Sumitomo Electric Industries, Limited

Sosaku Sawada

Takeshi Sekiguchi

Nobuo Shiga

Hiroshi Yano

Taizo Tatsumi

Goro Sasaki

Kentaro Doguchi

Hiroshi Hara

Keiji Tanaka

Hiromi Kurashima

Makoto Ito

Yutaka Moriyama

Daisuke Takagi

Ryoji Sakamoto

Yoshiyuki Sugimoto

Ichiro Tonai

Eiji Tsumura

Seiji Kumagai

Seigo Furudate

Ken-ichi Kitayama

Hisato Takahashi

Satoshi Ohe

Taizou Tatsumi

A driver with the arrangement of the travelling wave amplifier is disclosed. The driver provides n counts of cells each configuring the open collector arrangement and amplifying an input signal. The cells are arranged between an input interconnection and an output interconnection, and powered through the output interconnection. The power supply line to power the output interconnection is connected between m-th and (m+1)-th cells not through the output terminal of the output interconnection.

Driver circuit configured with travelling wave amplifier

A front end module for an optical receiver is disclosed. The module includes a PD, a trans-impedance amplifier (TIA), an insulating carrier for mounting the PD, and a conductive base for mounting the carrier. The carrier provides first and second metal films thereon. The first metal film carries a photocurrent from the PD to the TIA, while, the second metal film carries the bias supply to the PD. The PD is mounted on the first and second metal films by the flip-chip arrangement. The second metal film surrounds the first metal film to suppress resonances appeared in the trans-impedance spectrum of the front end module.

Front end module for optical receiver

A traveling wave amplifier (TWA) with suppressed jitter is disclosed. The TWA includes a plurality of unit amplifiers with the differential arrangement comprised of a pair of transistors and a cascade transistors connected in series to the switching transistors. The unit amplifiers further includes current sources to provide idle currents to the cascade transistors. Even when the switching transistors fully turn off, the idle currents are provided to the cascade transistors, which set the operating point of the cascade transistor in a region where an increase of the base-emitter resistance is suppressed.

Traveling wave amplifier with suppressed jitter

A differential circuit with a function of a variable gain without shifting the output cross point is disclosed. The differential circuit includes an amplifying stage and a control stage. The amplifying stage includes three units each having a pair of transistors, a pair of load resistors, and a pair of current sources. The second and third units each put between the first unit and the load resistor to bypass the current. The control stage includes two units and two current sources to compensate the current bypassed by the second or third unit to keep the DC output level substantially in constant.

Differential amplifier with function of variable gain and optical receiver implemented with the same

A traveling wave amplifier (TWA) primarily for driving a semiconductor optical device is disclosed. The TWA of an embodiment provides a plurality of differential amplifiers of the first type and an additional differential amplifier of the second type, where are they are connected between the input and the output of the TWA. The differential amplifiers of the first type provide a first delay from the input to the output, while, the differential amplifier of the second type provide a second delay longer than the first delay between the input and the output of the TWA.

Traveling wave amplifier with pre-emphasis function

An amplifier for receiving an optical signal is disclosed. The amplifier provides a response time controller including an integrator with two time constants, a linear amplifier, a hysteresis comparator, an another integrator, and a switch to change the time constant. The switch includes two voltage followers, one of which turns off the switch to set the time constant in a longer state; while, the other of which turns on the switch and reflects the input of the integrator to set the time constant in a shorter state.

Amplifier for receiving intermittent optical signal

A differential amplifier showing a suppressed output offset is disclosed. The differential amplifier includes a pair of differential transistors, a pair of cascode transistors, and a reference generator. One of differential transistors receives an AC signal, while, the other of differential transistors receives an average voltage of the AC signal. The reference generator receives the average voltage of the AC signal and outputs a bias commonly provided to the cascode transistor. The bias is raised by a substantially constant level from the average voltage, which compensates the output offset of the differential amplifier.

