A radio-frequency module includes duplexers and a phase circuit. A first transmitting-signal input terminal is connected to the duplexer, while a second transmitting-signal input terminal is connected to the duplexer. The phase circuit is connected between the first transmitting-signal input terminal and the duplexer. The phase circuit performs phase adjustment so that impedance matching between the first transmitting-signal input terminal and the duplexer is performed in the fundamental frequency band of a first transmitting signal, and so that the phase of the frequency band of a second transmitting signal in relation to the impedance characteristics of a first transmission path which ranges from the first transmitting-signal input terminal to the duplexer with the phase circuit provided therebetween appears in an open side on a Smith chart.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a radio-frequency module which transmits and receives radio-frequency signals of multiple communication bands.

2. Description of the Related Art

Hitherto, various radio-frequency modules which transmit and receive radio-frequency signals of multiple communication bands have been invented. For example, the radio-frequency module disclosed in Japanese Unexamined Patent Application Publication No. 2011-254505 includes a switch IC. An antenna is connected to a common terminal of the switch IC, and plural transmitting-signal input terminals and plural received-signal output terminals are connected to plural selection terminals. In the radio-frequency module disclosed in Japanese Unexamined Patent Application Publication No. 2011-254505, the switch IC performs connection switching control, so that one of the transmitting-signal input terminals or one of the received-signal output terminals can be connected to the antenna.

The radio-frequency module configured as described above is constituted by a multilayer body and mounting circuit devices. The multilayer body is constituted by dielectric layers stacked on each other having circuit patterns formed thereon. The mounting circuit devices are mounted on the multilayer body.

The transmitting-signal input terminals and the received-signal output terminals are realized by external-connecting lands arranged on the back surface of the multilayer body. The switch IC is realized by a mounting circuit device mounted on the front surface of the multilayer body.

Nowadays, there is a growing demand for decreasing the size of a radio-frequency module, such as that configured as described above, and the size of a multilayer body is also decreasing accordingly.

On the other hand, however, as the size of the multilayer body is decreasing, the distance between the external-connecting lands is becoming smaller. Accordingly, the isolation between transmission paths for transmitting plural radio-frequency signals, particularly between a transmission path for transmitting a high-power transmitting signal and another transmission path, is more likely to be decreased.

SUMMARY OF THE INVENTION

Accordingly, preferred embodiments of the present invention provide a radio-frequency module in which a decrease in isolation of a transmission path to transmit a signal is significantly reduced or prevented while a size of a multilayer body is decreased.

A radio-frequency module according to a preferred embodiment of the present invention includes a switch IC, first and second transmitting-signal input terminals, and a first-transmission-path phase circuit. The switch IC selects a selection terminal from among a plurality of selection terminals and connects the selected selection terminal to a common terminal connected to an antenna. The first transmitting-signal input terminal is connected to a first selection terminal, which is one of the plurality of selection terminals, with a first transmission path provided therebetween. The second transmitting-signal input terminal is connected to a second selection terminal, which is one of the plurality of selection terminals, with a second transmission path provided therebetween. The first-transmission-path phase circuit is connected to the first transmission path. Phase adjustment is made in the first-transmission-path phase circuit so that impedance matching is maintained in a frequency band of a first radio-frequency signal which is transmitted through the first transmission path. Phase adjustment is made in the first-transmission-path phase circuit so that a phase of a frequency band of a second radio-frequency signal transmitted through the second transmission path in relation to impedance characteristics of the first transmission path shifts to an open side on a Smith chart.

With this configuration, the isolation between the first transmission path and the second transmission path is enhanced.

A radio-frequency module according to a preferred embodiment of the present invention may include a switch IC, first and second transmitting-signal input terminals, and a second-transmission-path phase circuit. The second-transmission-path phase circuit is connected to a second transmission path. Phase adjustment is made in the second-transmission-path phase circuit so that impedance matching is maintained in a frequency band of a second radio-frequency signal which is transmitted through the second transmission path. Phase adjustment is made in the second-transmission-path phase circuit so that a phase of the frequency band of the first radio-frequency signal transmitted through a first transmission path in relation to impedance characteristics of the second transmission path shifts to an open side on a Smith chart.

With this configuration, the isolation between the first transmission path and the second transmission path is enhanced.

