RADIO-FREQUENCY CIRCUIT AND COMMUNICATION DEVICE

A radio-frequency circuit includes a power amplifier configured to output a first maximum transmit power, a power amplifier configured to output a second maximum transmit power that is higher than the first maximum transmit power, a filter having a pass band that includes a band A, a filter having a pass band that includes a band B different from the band A, a switch coupled between the power amplifier and the filter and between the power amplifier and the filter, and a switch coupled between the switch and the filter and between the power amplifier and the filter.

TECHNICAL FIELD

The present disclosure relates to a radio-frequency circuit and a communication device.

BACKGROUND ART

Patent Document 1 (FIG. 8) discloses a power amplifier system including a first power amplifier and a second power amplifier, a first switch coupled to the output end of the first power amplifier, a first signal path coupled between the first switch and a first antenna, a second signal path coupled between the first switch and a second antenna, and a third signal path coupled to the output end of the second power amplifier and the second antenna. In the power amplifier system, assuming signals in a first frequency band are exclusively transmitted, the signals in the first frequency band are amplified by the first power amplifier and transferred through the first signal path. Assuming signals in a second frequency band are exclusively transmitted, the signals in the second frequency band are amplified by the second power amplifier and transferred through the third signal path. Assuming signals in the first frequency band and the second frequency band are simultaneously transmitted, the signals in the first frequency band are amplified by the first power amplifier and transferred through the first signal path, and the signals in the second frequency band are amplified by the second power amplifier and transferred through the third signal path.

CITATION LIST

Patent Document

SUMMARY OF DISCLOSURE

Technical Problem

However, the power amplifier system (radio-frequency circuit) disclosed in Patent Document 1 has problems such as difficulty in optimizing power efficiency when amplifying radio-frequency signals in different frequency bands.

It is therefore an feature of the present disclosure to provide a radio-frequency circuit and a communication device that optimize power efficiency when amplifying radio-frequency signals in different frequency bands.

Solution to Problem

To achieve the feature described above, a radio-frequency circuit according to an embodiment of the present disclosure includes a first power amplifier configured to output a first maximum transmit power, a second power amplifier configured to output a second maximum transmit power that is higher than the first maximum transmit power, a first filter having a pass band that includes a first band, a second filter having a pass band that includes a second band different from the first band, a first switch coupled between the first power amplifier and the first filter and between the first power amplifier and the second filter, and a second switch coupled between the first switch and the second filter and between the second power amplifier and the second filter.

Advantageous Effects of Disclosure

The present disclosure provides a radio-frequency circuit and a communication device that optimize power efficiency when amplifying radio-frequency signals in different frequency bands.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. It should be noted that the embodiments described below provide comprehensive or specific examples. Details such as numerical values, shapes, materials, constituent elements, and arrangements and connection modes of the constituent elements provided in the following embodiments are illustrative and are not intended to limit the present disclosure.

The drawings are schematically illustrated with necessary emphasis, omissions, or proportion adjustments to depict the present disclosure and do not necessarily represent exact details; thus, the shapes, positional relationships, and proportions can differ from actual implementations. Identical reference numerals are assigned to substantially the same configuration elements across the drawings, and redundant descriptions of these configuration elements can be omitted or simplified.

In the present disclosure, the term “couple” refers to a situation where a circuit element is directly connected to another circuit element by using a connection terminal and/or a wire line conductor, as well as to a situation where a circuit element is electrically connected to another circuit element via an additional circuit element. The expression “coupled between A and B” refers to a situation where a circuit element is connected to both A and B in a path that connects A and B.

In the present disclosure, the term “transmit path” refers to a transfer line formed by, for example, wire lines for transferring radio-frequency transmit signals, electrodes directly coupled to the wire line, and terminals directly coupled to the wire line or electrode. The term “receive path” refers to a transfer line formed by, for example, wire lines for transferring radio-frequency receive signals, electrodes directly coupled to the wire line, and terminals directly coupled to the wire line or electrode.

In the present disclosure, a first band (band A) and a second band (band B) represent frequency bands defined by, for example, standards organizations such as the 3rd Generation Partnership Project (3GPP (registered trademark)) and the Institute of Electrical and Electronics Engineers (IEEE)), for communication systems that are built using radio access technology (RAT). As the communication system in the present embodiment and modifications, for example, a 2nd Generation (2G) system, a 4th Generation Long Term Evolution (4G LTE) system, a 5th Generation New Radio (5G NR) system, or a Wireless Local Area Network (WLAN) system may be used, but these are not to be interpreted as limiting.

Embodiment

A circuit configuration of a radio-frequency circuit1and a communication device4according to the present embodiment will be described with reference toFIG.1.FIG.1is a circuit configuration diagram of the radio-frequency circuit1and the communication device4according to the embodiment.

[1.1 Circuit Configuration of Communication Device4]

First, a circuit configuration of the communication device4will be described. As illustrated inFIG.1, the communication device4according to the present embodiment includes the radio-frequency circuit1, antennas2A and2B, and a radio-frequency (RF) signal processing circuit (RFIC)3.

The radio-frequency circuit1is operable to transfer radio-frequency signals between the antennas2A and2B and the RFIC3. A detailed circuit configuration of the radio-frequency circuit1will be described later.

The antenna2A is coupled to an antenna connection terminal101of the radio-frequency circuit1. The antenna2A is operable to transmit radio-frequency signals outputted from the radio-frequency circuit1and to receive radio-frequency signals from outside and output the radio-frequency signals to the radio-frequency circuit1.

