Amplification circuit

Abstract

Provided is an amplifier circuit capable of suppressing harmonics with high precision. An amplifier circuit (1) is provided with: a power amplifier circuit (20) including a power amplifier (21); a power amplifier circuit (30) including a power amplifier (31), the phase of the fundamental wave at the output of the power amplifier (31) being delayed by 90 DEG with respect to the power amplifier (21); and an in-phase combining circuit (40) configured so as to combine the fundamental wave of the first output signal output from the power amplifier circuit (20) of the inverse E type and the fundamental wave of the second output signal output from the power amplifier circuit (30) of the E type, the in-phase combining circuit (40) being configured so as to combine the fundamental wave of the first output signal output from the power amplifier circuit (20) and the fundamental wave of the second output signal output from the power amplifier circuit (30).

Description

Technical Field

[0001] The present invention relates to an amplifier circuit. Background Art

[0002] Patent Document 1 discloses a power amplifier comprising: a first amplifying unit and a second amplifying unit, the first and second amplifying units forming a balanced amplifier that performs Class F operation; and a filter connected between the output of the first amplifying unit and the output of the second amplifying unit to pass the second harmonic. By canceling the second harmonic at the output of the first and second amplifying units, the power efficiency of the fundamental wave can be improved.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 63-153904 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] However, in the power amplifier disclosed in Patent Document 1, the amplification unit performs Class F operation, so the frequency range of the even-order harmonics that cause the load impedance to be short-circuited is narrow, making it difficult to accurately cancel the second harmonics within the entire frequency band specified by, for example, 3GPP (registered trademark: 3rd Generation Partnership Project) to ensure high power efficiency.

[0008] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an amplifier circuit capable of suppressing harmonics with high accuracy.

[0009] Solutions for solving problems

[0010] In order to achieve the above-mentioned purpose, an amplifier circuit involved in one embodiment of the present invention comprises: a first power amplifier circuit, which includes a first power amplifier; a second power amplifier circuit, which includes a second power amplifier whose fundamental wave at the output end lags behind the phase of the first power amplifier by 90°; and a synthesis circuit, which is configured to synthesize the fundamental wave of the first output signal output from the first power amplifier circuit and the fundamental wave of the second output signal output from the second power amplifier circuit, wherein the first power amplifier circuit is an inverse E class and the second power amplifier circuit is an E class.

[0011] In addition, an amplifier circuit involved in one embodiment of the present invention includes: a demultiplexer, which has a first input terminal, a first output terminal and a second output terminal, and is configured to demultiplex a fundamental wave signal of a transmission frequency band of a first frequency band input to the first input terminal, output a first signal from the first output terminal, and output a second signal with a phase of -90° relative to the first signal from the second output terminal; a first power amplifier, which has a fourth input terminal and a fourth output terminal, and the fourth input terminal is connected to the first output terminal; a second power amplifier, which has a fifth input terminal and a fifth output terminal, and the fifth input terminal is connected to the second output terminal; and a synthesizer, which has a second input terminal, a third input terminal and a third output terminal, and is configured to output a third output signal from the third output terminal, the third output signal being the result of inputting the first output signal output from the first power amplifier from the second input terminal and synthesizing the first output signal output from the first power amplifier from the second input terminal. A signal obtained by in-phase synthesis after the second output signal output by the two power amplifiers is input from the third input terminal; a first phase shifting circuit, which is connected between the first power amplifier and the synthesizer and is configured to phase-shift the fundamental wave and harmonics of the first frequency band; a second phase shifting circuit, which is connected between the second power amplifier and the synthesizer and is configured to phase-shift the fundamental wave and harmonics of the first frequency band in such a manner that the passing phase of the fundamental wave relative to the first phase shifting circuit is +90°; a first harmonic phase shifting circuit, which is connected to the path connecting the fourth output terminal and the second input terminal and is configured to phase-shift the harmonics; and a second harmonic phase shifting circuit, which is connected to the path connecting the fifth output terminal and the third input terminal and is configured to phase-shift the harmonics, wherein a phase shift difference obtained by subtracting the phase of the harmonic at the third input terminal from the phase of the harmonic at the second input terminal is greater than 90°.

[0012] Effects of the Invention

[0013] According to the present invention, it is possible to provide an amplifier circuit capable of suppressing harmonics with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a circuit configuration diagram of an amplifier circuit according to an embodiment.

[0015] Figure 2 1 is a Smith chart showing the harmonic impedances of the first power amplifier circuit and the second power amplifier circuit according to the embodiment.

[0016] Figure 3 is a circuit configuration diagram of an amplifier circuit according to a comparative example.

[0017] Figure 4A 1 is a diagram showing a circuit configuration example of a first harmonic phase shift circuit according to an embodiment.

[0018] Figure 4B 1 is a diagram showing a circuit configuration example of a second harmonic phase shift circuit according to an embodiment.

[0019] Figure 4C 1 is a diagram showing a circuit configuration example of a first phase shift circuit according to an embodiment.

[0020] Figure 4D 1 is a diagram showing a circuit configuration example of a second phase shift circuit according to the embodiment.

[0021] Figure 5 It is a circuit configuration diagram of an amplifier circuit according to Modification 1 of the embodiment.

[0022] Figure 6 It is a circuit configuration diagram of an amplifier circuit according to Modification 2 of the embodiment.

[0023] Figure 7 It is a circuit configuration diagram of an amplifier circuit according to Modification 3 of the embodiment.

[0024] Figure 8A It is a circuit configuration diagram of an amplifier circuit according to Modification 4 of the embodiment.

[0025] Figure 8B It is a circuit configuration diagram of an amplifier circuit according to Modification 5 of the embodiment.

[0026] Figure 9 It is a circuit configuration diagram of an amplifier circuit according to a sixth modification of the embodiment. DETAILED DESCRIPTION

[0027] The following drawings illustrate embodiments of the present disclosure in detail. The embodiments described below are general or specific examples. The values, shapes, materials, structural elements, configurations of structural elements, and connection methods shown in the following embodiments are examples and are not intended to limit the present invention.

[0028] In addition, each figure is a schematic diagram that has been appropriately emphasized, omitted, or adjusted in ratio to illustrate the present invention, and is not necessarily strictly illustrated, and may differ from the actual shape, positional relationship, and ratio. In each figure, substantially the same structure is marked with the same reference numeral, and repeated descriptions may be omitted or simplified.

[0029] In addition, in the present disclosure, terms such as parallel and perpendicular that indicate the relationship between elements, terms such as rectangular that indicate the shape of elements, and numerical ranges do not have strict meanings, but also include substantially equivalent ranges, for example, differences of a few percent.

[0030] In the circuit structure of this disclosure, "connected" includes not only direct connection via connection terminals and / or wiring conductors, but also electrical connection via other circuit elements. "Connected between A and B" means connection between A and B and both A and B.

[0031] In the present disclosure, a “path” refers to a transmission line composed of wiring for propagating high-frequency signals, electrodes directly connected to the wiring, and terminals directly connected to the wiring or the electrodes.

[0032] In addition, in the present disclosure, “component A is arranged in series on path B” means that both the signal input end and the signal output end of component A are connected to wiring, electrodes, or terminals constituting path B.

[0033] In the present invention, "terminal," "input end," and "output end" refer to the point where a conductor within an element terminates. Furthermore, when the impedance of the conductor between elements is sufficiently low, a terminal is to be interpreted as any point on the conductor between elements or as the entire conductor, rather than as a single point.

[0034] In addition, terms such as "parallel" and "perpendicular" that indicate the relationship between elements, terms such as "rectangular" that indicate the shape of elements, and numerical ranges do not have strict meanings, but also include substantially equivalent ranges, for example, also include errors of several percent.

[0035] The "passband" of a filter is the portion of the spectrum transmitted through the filter, defined as the frequency band where the output power does not decrease by more than 3dB from the maximum output power. Therefore, the high-frequency end and low-frequency end of the passband of a bandpass filter are defined as the higher and lower frequencies of the two points where the output power decreases by 3dB from the maximum output power.

[0036] "Transmission band" refers to the frequency band used for transmission in a communication device. "Reception band" refers to the frequency band used for reception in a communication device. For example, in frequency division duplex (FDD), different frequency bands are used as the transmission band and reception band, and in time division duplex (TDD), the same frequency band is used as the transmission band and reception band. In particular, in the case where the communication device is installed in a user terminal (UE: User Equipment) of a cellular network, if it is FDD, the uplink operation band (uplink operation band) is used as the transmission band, and the downlink operation band (downlink operation band) is used as the reception band. Conversely, in the case where the communication device is installed in a base station (BS: Base Station) of a cellular network, the downlink frequency band is used as the transmission band, and the uplink frequency band is used as the reception band.

[0037] The "pass phase" of a high-frequency signal between two terminals is obtained by contacting the two terminals with a measurement RF probe and measuring the pass characteristics using a network analyzer (S21). The "reflection phase" of a high-frequency signal at a single terminal is obtained by contacting the terminal with a measurement RF probe and measuring the pass characteristics using a network analyzer (S11).

[0038] In the present invention, the numerical values of the passing phase, the reflection phase, and the reflection phase difference do not have strict meanings, but include substantially equivalent ranges, for example, also including a difference of about 30%.

[0039] (Implementation Method)

[0040] [1 Circuit structure of amplifier circuit 1]

[0041] The circuit structure of the amplifier circuit 1 will be described. Figure 1 1 is a circuit diagram of an amplifier circuit 1 according to an embodiment. As shown in the diagram, the amplifier circuit 1 includes a branching filter 10 , power amplifier circuits 20 and 30 , and an in-phase combining circuit 40 .

[0042] The splitter 10 has an input terminal 101 (first input terminal), an output terminal 102 (first output terminal), and an output terminal 103 (second output terminal). It is configured to split a fundamental wave signal in a first frequency band transmission band input to input terminal 101, outputting a first signal from output terminal 102 and a second signal having a phase of -90° (lagging 90°) relative to the first signal from output terminal 103. In this embodiment, the first signal has a phase of +45° relative to the fundamental wave signal, and the second signal has a phase of -45° relative to the fundamental wave signal. The amplifier circuit 1 may also not include the splitter 10.

[0043] In addition, each of the input terminal and the output terminal in this embodiment may be a metal conductor such as a metal electrode or a metal bump, or may be a point (node) on a metal wiring.

[0044] The power amplifier circuit 20 is an example of a first power amplifier circuit, and includes a power amplifier 21. The power amplifier 21 includes an amplifying transistor, and has a fourth input terminal and a fourth output terminal. The fourth input terminal is connected to the output terminal 102.

[0045] The power amplifier circuit 30 is an example of a second power amplifier circuit, and includes a power amplifier 31 . The power amplifier 31 includes an amplifying transistor, and has a fifth input terminal and a fifth output terminal. The fifth input terminal is connected to the output terminal 103 .

[0046] Power amplifier 21 amplifies the first signal output from splitter 10, and power amplifier 31 amplifies the second signal output from splitter 10. Therefore, the phase of the fundamental wave at the fifth output terminal of power amplifier 31 lags by 90° relative to the phase of the fundamental wave at the fourth output terminal of power amplifier 21. In this embodiment, the phase of the fundamental wave at the fourth output terminal of power amplifier 21 is +45° relative to the fundamental wave signal input to input terminal 101 of splitter 10, and the phase of the fundamental wave at the fifth output terminal of power amplifier 31 is -45° relative to the fundamental wave signal.

[0047] Furthermore, the phase of the fundamental wave at the fifth output terminal of the power amplifier 31 lags by 90° relative to the phase of the fundamental wave at the fourth output terminal of the power amplifier 21. Therefore, the phase of the second harmonic at the fifth output terminal of the power amplifier 31 lags by 180° relative to the phase of the second harmonic at the fourth output terminal of the power amplifier 21. In this embodiment, the phase of the second harmonic at the fourth output terminal of the power amplifier 21 is +90°, and the phase of the second harmonic at the fifth output terminal of the power amplifier 31 is -90°.

[0048] In addition to the power amplifier 21, the power amplifier circuit 20 also includes a harmonic phase shift circuit 22. Harmonic phase shift circuit 22 is an example of a first harmonic phase shift circuit. It is connected to the path connecting the fourth output terminal of the power amplifier 21 and the in-phase synthesizer 41, and performs phase shifting on the harmonics of the first frequency band. Furthermore, harmonic phase shift circuit 22 performs almost no phase shifting on the fundamental wave of the first frequency band. In this embodiment, the second harmonic of harmonic phase shift circuit 22 passes through a phase of +45°.

[0049] In addition to the power amplifier 31, the power amplifier circuit 30 also includes a harmonic phase shift circuit 32. Harmonic phase shift circuit 32 is an example of a second harmonic phase shift circuit. It is connected to the path connecting the fifth output terminal of the power amplifier 31 and the in-phase synthesizer 41, and performs phase shifting on the harmonics of the first frequency band. Furthermore, harmonic phase shift circuit 32 performs almost no phase shifting on the fundamental wave of the first frequency band. In this embodiment, the second harmonic of harmonic phase shift circuit 32 passes through a phase of -45°.

[0050] The amplifier transistors included in each of power amplifiers 21 and 31 are, for example, bipolar transistors such as heterojunction bipolar transistors (HBTs) or field-effect transistors such as MOSFETs (metal-oxide-semiconductor field-effect transistors). Furthermore, if the amplifier transistors are bipolar transistors, the fourth input terminal of power amplifier 21 and the fifth input terminal of power amplifier 31 are, for example, the base terminals of the bipolar transistors, and the fourth output terminal of power amplifier 21 and the fifth output terminal of power amplifier 31 are, for example, the collector terminals of the bipolar transistors. Furthermore, if the amplifier transistors are field-effect transistors, the fourth input terminal of power amplifier 21 and the fifth input terminal of power amplifier 31 are, for example, the gate terminals of the field-effect transistors, and the fourth output terminal of power amplifier 21 and the fifth output terminal of power amplifier 31 are, for example, the drain terminals of the field-effect transistors.

[0051] The in-phase synthesizing circuit 40 is an example of a synthesizing circuit, and is configured to perform in-phase synthesis of the first output signal from the power amplifier circuit 20 and the second output signal from the power amplifier circuit 30. The in-phase synthesizing circuit 40 includes an in-phase synthesizer 41 and phase shift circuits 23 and 33.