A radio-frequency module according to a preferred embodiment of the present invention may include a first-transmission-path phase circuit connected to the first transmission path and a second-transmission-path phase circuit connected to the second transmission path. The first-transmission-path phase circuit maintains impedance matching in a frequency band of a first radio-frequency signal which is transmitted through the first transmission path. Phase adjustment is made in the first-transmission-path phase circuit so that a phase of a frequency band of a second radio-frequency signal transmitted through the second transmission path in relation to impedance characteristics of the first transmission path shifts to an open side on a Smith chart. The second-transmission-path phase circuit maintains impedance matching in the frequency band of the second radio-frequency signal which is transmitted through the second transmission path. Phase adjustment is made in the second-transmission-path phase circuit so that a phase of the frequency band of the first radio-frequency signal transmitted through the first transmission path in relation to impedance characteristics of the second transmission path shifts to an open side on a Smith chart.

With this configuration, the isolation between the first transmission path and the second transmission path is further enhanced.

A radio-frequency module according to a preferred embodiment of the present invention becomes more effective in a case in which the first and second transmission paths or the first and second transmitting-signal input terminals are located at positions at which the first and second transmission paths or the first and second transmitting-signal input terminals are electromagnetically coupled with each other.

A radio-frequency module according to a preferred embodiment of the present invention may include first and second transmission paths in a multilayer body including dielectric layers on which conductive patterns are provided, and first and second transmitting-signal input terminals provided on a back surface of the multilayer body.

With this configuration, the radio-frequency module has a desired shape and structure that is more effective.

A radio-frequency module according to a preferred embodiment of the present invention may include a third transmission path connected to a third selection terminal, which is one of the plurality of selection terminals of the switch IC. A frequency band of a transmitting signal of the first radio-frequency signal which is transmitted through the first transmission path overlaps a frequency band of a received signal of the second radio-frequency signal which is transmitted through a second reception path corresponding to the second transmission path. The radio-frequency module further includes a first separator including a transmit terminal connected to the first transmission path, a second separator including a transmit terminal connected to the second transmission path, and a third separator including a transmit terminal connected to the third transmission path. The first, second, and third separators include mounting components to be mounted on the multilayer body. The third separator is disposed between the first and second separators.

With this configuration, the distance between the first separator and the second separator in which overlapping frequency bands are used is increased. Accordingly, the occurrence of electromagnetic coupling between the first and second separators is significantly reduced or prevented. It is thus possible to significantly reduce or prevent a decrease in the isolation even if the frequency bands to be used overlap each other.

In a radio-frequency module according to a preferred embodiment of the present invention, the arrangement of the transmit terminal, a receive terminal, and an antenna terminal of each of the first, second, and third separators may preferably be the same when the first, second, and third separators are mounted.

With this configuration, it is possible to further reduce or prevent a decrease in the isolation between the first separator and the second separator.

In a radio-frequency module according to a preferred embodiment of the present invention, a distance between the antenna terminal of the third separator and the receive terminal of the first separator may preferably be greater than a distance between the antenna terminal of the third separator and the transmit terminal of the first separator.

With this configuration, isolation characteristics between the first separator and the third separator are enhanced.

In a radio-frequency module according to a preferred embodiment of the present invention, a distance between the antenna terminal of the second separator and the receive terminal of the third separator may preferably be greater than a distance between the antenna terminal of the second separator and the transmit terminal of the third separator.

With this configuration, isolation characteristics between the second separator and the third separator are enhanced.

According to various preferred embodiments of the present invention, it is possible to significantly reduce or prevent a decrease in the isolation of a transmission path to transmit a signal even though the size of a multilayer body is decreased.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A radio-frequency module according to a first preferred embodiment of the present invention is described below with reference to the drawings.FIG. 1is a circuit diagram illustrating the major configuration of the radio-frequency module according to the first preferred embodiment of the present invention.

As shown inFIG. 1, a radio-frequency module10includes a switch IC11, duplexers (separators)21,22, and23, SAW filters31,32, and33, a phase circuit41, and an antenna matching circuit60. An antenna ANT may be included in the radio-frequency module10or may be omitted.

The switch IC11includes a common terminal and plural selection terminals. The switch IC11selectively connects one of the plural selection terminals to the common terminal, based on a control signal input from an external source. The common terminal is connected to the antenna ANT with the antenna matching circuit60provided therebetween. The antenna matching circuit60performs impedance matching between the switch IC11and the antenna ANT.

A first selection terminal is connected to a first transmitting-signal input terminal Ptx1with the duplexer21and the phase circuit41provided therebetween. The first selection terminal is also connected to a first received-signal output terminal Prx1with the duplexer21and the SAW filter31provided therebetween.

