Nippon Telegraph and Telephone Corporation

Rakuten, Inc.

Ntt Electronics Corporation

Shinsuke Nakano

Hideyuki Nosaka

Munehiko Nagatani

Masafumi Nogawa

Josuke Ozaki

Masahiro Endo

Nobuhiro Kikuchi

Hiroaki Katsurai

Masatoshi Tobayashi

Toshiki Kishi

Kenji Tanaka

Kota Shikama

Hiromasa Tanobe

Naoki Miura

Teruo Jo

Yuta Ueda

Shunji Kimura

Shigeru Kanazawa

Yoshihiro Ogiso

Yuko Kawajiri

Yoshikazu Urabe

Eiichi Yamada

Hiroaki Sanjoh

Salaheldin Ahmed Ezzeldin Ibrahim Mohamed

Youhei Sakamaki

Shigehiro Kurita

Takayuki Oura

Yoshiro Hirai

In a terminator, a midpoint electrode is provided between a first signal electrode and a second signal electrode, a first resistor is connected between the first signal electrode and the midpoint electrode, a second resistor is connected between the second signal electrode and the midpoint electrode, a first GND electrode is provided on a side opposite to the side where the first resistor is provided with the first signal electrode interposed therebetween, a second GND electrode is provided on the side opposite to the side where the second resistor is provided with the second signal electrode interposed therebetween, and capacitances in the terminator are formed between the first signal electrode and the midpoint electrode, between the second signal electrode and the midpoint electrode, between the first signal electrode and the first GND electrode, and between the second signal electrode and the second GND electrode.

Optical modulator module

A clock generation circuit includes a mode-locked laser that generates an optical pulse, a photodiode that photoelectrically converts the optical pulse generated by the mode-locked laser, and a filter that attenuates at least one of a DC component and a harmonic component of the mode-locked laser included in an electric signal output from the photodiode.

Clock generation circuit

A CMOS inverter circuit is provided as a circuit to modulate a current flowing into a laser diode on the basis of a digital signal. An amplitude of a current flowing in a PMOSFET in the CMOS inverter circuit is made to contribute to an amplitude of the current flowing into the laser diode, to reduce an input amplitude.

DML driver

Provided is an optical modulator having an optical modulation high frequency line through which a high frequency electrical signal can be efficiently input to an optical modulation region and which is in a broadband. High frequency lines of an optical modulator, that is, an input high frequency line, an optical modulation high frequency line, and an output high frequency line have a line configuration in which each of the input high frequency line and the output high frequency line is divided into a plurality of segments, and adjacent segments of the plurality of the segments have different characteristic impedances and propagation constants. The input high frequency line and the output high frequency line may be implemented by changing a width or a thickness of a signal electrode formed on a dielectric forming a micro-strip line between adjacent segments. The characteristic impedances and the propagation constants may be changed by changing a dielectric constant of the dielectric instead of changing the width or the thickness of the signal electrode.

Optical modulator

A linear amplifier includes a pre-amplifier configured to amplify an input differential signal, a post-amplifier configured to amplify an output signal of the pre-amplifier, an amplitude detector configured to detect an amplitude of an output signal of the post-amplifier, and an output voltage corresponding to the detected amplitude, a comparator configured to control a tail current source of the pre-amplifier such that when the output voltage of the amplitude detector is less than or equal to a reference voltage, a tail current of the pre-amplifier is set to a constant value, and when the output voltage of the amplitude detector is larger than the reference voltage, the tail current is reduced to make the output voltage of the amplitude detector equal to the reference voltage.

Linear amplifier

A reception-side IC chip () includes a pad () which is connected to a transmission line () which is outside the chip and has a characteristic impedance Z0 of 50&#x3a9;, a signal line (), one end of which is connected to the pad (), a reception-side input unit circuit () configured to receive a signal (S) transmitted from a transmission-side IC chip via the transmission line (), a 50-&#x3a9; termination resistor (), for impedance matching, which is connected between a predetermined voltage and the other end of the signal line () and is configured to terminate the transmission line (), and a capacitor () inserted between a node (A) of the signal line () and the termination resistor () and an input terminal (In) of the reception-side input unit circuit (). A DC-blocking circuit is formed by the capacitor ().

IC chip

A signal processing circuit is provided that generates output signals to be output from spatially different output ports based on bit combinations of an input word consisting of a plurality of bit signals. A distributed memory, a ROM and a DAC in which the signal processing circuit is used are also provided. A recognition circuit includes a serial port to which a bit signal is input and 2output ports recognizing an input N-bit word and corresponding uniquely to 2bit combinations. Output ports of the recognition circuit are connected to 2input ports of an electric circuit. With no signal input to the recognition circuit, all outputs are constantly in a Low level state. In a case where a bit signal is input to the serial port of the recognition circuit, only one of the output ports corresponding to the bit combinations turns to a High level state.

Signal processing circuit, distributed memory, ROM, and DAC which signal processing circuit is embedded

An amplifier applied to TIA is provided to suppress the noise caused by a current source. An amplifier constituting a transimpedance amplifier includes an inductor element inserted between a current source connected to an input terminal of an amplification stage and a power source voltage line. The current source includes a first transistor in which a base terminal is connected to a current control bias and a collector terminal is connected to the input terminal. The inductor element is inserted between the emitter terminal of the first transistor and the power source voltage line.

Amplifier

An amplifier typically exemplified by a TIA is realized that provides an optimal band characteristic, that reduces the possibility of the oscillation, and that achieves a reduced dispersion of the band characteristics. An amplifier for amplifying an electric signal, comprising: a first buffer for amplifying the electric signal; a filter that is connected to an output of the first buffer and that includes a parallel circuit consisting of an inductor and a first capacity; and a second buffer connected to an output of the filter.

A positive-side power supply terminal (-) of a differential amplifier (-) is connected to a positive-side power supply line (L). A negative-side power supply terminal (-) of a differential amplifier (-) is connected to a negative-side power supply line (L). A negative-side power supply terminal (-) of the differential amplifier (-) and a positive-side power supply terminal (-) of the differential amplifier (-) are connected to each other. A final-stage amplifier () is connected between the positive-side power supply line (L) and the negative-side power supply line (L).

Driver circuit and optical transmitter

A driver circuitincludes a plurality of cascode-connected NMOS transistors, a modulating signal Vis applied to a gate terminal of a lowermost stage transistor Tlocated at a lowermost stage out of the NMOS transistors, and an upper stage bias potential Vthat is a sum of a minimum gate-source voltage Vand a maximum drain-source voltage Vof a transistor (T) located immediately below an upper stage transistor located at an upper stage above the lowermost stage transistor of the NMOS transistors is applied to the upper stage transistor T.

Directly modulated laser drive circuit

A content server () includes a receiving unit () that receives a request signal from a request source terminal, an acquisition unit () that acquires an IP address assigned to the request source terminal from the request signal, and a determination unit () that determines a location region of a user of the request source terminal by referring to an address storage unit () based on the acquired IP address. The address storage unit () stores address information including location regions of registered users set based on addresses of the registered users and IP addresses assigned to terminals of the registered users in association with each other.

Growing community of inventors

Tokyo, Japan

Shinsuke Nakano