[0052] The in-phase synthesizer 41 is an example of a synthesizer, having an input terminal 402 (second input terminal), an input terminal 403 (third input terminal) and an output terminal 401 (third output terminal), and outputting a third output signal generated by in-phase synthesis of the first output signal of the power amplifier circuit 20 input from the input terminal 402 and the second output signal of the power amplifier circuit 30 input from the input terminal 403 from the output terminal 401.

[0053] Phase shift circuit 23 is an example of a first phase shift circuit. It is connected between power amplifier circuit 20 and in-phase synthesizer 41 and is configured to phase shift the fundamental wave and harmonics in the first frequency band. In this embodiment, the fundamental wave of phase shift circuit 23 passes through a phase of -45°, and the second harmonic passes through a phase of -45°.

[0054] Phase shift circuit 33 is an example of a second phase shift circuit. It is connected between power amplifier circuit 30 and in-phase synthesizer 41 and is configured to phase-shift the fundamental wave and harmonics in the first frequency band so that the passing phase of the fundamental wave in the first frequency band relative to phase shift circuit 23 is +90°. In this embodiment, the passing phase of the fundamental wave in phase shift circuit 33 is +45°, and the passing phase of the second harmonic is +45°.

[0055] Alternatively, the second harmonic passing phase of the harmonic phase shift circuit 22 may be +X° (X>0), and the second harmonic passing phase of the phase shift circuit 23 may be -X° (X>0). In other words, the second harmonic passing phase of the circuit obtained by combining the harmonic phase shift circuit 22 and the phase shift circuit 23 may be 0°.

[0056] Alternatively, the second harmonic passing phase of the harmonic phase shift circuit 32 may be -Y° (Y>0), and the second harmonic passing phase of the phase shift circuit 33 may be +Y° (Y>0). In other words, the second harmonic passing phase of the circuit obtained by combining the harmonic phase shift circuit 32 and the phase shift circuit 33 may be 0°.

[0057] Figure 22 is a Smith chart showing the harmonic impedances of the power amplifier circuits 20 and 30 according to the embodiment. As shown in the chart, in the amplifier circuit 1 according to the embodiment, the second harmonic of the harmonic phase shift circuit 22 has a pass-through phase of +45° (+X°). Therefore, the impedance of the second harmonic when viewed from the connection point (node n1) between the fourth output terminal of the power amplifier 21 and the harmonic phase shift circuit 22 toward the in-phase synthesizer circuit 40 is in the inductive reactance region (inductive impedance). On the other hand, the second harmonic of the harmonic phase shift circuit 32 has a pass-through phase of -45° (-Y°). Therefore, the impedance of the second harmonic when viewed from the connection point (node n2) between the fifth output terminal of the power amplifier 31 and the harmonic phase shift circuit 32 toward the in-phase synthesizer circuit 40 is in the capacitive reactance region (capacitive impedance).

[0058] That is, in the amplifier circuit 1 according to this embodiment, the power amplifier circuit 20 is an inverse class E amplifier with an inductive load impedance for the second harmonic, and the power amplifier circuit 30 is a class E amplifier with a capacitive load impedance for the second harmonic.

[0059] In other words, the phase difference between the impedance with respect to the second harmonic at the node n1 of the power amplifier circuit 20 and the impedance with respect to the second harmonic at the node n2 of the power amplifier circuit 30 is 90° (or X+Y°).

[0060] Figure 3 is a circuit diagram of an amplifier circuit 500 according to a comparative example. As shown in this diagram, amplifier circuit 500 includes a demultiplexer 10, power amplifier circuits 520 and 530, phase shift circuits 23 and 33, and an in-phase combiner 41. Compared to amplifier circuit 1 according to the embodiment, amplifier circuit 500 according to the comparative example differs in the configuration of power amplifier circuits 520 and 530. Below, description of the amplifier circuit 500 according to the comparative example, which shares the same configuration as amplifier circuit 1 according to the embodiment, will be omitted, and the description will focus on the differing configurations.

[0061] The power amplifier circuit 520 includes the power amplifier 21. In this comparative example, the phase of the fundamental wave at the fourth output terminal (node n1) of the power amplifier 21 is +45° relative to the fundamental wave signal input to the input terminal 101 of the splitter 10, and the phase of the second harmonic is +90°.

[0062] The power amplifier circuit 530 includes the power amplifier 31. In this comparative example, the phase of the fundamental wave at the fifth output terminal (node n2) of the power amplifier 31 is -45° relative to the fundamental wave signal input to the input terminal 101 of the splitter 10, and the phase of the second harmonic is -90°.

[0063] According to the above-described configuration of amplifier circuit 500 according to the comparative example, the phase of the fundamental wave of the first output signal at node n1 outputted from power amplifier 21 is +45°, and after passing through phase shift circuit 23, the phase of the fundamental wave at input terminal 402 becomes 0°. Furthermore, the phase of the fundamental wave of the second output signal at node n2 outputted from power amplifier 31 is -45°, and after passing through phase shift circuit 33, the phase of the fundamental wave at input terminal 403 becomes 0°. Thus, the fundamental wave signal in the first frequency band is in-phase combined in the in-phase combiner 41 and outputted from output terminal 401 as the third output signal. Consequently, amplifier circuit 500 operates as a balanced amplifier with strong resistance to load fluctuations.

[0064] On the other hand, the second harmonic of the first output signal at node n1 output from power amplifier 21 has a phase of +90°. After passing through phase shift circuit 23, the phase of the second harmonic at input terminal 402 becomes +45°. Furthermore, the second harmonic of the second output signal at node n2 output from power amplifier 31 has a phase of -90°. After passing through phase shift circuit 33, the phase of the second harmonic at input terminal 403 becomes -45°. Consequently, the second harmonic in the first frequency band has a 90° phase difference between input terminals 402 and 403 of in-phase synthesizer 41 and is not suppressed. Consequently, amplifier circuit 500 fails to improve the quality and power efficiency of the transmitted signal.

[0065] In contrast, according to the above-described configuration of amplifier circuit 1 in accordance with this embodiment, the fundamental wave of the first output signal at node n1 outputted from power amplifier 21 has a phase of +45°, and after passing through phase shift circuit 23, the phase of the fundamental wave at input terminal 402 becomes 0°. Furthermore, the fundamental wave of the second output signal at node n2 outputted from power amplifier 31 has a phase of -45°, and after passing through phase shift circuit 33, the phase of the fundamental wave at input terminal 403 becomes 0°. Consequently, the fundamental wave signals in the first frequency band are in-phase combined in the in-phase combiner 41 and outputted from output terminal 401 as the third output signal. Consequently, amplifier circuit 1 operates as a balanced amplifier with strong resistance to load fluctuations.

[0066] On the other hand, the second harmonic of the first output signal at node n1 output from power amplifier 21 has a phase of +135° (or +90+X°). After passing through phase shift circuit 23, the phase of the second harmonic at input terminal 402 becomes +90°. Furthermore, the second harmonic of the second output signal at node n2 output from power amplifier 31 has a phase of -135° (or -90-Y°). After passing through phase shift circuit 33, the phase of the second harmonic at input terminal 403 becomes -90°. Consequently, the second harmonic in the first frequency band has a phase difference of 180° (in an anti-phase relationship) between input terminals 402 and 403 of in-phase synthesizer 41, thereby canceling out. Thus, amplifier circuit 1 suppresses the second harmonic, thereby improving the quality of the transmitted signal and power efficiency.

[0067] Furthermore, each of the power amplifier circuits 20 and 30 according to the present embodiment is not a Class F amplifier in which the load impedance of the even-order harmonics is short-circuited and the load impedance of the odd-order harmonics is open-circuited. Instead, the load impedance of the second harmonic can be divided into inductive and capacitive components. Therefore, it is possible to precisely cancel the second harmonic over the entire frequency band of a wideband frequency band specified by 3GPP, for example, to ensure high transmission quality and power efficiency.

[0068] Furthermore, in the amplifier circuit 1 according to the present embodiment, a first phase shift difference (90° or (+X+Y°)) obtained by subtracting the passing phase (-45° or (-Y°)) of the harmonics of the harmonic phase shift circuit 32 from the passing phase (+45° or (+X°)) of the harmonics of the harmonic phase shift circuit 22 is equal to a second phase shift difference (90° (or +Y+X°)) obtained by subtracting the passing phase (-45° (or -X°)) of the harmonics of the phase shift circuit 23 from the passing phase (+45° (or +Y°)) of the harmonics of the phase shift circuit 33.

[0069] As a result, the second harmonic of the first frequency band is offset by a 180° phase difference (opposite phase relationship) between input terminals 402 and 403 of the in-phase synthesizer 41. Therefore, the amplifier circuit 1 suppresses the second harmonic, thereby improving the quality and power efficiency of the transmitted signal.

[0070] Furthermore, the second harmonic of the first frequency band only needs to have a phase difference of 180° between the input terminals 402 and 403 of the in-phase synthesizer 41 , so the second harmonic can be canceled with high accuracy over the entire wide frequency band to ensure high transmission quality and power efficiency.

[0071] In the amplifier circuit 1 according to this embodiment, the phase difference obtained by subtracting the phase of the second harmonic of the first frequency band at the input terminal 403 from the phase of the second harmonic of the first frequency band at the input terminal 402 may be greater than 90°.

[0072] This makes it possible to suppress the second harmonic in the first frequency band compared to the amplifier circuit 500 according to the comparative example, thereby improving the quality of the transmitted signal and the power efficiency compared to conventional balanced amplifiers without an additional harmonic phase shift circuit.

[0073] Next, specific circuit configurations of the harmonic phase shift circuits 22 and 32 and the phase shift circuits 23 and 33 according to this embodiment will be described.

[0074] Figure 4A 2 is a diagram illustrating an example circuit configuration of a harmonic phase shift circuit 22 according to an embodiment. As shown in this diagram, the harmonic phase shift circuit 22 includes, for example, an inductor 221 and a capacitor 222. Inductor 221 (third inductor) and capacitor 222 (third capacitor) form an LC circuit connected in series. This LC circuit is connected between the path connecting the fourth output terminal to the inductor 231 of the phase shift circuit 23 and ground. The harmonic phase shift circuit 22 is a notch filter with a passband of the fundamental wave in the first frequency band and an attenuation band of the second harmonic. The passband phase of the fundamental wave is, for example, 0°, and the passband phase of the second harmonic is, for example, +45° (+X°: X>0).

[0075] Figure 4B is a diagram illustrating an example circuit configuration of a harmonic phase shift circuit 32 according to an embodiment. As shown in this diagram, the harmonic phase shift circuit 32 includes, for example, a capacitor 321 (fourth capacitor) connected between a path connecting the fifth output terminal and capacitor 331 of the phase shift circuit 33 and ground. The harmonic phase shift circuit 32 is a low-pass filter with a passband of the fundamental wave in the first frequency range and an attenuation band of the second harmonic. The pass phase of the fundamental wave is, for example, 0°, and the pass phase of the second harmonic is, for example, -45° (-Y°: Y>0).

[0076] Figure 4C This figure shows an example circuit configuration of a phase shift circuit 23 according to an embodiment. As shown in this figure, the phase shift circuit 23 includes, for example, an inductor 231 and a capacitor 232. Inductor 231 is an example of a first inductor and is connected between the fourth output terminal and the second input terminal. Capacitor 232 is an example of a first capacitor and is connected between the path connecting inductor 231 and the second input terminal and ground. The phase shift circuit 23 has a low-pass filter structure with passbands of the fundamental wave and the second harmonic of the first frequency band. The passband phase of the fundamental wave in the first frequency band is, for example, -45°, and the passband phase of the second harmonic is, for example, -45° (-X°).

[0077] Figure 4Dis a diagram illustrating an example circuit configuration of a phase shift circuit 33 according to an embodiment. As shown in this figure, phase shift circuit 33 includes, for example, a capacitor 331 and an inductor 332. Capacitor 331 is an example of a second capacitor and is connected between the fifth output terminal and the third input terminal. Inductor 332 is an example of a second inductor and is connected between the path connecting capacitor 331 and the third input terminal and ground. Phase shift circuit 33 has a high-pass filter structure with passbands in the fundamental frequency band and the second harmonic frequency band of the first frequency band. The passband phase of the fundamental frequency in the first frequency band is, for example, +45°, and the passband phase of the second harmonic is, for example, +45° (+Y°).

[0078] Alternatively, the phase shift circuits 23 and 33 and the harmonic phase shift circuits 22 and 32 may be included in a single semiconductor IC.

[0079] This allows the amplifier circuit 1 to be miniaturized, and also allows the signal wiring from the power amplifiers 21 and 31 to the in-phase combiner 41 to be shortened, thereby reducing signal transmission loss in the amplifier circuit 1 .

[0080] [2. Configuration of Amplifier Circuit 1A According to Modification 1]

[0081] Next, an amplifier circuit 1A according to Modification 1 of the embodiment will be described. Figure 5 This is a circuit diagram of an amplifier circuit 1A according to Modification 1 of the embodiment. As shown in this figure, amplifier circuit 1A includes a splitter 10, power amplifier circuits 20A and 30A, and an in-phase synthesizer circuit 40. Amplifier circuit 1A according to this modification differs from amplifier circuit 1 according to the embodiment in that the power amplifier circuits 20A and 30A have different structures. Below, description of the amplifier circuit 1A according to this modification, including the same structures as amplifier circuit 1 according to the embodiment, will be omitted, and the description will focus on the different structures.

[0082] Power amplifier circuit 20A is an example of a first power amplifier circuit and includes power amplifier 21. Power amplifier 21 has the same structure as power amplifier 21 described in the embodiment. In addition to power amplifier 21, power amplifier circuit 20A also includes a harmonic phase shift circuit 22A. Harmonic phase shift circuit 22A is an example of a first harmonic phase shift circuit and is connected to the path connecting the fourth output terminal of power amplifier 21 to in-phase synthesizer 41. It shifts the phase of the harmonics in the first frequency band. In addition, harmonic phase shift circuit 22A hardly shifts the phase of the fundamental wave in the first frequency band. In this modified example, the second harmonic of harmonic phase shift circuit 22A passes through a phase of +Z° (Z>0).

[0083] Power amplifier circuit 30A is an example of a second power amplifier circuit and includes power amplifier 31. Power amplifier 31 has the same structure as power amplifier 31 in the embodiment. In addition to power amplifier 31, power amplifier circuit 30A also includes a harmonic phase shift circuit 32A. Harmonic phase shift circuit 32A is an example of a second harmonic phase shift circuit and is connected to the path connecting the fifth output terminal of power amplifier 31 to in-phase synthesizer 41. It shifts the phase of the harmonics in the first frequency band. In addition, harmonic phase shift circuit 32A hardly shifts the phase of the fundamental wave in the first frequency band. In this modified example, the passing phase of the second harmonic of harmonic phase shift circuit 32A is -Z° (Z>0).

