Abstract: A multiband wireless communication method for performing a reception operation in a second frequency band while performing a transmission operation in a first frequency band selectively changes a gain characteristic of a power amplifier (1 or 2) for performing the transmission operation so that gain is lowered in the second frequency band, based on performing of the reception operation.

Abstract: A wireless communication apparatus of the present invention comprises a switching unit, provided between a transmitting circuit and/or a receiving circuit of at least one communication system and a demultiplexer, for connecting the transmitting circuit and/or the receiving circuit of the communication system to antenna either directly or by way of the demultiplexer. When a communication system having the switching unit is solely operated, the transmitting circuit and/or the receiving circuit of the operating communication system is connected directly to the antenna without the demultiplexer. Therefore, it is possible to reduce insertion loss of the circuit and thus to improve receiving sensitivity and reduce power consumption.

Abstract: A multiband radio communication device according to the present invention comprises: a radio communication unit configured to transmit a first radio signal in a first frequency band and to receive a second radio signal in a second frequency band different from the first frequency band; a filter connected to the radio communication unit and configured to attenuate the first radio signal; a switch configured to disconnect the filter from the radio communication unit; a communication data determination unit configured to determine a condition of communication data transmitted or received via the radio communication unit; and a switch controller configured to operate the switch, on the basis of the condition of the communication data determined by the communication data determination unit.

Abstract: There are provided a transmitter/receiver circuit and a transmission/reception method that can reduce the insertion loss of a circuit in a hybrid operation and are suitable for reducing the cost, size, and power consumption. An antenna switch 119 includes attenuation filters 201 to 203 for attenuating the frequency bands corresponding to a plurality of receiving systems, e.g., the frequency band of an 800 MHz band system, the frequency band of a 2 GHz band system, and GPS reception frequency components. These filters 201 to 203 are connected between a primary (main) antenna connection terminal T204 and a first switch group SWG201 through connection switches 204 to 206.

Abstract: A multiband wireless communication method for performing a reception operation in a second frequency band while performing a transmission operation in a first frequency band selectively changes a gain characteristic of a power amplifier (1 or 2) for performing the transmission operation so that gain is lowered in the second frequency band, based on performing of the reception operation.

Abstract: In a wireless communication device, a switching section (11) is arranged between a transmitting circuit (201) and/or a receiving circuit (202) of one communication system and a branching filter (353), for connecting the transmitting circuit (201) and/or the receiving circuit (202) of the communication system to an antenna (351) through the branching filter (353) or not through the branching filter (353). When the communication system having the switching section (11) is independently operated, the transmitting circuit (201) and/or the receiving circuit (202) of the communication system in operation is directly connected to the antenna (351), not through the branching filter (353). Thus, circuit insertion loss is reduced, receiving sensitivity is improved and consumption power is reduced.

Abstract: In a wireless communication apparatus of the present invention for transmitting a modulated signal using multi-carriers, a bias voltage of a power amplifier (101) for amplifying the modulated signal is controlled by control units (10, 102) according to the number of carriers in the modulated signal so as to reduce power consumption.

Abstract: There are provided a transmitter/receiver circuit and a transmission/reception method that can reduce the insertion loss of a circuit in a hybrid operation and are suitable for reducing the cost, size, and power consumption. An antenna switch 119 includes attenuation filters 201 to 203 for attenuating the frequency bands corresponding to a plurality of receiving systems, e.g., the frequency band of an 800 MHz band system, the frequency band of a 2 GHz band system, and GPS reception frequency components. These filters 201 to 203 are connected between a primary (main) antenna connection terminal T204 and a first switch group SWG201 through connection switches 204 to 206.

Abstract: A multiband radio communication device according to the present invention comprises: a radio communication unit configured to transmit a first radio signal in a first frequency band and to receive a second radio signal in a second frequency band different from the first frequency band; a filter connected to the radio communication unit and configured to attenuate the first radio signal; a switch configured to disconnect the filter from the radio communication unit; a communication data determination unit configured to determine a condition of communication data transmitted or received via the radio communication unit; and a switch controller configured to operate the switch, on the basis of the condition of the communication data determined by the communication data determination unit.

Abstract: The output frequency of a PLL frequency synthesizer and the output frequency of a fixed oscillator are mixed together in a mixer to produce sum and difference frequencies. The sum frequency is used as a local frequency, and the difference frequency is fed back to the PLL frequency synthesizer. In addition, the output frequency of the fixed oscillator is divided in a predetermined ratio to use it as a local frequency for the second or other subsequent frequency converting stage on the receiver or transmitter side.