The antenna2B is coupled to an antenna connection terminal102of the radio-frequency circuit1. The antenna2B is operable to transmit radio-frequency signals outputted from the radio-frequency circuit1and to receive radio-frequency signals from outside and output the radio-frequency signals to the radio-frequency circuit1.

The RFIC3is an example of a signal processing circuit for processing radio-frequency signals. Specifically, the RFIC3is operable to process, for example by up-conversion, transmit signals inputted from a baseband signal processing circuit (BBIC; not illustrated) and output the radio-frequency transmit signals generated by the signal processing to transmit paths in the radio-frequency circuit1. The RFIC3is operable to process, for example by down-conversion, radio-frequency receive signals inputted through receive paths of the radio-frequency circuit1and output the receive signals generated by the signal processing. The RFIC3includes a control unit for controlling elements included in the radio-frequency circuit1, such as switches and amplifiers. The function of the control unit of the RFIC3may be partially or entirely implemented outside the RFIC3; for example, the function of the control unit of the RFIC3may be partially or entirely implemented in the BBIC or the radio-frequency circuit1.

In the communication device4according to the present embodiment, the antennas2A and2B are non-essential constituent elements.

Next, a circuit configuration of the radio-frequency circuit1will be described. As illustrated inFIG.1, the radio-frequency circuit1includes power amplifiers10and20, filters41,42,43, and44, switches31,32, and33, the antenna connection terminals101and102, and radio-frequency input terminals111and112.

The antenna connection terminal101is an external connection terminal included in the radio-frequency circuit1and is coupled to the antenna2A. The antenna connection terminal102is an external connection terminal included in the radio-frequency circuit1and is coupled to the antenna2B. The radio-frequency input terminals111and112are external connection terminals included in the radio-frequency circuit1and are designed to receive radio-frequency transmit signals from the RFIC3. Each of the antenna connection terminals101and102, the radio-frequency input terminals111and112, and the terminals included in the switches31to33, which will be described later, may be a metal conductor such as a metal electrode or metal bump or may be a point (node) in a metal wire line.

The power amplifier10is an example of a first power amplifier. The input end of the power amplifier10is coupled to the radio-frequency input terminal111, and the output end of the power amplifier10is coupled to a common terminal31aof the switch31. The power amplifier10is capable of amplifying signals in a band A and a band B.

The power amplifier20is an example of a second power amplifier. The input end of the power amplifier20is coupled to the radio-frequency input terminal112, and the output end of the power amplifier20is coupled to a terminal32cof the switch32. The power amplifier20is capable of amplifying signals in the band B.

Each of the power amplifiers10and20has an amplifier transistor. The amplifier transistor is, for example, a bipolar transistor, such as a heterojunction bipolar transistor (HBT), or a field-effect transistor, such as a metal-oxide-semiconductor field-effect transistor (MOSFET).

The power amplifier10may be capable of outputting a first maximum transmit power, and the power amplifier20may be capable of outputting a second maximum transmit power that is higher than the first maximum transmit power. More specifically, the power amplifier10is capable of outputting transmit signals in a first power class, and the power amplifier20is capable of outputting transmit signals in a second power class that has a maximum output power higher than the maximum output power of the first power class.

The power amplifier20can handle higher power than the power amplifier10. However, because large current flows through the power amplifier20, the circuit size increases and the power efficiency can degrade due to the need for a low-impedance output matching circuit. Considering this, the power amplifier10can be used without using the power amplifier20to exclusively transmit band-A or band-B signals, which improves the power efficiency of the radio-frequency circuit1.

Power classes refer to classification divisions of user equipment (UE) output power, defined by, for example, maximum output power. As the power class number increases, the allowable output power increases. For example, in 3GPP (registered trademark), the allowable maximum output power for Power Class 1 is 31 dBm, the allowable maximum output power for Power Class 1.5 is 29 dBm, the allowable maximum output power for Power Class 2 is 26 dBm, and the allowable maximum output power for Power Class 3 is 23 dBm.

The maximum output power of a UE is defined based on the output power at the antenna end of the UE. The maximum output power of a UE can be measured using a method defined by, for example, 3GPP (registered trademark) or other standardization organizations. For example, inFIG.1, the maximum output power can be measured by measuring the power emitted from the antenna2A or2B. In place of measuring emitted power, the output power of the antenna2A or2B can be measured using a measuring device (for example, a spectrum analyzer) that is coupled to a terminal provided near the antenna2A or2B.

The filter41is an example of a first filter. The filter41is a transmit filter having a pass band that includes the band A. The input end of the filter41is coupled to a terminal31bof the switch31, and the output end of the filter41is coupleable to the antenna connection terminal101or102via the switch33.

The filter42is a receive filter having a pass band that includes the band A. The input end of the filter42is coupleable to the antenna connection terminal101or102via the switch33, and the output end of the filter42is coupled to a low-noise amplifier (not illustrated).

The filter43is an example of a second filter. The filter43is a transmit filter having a pass band that includes the band B, which differs from the band A. The input end of the filter43is coupled to a common terminal32aof the switch32, and the output end of the filter43is coupleable to the antenna connection terminal101or102via the switch33.

The filter44is a receive filter having a pass band that includes the band B. The input end of the filter44is coupleable to the antenna connection terminal101or102via the switch33, and the output end of the filter44is coupled to a low-noise amplifier (not illustrated).

