Amplifier circuit

Abstract

To provide an amplifier circuit capable of suppressing a harmonic wave with a high degree of accuracy.SOLUTION: An amplifier circuit 1 comprises: a power amplifier circuit 20 including a power amplifier 21; a power amplifier circuit 30 including a power amplifier 31 in which a phase of a fundamental wave at an output end is delayed by 90° with respect to the power amplifier 21; and an in-phase synthesis circuit 40 that is constituted to synthesize the fundamental wave of a first output signal output from the power amplifier circuit 20 and the fundamental wave of a second output signal output from the power amplifier circuit 30. The power amplifier circuit 20 is an inverse class-E one, and the power amplifier circuit 30 is an E-class one.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a power amplifier that comprises first and second amplifying means that constitute a balanced amplifier and operate in class F, and a filter that passes second harmonics and is connected between the output terminals of the first and second amplifying means. By canceling out the second harmonics at the output terminals of the first and second amplifying means, it is possible to improve power efficiency in the fundamental wave. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 63-153904 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the power amplifier disclosed in Patent Document 1, the amplifying means operates in class F, and therefore the frequency range of even-order harmonics where the load impedance is short-circuited is narrow, making it difficult to ensure high power efficiency by accurately canceling out second-order harmonics across the entire band defined by, for example, 3GPP (registered trademark: 3rd Generation Partnership Project).

[0005] 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 that can suppress harmonics with high precision. [Means for solving the problem]

[0006] In order to achieve the above object, an amplifier circuit according to one embodiment of the present invention comprises: a first power amplifier circuit including a first power amplifier; a second power amplifier circuit including a second power amplifier whose fundamental wave at an output terminal is delayed in phase by 90° relative to the first power amplifier; and a combining circuit configured to combine the fundamental wave of a first output signal output from the first power amplifier circuit and the fundamental wave of a second output signal output from the second power amplifier circuit, wherein the first power amplifier circuit is inverse class E and the second power amplifier circuit is class E.

[0007] Also, an amplifier circuit according to one aspect of the present invention includes a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, configured to demultiplex a fundamental wave signal of a first band transmission 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° relative to the first signal from the second output terminal; a first power amplifier having a fourth input terminal and a fourth output terminal, the fourth input terminal being connected to the first output terminal; a second power amplifier having a fifth input terminal and a fifth output terminal, the fifth input terminal being connected to the second output terminal; and a third input terminal and a third output terminal, the third output terminal receiving a first output signal output from the first power amplifier input from the second input terminal and a second output signal output from the second power amplifier input from the third input terminal, and outputting an in-phase combined third output signal. a combiner configured to output an output signal from the third output port; a first phase-shift circuit connected between the first power amplifier and the combiner and configured to phase-shift the fundamental wave and harmonics of the first band; a second phase-shift circuit connected between the second power amplifier and the combiner and configured to phase-shift the fundamental wave and harmonics of the first band so that the passing phase of the fundamental wave is +90° relative to the first phase-shift circuit; a first harmonic phase-shift circuit connected to a path connecting the fourth output port and the second input port and configured to phase-shift the harmonics; and a second harmonic phase-shift circuit connected to a path connecting the fifth output port and the third input port and configured to phase-shift the harmonics, wherein a phase shift difference obtained by subtracting the phase of the harmonics at the third input port from the phase of the harmonics at the second input port is greater than 90°. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an amplifier circuit that can suppress harmonics with high precision. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a circuit configuration diagram of an amplifier circuit according to an embodiment; [Figure 2] 4 is a Smith chart showing harmonic impedances of a first power amplifier circuit and a second power amplifier circuit according to the embodiment. [Figure 3] FIG. 1 is a circuit configuration diagram of an amplifier circuit according to a comparative example. [Figure 4A] FIG. 2 is a diagram illustrating an example of a circuit configuration of a first harmonic phase shift circuit according to an embodiment. [Figure 4B] FIG. 2 is a diagram illustrating an example of a circuit configuration of a second harmonic phase shift circuit according to an embodiment. [Figure 4C] FIG. 2 is a diagram illustrating an example of a circuit configuration of a first phase shift circuit according to an embodiment. [Figure 4D] FIG. 4 is a diagram illustrating an example of a circuit configuration of a second phase shift circuit according to an embodiment. [Figure 5] FIG. 10 is a circuit configuration diagram of an amplifier circuit according to a first modified example of the embodiment. [Figure 6] FIG. 10 is a circuit configuration diagram of an amplifier circuit according to a second modification of the embodiment. [Figure 7] FIG. 10 is a circuit configuration diagram of an amplifier circuit according to a third modification of the embodiment. [Figure 8A] FIG. 10 is a circuit configuration diagram of an amplifier circuit according to a fourth modified example of the embodiment. [Figure 8B] FIG. 10 is a circuit configuration diagram of an amplifier circuit according to a fifth modified example of the embodiment. [Figure 9] FIG. 13 is a circuit configuration diagram of an amplifier circuit according to a sixth modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, arrangements and connection forms of the components shown in the following embodiments are merely examples and are not intended to limit the present invention.