[0084] Phase shift circuit 23 is an example of a first phase shift circuit. It is connected between power amplifier circuit 20A and in-phase synthesizer 41 and is configured to phase shift the fundamental wave and harmonics in the first frequency band. In this modified example, the fundamental wave of phase shift circuit 23 passes through a phase of -45°, and the second harmonic passes through a phase of -X° (where X > 0).

[0085] Phase shift circuit 33 is an example of a second phase shift circuit. It is connected between power amplifier circuit 30A and in-phase synthesizer 41 and is configured to phase-shift the fundamental wave and harmonics in the first frequency band so that the passing phase of the fundamental wave in the first frequency band relative to phase shift circuit 23 is +90°. In this modified example, the passing phase of the fundamental wave in phase shift circuit 33 is +45°, and the passing phase of the second harmonic is +Y° (Y>0).

[0086] According to the above-described configuration of amplifier circuit 1A according to this variation, the fundamental wave of the first output signal at node n1 outputted from power amplifier 21 has a phase of +45°, and after passing through phase shift circuit 23, the phase of the fundamental wave at input terminal 402 becomes 0°. Furthermore, the fundamental wave of the second output signal at node n2 outputted from power amplifier 31 has a phase of -45°, and after passing through phase shift circuit 33, the phase of the fundamental wave at input terminal 403 becomes 0°. Consequently, the fundamental wave signal in the first frequency band is in-phase combined by in-phase combiner 41 and outputted from output terminal 401 as the third output signal. Consequently, amplifier circuit 1A operates as a balanced amplifier with strong resistance to load fluctuations.

[0087] On the other hand, the second harmonic of the first output signal at node n1 output from power amplifier 21 has a phase of +90+Z°. After passing through phase shift circuit 23, the phase of the second harmonic at input terminal 402 becomes +90+ZX°. Furthermore, the second harmonic of the second output signal at node n2 output from power amplifier 31 has a phase of -90-Z°. After passing through phase shift circuit 33, the phase of the second harmonic at input terminal 403 becomes -90-Z+Y°. Thus, the second harmonic of the first frequency band has a phase difference of (+90+ZX)-(-90-Z+Y)=180+2Z-XY between input terminals 402 and 403 of in-phase synthesizer 41. This phase difference is greater than 90°.

[0088] This suppresses the second harmonic in the first frequency band compared to the amplifier circuit 500 of the comparative example. Therefore, compared to conventional balanced amplifiers without an additional harmonic phase shift circuit, the second harmonic is suppressed, thereby improving the quality of transmitted signals and power efficiency.

[0089] [3. Configuration of Amplifier Circuit 1B According to Modification 2]

[0090] Next, an amplifier circuit 1B according to a second modification of the embodiment will be described. Figure 6 This is a circuit diagram of an amplifier circuit 1B according to a second variation of the embodiment. As shown, amplifier circuit 1B includes a splitter 10, power amplifiers 21 and 31, harmonic phase shift circuits 22 and 32, phase shift circuits 23 and 33, and an in-phase synthesizer 41. Compared to amplifier circuit 1 according to the embodiment, amplifier circuit 1B according to this variation differs in the connection structure between the harmonic phase shift circuit and the phase shift circuit. Below, description of the amplifier circuit 1B according to this variation, including components identical to those of amplifier circuit 1 according to the embodiment, will be omitted, and the description will focus on the components that differ.

[0091] Phase shift circuit 23 is an example of a first phase shift circuit. It is connected between power amplifier 21 and in-phase synthesizer 41 and is configured to phase shift the fundamental wave and harmonics in the first frequency band. In this variation, the fundamental wave of phase shift circuit 23 passes through a phase of -45°, and the second harmonic passes through a phase of -45° (or -X°: X>0).

[0092] Phase shift circuit 33 is an example of a second phase shift circuit. It is connected between power amplifier 31 and in-phase synthesizer 41 and is configured to phase-shift the fundamental wave and harmonics in the first frequency band so that the passing phase of the fundamental wave in the first frequency band relative to phase shift circuit 23 is +90°. In this modified example, the passing phase of the fundamental wave in phase shift circuit 33 is +45°, and the passing phase of the second harmonic is +45° (or +Y°: Y>0).

[0093] Harmonic phase shift circuit 22 is an example of a first harmonic phase shift circuit. It is connected to the path connecting phase shift circuit 23 and in-phase synthesizer 41, and performs phase shifting on the harmonics of the first frequency band. Furthermore, harmonic phase shift circuit 22 performs almost no phase shifting on the fundamental wave of the first frequency band. In this modified example, the second harmonic of harmonic phase shift circuit 22 passes through a phase of +45° (or +X°: X>0).

[0094] Harmonic phase shift circuit 32 is an example of a second harmonic phase shift circuit. It is connected to the path connecting phase shift circuit 33 and in-phase synthesizer 41, and performs phase shifting on the harmonics of the first frequency band. Furthermore, harmonic phase shift circuit 32 performs almost no phase shifting on the fundamental wave of the first frequency band. In this modified example, the second harmonic of harmonic phase shift circuit 32 passes through a phase of -45° (or -Y: Y>0).

[0095] According to the above-described configuration of amplifier circuit 1B according to this variation, the fundamental wave of the first output signal at the fourth output terminal (node n1) of power amplifier 21 has a phase of +45°. After passing through phase shift circuit 23 and harmonic phase shift circuit 22, the phase of the fundamental wave at input terminal 402 reaches 0°. Furthermore, the fundamental wave of the second output signal at the fifth output terminal (node n2) of power amplifier 31 has a phase of -45°. After passing through phase shift circuit 33 and harmonic phase shift circuit 32, the phase of the fundamental wave at input terminal 403 reaches 0°. Consequently, the fundamental wave signal in the first frequency band is in-phase combined in in-phase combiner 41 and output from output terminal 401 as the third output signal. Consequently, amplifier circuit 1B operates as a balanced amplifier with strong resistance to load fluctuations.

[0096] On the other hand, the second harmonic of the first output signal at node n1 outputted from power amplifier 21 has a phase of +90°. After passing through phase shift circuit 23 and harmonic phase shift circuit 22, the phase of the second harmonic at input terminal 402 becomes +90°. Furthermore, the second harmonic of the second output signal at node n2 outputted from power amplifier 31 has a phase of -90°. After passing through phase shift circuit 33 and harmonic phase shift circuit 32, the phase of the second harmonic at input terminal 403 becomes -90°. Consequently, the second harmonic in the first frequency band has a phase difference of 180° (an anti-phase relationship) between input terminals 402 and 403 of in-phase synthesizer 41, thereby canceling out. Consequently, amplifier circuit 1B suppresses the second harmonic, thereby improving the quality of the transmitted signal and power efficiency.

[0097] Furthermore, in the amplifier circuit 1B according to this modified example, the power amplifier 21, the phase shift circuit 23, and the harmonic phase shift circuit 22 are connected in this order. Therefore, the impedance of the second harmonic when viewed from the fourth output terminal (node n1) of the power amplifier 21 toward the in-phase combiner 41 is not inductive, and the power amplifier 21 is not an inverse class-E amplifier. Furthermore, the power amplifier 31, the phase shift circuit 33, and the harmonic phase shift circuit 32 are connected in this order. Therefore, the impedance of the second harmonic when viewed from the fifth output terminal (node n2) of the power amplifier 31 toward the in-phase combiner 41 is not capacitive, and the power amplifier 31 is not a class-E amplifier.

[0098] [4. Configuration of Amplifier Circuit 1C According to Modification 3]

[0099] Next, an amplifier circuit 1C according to a third modification of the embodiment will be described. Figure 7 This is a circuit diagram of an amplifier circuit 1C according to Modification 3 of the embodiment. As shown in this figure, amplifier circuit 1C includes a splitter 10, power amplifier circuits 20 and 30, and an inverting synthesis circuit 40C. Amplifier circuit 1C according to this modification differs from amplifier circuit 1 according to the embodiment in the structure of the synthesis circuit. Below, description of the amplifier circuit 1C according to this modification will be omitted for the same structures as amplifier circuit 1 according to the embodiment, and the description will focus on the different structures.

[0100] The anti-phase synthesizing circuit 40C is an example of a synthesizing circuit, and is configured to perform anti-phase synthesis of the first output signal from the power amplifier circuit 20 and the second output signal from the power amplifier circuit 30. The anti-phase synthesizing circuit 40C includes a transformer 42 and phase shift circuits 23C and 33C.

[0101] Transformer 42 has an input terminal 422 (second input terminal) serving as one end of the primary-side coil, an input terminal 423 (third input terminal) serving as the other end of the primary-side coil, and an output terminal 421 (third output terminal) serving as one end of the secondary-side coil that is electromagnetically coupled to the primary-side coil. The other end of the secondary-side coil is connected to ground. With this configuration, transformer 42 is configured to output, from output terminal 421, a third output signal generated by inversely combining the first output signal of power amplifier circuit 20 inputted from input terminal 422 and the second output signal of power amplifier circuit 30 inputted from input terminal 423.

[0102] Phase shift circuit 23C is an example of a first phase shift circuit. It is connected between power amplifier circuit 20 and transformer 42 and is configured to phase shift the fundamental wave and harmonics in the first frequency band. In this variation, phase shift circuit 23C has a fundamental wave passing phase of +45° and a second harmonic passing phase of +45°.

[0103] Phase shift circuit 33C is an example of a second phase shift circuit. It is connected between power amplifier circuit 30 and transformer 42 and is configured to phase-shift the fundamental wave and harmonics in the first frequency band so that the passing phase of the fundamental wave in the first frequency band relative to phase shift circuit 23C is -90°. In this modified example, the passing phase of the fundamental wave in phase shift circuit 33C is -45°, and the passing phase of the second harmonic is also -45°.

[0104] Alternatively, the second harmonic passing phase of the harmonic phase shift circuit 22 may be +X° (X>0), and the second harmonic passing phase of the phase shift circuit 23C may be +X° (X>0).

[0105] Alternatively, the second harmonic passing phase of the harmonic phase shift circuit 32 may be -Y° (Y>0), and the second harmonic passing phase of the phase shift circuit 33C may be -Y° (Y>0).

[0106] According to the amplifier circuit 1C of this modified example, the second harmonic of the harmonic phase shift circuit 22 has a pass phase of +45° (+X°). Therefore, the impedance of the second harmonic when viewed from the connection point (node n1) between the fourth output terminal of the power amplifier 21 and the harmonic phase shift circuit 22 toward the inverting synthesis circuit 40C is in the region of inductive reactance (inductive impedance). On the other hand, the second harmonic of the harmonic phase shift circuit 32 has a pass phase of -45° (-Y°). Therefore, the impedance of the second harmonic when viewed from the connection point (node n2) between the fifth output terminal of the power amplifier 31 and the harmonic phase shift circuit 32 toward the inverting synthesis circuit 40C is in the region of capacitive reactance (capacitive impedance).

[0107] That is, in the amplifier circuit 1C according to this modification, the power amplifier circuit 20 is an inverse class E amplifier with an inductive load impedance for the second harmonic, and the power amplifier circuit 30 is a class E amplifier with a capacitive load impedance for the second harmonic.

[0108] In other words, the phase difference between the impedance with respect to the second harmonic at the node n1 of the power amplifier circuit 20 and the impedance with respect to the second harmonic at the node n2 of the power amplifier circuit 30 is 90° (or X+Y°).

[0109] According to the above-described configuration of amplifier circuit 1C according to this variation, the fundamental wave of the first output signal at node n1 outputted from power amplifier 21 has a phase of +45°. After passing through phase shift circuit 23C, the phase of the fundamental wave at input terminal 422 becomes +90°. Furthermore, the fundamental wave of the second output signal at node n2 outputted from power amplifier 31 has a phase of -45°. After passing through phase shift circuit 33C, the phase of the fundamental wave at input terminal 423 becomes -90°. Consequently, the fundamental wave signal in the first frequency band is inverted and combined in transformer 42 and then output from output terminal 421 as the third output signal. Consequently, amplifier circuit 1C operates as a balanced amplifier with strong resistance to load fluctuations.

[0110] On the other hand, the second harmonic of the first output signal at node n1 output from power amplifier 21 has a phase of +135° (or +90+X°). After passing through phase shift circuit 23C, the phase of the second harmonic at input terminal 422 becomes +180°. Furthermore, the second harmonic of the second output signal at node n2 output from power amplifier 31 has a phase of -135° (or -90-Y°). After passing through phase shift circuit 33C, the phase of the second harmonic at input terminal 423 becomes -180°. Consequently, the second harmonic in the first frequency band has a phase difference of 360° (in-phase) between input terminals 422 and 423 of transformer 42, thereby canceling out. Consequently, amplifier circuit 1C suppresses the second harmonic, thereby improving the quality of the transmitted signal and power efficiency.

[0111] Furthermore, each of the power amplifier circuits 20 and 30 involved in this variant is not a Class F amplifier in which the load impedance of the even-order harmonics is short-circuited and the load impedance of the odd-order harmonics is open-circuited. Instead, it is sufficient that the load impedance of the second harmonic is distributed as inductive and capacitive. Therefore, it is possible to cancel the second harmonic with high precision within the entire frequency band of a wide-band frequency band specified by 3GPP, for example, to ensure high transmission quality and power efficiency.

[0112] Furthermore, in the amplifier circuit 1C according to this modified example, a first phase shift difference (90° or (+X+Y°)) obtained by subtracting the passing phase (-45° or (-Y°)) of the harmonics of the harmonic phase shift circuit 32 from the passing phase (+45° or (+X°)) of the harmonics of the harmonic phase shift circuit 22 is equal to a second phase shift difference (90° (or +Y+X°)) obtained by subtracting the passing phase (-45° (or -Y°)) of the harmonics of the phase shift circuit 33C from the passing phase (+45° (or +X°)) of the harmonics of the phase shift circuit 23C.

[0113] As a result, the second harmonics in the first frequency band are in phase with each other between the input terminals 422 and 423 of the transformer 42 and are canceled out. Therefore, the amplifier circuit 1C suppresses the second harmonics, thereby improving the quality of the transmission signal and the power efficiency.

[0114] Furthermore, the second harmonic of the first frequency band only needs to have a phase difference of 0° (±360×m: m is a natural number) between the input terminals 422 and 423 of the transformer 42, so the second harmonic can be canceled with high precision throughout the entire frequency band of the wide frequency band to ensure high transmission quality and power efficiency.