The filters41and42constitute a duplexer designed to transmit and receive band-A signals. The filters43and44constitute a duplexer designed to transmit and receive band-B signals. The radio-frequency circuit1according to the present embodiment does not necessarily include the filters42and44.

The switch31is an example of a first switch. The switch31is coupled between the power amplifier10and the filters41and43. The switch31is operable to alternate between coupling the power amplifier10to the filter41and coupling the power amplifier10to the filter43.

The switch32is an example of a second switch. The switch32is coupled between the switch31and the power amplifier20, and the filter43. The switch32is operable to alternate between coupling the power amplifier10to the filter43and coupling the power amplifier20to the filter43.

More specifically, the switch31has the common terminal31a(a first common terminal), the terminal31b(a first terminal), and the terminal31c(a second terminal). The switch32has the common terminal32a(a second common terminal), the terminal32b(a third terminal), and the terminal32c(a fourth terminal). The common terminal31ais coupled to the output end of the power amplifier10. The terminal31bis coupled to the input end of the filter41. The terminal31cis coupled to the terminal32b. The terminal32cis coupled to the output end of the power amplifier20. The common terminal32ais coupled to the input end of the filter43.

The switch33is an example of a fourth switch. The switch33is coupled between the filters41to44and the antenna connection terminals101and102. The switch33is operable to couple the filter41to the antenna connection terminal101or102and to couple the filter43to the antenna connection terminal101or102. By using the switch33, the antenna2A or2B can be selected to transmit or receive band-A signals or to transmit or receive band-B signals, depending on conditions such as antenna sensitivity and other factors.

More specifically, the switch33has terminals33a,33b,33c, and33d. The switch33is operable to couple the terminal33ato the terminal33cor33dand to couple the terminal33bto the terminal33cor33d. The terminal33ais coupled to the antenna connection terminal101. The terminal33bis coupled to the antenna connection terminal102. The terminal33cis coupled to the output end of the filter41and the input end of the filter42. The terminal33dis coupled to the output end of the filter43and the input end of the filter44.

The radio-frequency circuit1according to the present embodiment does not necessarily include the switch33. The output end of the filter41and the input end of the filter42may be directly coupled to the antenna connection terminal101, and the output end of the filter43and the input end of the filter44may be directly coupled to the antenna connection terminal102. In this case, band-A signals can be transmitted and received by the antenna2A, and band-B signals can be transmitted and received by the antenna2B.

[1.3 Circuit States in Different Transfer Modes]

FIG.2Aillustrates the circuit state of the radio-frequency circuit1according to the embodiment assuming band-A signals are exclusively transmitted.FIG.2Aillustrates the signal flow assuming signals in the band A out of the band A and the band B are exclusively transmitted (hereinafter referred to as mode A).

As illustrated inFIG.2A, assuming mode A is activated, the common terminal31ais connected to the terminal31b, the common terminal31ais disconnected from the terminal31c, and the terminal33ais connected to the terminal33c.

In this state, band-A transmit signals are transferred through the transmit path that includes the radio-frequency input terminal111, the power amplifier10, the switch31, the filter41, the switch33, the antenna connection terminal101, and the antenna2A. In mode A, under certain conditions such as antenna sensitivity and other factors, the terminals33band33cmay be connected, allowing band-A transmit signals to be output from the antenna2B.

FIG.2Billustrates the circuit state of the radio-frequency circuit1according to the embodiment assuming band-B signals are exclusively transmitted.FIG.2Billustrates the signal flow assuming signals in the band B out of the band A and the band B are exclusively transmitted (hereinafter referred to as mode B).

As illustrated inFIG.2B, assuming mode B is activated, the common terminal31ais connected to the terminal31c, the common terminal31ais disconnected from the terminal31b, the common terminal32ais connected to the terminal32b, and the terminal33ais connected to the terminal33d.

In this state, band-B transmit signals are transferred through the transmit path that includes the radio-frequency input terminal111, the power amplifier10, the switch31, the switch32, the filter43, the switch33, the antenna connection terminal101, and the antenna2A. In mode B, under certain conditions such as antenna sensitivity and other factors, the terminals33band33dmay be connected, allowing band-B transmit signals to be output from the antenna2B.

FIG.2Cillustrates the circuit state of the radio-frequency circuit1according to the embodiment assuming band-A signals and band-B signals are simultaneously transmitted.FIG.2Cillustrates the signal flow assuming signals in the band A and the band B are simultaneously transmitted (hereinafter referred to as mode C).

As illustrated inFIG.2C, assuming mode C is activated, the common terminal31ais connected to the terminal31b, the common terminal31ais disconnected from the terminal31c, the common terminal32ais connected to the terminal32c, the terminal33ais connected to the terminal33c, and the terminal33bis connected to the terminal33d.

In this state, band-A transmit signals are transferred through the transmit path that includes the radio-frequency input terminal111, the power amplifier10, the switch31, the filter41, the switch33, the antenna connection terminal101, and the antenna2A. Band-B transmit signals are transferred through the transmit path that includes the radio-frequency input terminal112, the power amplifier20, the switch32, the filter43, the switch33, the antenna connection terminal102, and the antenna2B. In mode C, under certain conditions such as antenna sensitivity and other factors, the terminals33band33cmay be connected, allowing band-A transmit signals to be output from the antenna2B, while the terminals33aand33dmay be connected, allowing band-B transmit signals to be output from the antenna2A.

