Ntt Docomo, Inc.

Kunihiro Kawai

Shoichi Narahashi

Hiroshi Okazaki

Kei Satoh

Daisuke Koizumi

Takayuki Furuta

Tetsuo Hirota

Yuta Takagi

Yasushi Yamao

Toshio Nojima

Atsushi Fukuda

A wireless circuit that can be used in a plurality of frequency bands even if its duplexer is formed of current variable frequency filters is provided. The circuit includes a transmission-reception antenna, a variable frequency duplexer, a double-pole six-throw switch, an RFIC, and a controllerwhich executes switching operations in accordance with control signals. The RFICdetermines a pair of frequency bands for transmission and reception signals input to the variable frequency duplexerand generates and sends the control signals to perform switching control operations to connect a transmission port corresponding to the determined transmission frequency band with the transmission terminal of the variable frequency duplexerand to connect a reception port corresponding to the determined reception frequency band with the reception terminal of the variable frequency duplexerand to perform a frequency switching operation of the variable frequency duplexer

Wireless circuit and frequency pair determination method

A front-end circuit includes an RFIC, an antenna, N duplexers, N variable impedance adjustment circuits, a switch for selecting any two of the N variable impedance adjustment circuits, and a control unit which receives a control signal from the RFIC, where 2&#x2266;N. The control unit executes switching operations of the N variable impedance adjustment circuits and the switch in accordance with control information. The control signal indicates to 1) control the switch to select two variable impedance adjustment circuits corresponding to a p-th frequency band and a q-th frequency band respectively, 2) control a variable impedance adjustment circuit corresponding to the p-th frequency band to increase input impedance in the q-th frequency band as viewed from the antenna side and 3) control a variable impedance adjustment circuit corresponding to the q-th frequency band to increase input impedance in the p-th frequency band as viewed from the side.

Front-end circuit and impedance adjustment method

A switch is replaced with a parallel resonant circuit. More specifically, a variable resonator includes a line partthat includes one or more lines and has an annular shape, at least two parallel resonant circuitscapable of changing a characteristic, and at least three variable reactance blockscapable of changing a reactance value, in which the parallel resonant circuitsare electrically connected to the line partat one end thereof at different positions on the line part, and the variable reactance blocksare electrically connected to the line partat predetermined intervals based on an electrical length at a resonance frequency.

Variable resonator and variable filter

A variable resonator includes a first transmission line, a second transmission lineand a plurality of switch circuits. The electrical length of the first transmission lineis equal to the electrical length of the second transmission line. The characteristic impedance for the even mode of the first transmission lineis equal to the characteristic impedance for the even mode of the second transmission line. The characteristic impedance for the odd mode of the first transmission lineis equal to the characteristic impedance for the odd mode of the second transmission line. Each switch circuitis connected to any of the first transmission lineand the second transmission line, and one of the switch circuitsis turned on.

Multirole circuit element capable of operating as variable resonator or transmission line and variable filter incorporating the same

A multimode frontend circuit of the present invention comprises two transmission paths. Each of the transmission paths comprises two input/output lines, a first transmission line having one end connected to one of the input/output lines and the other end connected to the other input/output line, a second transmission line connected to the one of the input/output lines and the other end connected to the other input/output line, and one or more termination switch circuits. The termination switch circuit or circuits comprise a switch having one end connected to one of the first and second transmission lines and a termination circuit connected to the other end of the switch. Each of the transmission lines may comprise one or more short-circuiting switches. The short-circuiting switch or switches are capable of short-circuiting between the two transmission lines at positions at the same electrical length from one of the input/output lines.

Multimode frontend circuit

A variable resonator includes a ring-shaped conductor line () which is provided on a dielectric substrate () and has a circumferential length of a wavelength at a resonance frequency or an integral multiple of the wavelength, and at least two circuit switches (), wherein the circuit switches () have one ends () electrically connected to the ring-shaped conductor line () and the other ends () electrically connected to a ground conductor () formed on the dielectric substrate (), electrical connection/disconnection between the ground conductor () and ring-shaped conductor line () can be switched, and the one ends () of the circuit switches () are connected to the ring-shaped conductor line () on different portions.

Variable resonator, variable bandwidth filter, and electric circuit device

A variable resonator that comprises a loop line () to which two or more switches () are connected and N of reactance circuits () (N&#x2267;3), in which switches () are severally connected to different positions on the loop line (), the other ends of the switches are severally connected to a ground conductor, and the switches are capable of switching electrical connection/non-connection between the ground conductor and the loop line (), the reactance circuits () severally have the same reactance value, the loop line () has a circumference corresponding to one wavelength or integral multiple thereof at a resonance frequency corresponding to each reactance value of each reactance circuit, and the reactance circuits () are electrically connected to the loop line () as branching circuits along the circumference direction of the loop line () at equal electrical length intervals.

Variable resonator, tunable bandwidth filter, and electric circuit device

A variable resonator that comprises a loop line () to which two or more switches () are connected and N variable reactance means () (N&#x2267;3), in which switches () are severally connected to different positions on the loop line (), the other ends of the switches are severally connected to a ground conductor, and the switches are capable of switching electrical connection/non-connection between the ground conductor and the loop line (), the variable reactance blocks () are severally settable to the same reactance value, and the variable reactance blocks () are electrically connected to the loop line () as branching circuits along the circumference direction of the loop line () at equal electrical length intervals.

Variable resonator, tunable filter, and electric circuit device

A duplexer according to the present invention includes a first port, a second port and a third port for external input/output, a first path formed between the first port and the third port, a second path formed between the second port and the third port, a phase shifting part provided for each path, and a resonating part provided for each path. At least any of the resonating parts has a ring conductor having a length equal to one wavelength at a resonant frequency or an integral multiple thereof, a plurality of passive circuits, and a plurality of switches each of which is connected to a different part of the ring conductor at one end and to any of the passive circuits at the other end. A switch may simply be connected to a ground conductor instead of being connected to the passive circuit.

Duplexer and transceiver

A signal selecting device according to the present invention has two input/output ports, a plurality of resonating parts, a plurality of impedance transforming parts, and a controlling part. The resonating parts have a ring conductor having a length equal to one wavelength at a resonant frequency or an integral multiple thereof and a plurality of switches each of which is connected to a different part of the ring conductor at one end and to a ground conductor at the other end. The controlling part controls the state of the switches. The resonating parts are disposed in series between the two input/output ports. The impedance transforming parts are disposed between the input/output ports in such a manner that the impedance transforming parts at the both ends are disposed between the input/output port and the resonating part and the remaining impedance transforming parts are disposed between the resonating parts.

Signal selecting device

A variable resonator has a dielectric substrate, an input/output lineformed on the dielectric substrate, a first resonatorthat has one end connected to the input/output lineand the other end grounded, and a second resonator that has one end connected to the input/output lineat the point of connection of the one end of the first resonatorand the other end grounded via a terminal switch. When the terminal switchis turned off, resonance occurs at a frequency at which the sum of the line lengths of the first resonatorand the second resonatorequals to a quarter of the wavelength. When the terminal switchis turned on, resonance occurs at a frequency at which a half of the sum of the line lengths equals to a quarter of the wavelength.

Variable resonator

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.

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Yokohama, Japan

Kunihiro Kawai