[0115] In the amplifier circuit 1C according to this modification, the phase difference obtained by subtracting the phase of the second harmonic of the first frequency band at the input terminal 423 from the phase of the second harmonic of the first frequency band at the input terminal 422 may be less than 90°.

[0116] According to this, compared with a conventional anti-phase synthesis type balanced amplifier without an additional harmonic phase shift circuit, the second harmonic in the first frequency band is suppressed, thereby improving the quality of the transmission signal and the power efficiency.

[0117] [5. Configuration of Amplifier Circuit 1D According to Modification 4]

[0118] Next, an amplifier circuit 1D according to a fourth modification of the embodiment will be described. Figure 8A This is a circuit diagram of an amplifier circuit 1D according to Modification 4 of the embodiment. As shown in this figure, the amplifier circuit 1D includes a splitter 10, power amplifiers 21 and 31, harmonic phase shift circuits 22 and 32, and a phase shift line 50. The amplifier circuit 1D according to this modification differs in that it also operates as a Doherty amplifier. The following description of the amplifier circuit 1D according to this modification will omit the components identical to those of the amplifier circuit 1 according to the embodiment, and will focus on the components that differ.

[0119] The demultiplexer 10 has an input terminal 101 (first input end), an output terminal 102 (first output end) and an output terminal 103 (second output end), and is configured to demultiplex a fundamental wave signal of a transmission band of a first frequency band input to the input terminal 101, output a first signal from the output terminal 102, and output a second signal having a phase of -90° (lagging 90°) relative to the first signal from the output terminal 103.

[0120] The power amplifier 21 is an example of a carrier amplifier, includes an amplifying transistor, and has a third input terminal and a fourth output terminal. The third input terminal is connected to the output terminal 102 of the branching filter 10 .

[0121] The power amplifier 31 is an example of a peak amplifier, includes an amplifying transistor, and has a fourth input terminal and a fifth output terminal. The fourth input terminal is connected to the output terminal 103 of the branching filter 10 .

[0122] The amplifying transistors of the power amplifiers 21 and 31 are, for example, bipolar transistors such as HBTs or field effect transistors such as MOSFETs.

[0123] Power amplifier 21 amplifies the transmission signal in the first frequency band input to the third input terminal. Power amplifier 21 is, for example, a Class A (or Class AB) amplifier circuit capable of amplifying the signal at all power levels. In particular, it is capable of highly efficient amplification in low and medium output ranges.

[0124] Power amplifier 31 amplifies the transmit signal in the first frequency band input to the fourth input terminal. Power amplifier 31 is, for example, a class C amplifier circuit capable of amplifying signals input to power amplifier 31 at high power levels. A bias current smaller than the bias current applied to the amplifier transistors of power amplifier 21 may be applied to the amplifier transistors of power amplifier 31. Consequently, the higher the power level of the signal input to power amplifier 31, the lower the output impedance. This enables power amplifier 31 to perform low-distortion amplification in the high-output range.

[0125] The power amplifier 21 amplifies the first signal output from the splitter 10, and the power amplifier 31 amplifies the second signal output from the splitter 10, so the phase of the fundamental wave at the fifth output end of the power amplifier 31 lags by 90° relative to the phase of the fundamental wave at the fourth output end of the power amplifier 21.

[0126] Phase-shift circuit 50 has a second input terminal and a third output terminal. The second input terminal is connected to the fourth output terminal, and the third output terminal is connected to the fifth output terminal via output terminal 104. Phase-shift circuit 50 is configured to lag the fundamental wave of the first output signal of power amplifier 21, input from the second input terminal, by 90°. By configuring phase-shift circuit 50, the phase of the fundamental wave of the first output signal output from power amplifier 21 is aligned with the phase of the fundamental wave of the second output signal output from power amplifier 31. As a result, the fundamental waves of the first and second output signals are combined in phase (current combination) at output terminal 104. Phase-shift circuit 50 and output terminal 104 form a combining circuit.

[0127] Harmonic phase shift circuit 22 is an example of a first harmonic phase shift circuit. It is connected to the path connecting the fourth output terminal of power amplifier 21 and the second input terminal of phase shift circuit 50, and performs phase shifting on harmonics in the first frequency band. Furthermore, harmonic phase shift circuit 22 performs almost no phase shifting on the fundamental wave in the first frequency band. In this modified example, the second harmonic of harmonic phase shift circuit 22 passes through a phase of +45°.

[0128] Harmonic phase shift circuit 32 is an example of a second harmonic phase shift circuit. It is connected to the path connecting the fifth output terminal of power amplifier 31 and output terminal 104, and performs phase shifting on the harmonics of the first frequency band. Furthermore, harmonic phase shift circuit 32 performs almost no phase shifting on the fundamental wave of the first frequency band. In this modified example, the second harmonic of harmonic phase shift circuit 32 passes through a phase of -45°.

[0129] Alternatively, the second harmonic passing phase of the harmonic phase shift circuit 22 may be +X° (X>0), and the second harmonic passing phase of the harmonic phase shift circuit 32 may be -Y° (Y>0).

[0130] The power amplifier 21 and the harmonic phase shift circuit 22 constitute a first power amplifier circuit, and the power amplifier 31 and the harmonic phase shift circuit 32 constitute a second power amplifier circuit.

[0131] With the above-described configuration of amplifier circuit 1D, the output impedance of power amplifier 21 becomes higher when a small signal is input than when a large signal is input. Specifically, when a small signal is input, power amplifier 31 is turned off, and the output impedance of power amplifier 21 becomes higher, thereby enabling amplifier circuit 1D to operate with high efficiency.

[0132] On the other hand, when a large signal is input, the power amplifiers 21 and 31 operate, thereby being able to output a high-power signal. Furthermore, the output impedance of the power amplifier 31 becomes low, thereby being able to suppress signal distortion.

[0133] Furthermore, the phase of the fundamental wave at the fifth output terminal of power amplifier 31 lags the phase of the fundamental wave at the fourth output terminal of power amplifier 21 by 90°. Therefore, the phase of the second harmonic at the fifth output terminal of power amplifier 31 lags the phase of the second harmonic at the fourth output terminal of power amplifier 21 by 180°. In this modified example, the phase of the second harmonic at the fourth output terminal of power amplifier 21 is set to +90°, and the phase of the second harmonic at the fifth output terminal of power amplifier 31 is set to -90°.

[0134] According to the above-described configuration of amplifier circuit 1D according to this variation, the phase of the second harmonic of the first output signal at the connection point (node n1) between the fourth output terminal of power amplifier 21 and harmonic phase shift circuit 22 is +135° (or +90+X°). After passing through phase shift circuit 50, the phase of the second harmonic at output terminal 104 becomes +45° (or X°). Furthermore, the phase of the second harmonic of the second output signal at node n2 output from power amplifier 31 is -135° (or -90-Y°), and the phase of the second harmonic at output terminal 104 becomes -135° (or -90-Y°). Consequently, the second harmonic of the first output signal and the second harmonic of the second output signal have a phase difference of 180° (in an anti-phase relationship) at output terminal 104, thereby canceling each other out. Thus, amplifier circuit 1D suppresses the second harmonic, thereby improving the quality of the transmitted signal and power efficiency.

[0135] In the amplifier circuit 1D according to this modification, the first power amplifier circuit is an inverse class E amplifier with an inductive load impedance for the second harmonic, and the second power amplifier circuit is an inverse class E amplifier with a capacitive load impedance for the second harmonic.

[0136] This makes it possible to accurately cancel the second harmonic over the entire frequency band of a wide-band frequency band specified by 3GPP, for example, and thereby ensure high transmission quality and power efficiency.

[0137] In the amplifier circuit 1D according to this modification, the phase difference obtained by subtracting the phase of the second harmonic of the second output signal at the output terminal 104 from the phase of the second harmonic of the first output signal at the output terminal 104 may be greater than 90°.

[0138] According to this, compared with a conventional Doherty amplifier without an additional harmonic phase shift circuit, the second harmonic in the first frequency band is suppressed, thereby improving the quality of the transmitted signal and the power efficiency.

[0139] [6. Configuration of Amplifier Circuit 1E According to Modification 5]

[0140] Next, an amplifier circuit 1E according to a fifth modification of the embodiment will be described. Figure 8B This is a circuit diagram of an amplifier circuit 1E according to Modification 5 of the embodiment. As shown in this diagram, amplifier circuit 1E includes a splitter 10, power amplifiers 21 and 31, harmonic phase shift circuits 22 and 32, a phase shift line 51, and a transformer 43. Amplifier circuit 1E according to this modification differs from amplifier circuit 1D according to Modification 4 in its signal synthesis structure. Below, description of the amplifier circuit 1E according to this modification will be omitted for structures identical to amplifier circuit 1D according to Modification 4, and the description will focus on the differing structures.

[0141] Transformer 43 has an input terminal 432 (third input terminal) serving as one end of the primary-side coil, an input terminal 433 (fourth input terminal) serving as the other end of the primary-side coil, and an output terminal 431 (fourth output terminal) serving as one end of the secondary-side coil that is electromagnetically coupled to the primary-side coil. The other end of the secondary-side coil is connected to ground. With this configuration, transformer 43 is configured to output, from output terminal 431, a third output signal generated by inversely combining the first output signal of power amplifier circuit 20 inputted from input terminal 432 and the second output signal of power amplifier circuit 30 inputted from input terminal 433.

[0142] Phase-shift circuit 51 has a second input terminal and a third output terminal, and is configured to lag the fundamental wave of the second output signal of power amplifier 31, input from the second input terminal, by 90°. Phase-shift circuit 51 is configured to cause the phase of the fundamental wave of the first output signal from power amplifier 21 to be in opposite phase to the phase of the fundamental wave of the second output signal from power amplifier 31. Consequently, the fundamental wave of the first output signal and the fundamental wave of the second output signal are combined in anti-phase (voltage combination) in transformer 43. Phase-shift circuit 51 and transformer 43 form a combining circuit.

[0143] The power amplifier 21 is an example of a carrier amplifier, includes an amplifying transistor, and has a fifth input terminal and a fifth output terminal. The fifth input terminal is connected to the output terminal 102 of the branch filter 10 , and the fifth output terminal is connected to the input terminal 432 .

[0144] The power amplifier 31 is an example of a peak amplifier, including an amplifying transistor, and has a sixth input terminal and a sixth output terminal. The sixth input terminal is connected to the output terminal 103 of the splitter 10 , and the sixth output terminal is connected to the second input terminal. The third output terminal is connected to the input terminal 433 .

[0145] Power amplifier 21 amplifies the transmit signal in the first frequency band input to the fifth input terminal. Power amplifier 21 is, for example, a Class A (or Class AB) amplifier circuit capable of amplifying the input signal at all power levels. In particular, it is capable of highly efficient amplification in low and medium power ranges.

[0146] Power amplifier 31 amplifies the transmit signal in the first frequency band input to the sixth input terminal. Power amplifier 31 is, for example, a class C amplifier circuit capable of amplifying signals input to power amplifier 31 at high power levels. A bias current smaller than the bias current applied to the amplifier transistors of power amplifier 21 may be applied to the amplifier transistors of power amplifier 31. Consequently, the higher the power level of the signal input to power amplifier 31, the lower the output impedance. This enables power amplifier 31 to perform low-distortion amplification in its high-output range.

[0147] The power amplifier 21 amplifies the first signal output from the splitter 10, and the power amplifier 31 amplifies the second signal output from the splitter 10, so the phase of the fundamental wave at the sixth output end of the power amplifier 31 lags by 90° relative to the phase of the fundamental wave at the fifth output end of the power amplifier 21.

[0148] Harmonic phase shift circuit 22 is an example of a first harmonic phase shift circuit. It is connected to the path connecting the fifth output terminal and input terminal 432, and performs phase shifting on the harmonics of the first frequency band. Furthermore, harmonic phase shift circuit 22 performs almost no phase shifting on the fundamental wave of the first frequency band. In this modified example, the second harmonic of harmonic phase shift circuit 22 passes through a phase of +45°.

[0149] Harmonic phase shift circuit 32 is an example of a second harmonic phase shift circuit. It is connected to the path connecting the sixth output terminal and the second input terminal, and performs phase shifting on the harmonics of the first frequency band. Furthermore, harmonic phase shift circuit 32 performs almost no phase shifting on the fundamental wave of the first frequency band. In this modified example, the second harmonic of harmonic phase shift circuit 32 passes through a phase of -45°.

[0150] Alternatively, the second harmonic passing phase of the harmonic phase shift circuit 22 may be +X° (X>0), and the second harmonic passing phase of the harmonic phase shift circuit 32 may be -Y° (Y>0).

[0151] The power amplifier 21 and the harmonic phase shift circuit 22 constitute a first power amplifier circuit, and the power amplifier 31 and the harmonic phase shift circuit 32 constitute a second power amplifier circuit.

[0152] With the above-described configuration of amplifier circuit 1E, the output impedance of power amplifier 21 becomes higher when a small signal is input compared to the output impedance of power amplifier 21 when a large signal is input. Specifically, when a small signal is input, power amplifier 31 is turned off, and the output impedance of power amplifier 21 becomes higher, thereby enabling amplifier circuit 1E to operate with high efficiency.

[0153] On the other hand, when a large signal is input, the power amplifiers 21 and 31 operate, thereby being able to output a high-power signal. Furthermore, the output impedance of the power amplifier 31 becomes low, thereby being able to suppress signal distortion.

[0154] Furthermore, the phase of the fundamental wave at the sixth output terminal of power amplifier 31 lags the phase of the fundamental wave at the fifth output terminal of power amplifier 21 by 90°. Therefore, the phase of the second harmonic at the sixth output terminal of power amplifier 31 lags the phase of the second harmonic at the fifth output terminal of power amplifier 21 by 180°. In this modified example, the phase of the second harmonic at the fifth output terminal is set to +90°, and the phase of the second harmonic at the sixth output terminal is set to -90°.

[0155] According to the above-described configuration of the amplifier circuit 1E according to this variation, the phase of the second harmonic of the first output signal at the connection point (node n1) between the fifth output terminal of the power amplifier 21 and the harmonic phase shift circuit 22 is +135° (or +90+X°), and the phase of the second harmonic at the input terminal 432 is +135° (or +90+X°). Furthermore, the phase of the second harmonic of the second output signal at the connection point (node n2) between the sixth output terminal of the power amplifier 31 and the harmonic phase shift circuit 32 is -135° (or -90-Y°), and after passing through the phase shift circuit 51, the phase of the second harmonic at the input terminal 433 is -225° (or -135-Y°). Consequently, the second harmonic of the first output signal and the second harmonic of the second output signal have a phase difference of 360° (in-phase) at the input terminals 432 and 433 of the transformer 43, thereby canceling each other out. According to this, the amplifier circuit 1E suppresses the second harmonic, thereby improving the quality of the transmission signal and the power efficiency.