The connection configurations of the radio-frequency circuit1illustrated inFIGS.2A to2Cenable the following operations: by coupling the power amplifier10and the filter41through control of the switch31, band-A signals can be exclusively transmitted using the signal path that includes the power amplifier10and the filter41; by coupling the power amplifier10to the filter43through control of the switches31and32, band-B signals can be exclusively transmitted using the signal path that includes the power amplifier10and the filter43; by coupling the power amplifier10to the filter41and coupling the power amplifier20to the filter43through control of the switches31and32, band-A signals can be transmitted using the signal path that includes the power amplifier10and the filter41, and at the same time, band-B signals can be transmitted using the signal path that includes the power amplifier20and the filter43.

Next, a radio-frequency circuit501according to a comparative example with a known configuration will be described for reference.

FIG.3is a circuit configuration diagram of a radio-frequency circuit501and a communication device504according to a comparative example. The radio-frequency circuit501illustrated in the drawing includes power amplifiers10and20, filters41,42,43, and44, a switch33, antenna connection terminals101and102, and radio-frequency input terminals111and112. The radio-frequency circuit501according to the comparative example differs from the radio-frequency circuit1according to the embodiment in that the switches31and32are not provided. The following describes the radio-frequency circuit501according to the comparative example with a main focus on configurational features different from the radio-frequency circuit1according to the embodiment, and descriptions of the same configurational features as the radio-frequency circuit1will not be repeated.

The input end of the filter41is coupled to the output end of the power amplifier10, and the output end of the filter41is coupleable to the antenna connection terminals101or102via the switch33. The input end of the filter43is coupled to the output end of the power amplifier20, and the output end of the filter43is coupleable to the antenna connection terminals101or102via the switch33.

Assuming signals in the band A out of the band A and the band B are exclusively transmitted (mode A), terminals33aand33care connected in the radio-frequency circuit501according to the comparative example. In this state, band-A transmit signals are transferred through the transmit path that includes the radio-frequency input terminal111, the power amplifier10, the filter41, the switch33, the antenna connection terminal101, and the antenna2A. In mode A, terminals33band33cmay be connected, allowing band-A transmit signals to be output from the antenna2B.

Assuming signals in the band B out of the band A and the band B are exclusively transmitted (mode B), terminals33band33dare connected in the radio-frequency circuit501according to the comparative example. In this state, band-B transmit signals are transferred through the transmit path that includes the radio-frequency input terminal112, the power amplifier20, the filter43, the switch33, the antenna connection terminal102, and the antenna2B. In mode B, the terminals33aand33dmay be connected, allowing band-B transmit signals to be output from the antenna2A.

Assuming signals in the band A and signals in the band B are simultaneously transmitted (mode C), the terminals33aand33care connected and the terminals33band33dare connected in the radio-frequency circuit501according to the comparative example. In this state, band-A transmit signals can be transferred through the transmit path that includes the radio-frequency input terminal111, the power amplifier10, the filter41, the switch33, the antenna connection terminal101, and the antenna2A, and at the same time, band-B transmit signals can be transferred through the transmit path that includes the radio-frequency input terminal112, the power amplifier20, the filter43, the switch33, the antenna connection terminal102, and the antenna2B. In mode C, the terminals33band33cmay be connected, allowing band-A transmit signals to be output from the antenna2B, while the terminals33aand33dmay be connected, allowing band-B transmit signals to be output from the antenna2A.

The connection configurations of the radio-frequency circuit501according to the comparative example enable the following operations: band-A signals can be exclusively transmitted using the signal path that includes the power amplifier10and the filter41; band-B signals can be exclusively transmitted using the signal path that includes the power amplifier20and the filter43; band-A signals can be transmitted using the signal path that includes the power amplifier10and the filter41, and at the same time, band-B signals can be transmitted using the signal path that includes the power amplifier20and the filter43.

In this case, different power amplifiers, specifically the power amplifiers10and20, are used respectively assuming band-A signals are exclusively transmitted and assuming band-B signals are exclusively transmitted. Thus, it is expected that the power efficiency of the radio-frequency circuit501can vary between assuming band-A signals are exclusively transmitted and assuming band-B signals are exclusively transmitted.

By contrast, the radio-frequency circuit1according to the present embodiment uses a single power amplifier for both exclusively transmitting band-A signals and exclusively transmitting band-B signals, aiming to avoid incorporating additional large-size power amplifiers. The power amplifier20has a higher maximum transmit power than the power amplifier10. However, because a high maximum transmit power is not required to exclusively transmit band-B signals, the power amplifier10is used to exclusively transmit band-B signals. This configuration optimizes the power efficiency of the radio-frequency circuit1.

More specifically, assuming signals in the band A out of the band A and the band B are exclusively transmitted, the power amplifier10and the filter41are coupled through control of the switch31. Assuming signals in the band B out of the band A and the band B are exclusively transmitted, the power amplifier10and the filter43are coupled through control of the switches31and32. Assuming signals in the band A and signals in the band B are simultaneously transmitted, the power amplifier10and the filter41are coupled and the power amplifier20and the filter43are coupled through control of the switches31and32.

As described above, because the same power amplifier10is used for both exclusively transmitting band-A signals and exclusively transmitting band-B signals, the power efficiency assuming exclusively transmitting band-A signals and the power efficiency assuming exclusively transmitting band-B signals can be optimized in the same manner. As such, the power efficiency assuming amplifying radio-frequency signals in different frequency bands can be optimized.