[0011] It should be noted that the drawings are schematic diagrams in which emphasis, omission, or adjustment of proportions has been appropriately made to illustrate the present invention, and are not necessarily strictly illustrated, and may differ from the actual shapes, positional relationships, and proportions. In the drawings, the same reference numerals are used to denote substantially the same components, and redundant explanations may be omitted or simplified.

[0012] Furthermore, in the present disclosure, terms indicating the relationship between elements, such as parallel and perpendicular, terms indicating the shape of elements, such as rectangular, and numerical ranges do not only represent strict meanings, but also include substantially equivalent ranges, for example, differences of a few percent.

[0013] In the circuit configuration of the present disclosure, "connected" includes not only direct connection by connection terminals and / or wiring conductors, but also electrical connection via other circuit elements. "Connected between A and B" means connected to both A and B between A and B.

[0014] In addition, in this disclosure, a "path" means a transmission line composed of a wiring through which a high-frequency signal propagates, an electrode directly connected to the wiring, and a terminal directly connected to the wiring or the electrode.

[0015] In addition, in this disclosure, "component A is arranged in series with path B" means that both the signal input terminal and the signal output terminal of component A are connected to the wiring, electrode, or terminal that constitutes path B.

[0016] In the present invention, the terms "terminal," "input end," and "output end" refer to the points at which conductors within elements terminate. However, if the impedance of the conductor between elements is sufficiently low, a terminal is interpreted as any point on the conductor between elements or the entire conductor, not just a single point.

[0017] Furthermore, terms indicating the relationship between elements, such as "parallel" and "perpendicular," terms indicating the shape of elements, such as "rectangle," and numerical ranges do not only represent the strict meaning, but also include a substantially equivalent range, for example, an error of a few percent.

[0018] The "passband of a filter" is defined as the portion of the frequency spectrum transmitted by the filter over which the output power is not attenuated by more than 3 dB below the maximum output power. The upper and lower ends of a bandpass filter's passband are therefore identified as the higher and lower frequencies of the two points where the output power is attenuated by 3 dB below the maximum output power.

[0019] A "transmission band" refers to a frequency band used for transmission in a communication device. A "reception band" refers to a 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 the reception band, while in Time Division Duplex (TDD), the same frequency band is used as the transmission band and the reception band. In particular, in FDD, when a communication device is implemented in a user equipment (UE) of a cellular network, the uplink operation band is used as the transmission band, and the downlink operation band is used as the reception band. Conversely, when a communication device is implemented as a base station (BS) of a cellular network, the downlink band is used as the transmission band, and the uplink band is used as the reception band.

[0020] The "pass phase" of a high-frequency signal between two terminals can be obtained by applying a measurement RF probe to the two terminals and measuring the pass characteristic (S21) with a network analyzer. The "reflection phase" of a high-frequency signal at one terminal can be obtained by applying a measurement RF probe to the one terminal and measuring the pass characteristic (S11) with a network analyzer.

[0021] In the present invention, the numerical values ​​of the transmission phase, reflection phase, and reflection phase difference do not only indicate the strict meaning, but also include a substantially equivalent range, for example, including a difference of about 30%.

[0022] (Embodiment) [1 Circuit configuration of amplifier circuit 1] The following describes the circuit configuration of the amplifier circuit 1. Fig. 1 is a circuit configuration diagram of the amplifier circuit 1 according to an embodiment. As shown in the figure, the amplifier circuit 1 includes a duplexer 10, power amplifier circuits 20 and 30, and an in-phase combiner circuit 40.

[0023] Demultiplexer 10 has input terminal 101 (first input terminal), output terminal 102 (first output terminal), and output terminal 103 (second output terminal), and is configured to demultiplex a fundamental wave signal of a first band transmission band input to input terminal 101, output a first signal from output terminal 102, and output a second signal from output terminal 103 that has a phase of -90° relative to the first signal (delayed by 90°). 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. Note that demultiplexer 10 does not necessarily have to be included in amplifier circuit 1.

[0024] Furthermore, each of the input terminal and 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.

[0025] 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, and the fourth input terminal is connected to the output terminal 102.

[0026] 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.

[0027] Since power amplifier 21 amplifies the first signal output from branching filter 10 and power amplifier 31 amplifies the second signal output from branching filter 10, the phase of the fundamental wave at the fifth output terminal of power amplifier 31 lags behind the phase of the fundamental wave at the fourth output terminal of power amplifier 21 by 90°. 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 branching filter 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.