[0156] In the amplifier circuit 1E according to this modification, the first power amplifier circuit is an inverse class E amplifier with an inductive load impedance for the second harmonic, and the second power amplifier circuit is an inverse class E amplifier with a capacitive load impedance for the second harmonic.

[0157] This makes it possible to accurately cancel the second harmonic over the entire frequency band of a wide-band frequency band specified by 3GPP, for example, and thereby ensure high transmission quality and power efficiency.

[0158] In the amplifier circuit 1E according to this modification, the phase difference obtained by subtracting the phase of the second harmonic of the second output signal at the input terminal 433 from the phase of the second harmonic of the first output signal at the input terminal 432 may be less than 90°.

[0159] According to this, compared with a conventional Doherty amplifier without an additional harmonic phase shift circuit, the second harmonic in the first frequency band is suppressed, thereby improving the quality of the transmitted signal and the power efficiency.

[0160] [7. Configuration of Amplifier Circuit 1F According to Modification 6]

[0161] Next, an amplifier circuit 1F according to a sixth modification of the embodiment will be described. Figure 9 This is a circuit diagram of an amplifier circuit 1F according to Modification 6 of the embodiment. As shown in this figure, amplifier circuit 1F includes a splitter 10, power amplifier circuits 20 and 30, and a 90° combiner 44. Amplifier circuit 1F according to this modification differs from amplifier circuit 1 according to the embodiment in the configuration of the combining circuit. Below, description of the amplifier circuit 1F according to this modification will be omitted for configurations identical to those of amplifier circuit 1 according to the embodiment, and the description will focus on the configurations that differ.

[0162] The synthesizer circuit according to this variation includes a 90° synthesizer 44, but does not include a phase shifting circuit. The 90° synthesizer 44 has an input terminal 442 (second input terminal), an input terminal 443 (third input terminal), and an output terminal 441 (third output terminal). The synthesizer 44 is configured to output, from output terminal 441, a third output signal generated by synthesizing a first output signal input from input terminal 442 and a second output signal input from input terminal 443 with its phase adjusted to +90° relative to the first output signal.

[0163] According to the amplifier circuit 1F of this modified example, the second harmonic of the harmonic phase shift circuit 22 has a pass phase of +45°. Therefore, the impedance of the second harmonic when viewed from the connection point (node n1) between the fourth output terminal of the power amplifier 21 and the harmonic phase shift circuit 22 toward the 90° combiner 44 is in the inductive reactance region (inductive impedance). On the other hand, the second harmonic of the harmonic phase shift circuit 32 has a pass phase of -45°. Therefore, the impedance of the second harmonic when viewed from the connection point (node n2) between the fifth output terminal of the power amplifier 31 and the harmonic phase shift circuit 32 toward the 90° combiner 44 is in the capacitive reactance region (capacitive impedance).

[0164] That is, in the amplifier circuit 1F according to this modification, the power amplifier circuit 20 is an inverse class E amplifier with an inductive load impedance for the second harmonic, and the power amplifier circuit 30 is a class E amplifier with a capacitive load impedance for the second harmonic.

[0165] In other words, the phase difference between the impedance with respect to the second harmonic at the node n1 of the power amplifier circuit 20 and the impedance with respect to the second harmonic at the node n2 of the power amplifier circuit 30 is 90°.

[0166] With the above-described configuration of amplifier circuit 1F according to this variation, the fundamental wave of the first output signal at node n1 output from power amplifier 21 has a phase of +45°, and the phase of the fundamental wave at input terminal 442 is also +45°. Furthermore, the fundamental wave of the second output signal at node n2 output from power amplifier 31 has a phase of -45°, and the phase of the fundamental wave at input terminal 443 is also -45°. Consequently, the fundamental wave signals in the first frequency band are synthesized in phase by 90° synthesizer 44 and output from output terminal 441 as the third output signal. Consequently, amplifier circuit 1F operates as a balanced amplifier with strong resistance to load fluctuations.

[0167] On the other hand, the second harmonic of the first output signal at node n1 output from power amplifier 21 has a phase of +135°, and the second harmonic at input terminal 442 has a phase of +135°. Furthermore, the second harmonic of the second output signal at node n2 output from power amplifier 31 has a phase of -135°, and the second harmonic at input terminal 443 has a phase of -135°. Thus, the second harmonic in the first frequency band has a phase difference of 270° between input terminals 442 and 443, but is reduced to a phase difference of 180° by 90° combiner 44, thereby canceling out. Thus, amplifier circuit 1F suppresses the second harmonic, thereby improving the quality of the transmitted signal and power efficiency.

[0168] Furthermore, each of the power amplifier circuits 20 and 30 involved in this variant is not a Class F amplifier in which the load impedance of the even-order harmonics is short-circuited and the load impedance of the odd-order harmonics is open-circuited. Instead, it is sufficient that the load impedance of the second harmonic is distributed as inductive and capacitive. Therefore, it is possible to cancel the second harmonic with high precision within the entire frequency band of a wide-band frequency band specified by 3GPP, for example, to ensure high transmission quality and power efficiency.

[0169] [8 Effects, etc.]

[0170] As described above, the amplifier circuit 1 involved in this embodiment (the amplifier circuit 1A involved in Modification 1 and the amplifier circuit 1D involved in Modification 4) includes: a power amplifier circuit 20 (20A), which includes a power amplifier 21; a power amplifier circuit 30 (30A), which includes a power amplifier 31, wherein the phase of the fundamental wave at the output end of the power amplifier 31 lags by 90° relative to the power amplifier 21; and an in-phase synthesis circuit 40 (phase shift line 50), which is configured to synthesize the fundamental wave of the first output signal output from the power amplifier circuit 20 (20A) and the fundamental wave of the second output signal output from the power amplifier circuit 30 (30A), wherein the power amplifier circuit 20 (20A) is an inverse E class and the power amplifier circuit 30 (30A) is an E class.

[0171] As a result, each of the power amplifier circuits 20 (20A) and 30 (30A) is not a Class F amplifier in which the load impedance for even-order harmonics is short-circuited and the load impedance for odd-order harmonics is open-circuited, but rather an inverse Class E amplifier and a Class E amplifier in which the load impedance for the second harmonic is divided into inductive and capacitive components. This allows for highly accurate cancellation of the second harmonic across the entire frequency band, such as the wideband frequency band specified by 3GPP. Consequently, it is possible to function as a balanced amplifier with strong resistance to load fluctuations, ensuring high transmission quality and power efficiency.

[0172] For example, the amplifier circuit 1 (1A) further includes a demultiplexer 10 having an input terminal 101 and output terminals 102 and 103, and is configured to demultiplex a fundamental wave signal of a transmission frequency band of a first frequency band input to the input terminal 101, output a first signal from the output terminal 102, and output a second signal having a phase of -90° with respect to the first signal from the output terminal 103. The in-phase synthesizer circuit 40 includes an in-phase synthesizer 41 having input terminals 402 and 403. 3 and an output terminal 401, and is configured to output, from the output terminal 401, a third output signal generated by in-phase synthesis of the first output signal of the power amplifier circuit 20 (20A) input from the input terminal 402 and the second output signal of the power amplifier circuit 30 (30A) input from the input terminal 403; a phase shift circuit 23, which is connected between the power amplifier circuit 20 (20A) and the in-phase synthesizer 41 and is configured to phase-shift the fundamental wave and the second harmonic of the first frequency band; and a phase shift circuit The circuit 33 is connected between the power amplifier circuit 30 (30A) and the in-phase synthesizer 41, and is configured to shift the phase of the fundamental wave and the second harmonic of the first frequency band so that the passing phase of the fundamental wave relative to the phase shift circuit 23 is +90°. The power amplifier circuit 20 (20A) includes: a power amplifier 21 having a fourth input terminal and a fourth output terminal, the fourth input terminal being connected to the output terminal 102; and a harmonic phase shift circuit 22 connected to the fourth output terminal and the input terminal 402. The power amplifier circuit 30 (30A) includes a power amplifier 31 having a fifth input terminal and a fifth output terminal, wherein the fifth input terminal is connected to the output terminal 103; and a harmonic phase shift circuit 32 connected to the path connecting the fifth output terminal to the input terminal 403, and configured to shift the phase of the second harmonic, wherein the phase shift difference obtained by subtracting the phase of the second harmonic at the input terminal 403 from the phase of the second harmonic at the input terminal 402 is greater than 90°.

[0173] This makes it possible to suppress the second harmonic in the first frequency band over a wide frequency band compared to conventional in-phase synthesis type balanced amplifiers without an additional harmonic phase shift circuit, thereby improving the quality of transmitted signals and power efficiency.

[0174] For another example, in the amplifier circuit 1, the first phase shift difference obtained by subtracting the passing phase of the second harmonic of the harmonic phase shift circuit 32 from the passing phase of the second harmonic of the harmonic phase shift circuit 22 is equal to the second phase shift difference obtained by subtracting the passing phase of the second harmonic of the phase shift circuit 23 from the passing phase of the second harmonic of the phase shift circuit 33.

[0175] Thus, the second harmonic of the first frequency band is canceled out by a phase difference of 180° (opposite phase relationship) between the input terminals 402 and 403 of the in-phase synthesizer 41. Therefore, an amplifier circuit 1 with improved transmission signal quality and power efficiency can be provided.

[0176] For example, in the amplifier circuit 1, the phase shift circuit 23 is configured so that the passing phase between the fundamental wave and the second harmonic is -45°, the phase shift circuit 33 is configured so that the passing phase between the fundamental wave and the second harmonic is +45°, the harmonic phase shift circuit 22 is configured so that the passing phase of the harmonic is +45°, and the harmonic phase shift circuit 32 is configured so that the passing phase of the harmonic is -45°.

[0177] Thus, the second harmonic of the first frequency band is canceled out by a phase difference of 180° (opposite phase relationship) between the input terminals 402 and 403 of the in-phase synthesizer 41. Therefore, an amplifier circuit 1 with improved transmission signal quality and power efficiency can be provided.

[0178] For example, in the amplifier circuit 1, the phase shift circuit 23 is configured so that the passing phase of the fundamental wave is -45° and the passing phase of the harmonics is -X° (X>0), the phase shift circuit 33 is configured so that the passing phase of the fundamental wave is +45° and the passing phase of the harmonics is +Y° (Y>0), the harmonic phase shift circuit 22 is configured so that the passing phase of the harmonics is +X° (X>0), and the harmonic phase shift circuit 32 is configured so that the passing phase of the harmonics is -Y° (Y>0).

[0179] Thus, the second harmonic of the first frequency band is canceled out by a phase difference of 180° (opposite phase relationship) between the input terminals 402 and 403 of the in-phase synthesizer 41. Therefore, an amplifier circuit 1 with improved transmission signal quality and power efficiency can be provided.

[0180] For example, the amplifier circuit 1D according to the fourth modification further includes a demultiplexer 10 having an input terminal 101 and output terminals 102 and 103, and is configured to demultiplex a fundamental wave signal of a transmission frequency band of a first frequency band input to the input terminal 101, output a first signal from the output terminal 102, and output a second signal having a phase of -90° with respect to the first signal from the output terminal 103. The synthesizing circuit includes a phase shifting circuit 50 having a second input terminal and a third output terminal, and is configured to lag the fundamental wave of the first output signal of the first power amplifier circuit input from the second input terminal by 90°. The first power amplifier circuit includes: a carrier amplifier (power amplifier 21) having a third input terminal and a fourth output terminal, and the third input terminal and the fourth output terminal. The input terminal is connected to the output terminal 102, and the fourth output terminal is connected to the second input terminal; and a harmonic phase shift circuit 22, which is connected to the path connecting the fourth output terminal and the second input terminal, and is configured to shift the phase of the second harmonic of the first frequency band, the second power amplifier circuit includes: a peak amplifier (power amplifier 31), which has a fourth input terminal and a fifth output terminal, the fourth input terminal is connected to the output terminal 103, and the fifth output terminal is connected to the third output terminal; and a harmonic phase shift circuit 32, which is connected to the path connecting the fifth output terminal and the third output terminal, and is configured to shift the phase of the second harmonic, and the phase shift difference obtained by subtracting the phase of the second harmonic input from the fifth output terminal to the third output terminal from the phase of the second harmonic input from the fourth output terminal to the third output terminal is greater than 90°.

[0181] This makes it possible to suppress the second harmonic in the first frequency band with high accuracy, compared to a conventional Doherty amplifier without an additional harmonic phase shift circuit, thereby improving the quality of the transmitted signal and the power efficiency.

[0182] For example, the amplifier circuit 1E according to the fifth modification further includes a demultiplexer 10 having an input terminal 101, and output terminals 102 and 103, and configured to demultiplex a fundamental wave signal of a transmission frequency band of a first frequency band input to the input terminal 101, output a first signal from the output terminal 102, and output a second signal having a phase of -90° with respect to the first signal from the output terminal 103. The synthesis circuit includes: a phase shifting circuit 51 having a second input terminal and a third output terminal, and configured to lag the fundamental wave of the second output signal input from the second input terminal by 90°; and a transformer 43 having input terminals 432 and 433 and an output terminal 431, and configured to output, from the output terminal 431, a third output signal generated by anti-phase synthesis of the first output signal input from the input terminal 432 and the second output signal input from the input terminal 433. Output signal, the first power amplifier circuit includes: a carrier amplifier (power amplifier 21), which has a fifth input terminal and a fifth output terminal, the fifth input terminal is connected to the output terminal 102, and the fifth output terminal is connected to the input terminal 432; and a harmonic phase shift circuit 22, which is connected to the path connecting the fifth output terminal to the input terminal 432, and is configured to shift the phase of the second harmonic of the first frequency band, the second power amplifier circuit includes: a peak amplifier (power amplifier 31), which has a sixth input terminal and a sixth output terminal, the sixth input terminal is connected to the output terminal 103, and the sixth output terminal is connected to the second input terminal; and a harmonic phase shift circuit 32, which is connected to the path connecting the sixth output terminal to the second input terminal, and is configured to shift the phase of the second harmonic, and the phase shift difference obtained by subtracting the phase of the second harmonic at the fourth input terminal from the phase of the second harmonic at the third input terminal is less than 90°.