Conversion circuit from single phase signal to differential phase signal

Provided are a source follower circuit having a current source having its improved current characteristics, laser driving apparatus, semiconductor laser apparatus, current-voltage conversion circuit, and light receiving circuit. Each of the laser driving apparatus, semiconductor laser apparatus, current-voltage conversion circuit, and light receiving circuit comprises the source follower circuit. The source follower circuit comprises a source follower stage and a bias stage . The source follower stage has III-V compound semiconductor transistors and . The bias stage has a first node for providing a first bias voltage and a second node for providing a second biasing voltage different from the first biasing voltage. The gate of transistor is coupled to input and a source thereof is coupled to output . The gate of transistor is connected to the second node . The gate of transistor is connected to the first node . The transistor is arranged between the source of the transistor and the drain of the transistor

Source follower circuit, laser driving apparatus, semiconductor laser apparatus, current-voltage convertion circuit, and light receiving circuit

The present invention provides an optical module, in which aligning adjustment is much easier than conventional module while a high optical coupling efficiency between an optical fiber and a semiconductor device is maintained. The module comprises a structure for effectively suppressing the decrease in optical coupling efficiency caused by changes in ambient temperature. The optical module comprises an optical reflecting member having a reflecting surface with a concave surface form for optically coupling the optical fiber and the semiconductor device to each other, and a deterioration-suppressing structure in which the change in shape of the reflecting member caused by changes in ambient temperature effectively suppresses the deterioration in optical coupling state between the optical fiber and semiconductor device due to changes in temperature or the like.

Optical module and optical reflecting member

A bonding method for effectively preventing once-adjusted members from positionally deviating is disclosed. In this method, when applied to a method of making an optical module in particular, a holding member such as a magnet which generates a magnetic force against a housing is attached to, and a relative position of an optical reflecting member once adjusted by the holding member is held. As a result of this configuration, the optical reflecting member is effectively prevented from positionally deviating.

Method of making optical module

The present invention relates to an optical module having a configuration in which centering adjustment can be effected much more easily than the prior art, while keeping a high optical coupling efficiency between an optical fiber and a semiconductor device, and can reduce the number of parts, for example; and a method of making the same. The optical module comprises, as an element for optically coupling the optical fiber and the semiconductor device together, an optical reflecting member having a concave reflecting surface. Since it is necessary for the reflecting member to be positioned with a high accuracy in the field of optical communications to which this optical module is supposed to be utilized, in particular, the reflecting member is provided with a specific positioning configuration.

Optical module and method of making the same

A plurality of n-channel FETs in predetermined combinations are grouped two by two into pairs, and their respective gates and sources are connected to each other in a crossing manner, thus forming a first current mirror circuit connected to a higher-potential side power supply. A second current mirror circuit constituted by another plurality of n-channel FETs, diodes, and a variable resistor, which is connected to a lower-potential side power supply, is connected to the first current mirror circuit connected to the higher-potential side power supply, thereby forming a reference voltage generating circuit which generates a constant voltage. Further, three other pieces of n-channel FETs biased by this constant voltage, a diode, and the like constitute a light emitting element driving circuit for driving a light emitting element.

Current mirror circuit and reference voltage generating and light

Optical receiver/transmitter module

It is an object of the present invention to provide a highly reliable optical module circuit board having a sufficient mechanical strength with respect to an external stress. An optical module circuit board according to the present invention includes a flexible printed circuit having at least a multilayered structure in which a layer containing a conductive metal interconnection is sandwiched between insulating layers, wherein the flexible printed circuit includes a main body portion having the multilayered structure, a first surface mounted with an electronic component, and a second surface opposite to the first surface, a neck portion having the multilayered structure and extending from one end of the main body portion, and a head portion positioned at a distal end of the neck portion extending from the one end of the main body portion, having the multilayered structure, and mounted with an optical operation element and a bypass capacitor, Particularly, the neck portion defines the positional relationship between the main body portion and the head portion so as to give the circuit board a sufficient mechanical strength.

Optical module circuit board having flexible structure

A pin type light-receiving device according to the present invention comprises (a) a semiconductor substrate, (b) a first semiconductor layer formed on a semiconductor substrate and doped with an impurity of a first conduction type, (c) a second semiconductor layer formed in a mesa shape on the first semiconductor layer and made of a first semiconductor material without intentionally doping the first semiconductor material with an impurity, (d) a third semiconductor layer formed in a mesa shape on the second semiconductor layer and made of the first semiconductor material doped with an impurity of a second conduction type different from the first conduction type, (e) a first electrode layer formed in ohmic contact on the first semiconductor layer, (f) a second electrode layer formed in ohmic contact on the third semiconductor layer, and (g) a fourth semiconductor layer formed around the first to the third semiconductor layers and made of a second semiconductor material having a band gap energy greater than the first semiconductor material without intentionally doping the second semiconductor material with an impurity. This arrangement can suppress the dark current, based on a reduction of leak current, thereby improving the device characteristics.

Growing community of inventors

Yokohama, Japan

Sosaku Sawada