Ntt Docomo, Inc.

Ntt Bocomo, Inc.

Tetsuo Hirota

Yasushi Yamao

Yasunori Suzuki

Shoichi Narahashi

Kei Satoh

Toshio Nojima

Hiroshi Okazaki

Atsushi Fukuda

Kunihiro Kawai

Daisuke Koizumi

Shinji Mizuta

Ning Chen

A matching circuit including a main matching blockinserted in a signal path and a series matching block, one end of which is connected to the main matching block, in which one end of a series connection of a switchand a parallel matching blockis connected to the signal path at the other end of the series matching blockand impedance matching between input/output is performed at any one of two frequencies by setting the switch to ON/OFF.

Matching circuit

A signal switching device including a plurality of transmission paths connected to an input path, the signal switching device outputting a signal from the input path through one of the transmission paths, including a first variable impedance unit connected to a first transmission path, the first variable impedance unit including a first section formed from a superconducting material, the first section being set to a non-superconducting state when the signal is to be output through a second transmission path, the first section including a portion of a predetermined length at an input end, the portion having an area of a cross section less than an area of a cross section of the first section at an output end.

Signal switching device

A signal switching device is disclosed that is capable of transmitting signals with less signal loss while securing a good isolation characteristic. The signal switching device includes a first section formed from a superconducting material connected to a first transmission path. The first section has a smaller cross section at the input end than at the output end or, the signal switching device may include a first section formed from a superconducting material connected to a first transmission path in series, and a second section formed from a superconducting material connected to a second transmission path in parallel. The cross section of the second section is smaller than that of the second transmission path. The length of the second transmission path is determined in such a way that an input impedance of the second transmission path is sufficiently large when the second section is in a superconducting state.

A plurality of one-quarter wavelength coplanar resonatorstoare formed in series on a dielectric substrate, and coplanar input/output terminal sectionsandare formed on the dielectric substrate at opposite ends of the series connection for coupling with resonatorsand, respectively. A center conductor line width wof each of the resonatorstois equal to a center conductor line width wof each of the input/output terminal sectionand, but a ground conductor spacing dof each of the resonatorstois greater than a ground conductor spacing dof each of input/output terminal sectionandMaintaining the accuracy of design is facilitated and a reduction in the maximum current density in the resonator is enabled.

Coplanar waveguide filter and method of forming same

A filter is provided which maintains a low insertion loss characteristic of a filter contained in a casing with a very simple construction that the internal wall of the casing is formed by a superconductor. A coplanar waveguide filtercomprises a dielectric substrate, a plurality of resonatorsandand input/output terminal sectionsand, each of which is formed by a center conductorand ground conductorsand, both formed on the same surface of the dielectric substrate, with the ground conductorstobeing formed on the opposite sides of and in parallel relationship with the center conductor. The filteris contained within a casinghaving an internal wall, the surface of which is formed with a layer of superconductor. By way of example, a high temperature superconductor such as lanthanum-, yttrium-, bismuth- or thallium-superconductor is deposited as a film on a substrate of a metal oxide material such as MgO, SrTiO, LaGaO, LaAlOto provide a superconductor filmed substrate, which is applied to the internal surface of the casing. Electromagnetic power which is irradiated from the filterdoes not produce a power loss when it impinges on the layer of superconductorin its superconducting state, but is reflected therefrom to be absorbed by the filter, thus reducing the filter insertion loss.

Casing contained filter

A combined signal of a digital pilot signal and a digital transmission signal is applied to a digital predistorter (), wherein it is added with odd-order distortions based on a power series model to generate a predistorted signal, then the predistorted signal is converted by a DA converter () to an analog signal, then the analog signal is upconverted by a frequency upconverting part () to a send frequency band, and the upconverted signal is output after being amplified by a power amplifier (). A pilot signal component is extracted from the power amplifier output, then odd-order distortion components of the power series model are extracted by a digital predistorter control part () from the pilot signal component, and the odd-order distortions in the digital predistorter () are controlled to decrease the levels of the distortion components.

Linear power amplification method and linear power amplifier

A power amplifier for receiving and amplifying an input signal and outputting an output signal includes N power amplifying units (N is an integer larger than 1) connected in parallel so as to output amplified signals in response to the input signal; an output combining unit for combining the output signals from the N power amplifying units and outputting a combined signal as the output signal of the power amplifier; and an amplitude controlling unit for selectively turning ON each of the N power amplifying units based on an amplitude of the input signal. In the power amplifier, the amplitude controlling unit may includes N amplitude adjusters connected in parallel for adjusting the amplitude of the input signal of the power amplifier; and a controller for selectively turning ON each of the N power amplifying units and controlling the amplitude adjusters so that an amplitude of the output signal becomes a substantially continuous function with respect to the amplitude of the input signal.

Power amplifier

In a quadrature hybrid circuit which has first and second two-port circuitsandinserted between I/O ports Pand Pand between I/O ports Pand P, respectively, and third and fourth two-port circuits inserted between I/O ports Pand Pand between I/O ports Pand P, respectively, and which is configured so that under the condition that the I/O ports Pto Pare matched, a high-frequency signal fed via the I/O port Pis divided between the I/O ports Pand Pand the divided two signals are output 90&#xb0; out of phase with each other but no signal is provided to the I/O ports P, there are provided SPST switchesandresponsive to external control to control electromagnetic connections or coupling across a plane of symmetryof the quadrature hybrid circuit passing through intermediate points of symmetryandof the third and fourth two-port circuitsand

Quadrature hybrid circuit

A radio communication system is comprised of: a transmitting system in which N transmission signals, frequency-converted to the same transmission frequency, are generated by N transmitters, N being an integer equal to or greater than 2, and the transmission signals are each applied to each one of N elements of an antenna for transmission; and a receiving system in which each transmitted signal is received by N-element antenna and the cross correlation coefficient between the transmitted signals received by the N-elements is minimized to thereby reconstruct each transmitted signal. The plural transmitted signals of the same frequency are received and the cross correlation coefficients of the received transmitted signals are minimized to thereby permit multiplexing of the transmission signal.

Space multiplex radio communication method and radio communication apparatus

A transmission signal and a pilot signal are predistorted by a digital predistorterby use of a power-series model, and the predistorted output is converted by a digital-analog converterto an analog signal. The analog signal is up converted by a frequency converterto an RF-band signal, which is transmitted after being power-amplified by a Doherty amplifier. The pilot signal is extracted by a pilot signal extractorfrom the output from the Doherty amplifier, and the extracted pilot signal is down converted by a frequency converterto a baseband signal. The baseband pilot signal is converted by an analog-digital converterto a digital pilot signal. A control partdetects an odd-order distortion component from the digital pilot signal, and based on the detected result, controls parameters of the digital predistorter.

High-efficiency linear power amplifier

A feed-forward amplifier configuration having a distortion detector circuit and a distortion canceller circuit is formed between an input port Ip and an output port OP of a multi-terminal power-combining power amplifier with a main amplifier M provided for each channel between an input-side multi-terminal power combiner and an output-side multi-terminal power combiner

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Kanazawa, Japan

Tetsuo Hirota