BACKGROUND OF THE DISCLOSURE

1. Field of the Disclosure

The present disclosure relates to a high-frequency front end module and a communication device that process a high-frequency signal.

2. Description of the Related Art

There is a demand for applying a carrier aggregation (CA) system in which different frequency bands are simultaneously used to a multi-band and multi-mode compatible high-frequency front end module.

Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2016-501467 discloses an antenna interface circuit that performs simultaneous transmission (two-uplink) and simultaneous reception (two-downlink) of signals in different frequency bands using two antennas. More specifically, the antenna interface circuit includes a first antenna interface circuit coupled to a first antenna and a second antenna interface circuit coupled to a second antenna. The first antenna interface circuit includes a first quadplexer for a first band and a second band. Additionally, the second antenna interface circuit includes a second quadplexer for the first band and the second band.

In a system applied to two-uplink two-downlink, as in the antenna interface circuit disclosed in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2016-501467, the two antennas are disposed in order to suppress mutual interference of two signals to be simultaneously transmitted, the first antenna is allocated to a primary antenna that is preferentially used in terms of antenna performance and the like, and the second antenna is allocated to a secondary antenna. In such a system, in order to optimize signal quality even in one-uplink, it is necessary to transmit and receive each of the first band and the second band by using the primary antenna. Therefore, each of the first antenna interface circuit and the second antenna interface circuit requires four filters of a transmission filter and a reception filter which take the first band as a pass band and a transmission filter and a reception filter which take the second band as a pass band. That is, since the antenna interface circuit disclosed in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2016-501467 requires a total of eight filters, there is a problem in that the circuit increases in size as the number of bands increases.

BRIEF SUMMARY OF THE DISCLOSURE

Accordingly, the present disclosure has been made in order to solve the above-described problem, and an object of the present disclosure is to provide a high-frequency front end module and a communication device which are reduced in size and in which CA of two-uplink two-downlink can be performed.

In order to achieve the above-described object, a high-frequency front end module according to a preferred embodiment of the present disclosure is a high-frequency front end module for executing two-uplink in which a signal in a first transmission band included in a first frequency band and a signal in a second transmission band included in a second frequency band which is different from the first frequency band are simultaneously transmitted, and two-downlink in which a signal in a first reception band included in the first frequency band and a signal in a second reception band included in the second frequency band are simultaneously received, the high-frequency front end module includes: a primary antenna and a secondary antenna; a first multiplexer and a second multiplexer; and a first switch circuit having a first terminal, a second terminal, a third terminal, and a fourth terminal, in which the first multiplexer has a first transmission filter which takes the first transmission band as a pass band and a first reception filter which takes the first reception band as a pass band, and does not have a transmission filter which takes the second transmission band as a pass band, the second multiplexer has a second transmission filter which takes the second transmission band as a pass band and a second reception filter which takes the second reception band as a pass band, and does not have a transmission filter which takes the first transmission band as a pass band, the first terminal is connected to the primary antenna, the second terminal is connected to the secondary antenna, the third terminal is connected to an output terminal of the first transmission filter and an input terminal of the first reception filter, and the fourth terminal is connected to an output terminal of the second transmission filter and an input terminal of the second reception filter.

In an existing system including a CA mode in which high-frequency signals in the first frequency band and the second frequency band which are two different bands are simultaneously used, in order to ensure signal quality such as isolation and the like of two high-frequency signals simultaneously transmitted/received, two antenna elements, such as a primary antenna which is preferentially used and a secondary antenna which is secondarily used, are disposed. In this case, because of necessity of making it possible to transmit/receive each of the high-frequency signals in the first frequency band and the second frequency band even by any of the antennas, a transmission path and a reception path of the first frequency band and a transmission path and a reception path of the second frequency band are connected to the primary antenna, and a transmission path and a reception path of the first frequency band and a transmission path and a reception path of the second frequency band are connected and disposed also to the secondary antenna. A filter for selectively allowing the desired frequency band to pass therethrough is disposed in each signal path, and in the existing configuration, it is necessary to connect four filters of a transmission filter and a reception filter of the first frequency band and a transmission filter and a reception filter of the second frequency band to each of the primary antenna and the secondary antenna, which increases the circuit in size.