[0183] This makes it possible to suppress the second harmonic in the first frequency band with high accuracy, compared to a conventional Doherty amplifier without an additional harmonic phase shift circuit, thereby improving the quality of the transmitted signal and the power efficiency.

[0184] For example, the amplifier circuit 1C further includes a demultiplexer 10, which has an input terminal 101, output terminals 102 and 103, and is configured to demultiplex a fundamental wave signal of a transmission frequency band of a first frequency band input to the input terminal 101, output a first signal from the output terminal 102, and output a second signal having a phase of -90° relative to the first signal from the output terminal 103. The anti-phase synthesis circuit 40C includes: a transformer 42, which has input terminals 422 and 423 and an output terminal 421, and is configured to output a third output signal generated by anti-phase synthesis of a first output signal input from the input terminal 422 and a second output signal input from the input terminal 423 from the output terminal 421; a phase shifting circuit 23C, which is connected between the power amplifier circuit 20 and the transformer 42 and is configured to phase shift the fundamental wave and the second harmonic of the first frequency band; and a phase shifting circuit 33C, which is connected to the power amplifier circuit 20. The power amplifier circuit 20 is connected between the power amplifier circuit 30 and the transformer 42, and is configured to phase-shift the fundamental wave and the second harmonic of the first frequency band so that the passing phase of the fundamental wave relative to the phase shift circuit 23C is -90°. The power amplifier circuit 20 includes: a power amplifier 21, which has a fourth input terminal and a fourth output terminal, and the fourth input terminal is connected to the output terminal 102; and a harmonic phase shift circuit 22, which is connected to the path connecting the fourth output terminal to the transformer 42 and is configured to phase-shift the second harmonic. The power amplifier circuit 30 includes: a power amplifier 31, which has a fifth input terminal and a fifth output terminal, and the fifth input terminal is connected to the output terminal 103; and a harmonic phase shift circuit 32, which is connected to the path connecting the fifth output terminal to the transformer 42 and is configured to phase-shift the second harmonic, and the phase shift difference obtained by subtracting the phase of the second harmonic at the input terminal 423 from the phase of the second harmonic at the input terminal 422 is less than 90°.

[0185] This makes it possible to suppress the second harmonics in the first frequency band over a wide frequency band compared to conventional inverting synthesis type balanced amplifiers without an additional harmonic phase shift circuit, thereby improving the quality of transmitted signals and power efficiency.

[0186] For another example, in the amplifier circuit 1C, the first phase shift difference obtained by subtracting the pass phase of the second harmonic of the harmonic phase shift circuit 32 from the pass phase of the second harmonic of the harmonic phase shift circuit 22 is equal to the second phase shift difference obtained by subtracting the pass phase of the second harmonic of the phase shift circuit 33C from the pass phase of the second harmonic of the phase shift circuit 23C.

[0187] As a result, the second harmonics in the first frequency band are in phase with each other between the input terminals 422 and 423 of the transformer 42 and are canceled out. Therefore, an amplifier circuit 1C having improved transmission signal quality and power efficiency can be provided.

[0188] For example, in the amplifier circuit 1C, the phase shift circuit 23C is configured so that the fundamental wave and the harmonics pass through a phase of +45°, the phase shift circuit 33C is configured so that the fundamental wave and the harmonics pass through a phase of -45°, the harmonic phase shift circuit 22 is configured so that the harmonics pass through a phase of +45°, and the harmonic phase shift circuit 32 is configured so that the harmonics pass through a phase of -45°.

[0189] As a result, the second harmonics in the first frequency band are in phase with each other between the input terminals 422 and 423 of the transformer 42 and are canceled out. Therefore, an amplifier circuit 1C having improved transmission signal quality and power efficiency can be provided.

[0190] For example, the amplifier circuit 1F involved in the modification example 6 further includes a demultiplexer 10, which has an input terminal 101, and output terminals 102 and 103, and is configured to demultiplex a fundamental wave signal of a transmission frequency band of a first frequency band input to the input terminal 101, output a first signal from the output terminal 102, and output a second signal having a phase of -90° relative to the first signal from the output terminal 103, and a synthesizing circuit includes a 90° synthesizer 44, which has an input terminal 442 (second input end), an input terminal 443 (third input end), and an output terminal 441 (third output end), and is configured to output from the output terminal 441 a first output signal input from the input terminal 442, and a second output signal input from the input terminal 443 having a phase of -90° relative to the first output signal. The power amplifier circuit 20 includes: a power amplifier 21 having a fourth input terminal and a fourth output terminal, the fourth input terminal being connected to the output terminal 102; and a harmonic phase shift circuit 22, which is connected to the path connecting the fourth output terminal to the input terminal 442, and is configured to shift the phase of the second harmonic of the first frequency band. The power amplifier circuit 30 includes: a power amplifier 31 having a fifth input terminal and a fifth output terminal, the fifth input terminal being connected to the output terminal 103; and a harmonic phase shift circuit 32, which is connected to the path connecting the fifth output terminal to the input terminal 443, and is configured to shift the phase of the second harmonic, and the phase shift difference obtained by subtracting the phase of the second harmonic at the input terminal 443 from the phase of the second harmonic at the input terminal 442 is 90°.

[0191] This method can suppress the second harmonic in the first frequency band over a wide bandwidth compared to conventional 90° synthesizer-type balanced amplifiers without an additional harmonic phase shift circuit, thereby improving the quality of transmitted signals and power efficiency.

[0192] For example, in the amplifier circuit 1F, the harmonic phase shift circuit 22 is configured to make the harmonic pass phase +45°, and the harmonic phase shift circuit 32 is configured to make the harmonic pass phase -45°.

[0193] Thus, the second harmonic of the first frequency band has a phase difference of 270° between input terminals 442 and 443 of the 90° synthesizer 44 and is inverted and canceled by the 90° synthesizer 44. Therefore, an amplifier circuit 1F having improved transmission signal quality and power efficiency can be provided.

[0194] In addition, the amplifier circuit 1 according to the present embodiment (the amplifier circuit 1A according to the first variant and the amplifier circuit 1C according to the second variant) includes: a demultiplexer 10 having an input terminal 101 and output terminals 102 and 103, and configured to demultiplex a fundamental wave signal of a transmission frequency band of a first frequency band input to the input terminal 101, output a first signal from the output terminal 102, and output a second signal having a phase of -90° with respect to the first signal from the output terminal 103; a power amplifier 21 having a fourth input terminal and a fourth output terminal, the fourth input terminal being connected to the output terminal 102; a power amplifier 31 having a fifth input terminal and a fifth output terminal, the fifth input terminal being connected to the output terminal 103; and an in-phase synthesizer 41 having input terminals 402 and 403 and an output terminal 401, and configured to output a third output signal from the output terminal 401, the third output signal being a combination of the first output signal output from the power amplifier 21 and the output terminal 402. The first frequency band is a first frequency band in which the first and second harmonics are phase-shifted. The first frequency band is a first frequency band in which the first and second harmonics are phase-shifted. The first frequency band is a first frequency band in which the first and second harmonics are phase-shifted. The first frequency band is a first frequency band in which the first and second harmonics are phase-shifted. The first frequency band is a first frequency band in which the first and second harmonics are phase-shifted. The first frequency band is a first frequency band in which the first and second harmonics are phase-shifted. The first frequency band is a first frequency band in which the first and second harmonics are phase-shifted. The second harmonic is phase-shifted; a harmonic phase-shifting circuit 22 (22A) is connected to a path connecting the fourth output terminal and the input terminal 402, and is configured to phase-shift the second harmonic; and a harmonic phase-shifting circuit 32 (32A) is connected to a path connecting the fifth output terminal and the input terminal 403, and is configured to phase-shift the second harmonic, wherein a phase shift difference obtained by subtracting the phase of the second harmonic at the input terminal 403 from the phase of the second harmonic at the input terminal 402 is greater than 90°.

[0195] This allows for highly accurate suppression of the second harmonic in the first frequency band compared to conventional in-phase synthesizer-type balanced amplifiers without an additional harmonic phase shift circuit. This allows the amplifier to function as a balanced amplifier with robustness against load fluctuations, improving both the quality of transmitted signals and power efficiency.

[0196] For another example, in the amplifier circuit 1B, the first phase shift difference obtained by subtracting the passing phase of the second harmonic of the harmonic phase shift circuit 32 from the passing phase of the second harmonic of the harmonic phase shift circuit 22 is equal to the second phase shift difference obtained by subtracting the passing phase of the second harmonic of the phase shift circuit 23 from the passing phase of the second harmonic of the phase shift circuit 33.

[0197] Thus, the second harmonic of the first frequency band is canceled out by a phase difference of 180° (in an anti-phase relationship) between the input terminals 402 and 403 of the in-phase synthesizer 41. Therefore, an amplifier circuit 1B having improved transmission signal quality and power efficiency can be provided.

[0198] For example, in amplifier circuit 1B, phase shift circuit 23 is configured so that the passing phase between the fundamental wave and the second harmonic is -45°, phase shift circuit 33 is configured so that the passing phase between the fundamental wave and the second harmonic is +45°, harmonic phase shift circuit 22 is configured so that the passing phase of the harmonic is +45°, and harmonic phase shift circuit 32 is configured so that the passing phase of the harmonic is -45°.

[0199] Thus, the second harmonic of the first frequency band is canceled out by a phase difference of 180° (in an anti-phase relationship) between the input terminals 402 and 403 of the in-phase synthesizer 41. Therefore, an amplifier circuit 1B having improved transmission signal quality and power efficiency can be provided.

[0200] For example, in the amplifier circuit 1B, the phase shift circuit 23 is configured so that the passing phase of the fundamental wave is -45° and the passing phase of the harmonics is -X° (X>0), the phase shift circuit 33 is configured so that the passing phase of the fundamental wave is +45° and the passing phase of the harmonics is +Y° (Y>0), the harmonic phase shift circuit 22 is configured so that the passing phase of the harmonics is +X° (X>0), and the harmonic phase shift circuit 32 is configured so that the passing phase of the harmonics is -Y° (Y>0).

[0201] Thus, the second harmonic of the first frequency band is canceled out by a phase difference of 180° (in an anti-phase relationship) between the input terminals 402 and 403 of the in-phase synthesizer 41. Therefore, an amplifier circuit 1B having improved transmission signal quality and power efficiency can be provided.

[0202] For example, in amplifier circuit 1 (1A and 1B), phase shift circuit 23 includes an inductor 231 connected between the fourth output terminal and input terminal 402, and a capacitor 232 connected between a path connecting inductor 231 and input terminal 402 and ground. Phase shift circuit 33 includes a capacitor 331 connected between the fifth output terminal and input terminal 403, and an inductor 332 connected between a path connecting capacitor 331 and input terminal 403 and ground.

[0203] Thus, the phase shift circuit 23 forms a low-pass filter with the fundamental wave band and the second harmonic band of the first frequency band as passbands, and can set the passing phase of the fundamental wave in the first frequency band to -45° and the passing phase of the second harmonic to -45° (-X°: X>0). Furthermore, the phase shift circuit 33 forms a high-pass filter with the fundamental wave band and the second harmonic band of the first frequency band as passbands, and can set the passing phase of the fundamental wave in the first frequency band to +45° and the passing phase of the second harmonic to +45° (+Y°: Y>0).

[0204] For example, in the amplifier circuit 1 (1A and 1B), the harmonic phase shift circuit 22 (22A) includes an LC circuit including an inductor 221 and a capacitor 222 connected in series with each other, and the LC circuit is connected between the path connecting the fourth output terminal and the inductor 231 and the ground, and the harmonic phase shift circuit 32 (32A) includes a capacitor 321, and the capacitor 321 is connected between the path connecting the fifth output terminal and the capacitor 331 and the ground.

[0205] Thus, the harmonic phase shift circuit 22 (22A) forms a notch filter having the fundamental wave band of the first frequency range as a passband and the second harmonic band as an attenuation band, and is capable of setting the passing phase of the fundamental wave to 0° and the passing phase of the second harmonic to +45° (+X°: X>0). Furthermore, the harmonic phase shift circuit 32 (32A) forms a low-pass filter having the fundamental wave band of the first frequency range as a passband and the second harmonic band as an attenuation band, and is capable of setting the passing phase of the fundamental wave to 0° and the passing phase of the second harmonic to -45° (-Y°: Y>0).

[0206] For example, in the amplifier circuit 1 (1A and 1B), the phase shift circuits 23 and 33 and the harmonic phase shift circuits 22 (22A) and 32 (32A) are included in one semiconductor IC.

[0207] This allows the amplifier circuit 1 (1A and 1B) to be miniaturized and shortens the signal wiring from the power amplifiers 21 and 31 to the in-phase combiner 41, thereby reducing signal transmission loss in the amplifier circuit 1 (1A and 1B).

[0208] (Other embodiments, etc.)

[0209] While the amplifier circuits according to the embodiments of the present invention have been described above by way of examples and variations, the amplifier circuits according to the present invention are not limited to the aforementioned embodiments and variations. Other embodiments implemented by combining arbitrary components of the aforementioned embodiments and variations, variations resulting from various modifications of the aforementioned embodiments and variations that would be conceivable by those skilled in the art without departing from the spirit of the present invention, and various devices incorporating the aforementioned amplifier circuits are also encompassed by the present invention.

[0210] For example, in the amplifier circuits according to the above-described embodiment and modified examples, second harmonics are used as harmonics, but third-order harmonics and higher-order harmonics may also be used.

[0211] For example, in the amplifier circuits according to the above-described embodiments and modifications, other circuit elements, wiring, etc. may be inserted between paths connecting the circuit elements and signal paths disclosed in the drawings.

[0212] Next, features of the amplifier circuit described in each of the above embodiments will be described.

[0213] <1>

[0214] An amplifier circuit comprising:

[0215] A first power amplifying circuit, comprising a first power amplifier;

[0216] a second power amplification circuit comprising a second power amplifier, wherein a phase of a fundamental wave at an output terminal of the second power amplifier lags by 90° relative to that of the first power amplifier; and

[0217] a synthesizing circuit configured to synthesize a fundamental wave of a first output signal output from the first power amplifier circuit and a fundamental wave of a second output signal output from the second power amplifier circuit;

[0218] Wherein, the first power amplifier circuit is an inverse E class,

[0219] The second power amplifier circuit is class E.