[1.4 Circuit Configuration of Radio-Frequency Circuit1A According to Modification]

FIG.4is a circuit configuration diagram of a radio-frequency circuit1A and a communication device4A according to a modification. As illustrated in the drawing, the communication device4A includes the radio-frequency circuit1A, antennas2A and2B, and an RFIC3. The communication device4A according to the present modification differs from the communication device4according to the embodiment in the circuit configuration of the radio-frequency circuit1A. The following describes a circuit configuration of the radio-frequency circuit1A according to the present modification.

The radio-frequency circuit1A includes power amplifiers10and20, filters41,42,43, and44, switches31,32,33A, and34, antenna connection terminals101and102, and radio-frequency input terminals111and112. The radio-frequency circuit1A according to the present modification differs from the radio-frequency circuit1according to the embodiment in the additional incorporation of the switch34and the configuration of the switch33A. The following describes the radio-frequency circuit1A according to the present modification with a main focus on configurational features different from the radio-frequency circuit1according to the embodiment, and descriptions of the same configurational features as the radio-frequency circuit1will not be repeated.

The power amplifier10is an example of a first power amplifier. The input end of the power amplifier10is coupled to the radio-frequency input terminal111, and the output end of the power amplifier10is coupled to a common terminal31a. The power amplifier10is capable of amplifying signals in a band A and a band B for 4G-LTE or 5G-NR.

The power amplifier20is an example of a second power amplifier. The input end of the power amplifier20is coupled to the radio-frequency input terminal112, and the output end of the power amplifier20is coupled to a common terminal34aof the switch34. The power amplifier20is capable of amplifying signals in the band B for 4G-LTE or 5G-NR, as well as 2G signals.

The power amplifier10is capable of outputting a first maximum transmit power, and the power amplifier20is capable of outputting a second maximum transmit power that is higher than the first maximum transmit power. More specifically, the power amplifier10is capable of outputting transmit signals in a first power class, and the power amplifier20is capable of outputting transmit signals in a second power class that has a maximum output power higher than the maximum output power of the first power class. The maximum output power of 2G signals is greater than the maximum output power of 4G-LTE signals and the maximum output power of 5G-NR signals.

The power amplifier20can handle higher power than the power amplifier10. However, because large current flows through the power amplifier20, the circuit size increases and the power efficiency can degrade due to the need for a low-impedance output matching circuit.

The filter41is an example of a first filter. The filter41is a transmit filter having a pass band that includes the band A. The input end of the filter41is coupled to a terminal31b, and the output end of the filter41is coupleable to the antenna connection terminal101or102via the switch33A.

The filter43is an example of a second filter. The filter43is a transmit filter having a pass band that includes the band B. The input end of the filter43is coupled to a common terminal32a, and the output end of the filter43is coupleable to the antenna connection terminal101or102via the switch33A.

The switch31is an example of a first switch. The switch31is coupled between the power amplifier10and the filters41and43. The switch31is operable to alternate between coupling the power amplifier10to the filter41and coupling the power amplifier10to the filter43.

The switch32is an example of a second switch. The switch32is coupled between the switches31and34and the filter43. The switch32is operable to alternate between coupling the power amplifier10to the filter43and coupling the power amplifier20to the filter43.

The switch34is an example of a third switch. The switch34is coupled between the power amplifier20, and the switch32and the antenna connection terminals101and102. The switch34is operable to alternate between coupling the power amplifier20to the filter43and coupling the power amplifier20to the antenna connection terminal101or102without involving the switch32and the filter43.

More specifically, the switch34has the common terminal34a(a third common terminal), a terminal34b(a fifth terminal), and a terminal34c(a sixth terminal). The common terminal34ais coupled to the output end of the power amplifier20. The terminal34bis coupled to the terminal32c. The terminal34cis coupleable to the antenna connection terminal101or102via the switch33a.

The switch33A is an example of a fourth switch. The switch33A is coupled between the antenna connection terminals101and102, and the filters41and43and the switch34. The switch33A is operable to couple the antenna connection terminal101to any one of the filters41,43, and the switch34and to couple the antenna connection terminal102to any one of the filters41,43, and the switch34.

More specifically, the switch33A has terminals33a,33b,33c,33d, and33e. The terminal33ais coupled to the antenna connection terminal101. The terminal33bis coupled to the antenna connection terminal102. The terminal33cis coupled to the output end of the filter41and the input end of the filter42. The terminal33dis coupled to the output end of the filter43and the input end of the filter44. The terminal33eis directly coupled to the terminal34c. By using the switch33A, the antenna2A or2B can be selected to transmit or receive band-A signals, to transmit or receive band-B signals, or to transmit 2G signals, depending on conditions such as antenna sensitivity and other factors.

[1.5 Circuit States in Different Transfer Modes in Radio-Frequency Circuit1A According to Modification]

The radio-frequency circuit1A according to the modification enables (1) exclusive transmission of band-A signal (mode A), (2) exclusive transmission of band-B signal (mode B), (3) simultaneous transmission of band-A signal and band-B signal (mode C), and (4) transmission of 2G signal (mode D).

Assuming mode A is activated, the common terminal31ais connected to the terminal31b, the common terminal31ais disconnected from the terminal31c, and the terminal33ais connected to the terminal33c.

In this state, band-A transmit signals are transferred through the transmit path that includes the radio-frequency input terminal111, the power amplifier10, the switch31, the filter41, the switch33A, the antenna connection terminal101, and the antenna2A. In mode A, under certain conditions such as antenna sensitivity and other factors, the terminals33band33cmay be connected, allowing band-A transmit signals to be output from the antenna2B.