A second selection terminal is connected to a second transmitting-signal input terminal Ptx2with the duplexer22provided therebetween. The second selection terminal is also connected to a second received-signal output terminal Prx2with the duplexer22and the SAW filter32provided therebetween.

A third selection terminal is connected to a third transmitting-signal input terminal Ptx3with the duplexer23provided therebetween. The third selection terminal is also connected to a third received-signal output terminal Prx3with the duplexer23and the SAW filter33provided therebetween.

The duplexer21transmits a first transmitting signal (a transmitting signal of a first communication band) input from the first transmitting-signal input terminal Ptx1to the first selection terminal of the switch IC11. The duplexer21outputs a first received signal (a received signal of the first communication band) input from the first selection terminal to the first received-signal output terminal Prx1with the SAW filter31provided therebetween. The filtering function of the SAW filter31is set so that the fundamental frequency band of the first received signal is included within the pass band and the other frequency bands are included within the attenuation bands.

The duplexer22transmits a second transmitting signal (a transmitting signal of a second communication band) input from the second transmitting-signal input terminal Ptx2to the second selection terminal of the switch IC11. The duplexer22outputs a second received signal (a received signal of the second communication band) input from the second selection terminal to the second received-signal output terminal Prx2with the SAW filter32provided therebetween. The filtering function of the SAW filter32is set so that the fundamental frequency band of the second received signal is included within the pass band and the other frequency bands are included within the attenuation bands.

The duplexer23transmits a third transmitting signal (a transmitting signal of a third communication band) input from the third transmitting-signal input terminal Ptx3to the third selection terminal of the switch IC11. The duplexer23outputs a third received signal (a received signal of the third communication band) input from the third selection terminal to the third received-signal output terminal Prx3with the SAW filter33provided therebetween. The filtering function of the SAW filter33is set so that the fundamental frequency band of the third received signal is included within the pass band and the other frequency bands are included within the attenuation bands. The first, second, and third received-signal output terminals each includes a balanced terminal to output a balanced signal.

In the phase circuit41, phase adjustment is made so that impedance matching between the first transmitting-signal input terminal Ptx1and the duplexer21is performed in the fundamental frequency band of the first transmitting signal. In the phase circuit41, phase adjustment is also made so that the phase of the frequency band of the second transmitting signal in relation to the impedance characteristics of a first transmission path which ranges from the first transmitting-signal input terminal Ptx1to the duplexer21with the phase circuit41provided therebetween appears in the open side on a Smith chart.

FIG. 2Ashows a Smith chart representing the impedance characteristics of a radio-frequency module without a phase circuit, which is a comparative example of the radio-frequency module according to the first preferred embodiment of the present invention.FIG. 2Bshows a Smith chart representing the impedance characteristics of the radio-frequency module according to the first preferred embodiment of the present invention.

As shown inFIG. 2A, in the case of the radio-frequency module without the phase circuit41, the phase of the frequency band of the second transmitting signal in relation to the impedance characteristics of the first transmission path appears in the short side on the Smith chart.

In contrast, as shown inFIG. 2B, in the case of the radio-frequency module with the phase circuit41, the phase of the frequency band of the second transmitting signal in relation to the impedance characteristics of the first transmission path has shifted to the open side on the Smith chart. As a result of implementing such a phase shift to the open side, the isolation between the first transmission path and a second transmission path is improved.

FIG. 3is a graph illustrating the frequency characteristics regarding the insertion loss of the radio-frequency module according to the first preferred embodiment of the present invention and those of the comparative example.

As shown inFIG. 3, the insertion loss is able to be decreased by using the phase circuit, as in this preferred embodiment.

In this manner, by using the configuration of this preferred embodiment, it is possible to realize the radio-frequency module10in which the isolation between the first transmission path and the second transmission path is improved.

The configuration of this preferred embodiment becomes more effective when the radio-frequency module10has the following structure.

FIG. 4is a view illustrating the arrangement pattern of external-connecting lands of the radio-frequency module according to the first preferred embodiment of the present invention.FIG. 5is a sectional side view illustrating the structure of a multilayer body of the radio-frequency module according to the first preferred embodiment of the present invention.

The radio-frequency module10includes a multilayer body90preferably having a substantially rectangular-parallelepiped shape, for example. The multilayer body90includes plural dielectric layers stacked on each other. On certain dielectric layers, conductive patterns are provided and define major circuit patterns other than mounting components of the switch IC11, the duplexers21,22, and23, and the SAW filters31,32, and33shown inFIG. 1, etc.