In contrast, according to the above-described configuration, by disposing the first switch circuit, it is possible to arbitrarily distribute the high-frequency signals in the first frequency band and the second frequency band to the primary antenna and the secondary antenna, and execute CA of two-uplink two-downlink. Therefore, in the first multiplexer connected to one of the antennas, one of the two transmission filters of the first frequency band and the second frequency band can be reduced. In the same manner, in the second multiplexer, the other of the two transmission filters of the first frequency band and the second frequency band can be reduced. That is, two or more filters can be reduced as compared with the existing configuration. In this configuration, one switch circuit of a two-input two-output type is added, but the switch circuit is sufficiently smaller than the filter. Accordingly, it is possible to provide a small-sized high-frequency front end module in which CA of two-uplink two-downlink can be performed.

Furthermore, in the first switch circuit, conduction between the third terminal and the first terminal and conduction between the third terminal and the second terminal may be exclusively switched, and conduction between the fourth terminal and the first terminal and conduction between the fourth terminal and the second terminal may be exclusively switched.

According to this configuration, by switching the connection state of the first switch circuit, it is possible to arbitrarily distribute the high-frequency signals in the first frequency band and the second frequency band to the primary antenna and the secondary antenna, and execute CA of two-uplink two-downlink. Therefore, in the first multiplexer connected to one of the antennas, one of the two transmission filters of the first frequency band and the second frequency band can be reduced. In the same manner, in the second multiplexer, the other of the two transmission filters of the first frequency band and the second frequency band can be reduced.

Furthermore, the first multiplexer may not have a filter which takes the second reception band as a pass band, and the second multiplexer may not have a filter which takes the first reception band as a pass band.

According to this configuration, in the first multiplexer connected to one of the antennas, the transmission filter and the reception filter of one of the first frequency band and the second frequency band can be reduced. Additionally, in the second multiplexer connected to the other of the antennas, the transmission filter and the reception filter of the other of the first frequency band and the second frequency band can be reduced. That is, four or more filters can be reduced as compared with the existing configuration. Accordingly, it is possible to provide a smaller-sized high-frequency front end module in which CA of two-uplink two-downlink can be performed.

Furthermore, in a case where the two-uplink and the two-downlink are performed in the first frequency band and the second frequency band, and in a case where one-uplink in which only one of a signal in the first transmission band and a signal in the second transmission band is transmitted and the two-downlink in the first frequency band and the second frequency band are performed, one of a first connection state in which the third terminal and the first terminal are conductive to each other and the fourth terminal and the second terminal are conductive to each other, and a second connection state in which the third terminal and the second terminal are conductive to each other and the fourth terminal and the first terminal are conductive to each other may be selected.

According to this configuration, for example, in the case of two-uplink two-downlink, a frequency band to be transmitted/received by the primary antenna can be arbitrarily selected. Additionally, for example, in the case of one-uplink two-downlink, even in a mode in which a high-frequency signal in any of frequency bands is transmitted, a signal path for transporting a signal in a frequency band to be transmitted and received can be connected to the primary antenna, and a signal path for transporting a signal in a frequency band only for reception can be connected to the secondary antenna.

Furthermore, the first multiplexer may further have a fourth reception filter which takes the second reception band as a pass band, and the second multiplexer may further have a third reception filter which takes the first reception band as a pass band.

According to this configuration, since the first multiplexer has the first reception filter corresponding to the first frequency band and the fourth reception filter corresponding to the second frequency band, in a case of one-uplink two-downlink in which a high-frequency signal in the first frequency band is transmitted, for example, only one of the primary antenna and the secondary antenna may be used. Additionally, since the second multiplexer has the third reception filter corresponding to the first frequency band and the second reception filter corresponding to the second frequency band, in a case of one-uplink two-downlink in which a high-frequency signal in the second frequency band is transmitted, for example, only one of the primary antenna and the secondary antenna may be used. Accordingly, it is possible to simplify the CA operation of one-uplink two-downlink.

Furthermore, in a case where the two-uplink and the two-downlink are performed in the first frequency band and the second frequency band, one of a first connection state in which the third terminal and the first terminal are conductive to each other and the fourth terminal and the second terminal are conductive to each other, and a second connection state in which the third terminal and the second terminal are conductive to each other and the fourth terminal and the first terminal are conductive to each other may be selected, in a case of one-uplink two-downlink in which transmission in the first frequency band is performed and a signal in the first reception band and a signal in the second reception band are simultaneously received, one of a third connection state in which the third terminal and the first terminal are conductive to each other, and a fourth connection state in which the third terminal and the second terminal are conductive to each other may be selected, and in a case of one-uplink two-downlink in which transmission in the second frequency band is performed and a signal in the first reception band and a signal in the second reception band are simultaneously received, one of a fifth connection state in which the fourth terminal and the first terminal are conductive to each other, and a sixth connection state in which the fourth terminal and the second terminal are conductive to each other may be selected.