[0028] Furthermore, because the phase of the fundamental wave at the fifth output port of power amplifier 31 lags behind the phase of the fundamental wave at the fourth output port of power amplifier 21 by 90°, the phase of the second harmonic at the fifth output port of power amplifier 31 lags behind the phase of the second harmonic at the fourth output port of power amplifier 21 by 180°. In this embodiment, the phase of the second harmonic at the fourth output port of power amplifier 21 is +90°, and the phase of the second harmonic at the fifth output port of power amplifier 31 is −90°.

[0029] The power amplifier circuit 20 includes a harmonic phase shift circuit 22 in addition to a power amplifier 21. The harmonic phase shift circuit 22 is an example of a first harmonic phase shift circuit, and is connected to a path connecting the fourth output terminal of the power amplifier 21 and the in-phase combiner 41, and shifts the phase of the harmonics of the first band. Note that the harmonic phase shift circuit 22 hardly shifts the phase of the fundamental wave of the first band. In this embodiment, the passing phase of the second harmonic of the harmonic phase shift circuit 22 is +45°.

[0030] The power amplifier circuit 30 includes a harmonic phase shift circuit 32 in addition to the power amplifier 31. The harmonic phase shift circuit 32 is an example of a second harmonic phase shift circuit, and is connected to a path connecting the fifth output terminal of the power amplifier 31 and the in-phase combiner 41 to shift the phase of the harmonics of the first band. Note that the harmonic phase shift circuit 32 hardly shifts the phase of the fundamental wave of the first band. In this embodiment, the passing phase of the second harmonic of the harmonic phase shift circuit 32 is −45°.

[0031] The amplifying transistors included in each of the 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). If the amplifying transistors are bipolar transistors, the fourth input terminal of the power amplifier 21 and the fifth input terminal of the power amplifier 31 are, for example, base terminals of the bipolar transistors, and the fourth output terminal of the power amplifier 21 and the fifth output terminal of the power amplifier 31 are, for example, collector terminals of the bipolar transistors. If the amplifying transistors are field-effect transistors, the fourth input terminal of the power amplifier 21 and the fifth input terminal of the power amplifier 31 are, for example, gate terminals of the field-effect transistors, and the fourth output terminal of the power amplifier 21 and the fifth output terminal of the power amplifier 31 are, for example, drain terminals of the field-effect transistors.

[0032] The in-phase combining circuit 40 is an example of a combining circuit, and is configured to in-phase combine the first output signal output from the power amplifier circuit 20 and the second output signal output from the power amplifier circuit 30. The in-phase combining circuit 40 includes an in-phase combiner 41 and phase shift circuits 23 and 33.

[0033] The in-phase combiner 41 is an example of a combiner, and has an input terminal 402 (second input terminal), an input terminal 403 (third input terminal), and an output terminal 401 (third output terminal), and is configured to output from the output terminal 401 a third output signal generated by in-phase combining 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.

[0034] Phase shift circuit 23 is an example of a first phase shift circuit, and is connected between power amplifier circuit 20 and in-phase combiner 41, and is configured to shift the phase of the fundamental wave and harmonics of the first band. In this embodiment, the phase shift circuit 23 passes the fundamental wave at a phase of −45°, and the second harmonic at a phase of −45°.

[0035] Phase shift circuit 33 is an example of a second phase shift circuit, and is connected between power amplifier circuit 30 and in-phase combiner 41, and is configured to shift the phase of the fundamental wave and harmonics of the first band so that the passing phase of the fundamental wave of the first band becomes +90° relative to phase shift circuit 23. In this embodiment, the passing phase of the fundamental wave of phase shift circuit 33 is +45°, and the passing phase of the second harmonic is +45°.

[0036] The passing phase of the second harmonic in harmonic phase shift circuit 22 may be +X° (X>0), and the passing phase of the second harmonic in phase shift circuit 23 may be -X° (X>0). In other words, it is sufficient that the passing phase of the second harmonic in the combined circuit of harmonic phase shift circuit 22 and phase shift circuit 23 is 0°.

[0037] Furthermore, the passing phase of the second harmonic in harmonic phase shift circuit 32 may be -Y° (Y>0), and the passing phase of the second harmonic in phase shift circuit 33 may be +Y° (Y>0). In other words, the passing phase of the second harmonic in the combined circuit of harmonic phase shift circuit 32 and phase shift circuit 33 should be 0°.

[0038] 2 is a Smith chart showing the harmonic impedances of the power amplifier circuits 20 and 30 according to the embodiment. As shown in the figure, in the amplifier circuit 1 according to the embodiment, the passing phase of the second harmonic in the harmonic phase shift circuit 22 is +45° (+X°), so 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 combining circuit 40 is located in the inductive reactance region (inductive impedance). On the other hand, the passing phase of the second harmonic in the harmonic phase shift circuit 32 is −45° (−Y°), so 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 combining circuit 40 is located in the capacitive reactance region (capacitive impedance).

