Ntt Docomo, Inc.

Hiroshi Okazaki

Shoichi Narahashi

Atsushi Fukuda

Kunihiro Kawai

Takayuki Furuta

Yasushi Yamao

Tetsuo Hirota

Yuta Takagi

Kei Satoh

Daisuke Koizumi

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 first line stub SBand one end of each of two switches SWand SWare connected to a transmission lineL at spacings L, Land Lin order from the input end of the transmission lineL, the other ends of the two switches are connected to a second line stub SB, the first and second line stubs have an open end or short-circuit end, and matching at any of four frequency bands can be selected by combining on and off of the two switches SWand SW

Variable matching circuit

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 bias circuit includes: a bias supply terminal; a parallel capacitorconnected at one end thereof to the bias supply terminaland grounded at the other end thereof; and a parallel circuitL connected in parallel with the parallel capacitorand connected at one end thereof to the bias supply terminal. Let 2&#x2266;N. The parallel circuitL includes: a direct-current power supply connection terminal; N parallel inductorstoconnected in series with each other between the bias supply terminaland the direct-current power supply connection terminal; and N&#x2212;1 series resonatorsto. Each series resonatortoincludes: a resonant capacitortoconnected at one end thereof to a connecting point between adjacent parallel inductors; and a resonant inductortoconnected at one end thereof to the other end of the resonant capacitortoand grounded at the other end thereof.

Bias circuit

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 multiband matching circuit includes a first matching unit for converting an impedance in a signal path to Zin a first frequency band, and a second matching unit formed of a series matching section connected at one end in series with the first matching unit in the signal path, which is a transmission line whose characteristic impedance is equal to the matching impedance Zor a circuit equivalent to the transmission line at least in the first frequency band, and a parallel matching section connected at one end to the signal path at the other end of the series matching section and grounded at the other end. The parallel matching section is configured to open in impedance the connection point to the signal path in the first frequency band. The series matching section and the parallel matching section are designed to match an impedance in a second frequency band with Z

Multiband matching circuit and multiband power amplifier

A multiband matching circuit of the present invention includes an inductive element having one end connected to an input terminal, a first switch having one end connected to the other end of the inductive element and the other end grounded, a capacitive element having one end connected to the input terminal, a second switch having one end connected to the other end of the capacitive element and the other end grounded, a first-band matching circuit that is connected between the other end of the inductive element and a first output terminal and performs impedance matching in a first frequency band, and a second-band matching circuit that is connected between the other end of the capacitive element and a second output terminal and performs impedance matching in a second frequency band higher than the first frequency band.

Multiband matching circuit

A multiband matching circuit includes a first matching unit, a second matching unit, and a third matching unit, with all units being connected in series in a signal path. Matching with target impedance is established at a first frequency by appropriately designing the first matching unit and at a second frequency by appropriately designing the second and third matching units. The second matching unit and the third matching unit are designed to make the conversion ratio of the impedance viewed from the connection point between the second matching unit and the third matching unit to a circuit element to the target impedance smaller than the conversion ratio of the impedance viewed from the connection point between the first matching unit and the second matching unit to the circuit element to the target impedance, at the second frequency.

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.

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Zushi, Japan

Hiroshi Okazaki