[0220] <2>

[0221] according to <1> The amplifier circuit, wherein

[0222] The device further comprises a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, and configured to demultiplex a fundamental wave signal of a transmission frequency band of a first frequency band input to the first input terminal, output a first signal from the first output terminal, and output a second signal having a phase of -90° with respect to the first signal from the second output terminal.

[0223] The synthesis circuit comprises:

[0224] a synthesizer having a second input terminal, a third input terminal, and a third output terminal, and configured to output, from the third output terminal, a third output signal generated by in-phase synthesizing the first output signal input from the second input terminal and the second output signal input from the third input terminal;

[0225] a first phase shift circuit connected between the first power amplifier circuit and the synthesizer, and configured to shift the phase of the fundamental wave and harmonics of the first frequency band; and

[0226] a second phase shift circuit connected between the second power amplifier circuit and the synthesizer and configured to shift the phase of the fundamental wave and harmonics of the first frequency band so that the passing phase of the fundamental wave relative to the first phase shift circuit is +90°;

[0227] The first power amplifier circuit includes:

[0228] a first power amplifier having a fourth input terminal and a fourth output terminal, wherein the fourth input terminal is connected to the first output terminal; and

[0229] a first harmonic phase shift circuit connected to a path connecting the fourth output terminal and the second input terminal and configured to shift the phase of the harmonic;

[0230] The second power amplifier circuit includes:

[0231] a second power amplifier having a fifth input terminal and a fifth output terminal, wherein the fifth input terminal is connected to the second output terminal; and

[0232] a second harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third input terminal and configured to shift the phase of the harmonic;

[0233] A phase shift difference obtained by subtracting the phase of the harmonic at the third input terminal from the phase of the harmonic at the second input terminal is greater than 90°.

[0234] <3>

[0235] according to <2> The amplifier circuit, wherein

[0236] A first phase shift difference obtained by subtracting the passing phase of the harmonic of the second harmonic phase shift circuit from the passing phase of the harmonic of the first harmonic phase shift circuit is equal to a second phase shift difference obtained by subtracting the passing phase of the harmonic of the first phase shift circuit from the passing phase of the harmonic of the second phase shift circuit.

[0237] <4>

[0238] according to <3> The amplifier circuit, wherein

[0239] The first phase shift circuit is configured to make the passing phase of the fundamental wave and the harmonics -45 degrees.

[0240] The second phase shift circuit is configured to make the passing phase of the fundamental wave and the harmonics +45°.

[0241] The first harmonic phase shift circuit is configured to make the passing phase of the harmonic +45°.

[0242] The second harmonic phase shift circuit is configured to make the passing phase of the harmonics -45 degrees.

[0243] <5>

[0244] according to <3> The amplifier circuit, wherein

[0245] The first phase shift circuit is configured to make the passing phase of the fundamental wave -45° and the passing phase of the harmonic wave -X°, where X>0.

[0246] The second phase shift circuit is configured to make the passing phase of the fundamental wave +45° and the passing phase of the harmonic wave +Y°, where Y>0.

[0247] The first harmonic phase shift circuit is configured to make the passing phase of the harmonic +X°, where X>0,

[0248] The second harmonic phase shift circuit is configured to make the passing phase of the harmonic be -Y°, where Y>0.

[0249] <6>

[0250] according to <1> The amplifier circuit, wherein

[0251] The device further comprises a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, and configured to demultiplex a fundamental wave signal of a transmission frequency band of a first frequency band input to the first input terminal, output a first signal from the first output terminal, and output a second signal having a phase of -90° with respect to the first signal from the second output terminal.

[0252] The synthesizing circuit includes a phase shift circuit having a second input terminal and a third output terminal, and configured to delay the fundamental wave of the first output signal input from the second input terminal by 90°.

[0253] The first power amplifier circuit includes:

[0254] a carrier amplifier having a third input terminal and a fourth output terminal, wherein the third input terminal is connected to the first output terminal, and the fourth output terminal is connected to the second input terminal; and

[0255] a first harmonic phase shift circuit connected to a path connecting the fourth output terminal and the second input terminal and configured to shift the phase of harmonics in the first frequency band;

[0256] The second power amplifier circuit includes:

[0257] a peak amplifier having a fourth input terminal and a fifth output terminal, wherein the fourth input terminal is connected to the second output terminal and the fifth output terminal is connected to the third output terminal; and

[0258] a second harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third output terminal and configured to shift the phase of the harmonic;

[0259] A phase shift difference obtained by subtracting a phase of the harmonic input from the fifth output terminal to the third output terminal from a phase of the harmonic input from the fourth output terminal to the third output terminal is greater than 90°.

[0260] <7>

[0261] according to <1> The amplifier circuit, wherein

[0262] The device further comprises a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, and configured to demultiplex a fundamental wave signal of a transmission frequency band of a first frequency band input to the first input terminal, output a first signal from the first output terminal, and output a second signal having a phase of -90° with respect to the first signal from the second output terminal.

[0263] The synthesis circuit comprises:

[0264] a phase shift circuit having a second input terminal and a third output terminal, and configured to delay a fundamental wave of the second output signal input from the second input terminal by 90°; and

[0265] a transformer having a third input terminal, a fourth input terminal, and a fourth output terminal, and configured to output, from the fourth output terminal, a third output signal generated by inversely combining the first output signal input from the third input terminal and the second output signal input from the fourth input terminal;

[0266] The first power amplifier circuit includes:

[0267] a carrier amplifier having a fifth input terminal and a fifth output terminal, wherein the fifth input terminal is connected to the first output terminal, and the fifth output terminal is connected to the third input terminal; and

[0268] a first harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third input terminal and configured to shift the phase of harmonics in the first frequency band;

[0269] The second power amplifier circuit includes:

[0270] a peak amplifier having a sixth input terminal and a sixth output terminal, the sixth input terminal being connected to the second output terminal, the sixth output terminal being connected to the second input terminal; and

[0271] a second harmonic phase shift circuit connected to a path connecting the sixth output terminal and the second input terminal and configured to shift the phase of the harmonic;

[0272] A phase shift difference obtained by subtracting the phase of the harmonic at the fourth input terminal from the phase of the harmonic at the third input terminal is less than 90°.

[0273] <8>

[0274] according to <1> The amplifier circuit, wherein

[0275] The device further comprises a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, and configured to demultiplex a fundamental wave signal of a transmission frequency band of a first frequency band input to the first input terminal, output a first signal from the first output terminal, and output a second signal having a phase of -90° with respect to the first signal from the second output terminal.

[0276] The synthesis circuit comprises:

[0277] a transformer having a second input terminal, a third input terminal, and a third output terminal, and configured to output, from the third output terminal, a third output signal generated by inversely combining the first output signal input from the second input terminal and the second output signal input from the third input terminal;

[0278] a first phase shift circuit connected between the first power amplifier circuit and the transformer, and configured to perform phase shifting on the fundamental wave and harmonics of the first frequency band; and

[0279] a second phase shift circuit connected between the second power amplifier circuit and the transformer and configured to phase shift the fundamental wave and harmonics of the first frequency band so that the passing phase of the fundamental wave relative to the first phase shift circuit is -90°;

[0280] The first power amplifier circuit includes:

[0281] a first power amplifier having a fourth input terminal and a fourth output terminal, wherein the fourth input terminal is connected to the first output terminal; and

[0282] a first harmonic phase shift circuit connected to a path connecting the fourth output terminal and the second input terminal and configured to shift the phase of the harmonic;

[0283] The second power amplifier circuit includes:

[0284] a second power amplifier having a fifth input terminal and a fifth output terminal, wherein the fifth input terminal is connected to the second output terminal; and

[0285] a second harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third input terminal and configured to shift the phase of the harmonic;

[0286] A phase shift difference obtained by subtracting the phase of the harmonic at the third input terminal from the phase of the harmonic at the second input terminal is less than 90°.

[0287] <9>

[0288] according to <8> The amplifier circuit, wherein

[0289] A first phase shift difference obtained by subtracting the passing phase of the harmonic of the second harmonic phase shift circuit from the passing phase of the harmonic of the first harmonic phase shift circuit is equal to a second phase shift difference obtained by subtracting the passing phase of the harmonic of the second phase shift circuit from the passing phase of the harmonic of the first phase shift circuit.

[0290] <10>

[0291] according to <9> The amplifier circuit, wherein

[0292] The first phase shift circuit is configured to make the passing phase of the fundamental wave and the harmonics +45°.

[0293] The second phase shift circuit is configured to make the passing phase of the fundamental wave and the harmonics -45 degrees.

[0294] The first harmonic phase shift circuit is configured to make the passing phase of the harmonic +45°.

[0295] The second harmonic phase shift circuit is configured to make the passing phase of the harmonics -45 degrees.

[0296] <11>

[0297] according to <1> The amplifier circuit, wherein

[0298] The device further comprises a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, and configured to demultiplex a fundamental wave signal of a transmission frequency band of a first frequency band input to the first input terminal, output a first signal from the first output terminal, and output a second signal having a phase of -90° with respect to the first signal from the second output terminal.

[0299] The synthesizer circuit includes a synthesizer having a second input terminal, a third input terminal, and a third output terminal, and is configured to output from the third output terminal a third output signal generated by synthesizing the first output signal input from the second input terminal and the second output signal input from the third input terminal with a phase of +90° relative to the first output signal.

[0300] The first power amplifier circuit includes:

[0301] a first power amplifier having a fourth input terminal and a fourth output terminal, wherein the fourth input terminal is connected to the first output terminal; and

[0302] a first harmonic phase shift circuit connected to a path connecting the fourth output terminal and the second input terminal and configured to shift the phase of harmonics in the first frequency band;

[0303] The second power amplifier circuit includes:

[0304] a second power amplifier having a fifth input terminal and a fifth output terminal, wherein the fifth input terminal is connected to the second output terminal; and

[0305] a second harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third input terminal and configured to shift the phase of the harmonic;

[0306] The phase shift difference obtained by subtracting the phase of the harmonic at the second input terminal from the phase of the harmonic at the third input terminal is 90°.

[0307] <12>

[0308] according to <11> The amplifier circuit, wherein

[0309] The first harmonic phase shift circuit is configured to make the passing phase of the harmonic +45°.

[0310] The second harmonic phase shift circuit is configured to make the passing phase of the harmonics -45 degrees.

[0311] <13>

[0312] An amplifier circuit comprising:

[0313] a wave splitter having a first input terminal, a first output terminal, and a second output terminal, and configured to split a fundamental wave signal of a transmission frequency band in a first frequency range input to the first input terminal, output a first signal from the first output terminal, and output a second signal having a phase of -90° relative to the first signal from the second output terminal;

[0314] a first power amplifier having a fourth input terminal and a fourth output terminal, wherein the fourth input terminal is connected to the first output terminal;

[0315] a second power amplifier having a fifth input terminal and a fifth output terminal, wherein the fifth input terminal is connected to the second output terminal;

[0316] a synthesizer having a second input terminal, a third input terminal, and a third output terminal, and configured to output a third output signal from the third output terminal, the third output signal being a signal obtained by in-phase synthesizing the first output signal output from the first power amplifier input through the second input terminal and the second output signal output from the second power amplifier input through the third input terminal;

[0317] a first phase shift circuit connected between the first power amplifier and the synthesizer and configured to shift the phase of the fundamental wave and harmonics of the first frequency band;

[0318] a second phase shift circuit connected between the second power amplifier and the synthesizer and configured to shift the phase of the fundamental wave and harmonics of the first frequency band so that the passing phase of the fundamental wave relative to the first phase shift circuit is +90°;

[0319] a first harmonic phase shift circuit connected to a path connecting the fourth output terminal and the second input terminal and configured to shift the phase of the harmonic; and

[0320] a second harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third input terminal and configured to shift the phase of the harmonic;

[0321] The phase shift difference obtained by subtracting the phase of the harmonic at the third input terminal from the phase of the harmonic at the second input terminal is greater than 90°.

[0322] <14>

[0323] according to <13> The amplifier circuit, wherein

[0324] A first phase shift difference obtained by subtracting the passing phase of the harmonic of the second harmonic phase shift circuit from the passing phase of the harmonic of the first harmonic phase shift circuit is equal to a second phase shift difference obtained by subtracting the passing phase of the harmonic of the first phase shift circuit from the passing phase of the harmonic of the second phase shift circuit.

[0325] <15>

[0326] according to <14> The amplifier circuit, wherein

[0327] The first phase shift circuit is configured to make the passing phase of the fundamental wave and the harmonics -45 degrees.

[0328] The second phase shift circuit is configured to make the passing phase of the fundamental wave and the harmonics +45°.

[0329] The first harmonic phase shift circuit is configured to make the passing phase of the harmonic +45°.

[0330] The second harmonic phase shift circuit is configured to make the passing phase of the harmonics -45 degrees.

[0331] <16>

[0332] according to <14> The amplifier circuit, wherein

[0333] The first phase shift circuit is configured to make the passing phase of the fundamental wave -45° and the passing phase of the harmonic wave -X°, where X>0.

[0334] The second phase shift circuit is configured to make the passing phase of the fundamental wave +45° and the passing phase of the harmonic wave +Y°, where Y>0.

[0335] The first harmonic phase shift circuit is configured to make the passing phase of the harmonic +X°, where X>0,

[0336] The second harmonic phase shift circuit is configured to make the passing phase of the harmonic be -Y°, where Y>0.

[0337] <17>

[0338] according to <13> ~ <16> The amplifier circuit according to any one of claims 1 to 5, wherein:

[0339] The first phase shift circuit includes:

[0340] a first inductor connected between the fourth output terminal and the second input terminal; and

[0341] a first capacitor connected between a path connecting the first inductor and the second input terminal and ground;

[0342] The second phase shift circuit includes:

[0343] a second capacitor connected between the fifth output terminal and the third input terminal; and

[0344] A second inductor is connected between a path connecting the second capacitor and the third input terminal and a ground.

[0345] <18>

[0346] according to <17> The amplifier circuit, wherein

[0347] The first harmonic phase shift circuit has an LC circuit including a third inductor and a third capacitor connected in series with each other.

[0348] The LC circuit is connected between a path connecting the fourth output terminal and the first inductor and a ground.

[0349] The second harmonic phase shift circuit includes a fourth capacitor connected between a path connecting the fifth output terminal and the second capacitor and a ground.

[0350] <19>

[0351] according to <13> ~ <18> The amplifier circuit according to any one of claims 1 to 5, wherein:

[0352] The first phase shift circuit, the second phase shift circuit, the first harmonic phase shift circuit, and the second harmonic phase shift circuit are included in one semiconductor IC.