Assuming mode B is activated, the common terminal31ais connected to the terminal31c, the common terminal31ais disconnected from the terminal31b, the common terminal32ais connected to the terminal32b, and the terminal33ais connected to the terminal33d.

In this state, band-B transmit signals are transferred through the transmit path that includes the radio-frequency input terminal111, the power amplifier10, the switch31, the switch32, the filter43, the switch33A, the antenna connection terminal101, and the antenna2A. In mode B, under certain conditions such as antenna sensitivity and other factors, the terminals33band33dmay be connected, allowing band-B transmit signals to be output from the antenna2B.

Assuming mode C is activated, the common terminal31ais connected to the terminal31b, the common terminal31ais disconnected from the terminal31c, the common terminal34ais connected to the terminal34b, the common terminal34ais disconnected from the terminal34c, the common terminal32ais connected to the terminal32c, the terminal33ais connected to the terminal33c, and the terminal33bis connected to the terminal33d.

In this state, band-A transmit signals are transferred through the transmit path that includes the radio-frequency input terminal111, the power amplifier10, the switch31, the filter41, the switch33A, the antenna connection terminal101, and the antenna2A. Band-B transmit signals are transferred through the transmit path that includes the radio-frequency input terminal112, the power amplifier20, the switch34, the switch32, the filter43, the switch33A, the antenna connection terminal102, and the antenna2B. In mode C, under certain conditions such as antenna sensitivity and other factors, the terminals33band33cmay be connected, allowing band-A transmit signals to be output from the antenna2B, while the terminals33aand33dmay be connected, allowing band-B transmit signals to be output from the antenna2A.

In the connection configurations of the radio-frequency circuit1A, assuming signals in the band A out of the band A and the band B are exclusively transmitted, the power amplifier10and the filter41are coupled through control of the switch31. Assuming signals in the band B out of the band A and the band B are exclusively transmitted, the power amplifier10and the filter43are coupled through control of the switches31and32. Assuming signals in the band A and signals in the band B are simultaneously transmitted, the power amplifier10and the filter41are coupled and the power amplifier20and the filter43are coupled through control of the switches31,32, and34. As described above, because the same power amplifier10is used for both exclusively transmitting band-A signals and exclusively transmitting band-B signals, the power efficiency assuming exclusively transmitting band-A signals and the power efficiency assuming exclusively transmitting band-B signals can be optimized in the same manner.

Next, the case in which mode D is activated will be described with reference toFIG.5.FIG.5illustrates the circuit state of the radio-frequency circuit1A according to the modification assuming 2G signals are transmitted.

As illustrated inFIG.5, assuming mode D is activated, the common terminal34ais connected to the terminal34c, the common terminal34ais disconnected from the terminal34b, and the terminal33bis connected to the terminal33e.

In this state, 2G transmit signals are transferred through the transmit path that includes the radio-frequency input terminal112, the power amplifier20, the switch34, the switch33A, the antenna connection terminal102, and the antenna2B. In mode D, under certain conditions such as antenna sensitivity and other factors, the terminals33aand33emay be connected, allowing 2G transmit signals to be output from the antenna2A.

With the connection configuration of the radio-frequency circuit1A illustrated inFIG.5, by coupling the power amplifier20and the antenna connection terminal101or102via the switch34without involving the switch32and the filter43, 2G signals can be transmitted using the signal path that includes the power amplifier20and the antenna connection terminal101or102.

As described, because the power amplifier20is used to amplify 2G signals, which require higher-power transmission compared to 4G and 5G signals, the power amplifier10does not need to support high-power operation. The power efficiency of the power amplifier10, which is used for exclusive transmission of 4G or 5G band-A signals and for exclusive transmission of 4G or 5G band-B signals, can thus be optimized rather than reduced. Furthermore, because high-power 2G transmit signals can be transferred without involving the switch32and the filter43, 2G signals can be transmitted with low loss.

As described above, the radio-frequency circuit1according to the present embodiment includes the power amplifier10configured to output the first maximum transmit power, the power amplifier20configured to output the second maximum transmit power that is higher than the first maximum transmit power, the filter41having a pass band that includes the band A, the filter43having a pass band that includes the band B different from the band A, the switch31coupled between the power amplifier10and the filter41and between the power amplifier10and the filter43, and the switch32coupled between the switch31and the filter43and between the power amplifier20and the filter43.

With this configuration, assuming signals in the band A are exclusively transmitted, the power amplifier10and the filter41can be coupled through control of the switch31. Assuming signals in the band B are exclusively transmitted, the power amplifier10and the filter43can be coupled through control of the switches31and32. Assuming signals in the band A and signals in the band B are simultaneously transmitted, the power amplifier10and the filter41can be coupled and the power amplifier20and the filter43can be coupled through control of the switches31and32. As described above, because the same power amplifier10is used for both exclusively transmitting band-A signals and exclusively transmitting band-B signals, the power efficiency assuming exclusively transmitting band-A signals and the power efficiency assuming exclusively transmitting band-B signals can be optimized in the same manner. As such, the power efficiency assuming amplifying radio-frequency signals in different frequency bands can be optimized.

The power amplifier20can handle higher power than the power amplifier10. However, the circuit size can increase and the power efficiency can degrade. Considering this, the power amplifier10is used without using the power amplifier20to exclusively transmit band-A or band-B signals, which improves the power efficiency of the radio-frequency circuit1.