According to this configuration, in the case of one-uplink two-downlink, only one of the primary antenna and the secondary antenna may be used. Accordingly, it is possible to simplify the CA operation of one-uplink two-downlink.

Furthermore, a second switch circuit having a fifth terminal, a sixth terminal, a seventh terminal, and an eighth terminal, a first amplifier whose output terminal is connected to an input terminal of the first transmission filter, and a second amplifier whose output terminal is connected to an input terminal of the second transmission filter may further be included, the fifth terminal may be connected to an input terminal of the first amplifier, the sixth terminal may be connected to an input terminal of the second amplifier, a signal for the primary antenna may be inputted to the seventh terminal, a signal for the secondary antenna may be inputted to the eighth terminal, and in the second switch circuit, conduction between the seventh terminal and the fifth terminal may be selected in a case where conduction between the third terminal and the first terminal is selected, conduction between the eighth terminal and the fifth terminal may be selected in a case where conduction between the third terminal and the second terminal is selected, conduction between the seventh terminal and the sixth terminal may be selected in a case where conduction between the fourth terminal and the first terminal is selected, and conduction between the eighth terminal and the sixth terminal may be selected in a case where conduction between the fourth terminal and the second terminal is selected.

According to this configuration, since the second switch circuit achieves the connection state corresponding to the connection state of the first switch circuit, it is possible to output or input a signal for the primary antenna and a signal for the secondary antenna without changing terminal arrangement of a high-frequency signal processing circuit (RFIC) that outputs a high-frequency signal to the high-frequency front end module and to which the high-frequency signal from the high-frequency front end module is inputted, for example. Accordingly, it is possible to simplify the circuit configurations of the high-frequency front end circuit and the peripheral circuits thereof. In addition, in the existing configuration, it is necessary to provide a switch for switching connection between a transmission amplifier and a plurality of transmission filters included in a multiplexer, but in this configuration, since each of the first multiplexer and the second multiplexer has only the transmission filter of one of the first frequency band and the second frequency band, the switch that is necessary in the existing configuration becomes unnecessary. Accordingly, it is possible to provide a small-sized and simplified high-frequency front end module in which CA of two-uplink two-downlink can be performed.

Furthermore, two-uplink in which two transmission signals among a transmission signal in the first transmission band included in the first frequency band, a transmission signal in the second transmission band included in the second frequency band which is different from the first frequency band, and a transmission signal in a third transmission band included in a third frequency band which is different from the first frequency band and the second frequency band are simultaneously transmitted, and two-downlink in which two reception signals among a reception signal in the first reception band included in the first frequency band, a reception signal in the second reception band included in the second frequency band, and a reception signal in a third reception band included in the third frequency band are simultaneously received may be executed, the first multiplexer may further have a fifth transmission filter which takes the third transmission band as a pass band and a fifth reception filter which takes the third reception band as a pass band, and the second multiplexer may further have a sixth transmission filter which takes the third transmission band as a pass band and a sixth reception filter which takes the third reception band as a pass band.

In an existing system including a CA mode in which two high-frequency signals among high-frequency signals in the first frequency band, the second frequency band, and the third frequency band which are three different bands are simultaneously used, in order to ensure signal quality such as isolation and the like of two high-frequency signals simultaneously transmitted/received, two antenna elements, such as a primary antenna which is preferentially used and a secondary antenna which is secondarily used, are disposed. In this case, because of necessity of making it possible to transmit/receive each of the high-frequency signals in the first frequency band, the second frequency band, and the third frequency band even by any of the antennas, a transmission path and a reception path of the first frequency band, a transmission path and a reception path of the second frequency band, and a transmission path and a reception path of the third frequency band are connected to the primary antenna, and transmission paths and reception paths are connected and disposed also to the secondary antenna in the same manner. That is, in the existing configuration, it is necessary to connect transmission filters and reception filters (six filters in total) of the first frequency band, the second frequency band, and the third frequency band to each of the primary antenna and the secondary antenna, which increases the circuit in size.