[0353] Industrial applicability

[0354] The present invention can be widely used in communication devices such as mobile phones as an amplifier circuit arranged at the front end.

[0355] Description of Reference Numerals

[0356] 1, 1A, 1B, 1C, 1D, 1E, 1F, 500: amplifier circuit; 10: splitter; 20, 20A, 30, 30A, 520, 530: power amplifier circuit; 21, 31: power amplifier; 22, 22A, 32, 32A: harmonic phase shift circuit; 23, 23C, 33, 33C: phase shift circuit; 40: in-phase synthesis circuit; 40C: anti-phase synthesis circuit; 41: in-phase synthesis circuit Synthesizer; 42, 43: Transformer; 44: 90° synthesizer; 50, 51: Phase-shift circuit; 101, 402, 403, 422, 423, 432, 433, 442, 443: Input terminals; 102, 103, 104, 401, 421, 431, 441: Output terminals; 221, 231, 332: Inductors; 222, 232, 321, 331: Capacitors.

Claims

1. An amplifier circuit comprising: A first power amplifying circuit, comprising a first power amplifier; a second power amplification circuit comprising a second power amplifier, wherein a phase of a fundamental wave at an output terminal of the second power amplifier lags by 90° relative to that of the first power amplifier; and a synthesizing circuit configured to synthesize a fundamental wave of a first output signal output from the first power amplifier circuit and a fundamental wave of a second output signal output from the second power amplifier circuit; in, The first power amplifier circuit is an inverse E class, The second power amplifier circuit is class E.

2. The amplifier circuit according to claim 1, wherein: The device further comprises a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, and configured to demultiplex a fundamental wave signal of a transmission frequency band of a first frequency band input to the first input terminal, output a first signal from the first output terminal, and output a second signal having a phase of -90° with respect to the first signal from the second output terminal. The synthesis circuit comprises: a synthesizer having a second input terminal, a third input terminal, and a third output terminal, and configured to output, from the third output terminal, a third output signal generated by in-phase synthesizing the first output signal input from the second input terminal and the second output signal input from the third input terminal; a first phase shift circuit connected between the first power amplifier circuit and the synthesizer, and configured to shift the phase of the fundamental wave and harmonics of the first frequency band; and a second phase shift circuit connected between the second power amplifier circuit and the synthesizer and configured to shift the phase of the fundamental wave and harmonics of the first frequency band so that the passing phase of the fundamental wave relative to the first phase shift circuit is +90°; The first power amplifier circuit includes: a first power amplifier having a fourth input terminal and a fourth output terminal, wherein the fourth input terminal is connected to the first output terminal; and a first harmonic phase shift circuit connected to a path connecting the fourth output terminal and the second input terminal and configured to shift the phase of the harmonic; The second power amplifier circuit includes: a second power amplifier having a fifth input terminal and a fifth output terminal, wherein the fifth input terminal is connected to the second output terminal; and a second harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third input terminal and configured to shift the phase of the harmonic; A phase shift difference obtained by subtracting the phase of the harmonic at the third input terminal from the phase of the harmonic at the second input terminal is greater than 90°.

3. The amplifier circuit according to claim 2, wherein: A first phase shift difference obtained by subtracting the passing phase of the harmonic of the second harmonic phase shift circuit from the passing phase of the harmonic of the first harmonic phase shift circuit is equal to a second phase shift difference obtained by subtracting the passing phase of the harmonic of the first phase shift circuit from the passing phase of the harmonic of the second phase shift circuit.

4. The amplifier circuit according to claim 3, wherein: The first phase shift circuit is configured to make the passing phase of the fundamental wave and the harmonics -45 degrees. The second phase shift circuit is configured to make the passing phase of the fundamental wave and the harmonics +45°. The first harmonic phase shift circuit is configured to make the passing phase of the harmonic +45°. The second harmonic phase shift circuit is configured to make the passing phase of the harmonics -45 degrees.

5. The amplifier circuit according to claim 3, wherein: The first phase shift circuit is configured to make the passing phase of the fundamental wave -45° and the passing phase of the harmonic wave -X°, where X>0. The second phase shift circuit is configured to make the passing phase of the fundamental wave +45° and the passing phase of the harmonic wave +Y°, where Y>0. The first harmonic phase shift circuit is configured to make the passing phase of the harmonic +X°, where X>0, The second harmonic phase shift circuit is configured to make the passing phase of the harmonic be -Y°, where Y>0.

6. The amplifier circuit according to claim 1, wherein: The device further comprises a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, and configured to demultiplex a fundamental wave signal of a transmission frequency band of a first frequency band input to the first input terminal, output a first signal from the first output terminal, and output a second signal having a phase of -90° with respect to the first signal from the second output terminal. The synthesizing circuit includes a phase shift circuit having a second input terminal and a third output terminal, and configured to delay the fundamental wave of the first output signal input from the second input terminal by 90°. The first power amplifier circuit includes: a carrier amplifier having a third input terminal and a fourth output terminal, wherein the third input terminal is connected to the first output terminal, and the fourth output terminal is connected to the second input terminal; and a first harmonic phase shift circuit connected to a path connecting the fourth output terminal and the second input terminal and configured to shift the phase of harmonics in the first frequency band; The second power amplifier circuit includes: a peak amplifier having a fourth input terminal and a fifth output terminal, wherein the fourth input terminal is connected to the second output terminal and the fifth output terminal is connected to the third output terminal; and a second harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third output terminal and configured to shift the phase of the harmonic; A phase shift difference obtained by subtracting a phase of the harmonic input from the fifth output terminal to the third output terminal from a phase of the harmonic input from the fourth output terminal to the third output terminal is greater than 90°.

7. The amplifier circuit according to claim 1, wherein: The device further comprises a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, and configured to demultiplex a fundamental wave signal of a transmission frequency band of a first frequency band input to the first input terminal, output a first signal from the first output terminal, and output a second signal having a phase of -90° with respect to the first signal from the second output terminal. The synthesis circuit comprises: a phase shift circuit having a second input terminal and a third output terminal, and configured to delay a fundamental wave of the second output signal input from the second input terminal by 90°; and a transformer having a third input terminal, a fourth input terminal, and a fourth output terminal, and configured to output, from the fourth output terminal, a third output signal generated by inversely combining the first output signal input from the third input terminal and the second output signal input from the fourth input terminal; The first power amplifier circuit includes: a carrier amplifier having a fifth input terminal and a fifth output terminal, wherein the fifth input terminal is connected to the first output terminal, and the fifth output terminal is connected to the third input terminal; and a first harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third input terminal and configured to shift the phase of harmonics in the first frequency band; The second power amplifier circuit includes: a peak amplifier having a sixth input terminal and a sixth output terminal, the sixth input terminal being connected to the second output terminal, the sixth output terminal being connected to the second input terminal; and a second harmonic phase shift circuit connected to a path connecting the sixth output terminal and the second input terminal and configured to shift the phase of the harmonic; A phase shift difference obtained by subtracting the phase of the harmonic at the fourth input terminal from the phase of the harmonic at the third input terminal is less than 90°.

8. The amplifier circuit according to claim 1, wherein: The device further comprises a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, and configured to demultiplex a fundamental wave signal of a transmission frequency band of a first frequency band input to the first input terminal, output a first signal from the first output terminal, and output a second signal having a phase of -90° with respect to the first signal from the second output terminal. The synthesis circuit comprises: a transformer having a second input terminal, a third input terminal, and a third output terminal, and configured to output, from the third output terminal, a third output signal generated by inversely combining the first output signal input from the second input terminal and the second output signal input from the third input terminal; a first phase shift circuit connected between the first power amplifier circuit and the transformer, and configured to perform phase shifting on the fundamental wave and harmonics of the first frequency band; and a second phase shift circuit connected between the second power amplifier circuit and the transformer and configured to phase shift the fundamental wave and harmonics of the first frequency band so that the passing phase of the fundamental wave relative to the first phase shift circuit is -90°; The first power amplifier circuit includes: a first power amplifier having a fourth input terminal and a fourth output terminal, wherein the fourth input terminal is connected to the first output terminal; and a first harmonic phase shift circuit connected to a path connecting the fourth output terminal and the second input terminal and configured to shift the phase of the harmonic; The second power amplifier circuit includes: a second power amplifier having a fifth input terminal and a fifth output terminal, wherein the fifth input terminal is connected to the second output terminal; and a second harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third input terminal and configured to shift the phase of the harmonic; A phase shift difference obtained by subtracting the phase of the harmonic at the third input terminal from the phase of the harmonic at the second input terminal is less than 90°.

9. The amplifier circuit according to claim 8, wherein: A first phase shift difference obtained by subtracting the passing phase of the harmonic of the second harmonic phase shift circuit from the passing phase of the harmonic of the first harmonic phase shift circuit is equal to a second phase shift difference obtained by subtracting the passing phase of the harmonic of the second phase shift circuit from the passing phase of the harmonic of the first phase shift circuit.

10. The amplifier circuit according to claim 9, wherein: The first phase shift circuit is configured to make the passing phase of the fundamental wave and the harmonics +45°. The second phase shift circuit is configured to make the passing phase of the fundamental wave and the harmonics -45 degrees. The first harmonic phase shift circuit is configured to make the passing phase of the harmonic +45°. The second harmonic phase shift circuit is configured to make the passing phase of the harmonics -45 degrees.

11. The amplifier circuit according to claim 1, wherein: The device further comprises a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, and configured to demultiplex a fundamental wave signal of a transmission frequency band of a first frequency band input to the first input terminal, output a first signal from the first output terminal, and output a second signal having a phase of -90° with respect to the first signal from the second output terminal. The synthesizer circuit includes a synthesizer having a second input terminal, a third input terminal, and a third output terminal, and is configured to output from the third output terminal a third output signal generated by synthesizing the first output signal input from the second input terminal and the second output signal input from the third input terminal with a phase of +90° relative to the first output signal. The first power amplifier circuit includes: a first power amplifier having a fourth input terminal and a fourth output terminal, wherein the fourth input terminal is connected to the first output terminal; and a first harmonic phase shift circuit connected to a path connecting the fourth output terminal and the second input terminal and configured to shift the phase of harmonics in the first frequency band; The second power amplifier circuit includes: a second power amplifier having a fifth input terminal and a fifth output terminal, wherein the fifth input terminal is connected to the second output terminal; and a second harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third input terminal and configured to shift the phase of the harmonic; The phase shift difference obtained by subtracting the phase of the harmonic at the second input terminal from the phase of the harmonic at the third input terminal is 90°.

12. The amplifier circuit according to claim 11, wherein: The first harmonic phase shift circuit is configured to make the passing phase of the harmonic +45°. The second harmonic phase shift circuit is configured to make the passing phase of the harmonics -45 degrees.

13. An amplifier circuit comprising: a wave splitter having a first input terminal, a first output terminal, and a second output terminal, and configured to split a fundamental wave signal of a transmission frequency band in a first frequency range input to the first input terminal, output a first signal from the first output terminal, and output a second signal having a phase of -90° relative to the first signal from the second output terminal; a first power amplifier having a fourth input terminal and a fourth output terminal, wherein the fourth input terminal is connected to the first output terminal; a second power amplifier having a fifth input terminal and a fifth output terminal, wherein the fifth input terminal is connected to the second output terminal; a synthesizer having a second input terminal, a third input terminal, and a third output terminal, and configured to output a third output signal from the third output terminal, the third output signal being a signal obtained by in-phase synthesizing the first output signal output from the first power amplifier input through the second input terminal and the second output signal output from the second power amplifier input through the third input terminal; a first phase shift circuit connected between the first power amplifier and the synthesizer and configured to shift the phase of the fundamental wave and harmonics of the first frequency band; a second phase shift circuit connected between the second power amplifier and the synthesizer and configured to shift the phase of the fundamental wave and harmonics of the first frequency band so that the passing phase of the fundamental wave relative to the first phase shift circuit is +90°; a first harmonic phase shift circuit connected to a path connecting the fourth output terminal and the second input terminal and configured to shift the phase of the harmonic; as well as a second harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third input terminal and configured to shift the phase of the harmonic; The phase shift difference obtained by subtracting the phase of the harmonic at the third input terminal from the phase of the harmonic at the second input terminal is greater than 90°.

14. The amplifier circuit according to claim 13, wherein: A first phase shift difference obtained by subtracting the passing phase of the harmonic of the second harmonic phase shift circuit from the passing phase of the harmonic of the first harmonic phase shift circuit is equal to a second phase shift difference obtained by subtracting the passing phase of the harmonic of the first phase shift circuit from the passing phase of the harmonic of the second phase shift circuit.

15. The amplifier circuit according to claim 14, wherein: The first phase shift circuit is configured to make the passing phase of the fundamental wave and the harmonics -45 degrees. The second phase shift circuit is configured to make the passing phase of the fundamental wave and the harmonics +45°. The first harmonic phase shift circuit is configured to make the passing phase of the harmonic +45°. The second harmonic phase shift circuit is configured to make the passing phase of the harmonics -45 degrees.

16. The amplifier circuit according to claim 14, wherein: The first phase shift circuit is configured to make the passing phase of the fundamental wave -45° and the passing phase of the harmonic wave -X°, where X>0. The second phase shift circuit is configured to make the passing phase of the fundamental wave +45° and the passing phase of the harmonic wave +Y°, where Y>0. The first harmonic phase shift circuit is configured to make the passing phase of the harmonic +X°, where X>0, The second harmonic phase shift circuit is configured to make the passing phase of the harmonic be -Y°, where Y>0.

17. The amplifier circuit according to any one of claims 13 to 16, wherein: The first phase shift circuit includes: a first inductor connected between the fourth output terminal and the second input terminal; and a first capacitor connected between a path connecting the first inductor and the second input terminal and ground; The second phase shift circuit includes: a second capacitor connected between the fifth output terminal and the third input terminal; and A second inductor is connected between a path connecting the second capacitor and the third input terminal and a ground.

18. The amplifier circuit according to claim 17, wherein: The first harmonic phase shift circuit has an LC circuit including a third inductor and a third capacitor connected in series with each other. The LC circuit is connected between a path connecting the fourth output terminal and the first inductor and a ground. The second harmonic phase shift circuit includes a fourth capacitor connected between a path connecting the fifth output terminal and the second capacitor and a ground.

19. The amplifier circuit according to any one of claims 13 to 18, wherein: The first phase shift circuit, the second phase shift circuit, the first harmonic phase shift circuit, and the second harmonic phase shift circuit are included in one semiconductor integrated circuit, ie, a semiconductor IC.

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