In an example, in the radio-frequency circuit1, the switches31and32may be configured to alternate between coupling the power amplifier10to the filter41and coupling the power amplifier10to the filter43in a configuration in which the power amplifier10operates, and the switches31and32may be configured to couple the power amplifier10to the filter41and to couple the power amplifier20to the filter43in a configuration in which the power amplifiers10and20simultaneously operate.

These configurations enable switching among exclusive transmission of band-A signal, exclusive transmission of band-B signal, and simultaneous transmission of band-A and band-B signals.

In an example, in the radio-frequency circuit1, the switch31may have the common terminal31aand the terminals31band31c, and the switch32may have the common terminal32aand the terminals32band32c. The common terminal31amay be coupled to the output end of the power amplifier10. The terminal31bmay be coupled to the input end of the filter41. The terminal31cmay be coupled to the terminal32b. The terminal32cmay be coupled to the output end of the power amplifier20. The common terminal32amay be coupled to the input end of the filter43.

In an example, in the radio-frequency circuit1, the switches31and32may be configured to alternate between coupling the common terminal31ato the terminal31b, and coupling the common terminal31ato the terminal31cwhile coupling the common terminal32ato the terminal32b, in a configuration in which the power amplifier10operates, the switches31and32may be configured to couple the common terminal31ato the terminal31band couple the common terminal32ato the terminal32cin a configuration in which the power amplifiers10and20simultaneously operate.

These configurations enable switching among exclusive transmission of band-A signal, exclusive transmission of band-B signal, and simultaneous transmission of band-A and band-B signals based on switch configurations, thereby simplifying the radio-frequency circuit1.

In an example, in radio-frequency circuit1, the power amplifier10may be configured to amplify signals in the band A and the band B, and the power amplifier20may be configured to amplify signals in the band B.

In an example, the radio-frequency circuit1A according to the modification may include the power amplifiers10and20, the filter41having a pass band that includes the band A, the filter43having a pass band that includes the band B, the switch31coupled between the power amplifier10and the filters41and43, configured to alternate between coupling the power amplifier10to the filter41and coupling the power amplifier10to the filter43, the switch32coupled between the switch31and the power amplifier20, and the filter43, configured to alternate between coupling the power amplifier10to the filter43and coupling the power amplifier20to the filter43, the antenna connection terminal101coupled to one of the filters41and43, the antenna connection terminal102coupled to the other of the filters41and43, and the switch34coupled between the power amplifier20, and the switch32and the antenna connection terminals101and102, configured to alternate between coupling the power amplifier20to the filter43and coupling the power amplifier20to the antenna connection terminal101or102.

In an example, the radio-frequency circuit1A may be configured such that the power amplifier20is coupled to the antenna connection terminal101or102without involving the switch32and the filter43.

With this configuration, assuming the power amplifier20is used to amplify 2G signals, which require higher-power transmission compared to 4G and 5G signals, the power amplifier10does not need to support high-power operation. The power efficiency of the power amplifier10, which is used for exclusive transmission of 4G or 5G band-A signals and for exclusive transmission of 4G or 5G band-B signals, can thus be optimized rather than reduced. Furthermore, because high-power 2G transmit signals can be transferred without involving the switch32and the filter43, 2G signals can be transmitted with low loss.

In an example, in the radio-frequency circuit1A, the power amplifier10may be configured to amplify 4G-LTE signals and 5G-NR signals, and the power amplifier20may be configured to amplify 2G signals, 4G-LTE signals, and 5G-NR signals.

In an example, in the radio-frequency circuit1A, the switch34may have the common terminal34aand the terminals34band34c. The common terminal34amay be coupled to the output end of the power amplifier20, the terminal34bmay be coupled to the switch32, and the terminal34cmay be coupled to the antenna connection terminal101or102.

In an example, in the radio-frequency circuit1A, the switch34may be configured such that the common terminal34aand the terminal34care coupled.

With this configuration, switching between transmitting 2G signals and transmitting 4G or 5G signals can be achieved based om switch configurations, thereby simplifying the radio-frequency circuit1A.

In an example, the radio-frequency circuit1A may further include the switch33A coupled between the antenna connection terminals101and102, and the filters41and43and the switch34, configured to couple the antenna connection terminal101to any one of the filters41,43, and the switch34and to couple the antenna connection terminal102to any one of the filters41,43, and the switch34.

With this configuration, the antenna2A or2B can be selected to transmit or receive band-A signals, to transmit or receive band-B signals, or to transmit 2G signals, depending on conditions such as antenna sensitivity and other factors.

In an example, in the radio-frequency circuits1and1A, each of the band A and the band B may be 4G-LTE Band B8, 5G-NR Band n8, 4G-LTE Band B20, 5G-NR Band n20, 4G-LTE Band B26, 5G-NR Band n26, 4G-LTE Band B28, or 5G-NR Band n28.

The communication device4according to the present embodiment includes the RFIC3configured to process radio-frequency signals and the radio-frequency circuit1configured to transfer radio-frequency signals between the RFIC3and the antennas2A and2B.

This configuration enables the communication device4to achieve the same effects as the radio-frequency circuit1.

Other Embodiments

The radio-frequency circuit and the communication device according to the present disclosure have been described by using the embodiment and modification, but the radio-frequency circuit and the communication device according to the present disclosure are not limited to the embodiment and modification. The present disclosure also embraces other embodiments implemented as any combination of the constituent elements of the embodiment and modification, other modifications obtained by making various modifications to the embodiment that occur to those skilled in the art without departing from the scope of the present disclosure, and various hardware devices including the radio-frequency circuit or communication device according to the present disclosure.