In contrast, according to the above-described configuration, by switching the connection state of the first switch circuit, it is possible to arbitrarily distribute the high-frequency signals in the first frequency band, the second frequency band, and the third frequency band to the primary antenna and the secondary antenna, and execute CA of two-uplink two-downlink. Therefore, in the first multiplexer connected to one of the antennas, for example, the transmission filter of the second frequency band can be reduced. In the same manner, in the second multiplexer, for example, the transmission filter of the first frequency band can be reduced. That is, two or more filters can be reduced as compared with the existing configuration. In this configuration, one switch circuit of a two-input two-output type is added, but the switch circuit is sufficiently smaller than the filter. Accordingly, it is possible to provide a small-sized high-frequency front end module in which CA of two-uplink two-downlink can be performed.

Furthermore, among a transmission signal in the first transmission band included in the first frequency band, a transmission signal in the second transmission band included in the second frequency band which is different from the first frequency band, and a transmission signal in a third transmission band included in a third frequency band which is different from the first frequency band and the second frequency band, (1) two-uplink of the transmission signal in the first transmission band and the transmission signal in the second transmission band, and (2) two-uplink of the transmission signal in the first transmission band and the transmission signal in the third transmission band may be executed, among a reception signal in the first reception band included in the first frequency band, a reception signal in the second reception band included in the second frequency band, and a reception signal in a third reception band which is included in the third frequency band and includes the second reception band, (3) two-downlink of the reception signal in the first reception band and the reception signal in the second reception band, and (4) two-downlink of the reception signal in the first reception band and the reception signal in the third reception band may be executed, the first multiplexer may further have a fourth reception filter which takes the third reception band as a pass band, the second multiplexer may further have a third reception filter which takes the first reception band as a pass band, and a sixth transmission filter which takes the third transmission band as a pass band, and the second reception filter may take, as a pass band, the third reception band which includes the second reception band.

According to the above-described configuration, since the first multiplexer does not have transmission filters of the second frequency band and the third frequency band and a reception filter of the second frequency band, and the second multiplexer does not have a transmission filter of the first frequency band and a reception filter dedicated to the second frequency band, it is possible to provide a small-sized high-frequency front end module in which CA of two-uplink two-downlink of three bands including two bands in an overlapping relationship can be performed.

Furthermore, the high-frequency front end module may (1) execute the two-uplink and the two-downlink of the first frequency band and the second frequency band, and (2) be capable of executing two-uplink two-downlink in which a high-frequency signal in a fourth frequency band which is different from the first frequency band and the second frequency band, and a high-frequency signal in a fifth frequency band which is different from the first frequency band, the second frequency band, and the fourth frequency band are simultaneously transmitted and simultaneously received, the first frequency band may be a band 66 of LTE (Long Term Evolution), the second frequency band may be a band 25 of LTE, the fourth frequency band may be a band 1 of LTE, and the fifth frequency band may be a band 3 of LTE.

According to this configuration, it is possible to provide a small-sized high-frequency front end module to which the bands 66, 25, 1, and 3 of LTE are applied and in which CA of two-uplink two-downlink of the band 66 and the band 25, and two-uplink two-downlink of the band 1 and the band 3 can be performed.

Furthermore, the high-frequency front end module may (1) execute the two-uplink and the two-downlink of the first frequency band and the second frequency band, and (2) be capable of executing two-uplink two-downlink in which a high-frequency signal in a fourth frequency band which is different from the first frequency band and the second frequency band, and a high-frequency signal in a fifth frequency band which is different from the first frequency band, the second frequency band, and the fourth frequency band are simultaneously transmitted and simultaneously received, the first frequency band may be a band 1 of LTE, the second frequency band may be a band 3 of LTE, the fourth frequency band may be a band 66 of LTE, and the fifth frequency band may be a band 25 of LTE.

According to this configuration, it is possible to provide a small-sized high-frequency front end module to which the bands 66, 25, 1, and 3 of LTE are applied and in which CA of two-uplink two-downlink of the band 66 and the band 25, and two-uplink two-downlink of the band 1 and the band 3 can be performed.

Furthermore, a communication device according to a preferred embodiment of the present disclosure includes: the high-frequency front end module according to any one of those described above, and an RF signal processing circuit configured to process a high-frequency signal transmitted and received by the high-frequency front end module.

According to this configuration, it is possible to provide a small-sized communication device in which CA of two-uplink two-downlink can be performed.

Other features, elements, characteristics and advantages of the present disclosure will become more apparent from the following detailed description of preferred embodiments of the present disclosure with reference to the attached drawings.