On the top surface of the multilayer body90, mounting components defining the switch IC11, the duplexers21,22, and23, the SAW filters31,32, and33, etc. are mounted. If necessary, other components such as capacitors and inductors defining the radio-frequency module10are also mounted.

On the back surface of the multilayer body90, plural external-connecting lands defining the first transmitting-signal input terminal Ptx1, the second transmitting-signal input terminal Ptx2, the third transmitting-signal input terminal Ptx3, the first received-signal output terminal Prx1, the second received-signal output terminal Prx2, and the third received-signal output terminal Prx3shown inFIG. 1, and an antenna connecting terminal PANT (seeFIG. 4), which is not shownFIG. 1, are arranged.

The external-connecting land of the first transmitting-signal input terminal Ptx1and that of the second transmitting-signal input terminal Ptx2are disposed close to and adjacent to each other. If the external-connecting land of the first transmitting-signal input terminal Ptx1and that of the second transmitting-signal input terminal Ptx2are disposed close to and adjacent to each other in this manner, these external-connecting lands or wiring patterns connected thereto are electromagnetically coupled with each other. That is, the first transmission path and the second transmission path may be electromagnetically coupled with each other. However, by the provision of the above-described phase circuit41, the isolation between the first transmission path and the second transmission path is enhanced.

The first and second transmitting-signal input terminals Ptx1and Ptx2(and also the third transmitting-signal input terminal Ptx3) may be separated from the first and second received-signal output terminals Prx1and Prx2(and also the third received-signal output terminal Prx3), as shown inFIG. 4, and external-connecting lands connected to grounds may be interposed therebetween. With this configuration, the isolation between the transmission path and the reception path is also enhanced.

Moreover, as shown inFIG. 4, the antenna connecting terminal PANT may be separated from the first, second, and third transmitting-signal input terminals Ptx1, Ptx2, and Ptx3and the first, second, and third received-signal output terminals Prx1, Prx2, and Prx3. With this configuration, the isolation between the antenna ANT and each of the transmission path and the reception path is also enhanced.

The phase circuit41may include a conductive pattern within the multilayer body90, as shown inFIG. 5. Alternatively, a mounting component to be mounted on the top surface of the multilayer body90may be used to provide the phase circuit41. If the phase circuit41is provided within the multilayer body90, the space for the phase circuit41is conserved, thus making it possible to provide an even smaller radio-frequency module10.

A radio-frequency module according to a second preferred embodiment of the present invention is described below with reference to the drawings.FIG. 6is a circuit diagram illustrating the major configuration of the radio-frequency module according to the second preferred embodiment of the present invention.

A radio-frequency module10A according to this preferred embodiment is different from the radio-frequency module10according to the first preferred embodiment in that the phase circuit41is replaced by a phase circuit42. The configurations of the other portions of the radio-frequency module10A are the same as those of the radio-frequency module10according to the first preferred embodiment.

The phase circuit42is connected between the second transmitting-signal input terminal Ptx2and the duplexer22.

FIG. 7shows a Smith chart representing the impedance characteristics of the radio-frequency module according to the second preferred embodiment of the present invention.

As shown inFIG. 7, phase adjustment is made in the phase circuit42so that impedance matching is maintained in the frequency band of a second radio-frequency signal transmitted through the second transmission path and so that the phase of the frequency band of the first radio-frequency signal in relation to the impedance characteristics of the second transmission path shifts to the open side on the Smith chart.

With this configuration, the possibility that the second transmitting signal input from the second transmitting-signal input terminal Ptx2leaks to and transmitted through the first transmission path is significantly reduced or prevented.

Thus, in a manner similar to the first preferred embodiment, it is possible to realize the radio-frequency module10A in which the isolation between the first transmission path and the second transmission path is improved.

Only the phase circuit41is included in the radio-frequency module10according to the first preferred embodiment, and only the phase circuit42is included in the radio-frequency module10A according to the second preferred embodiment. However, a radio-frequency module including both of the phase circuits41and42may be provided.

A radio-frequency module according to a third preferred embodiment of the present invention is described below with reference to the drawings.FIG. 8is a plan view illustrating a multilayer body of the radio-frequency module according to the third preferred embodiment of the present invention. The basic circuit configuration of a radio-frequency module10B according to this preferred embodiment is the same as that of the radio-frequency module10according to the first preferred embodiment.

The radio-frequency module10B includes a multilayer body90B. On the top surface of the multilayer body90B, a switch IC11and three duplexers21,22, and23are mounted. SAW filters and other mounting components are also mounted, though they are not shown.