[0039] That is, in the amplifier circuit 1 according to this embodiment, the power amplifier circuit 20 is an inverse class E amplifier that makes the load impedance inductive with respect to the second harmonic, and the power amplifier circuit 30 is a class E amplifier that makes the load impedance capacitive with respect to the second harmonic.

[0040] In other words, there is a phase difference of 90° (or X+Y°) between the phase of the impedance for the second harmonic at node n1 of the power amplifier circuit 20 and the phase of the impedance for the second harmonic at node n2 of the power amplifier circuit 30.

[0041] 3 is a circuit configuration diagram of an amplifier circuit 500 according to a comparative example. As shown in the figure, the amplifier circuit 500 includes a branching filter 10, power amplifier circuits 520 and 530, phase shift circuits 23 and 33, and an in-phase combiner 41. The amplifier circuit 500 according to the comparative example differs from the amplifier circuit 1 according to the embodiment in the configurations of the power amplifier circuits 520 and 530. Below, a description of the amplifier circuit 500 according to the comparative example will be omitted, and the description will focus on the different configurations from the amplifier circuit 1 according to the embodiment.

[0042] Power amplification circuit 520 includes power amplifier 21. In this comparative example, the phase of the fundamental wave at the fourth output terminal (node ​​n1) of power amplifier 21 is +45° relative to the fundamental wave signal input to input terminal 101 of branching filter 10, and the phase of the second harmonic is +90°.

[0043] Power amplification circuit 530 includes power amplifier 31. In this comparative example, the phase of the fundamental wave at the fifth output terminal (node ​​n2) of power amplifier 31 is −45° relative to the fundamental wave signal input to input terminal 101 of branching filter 10, and the phase of the second harmonic is −90°.

[0044] According to the above-described configuration of amplifier circuit 500 of the comparative example, the phase of the fundamental wave of the first output signal output from power amplifier 21 at node n1 is +45°, and the phase of the fundamental wave at input terminal 402 becomes 0° after passing through phase shift circuit 23. Furthermore, the phase of the fundamental wave of the second output signal output from power amplifier 31 at node n2 is −45°, and the phase of the fundamental wave at input terminal 403 becomes 0° after passing through phase shift circuit 33. As a result, the fundamental wave signals of the first band are in-phase combined by in-phase combiner 41 and output from output terminal 401 as a third output signal. This allows amplifier circuit 500 to operate as a balanced amplifier that is resistant to load fluctuations.

[0045] On the other hand, the phase of the second harmonic of the first output signal at node n1 output from power amplifier 21 is +90°, and after passing through phase shift circuit 23, the phase of the second harmonic at input terminal 402 becomes +45°. Also, the phase of the second harmonic of the second output signal at node n2 output from power amplifier 31 is −90°, and after passing through phase shift circuit 33, the phase of the second harmonic at input terminal 403 becomes −45°. As a result, the second harmonic of the first band has a phase difference of 90° between input terminals 402 and 403 of in-phase combiner 41 and is not suppressed. As a result, amplifier circuit 500 cannot improve the quality and power efficiency of the transmission signal.

[0046] In contrast, with the above-described configuration of amplifier circuit 1 according to the present embodiment, the phase of the fundamental wave of the first output signal output from power amplifier 21 at node n1 is +45°, and the phase of the fundamental wave at input terminal 402 becomes 0° after passing through phase shift circuit 23. Furthermore, the phase of the fundamental wave of the second output signal output from power amplifier 31 at node n2 is −45°, and the phase of the fundamental wave at input terminal 403 becomes 0° after passing through phase shift circuit 33. As a result, the fundamental wave signals of the first band are in-phase combined by in-phase combiner 41 and output from output terminal 401 as the third output signal. This allows amplifier circuit 1 to operate as a balanced amplifier that is resistant to load fluctuations.

[0047] On the other hand, the phase of the second harmonic of the first output signal at node n1 output from power amplifier 21 is +135° (or +90+X°), and by passing through phase shift circuit 23, the phase of the second harmonic at input terminal 402 becomes +90°. Also, 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 by passing through phase shift circuit 33, the phase of the second harmonic at input terminal 403 becomes −90°. As a result, the second harmonic of the first band has a phase difference of 180° between input terminals 402 and 403 of in-phase combiner 41 (becoming in anti-phase), and is canceled out. As a result, the amplifier circuit 1 suppresses the second harmonic, thereby improving the quality and power efficiency of the transmission signal.

[0048] 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 even-order harmonics is short-circuited and the load impedance of odd-order harmonics is open, but rather only requires that the load impedance of second-order harmonics is divided into inductive and capacitive, making it possible to cancel second-order harmonics with high precision across the entire bandwidth of the wide band specified by 3GPP, for example, and ensure high transmission quality and power efficiency.

