a second operating amplifier connected in parallel with each other. The input end of the second inverting amplifier is connected to a cathode of a second photodiode. The second inverting amplifier outputs a second signal from the output end. A comparator receives the first and second signals and outputs a comparison amplified signal.

Optical coupling device having dual inverting amplifier and a comparison amplified output signal

According to one embodiment, a voltage regulator includes an output transistor, a voltage detector, a controller, and a discharge circuit. The output transistor is connected between a power supply terminal and an output terminal. The voltage detector is connected between the output terminal and a ground terminal. The voltage detector is configured to divide an output voltage between the output terminal and the ground terminal according to an inputted voltage switching signal and generates a first voltage on the ground terminal side and a second voltage having a polarity the same as a polarity of the first voltage and having an absolute value lower than or equal to an absolute value of the first voltage. The controller is configured to detect a difference between the first voltage and a reference voltage and control the output transistor.

Voltage regulator for high speed switching of voltages

A transimpedance amplifier includes a first MOS transistor, a current mirror circuit, a second MOS transistor, a load and a first feed back resistor. The first MOS transistor has a gate terminal to which a photodiode is connected. An output current of the first MOS transistor is input to the current mirror. The second MOS transistor has a gate terminal to which a voltage of an output terminal of the current mirror circuit is input. A source of the second MOS transistor is grounded. A polarity of the second MOS transistor is same as a polarity of the first MOS transistor. A first feedback resistor is connected between the gate terminal of the first MOS transistor and a drain terminal of the second MOS transistor. The second MOS transistor outputs a voltage corresponding to the voltage of the output terminal from the drain terminal.

Transimpedance amplifier and light receiving circuit

A light receiving circuit includes: a transimpedance amplifier circuit which is connected to a light receiving element; a differential amplifier which operates by a predetermined current supplied by a current source to output a current corresponding to a differential signal between a signal outputted from the transimpedance amplifier circuit and a predetermined reference signal; a current mirror unit which outputs a current corresponding to the current outputted from the differential amplifier; and a conversion unit which converts the current outputted from the current mirror unit into voltage.

There is provided a light receiving circuit including, a light receiving element outputting electrical current corresponding to input light, and a current-voltage converter having current-voltage conversion characteristic, the current-voltage conversion characteristic becoming smaller at a low frequency side and larger at a high frequency side, the current-voltage converter converting the current to the voltage and outputting the voltage.

There may be provided a receiving apparatus including: a light receiving element which receives an optical signal and generates a current signal dependent on the optical signal; a conversion unit which converts the current signal into a voltage signal; a reference voltage generation unit which generates a reference voltage; a threshold voltage generation unit which generates, based on the voltage signal outputted from the conversion unit and the reference voltage outputted from the reference voltage generation unit, a threshold voltage signal having an amplitude smaller than an amplitude of the voltage signal with reference to substantially the center of amplitude range of the voltage signal and delayed by a predetermined time period from the voltage signal; and a comparison unit which compares the voltage signal outputted from the conversion unit with the threshold voltage signal outputted from the threshold voltage generation unit.

Growing community of inventors

Kanagawa-ken, Japan

Shigeyuki Sakura