Nec Corporation

Nec Engineering, Ltd.

Yuuichi Aoki

Tohru Kimura

Hitoshi Yano

Koji Fukami

Nobuhide Yoshida

Jun Noda

Akitake Mitsuhashi

Daigo Taguchi

Teruki Sukenari

Kunihiro Suzuki

A communication network of the present invention includes: a plurality of superordinate nodestoforming a cascade type topology; and a plurality of terminal nodesto, connected to at least one superordinate node from among said plurality of superordinate nodes and forming a star type topology with the superordinate node connected.

Communication network, information processor and address assigning method

A signal receiving device is provided which can prevent the imbalance occurring between in-phase and quadrature signals. A polarity of a local oscillator output signal to be outputted from a local oscillatoris switched by a polarity switching unitin a time division way. Each of signals outputted from the polarity switching unitis frequency divided by a frequency divider. The frequency-divided local oscillation signal is supplied to a mixer. Frequency conversion of a receiving signal is performed by the mixerwhich receives the signal and local oscillation signal to demodulate received data.

Signal receiving device and signal receiving method using same, and signal supplying unit and signal supplying method using same

The present invention comprising: a first local oscillator for generating a first frequency; a second local oscillator for generating a second frequency; phase-difference setting means for setting a first phase difference between a transmission signal and an output of the aforementioned first local oscillator; phase-difference detection means for detecting a second phase difference which is the phase difference between a reception signal and an output of the aforementioned second local oscillator, and calculation means for calculating a distance to a communication counterpart from a third phase difference and a fourth phase difference which are notified by the communication counterpart, and from the aforementioned first phase difference and second phase difference, wherein the third phase difference is set to the second frequency by the communication counterpart, and the fourth phase difference is set to the first frequency by the communication counterpart.

Multiband transceiver and positioning system using the transceiver

The present invention provides compensation for distortions in a multi-stage amplifier having a gain expansion characteristic. The present invention also provides an approach for using an amplification stage biased in a state close to B-class, which exhibits high power with added efficiency at low output, in order to have a gain expansion characteristic in all stages of a multi-stage amplifier. The amplifier of the present invention has a gain expansion characteristic which presents an increase in gain in response to an increase in input power or output power in a certain range of the input power or the output power. The amplifier is characterized in that an emitter grounded amplifier circuit comprising a first bipolar transistor has a base terminal to which an input matching circuit and a cathode of a first diode for supplying a bias voltage are connected through a first impedance element which does not block a direct current, and the first diode has an anode which is connected to a reference power supply which presents a sufficiently low impedance at high frequencies.

Amplifier

An electronic circuit includes transistors having first to third terminals, the third terminal controlling the current between the first terminal and the third terminal. The electronic circuit includes: a cascode amplifier () including an input transistor (Q) receiving an input signal (IN) through the third terminal, and an output transistor (QO) having the first terminal connected to the second terminal of the input transistor (QI), the third terminal connected to the ground potential via a capacitor (C) and the second terminal outputting therethrough an output signal; and a control circuit () including a control transistor receiving a control signal through the third terminal, and a diode connected to the first and second terminals of the control transistor (QC) in series. The third terminal of the output transistor (QO) of the cascode amplifier () is connected to the ground potential through the control transistor (QC) and the diode (D). The electronic circuit has a reduced signal switching time.

Electronic circuit

There is disclosed a variable-gain amplifier circuit comprising an adjustable impedance circuit part including a bipolar transistor having a base connected to a control terminal for receiving a controlled bias voltage, a collector connected to a positive power supply voltage terminal, and an emitter connected to ground through a diode in such a manner that an anode of the diode is connected to the emitter of the transistor and a cathode of the diode is connected to the ground. The variable-gain amplifier circuit further comprises a variable-gain amplifying circuit part having an amplifying circuit having an input coupled through an DC blocking capacitor to an input terminal for receiving an input signal and an output connected to an output terminal. The emitter of the bipolar transistor is connected to a node between the input terminal and the DC blocking capacitor. By controlling the bias voltage applied to the base of the transistor, it is possible to adjust the gain of the whole circuit by action of the adjustable impedance circuit part, and at the same time, it is possible to allow the amplifying circuit having a high S/N ratio, to operate under a low power supply voltage with a low noise factor.

Variable-gain amplifier circuit

A variable-gain circuit includes an amplifying transistor, a first gain control section for receiving a first gain control signal to control the amplifying transistor to have a first gain curve of decibel gain convex toward the bottom of graph, and a second gain control section for receiving a second control signal to control the first transistor to have a second gain curve of decibel gain convex toward the top of graph. The first and second control signals are fed at a time to cancel the non-linearity of the gain curves to have an overall linear gain curve.

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Tokyo, Japan

Yuuichi Aoki