[0049] In the amplifier circuit 1 according to this embodiment, the first phase difference (90° or (+X+Y°)) obtained by subtracting the harmonic phase shift circuit 32's passing phase (-45° or (-Y°)) from the harmonic phase shift circuit 22's passing phase (+45° or (+X°)) is equal to the second phase difference (90° (or +Y+X°)) obtained by subtracting the harmonic phase shift circuit 23's passing phase (-45° (or -X°)) from the harmonic phase shift circuit 33's passing phase (+45° (or +Y°)).

[0050] As a result, the second harmonic of the first band has a phase difference of 180° (out-of-phase relationship) between input terminals 402 and 403 of in-phase combiner 41 and is cancelled out. Therefore, amplifier circuit 1 can suppress the second harmonic, thereby improving the quality and power efficiency of the transmission signal.

[0051] Furthermore, since the second harmonic of the first band only needs to have a relative phase difference of 180° between the input terminals 402 and 403 of the in-phase combiner 41, it is possible to cancel out the second harmonic with high precision across the entire wideband band, ensuring high transmission quality and power efficiency.

[0052] In amplifier circuit 1 according to this embodiment, the phase difference obtained by subtracting the phase of the second harmonic of the first band at input terminal 403 from the phase of the second harmonic of the first band at input terminal 402 is only required to be greater than 90°.

[0053] This makes it possible to suppress second harmonics in the first band more effectively than in the amplifier circuit 500 according to the comparative example, thereby improving the quality of the transmission signal and power efficiency more effectively than in a conventional balanced amplifier that does not include a harmonic phase shift circuit.

[0054] 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.

[0055] 4A is a diagram showing an example of a circuit configuration of harmonic phase-shift circuit 22 according to an embodiment. As shown in the diagram, harmonic phase-shift circuit 22 includes, for example, inductor 221 and capacitor 222. Inductor 221 (third inductor) and capacitor 222 (third capacitor) are connected in series to form an LC circuit, and this LC circuit is connected between ground and a path connecting the fourth output port and inductor 231 of phase-shift circuit 23. Harmonic phase-shift circuit 22 is a notch filter that has the fundamental wave band of the first band as its pass band and the second harmonic band as its attenuation band, and the passing phase of the fundamental wave is, for example, 0° and the passing phase of the second harmonic is, for example, +45° (+X°: X>0).

[0056] 4B is a diagram showing an example of a circuit configuration of harmonic phase-shift circuit 32 according to an embodiment. As shown in the figure, harmonic phase-shift circuit 32 includes, for example, capacitor 321 (fourth capacitor) connected between ground and a path connecting the fifth output port and capacitor 331 of phase-shift circuit 33. Harmonic phase-shift circuit 32 is a low-pass filter that has the fundamental wave band of the first band as its pass band and the second harmonic as its attenuation band, with the fundamental wave passing through a phase of 0°, for example, and the second harmonic passing through a phase of −45° (−Y°: Y>0), for example.

[0057] 4C is a diagram illustrating an example of a circuit configuration of the phase-shift circuit 23 according to an embodiment. As illustrated in the diagram, the phase-shift circuit 23 includes, for example, an inductor 231 and a capacitor 232. The inductor 231 is an example of a first inductor and is connected between the fourth output terminal and the second input terminal. The capacitor 232 is an example of a first capacitor and is connected between a path connecting the inductor 231 and the second input terminal and ground. The phase-shift circuit 23 has a low-pass filter configuration in which the fundamental wave band and second harmonic band of the first band are used as passbands, and the passing phase of the fundamental wave of the first band is, for example, −45°, and the passing phase of the second harmonic is, for example, −45° (−X°).

[0058] 4D is a diagram showing an example of a circuit configuration of a phase-shift circuit 33 according to an embodiment. As shown in the figure, the phase-shift circuit 33 includes, for example, a capacitor 331 and an inductor 332. The capacitor 331 is an example of a second capacitor and is connected between the fifth output terminal and the third input terminal. The inductor 332 is an example of a second inductor and is connected between ground and a path connecting the capacitor 331 and the third input terminal. The phase-shift circuit 33 has a high-pass filter configuration in which the fundamental wave band and the second harmonic band of the first band are used as passbands. The passing phase of the fundamental wave of the first band is, for example, +45°, and the passing phase of the second harmonic is, for example, +45° (+Y°).

[0059] The phase shift circuits 23 and 33 and the harmonic phase shift circuits 22 and 32 may be included in one semiconductor IC.

[0060] 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 the signal transmission loss of the amplifier circuit 1.