For example, in the circuit configurations of the radio-frequency circuit and communication device according to the embodiment and modification described above, other circuit elements and wire lines may be inserted in the paths connecting the circuit elements and signal paths that are illustrated in the drawings.

5G-NR or 4G-LTE bands are used in the embodiment and modification described above. However, other communication bands for different radio access technologies may be used in addition to or instead of 5G-NR or 4G-LTE. For example, communication bands for wireless local area networks may be used. For example, millimeter-wave bands at 7 gigahertz or higher may be used. In this case, the radio-frequency circuit1, the antennas2A and2B, and the RFIC3form a millimeter-wave antenna circuit, and, for example, distributed constant filter may be used as filters.

The following describes the features of the amplifier circuit and the communication device explained based on the embodiment.

A radio-frequency circuit comprising:a first power amplifier and a second power amplifier;a first filter having a pass band that includes a first band;a second filter having a pass band that includes a second band;a first switch coupled between the first power amplifier, and the first filter and the second filter; anda second switch coupled between the first switch and the second power amplifier, and the second filter.
<2>

The radio-frequency circuit according to <1>, whereinthe first switch and the second switch are configured toalternate among (1) coupling the first power amplifier to the first filter, (2) coupling the first power amplifier to the second filter, and (3) coupling the first power amplifier to the first filter and coupling the second power amplifier to the second filter.
<3>

The radio-frequency circuit according to <1> or <2>, whereinthe first switch has a first common terminal, a first terminal, and a second terminal,the second switch has a second common terminal, a third terminal, and a fourth terminal, andthe first common terminal is coupled to an output end of the first power amplifier, the first terminal is coupled to an input end of the first filter, the second terminal is coupled to the third terminal, the fourth terminal is coupled to an output end of the second power amplifier, and the second common terminal is coupled to an input end of the second filter.
<4>

The radio-frequency circuit according to <3>, whereinthe first switch and the second switch are configured toalternate among (1) coupling the first common terminal to the first terminal, (2) coupling the first common terminal to the second terminal while coupling the second common terminal to the third terminal, and (3) coupling the first common terminal to the first terminal and coupling the second common terminal to the fourth terminal.
<5>

The radio-frequency circuit according to any of <1> to <4>, whereinthe first power amplifier is configured to amplify a signal in the first band and a signal in the second band, andthe second power amplifier is configured to amplify a signal in the second band.
<6>

The radio-frequency circuit according to any of <1> to <5>, whereinthe first power amplifier is configured to output a first maximum transmit power, andthe second power amplifier is configured to output a second maximum transmit power that is higher than the first maximum transmit power.
<7>

The radio-frequency circuit according to any of <1> to <6>, further comprising:a first antenna connection terminal coupled to one of the first filter and the second filter;a second antenna connection terminal coupled to another of the first filter and the second filter; anda third switch coupled between the second power amplifier, and the second switch, the first antenna connection terminal, and the second antenna connection terminal, the third switch being configured to alternate between coupling the second power amplifier to the second filter and coupling the second power amplifier to the first antenna connection terminal or the second antenna connection terminal.
<8>

The radio-frequency circuit according to <7>, configured such thatthe second power amplifier is coupled to the first antenna connection terminal or the second antenna connection terminal without involving the second switch and the second filter.
<9>

The radio-frequency circuit according to <7> or <8>, whereinthe first power amplifier is configured to amplify a 4G Long Term Evolution (LTE) signal and a 5th Generation (5G) New Radio (NR) signal, andthe second power amplifier is configured to amplify a 2G signal, a 4G-LTE signal, and a 5G-NR signal.
<10>

The radio-frequency circuit according to any of <7> to <9>, whereinthe third switch has a third common terminal, a fifth terminal, and a sixth terminal, andthe third common terminal is coupled to an output end of the second power amplifier, the fifth terminal is coupled to the second switch, and the sixth terminal is coupled to the first antenna connection terminal or the second antenna connection terminal.
<11>

The radio-frequency circuit according to <10>, whereinthe third switch is configured such that the third common terminal is coupled to the sixth terminal.
<12>

The radio-frequency circuit according to any of <7> to <11>, further comprising:a fourth switch coupled between the first antenna connection terminal and the second antenna connection terminal, and the first filter, the second filter, and the third switch, the fourth switch being configured to couple the first antenna connection terminal to any one of the first filter, the second filter, and the third switch, and to couple the second antenna connection terminal to any one of the first filter, the second filter, and the third switch.
<13>

The radio-frequency circuit according to any of <1> to <12>, whereineach of the first band and the second band is 4G-LTE Band B8, 5G-NR Band n8, 4G-LTE Band B20, 5G-NR Band n20, 4G-LTE Band B26, 5G-NR Band n26, 4G-LTE Band B28, or 5G-NR Band n28.
<14>

A communication device comprising:a signal processing circuit configured to process a radio-frequency signal; andthe radio-frequency circuit according to any of <1> to <13>, the radio-frequency circuit being configured to transfer the radio-frequency signal between the signal processing circuit and an antenna.

INDUSTRIAL APPLICABILITY

The present disclosure can be used as a radio-frequency circuit provided at the front-end, in a wide variety of communication hardware, such as mobile phones.

REFERENCE SIGNS LIST