The duplexers21,22, and23have the same arrangement of terminals. More specifically, the arrangement of an antenna terminal PANT1, a transmit terminal PTX1, and a receive terminal PRX1, the arrangement of an antenna terminal PANT2, a transmit terminal PTX2, and a receive terminal PRX2, and the arrangement of an antenna terminal PANTS, a transmit terminal PTX3, and a receive terminal PRX3are the same. The duplexers21,22, and23are mounted on the multilayer body90B so that the arrangements of the terminals of the duplexers21,22, and23are the same, as viewed from above.

The duplexers21,22, and23are mounted along one direction of the top surface (mounting surface) of the multilayer body90B in order of the duplexers21,23, and22. With this configuration, the duplexer23is interposed between the duplexers21and22, so that the duplexers21and22are able to be separated from each other.

FIG. 9is a table indicating the frequency bands of multiple communication bands used in the radio-frequency module according to this preferred embodiment. Signals of the communication band Band1are separated by the duplexer21. Signals of the communication band Band2are separated by the duplexer22. Signals of the communication band Band3are separated by the duplexer23.

As shown inFIG. 9, the transmit frequency band of the communication band Band1overlaps the receive frequency band of the communication band Band2, and the transmit frequency band of the communication band Band2overlaps the receive frequency band of the communication band Band3.

However, with the configuration of this preferred embodiment, it is possible to secure the isolation between transmission paths through which signals of overlapping frequency bands are transmitted.

FIG. 10is a view schematically illustrating the influence of a transmitting signal of the communication band Band1(first transmitting signal) on the reception path of the communication band Band2. It is assumed that, as shown inFIG. 10, the first transmitting signal leaks to the reception path of the communication band Band2. In this case, on the top surface of the multilayer body90B, the first transmitting signal may leak from the transmit terminal PTX1and the antenna terminal PANT1of the duplexer21to the antenna terminal PANT2and the receive terminal PRX2of the duplexer22.

However, with the configuration of this preferred embodiment, the transmit terminal PTX1and the antenna terminal PANT1of the duplexer21are separated from the antenna terminal PANT2and the receive terminal PTX2of the duplexer22by a large distance, thus making it possible to significantly reduce or prevent a leakage of the first transmitting signal to the reception path of the communication band Band2. Moreover, in the configuration of this preferred embodiment, since the duplexer23is interposed between the duplexers21and22, it is possible to further reduce or prevent a leakage of the first transmitting signal to the reception path of the communication band Band2.

FIG. 11is a view schematically illustrating the influence of a transmitting signal of the communication band Band2(second transmitting signal) on the reception path of the communication band Band3. It is assumed that, as shown inFIG. 11, the second transmitting signal leaks to the reception path of the communication band Band3. In this case, on the top surface of the multilayer body90B, the second transmitting signal may leak from the transmit terminal PTX2and the antenna terminal PANT2of the duplexer22to the antenna terminal PANT3and the receive terminal PRX3of the duplexer23.

However, with the configuration of this preferred embodiment, particularly with the configuration in which the arrangements of the terminals of the duplexers21,22, and23are the same, the distances from the transmit terminal PTX2and the antenna terminal PANT2of the duplexer22to the antenna terminal PANT3and the receive terminal PRX3of the duplexer23are greater than those of a case in which the arrangements of the terminals of the duplexers21,22, and23are not the same. As a result, a leakage of the second transmitting signal to the reception path of the communication band Band3is significantly reduced or prevented.

In this manner, the duplexers are disposed so that the distances between the terminals to transmit and receiving signals of overlapping frequency bands are increased. It is thus possible to significantly reduce or prevent a decrease in the isolation between transmission paths through which signals of overlapping frequency bands are transmitted even though the size of a multilayer body is decreased.

In this preferred embodiment, the duplexers21,22, and23are located such that the transmit terminals PTX1, PTX2, and PTX3of the duplexers21,22, and23are positioned closer to the external-connecting lands of the first, second, and third transmitting-signal input terminals Pt11, Ptx2, and Ptx3and such that the receive terminals PRX1, PRX2, and PRX3of the duplexers21,22, and23are positioned closer to the external-connecting lands of the first, second, and third received-signal output terminals Prx1, Prx2, and Prx3. With this configuration, within the multilayer body90B, the transmission path and the reception path are less likely to overlap each other, thus securing high isolation between the transmission path and the reception path. Additionally, by disposing an internal ground conductor between the conductive patterns of the transmission path and those of the reception path, even higher isolation is secured between the transmission path and the reception path.