[0061] [2. Configuration of Amplifier Circuit 1A According to Modification 1] Next, an amplifier circuit 1A according to a first modification of the embodiment will be described. FIG. 5 is a circuit configuration diagram of the amplifier circuit 1A according to the first modification of the embodiment. As shown in the figure, the amplifier circuit 1A includes a branching filter 10, power amplifier circuits 20A and 30A, and an in-phase combining circuit 40. The amplifier circuit 1A according to this modification differs from the amplifier circuit 1 according to the embodiment in the configurations of the power amplifier circuits 20A and 30A. Hereinafter, a description of the amplifier circuit 1A according to this modification that is the same as that of the amplifier circuit 1 according to the embodiment will be omitted, and the description will focus on the different configurations.

[0062] The power amplifier circuit 20A is an example of a first power amplifier circuit and includes a power amplifier 21. The power amplifier 21 has the same configuration as the power amplifier 21 according to the embodiment. The power amplifier circuit 20A includes, in addition to the power amplifier 21, a harmonic phase shift circuit 22A. The harmonic phase shift circuit 22A is an example of a first harmonic phase shift circuit and is connected to a path connecting the fourth output terminal of the power amplifier 21 and the in-phase combiner 41, and shifts the phase of the harmonics of the first band. Note that the harmonic phase shift circuit 22A hardly shifts the phase of the fundamental wave of the first band. In this modification, the passing phase of the second harmonic of the harmonic phase shift circuit 22A is +Z° (Z>0).

[0063] The power amplifier circuit 30A is an example of a second power amplifier circuit and includes a power amplifier 31. The power amplifier 31 has the same configuration as the power amplifier 31 according to the embodiment. The power amplifier circuit 30A includes, in addition to the power amplifier 31, a harmonic phase shift circuit 32A. The harmonic phase shift circuit 32A is an example of a second harmonic phase shift circuit and is connected to a path connecting the fifth output terminal of the power amplifier 31 and the in-phase combiner 41, and shifts the phase of the harmonics of the first band. Note that the harmonic phase shift circuit 32A hardly shifts the phase of the fundamental wave of the first band. In this modification, the passing phase of the second harmonic of the harmonic phase shift circuit 32A is -Z° (Z>0).

[0064] The phase shift circuit 23 is an example of a first phase shift circuit, and is connected between the power amplifier circuit 20A and the in-phase combiner 41, and is configured to shift the phase of the fundamental wave and harmonics of the first band. In this modification, the phase shift circuit 23 passes the fundamental wave at a phase of −45°, and the second harmonic at a phase of −X° (X>0).

[0065] Phase shift circuit 33 is an example of a second phase shift circuit, and is connected between power amplifier circuit 30A and in-phase combiner 41, and is configured to shift the phase of the fundamental wave and harmonics of the first band so that the passing phase of the fundamental wave of the first band becomes +90° relative to phase shift circuit 23. In this modification, the passing phase of the fundamental wave of phase shift circuit 33 is +45°, and the passing phase of the second harmonic is +Y° (Y>0).

[0066] According to the above-described configuration of amplifier circuit 1A of this modification, the phase of the fundamental wave of the first output signal output from power amplifier 21 at node n1 is +45°, and the phase of the fundamental wave at input terminal 402 becomes 0° after passing through phase shift circuit 23. Furthermore, the phase of the fundamental wave of the second output signal output from power amplifier 31 at node n2 is −45°, and the phase of the fundamental wave at input terminal 403 becomes 0° after passing through phase shift circuit 33. As a result, the fundamental wave signals of the first band are in-phase combined by in-phase combiner 41 and output from output terminal 401 as the third output signal. This allows amplifier circuit 1A to operate as a balanced amplifier that is resistant to load fluctuations.

[0067] On the other hand, the phase of the second harmonic of the first output signal at node n1 output from power amplifier 21 is +90+Z°, and after passing through phase shift circuit 23, the phase of the second harmonic at input terminal 402 becomes +90+ZX°. Also, the phase of the second harmonic of the second output signal at node n2 output from power amplifier 31 is -90-Z°, and after passing through phase shift circuit 33, the phase of the second harmonic at input terminal 403 becomes -90-Z+Y°. As a result, the second harmonic of the first band has a phase difference of (+90+ZX)-(-90-Z+Y)=180+2Z-XY between input terminals 402 and 403 of in-phase combiner 41. This phase difference is greater than 90°.

[0068] This makes it possible to suppress second harmonics in the first band compared to the amplifier circuit 500 according to the comparative example. Therefore, compared to a conventional balanced amplifier without a harmonic phase shift circuit, second harmonics are suppressed, and therefore the quality of the transmission signal and power efficiency can be improved.

[0069] [3. Configuration of Amplifier Circuit 1B According to Modification 2] Next, an amplifier circuit 1B according to a second modification of the embodiment will be described. FIG. 6 is a circuit configuration diagram of the amplifier circuit 1B according to the second modification of the embodiment. As shown in the figure, the amplifier circuit 1B includes a branching filter 10, power amplifiers 21 and 31, harmonic phase shift circuits 22 and 32, phase shift circuits 23 and 33, and an in-phase combiner 41. The amplifier circuit 1B according to this modification differs from the amplifier circuit 1 according to the embodiment in the connection configuration of the harmonic phase shift circuits and the phase shift circuits. Hereinafter, a description of the amplifier circuit 1B according to this modification that is the same as that of the amplifier circuit 1 according to the embodiment will be omitted, and the description will focus on the different configuration.

[0070] Phase shift circuit 23 is an example of a first phase shift circuit, and is connected between power amplifier 21 and in-phase combiner 41, and configured to shift the phase of the fundamental wave and harmonics of the first band. In this modification, the phase shift circuit 23 passes the fundamental wave at a phase of −45°, and the second harmonic at a phase of −45° (or −X°: X>0).

[0071] Phase shift circuit 33 is an example of a second phase shift circuit, and is connected between power amplifier 31 and in-phase combiner 41, and is configured to shift the phase of the fundamental wave and harmonics of the first band so that the passing phase of the fundamental wave of the first band becomes +90° relative to phase shift circuit 23. In this modification, the passing phase of the fundamental wave of phase shift circuit 33 is +45°, and the passing phase of the second harmonic is +45° (or +Y°: Y>0).

[0072] The harmonic phase shift circuit 22 is an example of a first harmonic phase shift circuit, and is connected to a path connecting the phase shift circuit 23 and the in-phase combiner 41 to shift the phase of the harmonics of the first band. Note that the harmonic phase shift circuit 22 does not substantially shift the phase of the fundamental wave of the first band. In this modification, the passing phase of the second harmonic of the harmonic phase shift circuit 22 is +45° (or +X°: X>0).

[0073] The harmonic phase shift circuit 32 is an example of a second harmonic phase shift circuit, and is connected to a path connecting the phase shift circuit 33 and the in-phase combiner 41 to shift the phase of the harmonics of the first band. Note that the harmonic phase shift circuit 32 does not shift the phase of the fundamental wave of the first band at all. In this modification, the passing phase of the second harmonic of the harmonic phase shift circuit 32 is -45° (or -Y:Y>0).

[0074] According to the above-described configuration of amplifier circuit 1B of this modification, the phase of the fundamental wave of the first output signal at the fourth output terminal (node ​​n1) of power amplifier 21 is +45°, and the phase of the fundamental wave at input terminal 402 becomes 0° after passing through phase shift circuit 23 and harmonic phase shift circuit 22. Furthermore, the phase of the fundamental wave of the second output signal at the fifth output terminal (node ​​n2) of power amplifier 31 is −45°, and the phase of the fundamental wave at input terminal 403 becomes 0° after passing through phase shift circuit 33 and harmonic phase shift circuit 32. As a result, the fundamental wave signals of the first band are in-phase combined by in-phase combiner 41 and output from output terminal 401 as the third output signal. This allows amplifier circuit 1B to operate as a balanced amplifier that is resistant to load fluctuations.

[0075] On the other hand, the phase of the second harmonic of the first output signal output from power amplifier 21 at node n1 is +90°, and by passing through phase shift circuit 23 and harmonic phase shift circuit 22, the phase of the second harmonic at input terminal 402 becomes +90°. Also, the phase of the second harmonic of the second output signal output from power amplifier 31 at node n2 is −90°, and by passing through phase shift circuit 33 and harmonic phase shift circuit 32, the phase of the second harmonic at input terminal 403 becomes −90°. As a result, the second harmonic of the first band has a phase difference of 180° between input terminals 402 and 403 of in-phase combiner 41 (becoming in anti-phase), and is canceled out. As a result, amplifier circuit 1B suppresses second harmonics, thereby improving the quality and power efficiency of the transmission signal.

[0076] In amplifier circuit 1B according to this modification, power amplifier 21, phase shift circuit 23, and harmonic phase shift circuit 22 are connected in this order, so the impedance of the second harmonic when viewed from the fourth output terminal (node ​​n1) of power amplifier 21 toward in-phase combiner 41 is not inductive, and power amplifier 21 does not become an inverse class E amplifier. Also, because power amplifier 31, phase shift circuit 33, and harmonic phase shift circuit 32 are connected in this order, the impedance of the second harmonic when viewed from the fifth output terminal (node ​​n2) of power amplifier 31 toward in-phase combiner 41 is not capacitive, and power amplifier 31 does not become an E class amplifier.

[0077] [4. Configuration of Amplifier Circuit 1C According to Modification 3] Next, an amplifier circuit 1C according to a third modification of the embodiment will be described. FIG. 7 is a circuit configuration diagram of the amplifier circuit 1C according to the third modification of the embodiment. As shown in the figure, the amplifier circuit 1C includes a branching filter 10, power amplifier circuits 20 and 30, and an anti-phase combining circuit 40C. The amplifier circuit 1C according to this modification has a different configuration from the amplifier circuit 1 according to the embodiment. Hereinafter, a description of the same configuration as the amplifier circuit 1 according to the embodiment will be omitted, and the description will focus on the different configuration.

[0078] The anti-phase combining circuit 40C is an example of a combining circuit, and is configured to perform anti-phase combining of a first output signal output from the power amplifier circuit 20 and a second output signal output from the power amplifier circuit 30. The anti-phase combining circuit 40C includes a transformer 42 and phase shift circuits 23C and 33C.

[0079] The transformer 42 has an input terminal 422 (second input terminal) which is one end of the primary coil, an input terminal 423 (third input terminal) which is the other end of the primary coil, and an output terminal 421 (third output terminal) which is one end of the secondary coil that is electromagnetically coupled with the primary coil. The other end of the secondary coil is connected to ground. With the above configuration, the transformer 42 is configured to output from the output terminal 421 a third output signal generated by combining, in antiphase, the first output signal of the power amplifier circuit 20 input from the input terminal 422 and the second output signal of the power amplifier circuit 30 input from the input terminal 423.

[0080] The phase shift circuit 23C is an example of a first phase shift circuit, and is connected between the power amplifier circuit 20 and the transformer 42, and is configured to shift the phase of the fundamental wave and harmonics of the first band. In this modification, the phase shift circuit 23C passes the fundamental wave at a phase of +45°, and the second harmonic at a phase of +45°.

[0081] Phase shift circuit 33C is an example of a second phase shift circuit, and is connected between power amplifier circuit 30 and transformer 42. It is configured to shift the phase of the fundamental wave and harmonics of the first band so that the passing phase of the fundamental wave of the first band becomes −90° relative to phase shift circuit 23C. In this modification, the passing phase of the fundamental wave of phase shift circuit 33C is −45°, and the passing phase of the second harmonic is −45°.

[0082] The phase through which the second harmonic passes through harmonic phase shift circuit 22 may be +X° (X>0), and the phase through which the second harmonic passes through phase shift circuit 23C may be +X° (X>0).

[0083] Furthermore, the passing phase of the second harmonic wave through harmonic phase shift circuit 32 may be −Y° (Y>0), and the passing phase of the second harmonic wave through phase shift circuit 33C may be −Y° (Y>0).

[0084] In the amplifier circuit 1C according to this modification, the second harmonic passes through the harmonic phase shift circuit 22 at a phase of +45° (+X°), so the impedance of the second harmonic when viewed from the node (node ​​n1) between the fourth output terminal of the power amplifier 21 and the harmonic phase shift circuit 22 toward the anti-phase combiner circuit 40C is in the inductive reactance region (inductive impedance). On the other hand, the second harmonic passes through the harmonic phase shift circuit 32 at a phase of −45° (−Y°), so the impedance of the second harmonic when viewed from the node (node ​​n2) between the fifth output terminal of the power amplifier 31 and the harmonic phase shift circuit 32 toward the anti-phase combiner circuit 40C is in the capacitive reactance region (capacitive impedance).

[0085] That is, in the amplifier circuit 1C according to this modified example, the power amplifier circuit 20 is an inverse class E amplifier that makes the load impedance inductive with respect to the second harmonic, and the power amplifier circuit 30 is an E class amplifier that makes the load impedance capacitive with respect to the second harmonic.

[0086] In other words, there is a phase difference of 90° (or X+Y°) between the phase of the impedance for the second harmonic at node n1 of the power amplifier circuit 20 and the phase of the impedance for the second harmonic at node n2 of the power amplifier circuit 30.

[0087] According to the above-described configuration of amplifier circuit 1C of this modification, the phase of the fundamental wave of the first output signal output from power amplifier 21 at node n1 is +45°, and by passing through phase-shift circuit 23C, the phase of the fundamental wave at input terminal 422 becomes +90°. Furthermore, the phase of the fundamental wave of the second output signal output from power amplifier 31 at node n2 is −45°, and by passing through phase-shift circuit 33C, the phase of the fundamental wave at input terminal 423 becomes −90°. As a result, the fundamental wave signals of the first band are combined in reverse phase by transformer 42 and output as a third output signal from output terminal 421. This allows amplifier circuit 1C to operate as a balanced amplifier that is resistant to load fluctuations.

[0088] On the other hand, the phase of the second harmonic of the first output signal at node n1 output from power amplifier 21 is +135° (or +90+X°), and by passing through phase shift circuit 23C, the phase of the second harmonic at input terminal 422 becomes +180°. Also, 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 by passing through phase shift circuit 33C, the phase of the second harmonic at input terminal 423 becomes −180°. As a result, the second harmonic of the first band has a phase difference of 360° between input terminals 422 and 423 of transformer 42 (becoming in-phase), and is canceled out. As a result, amplifier circuit 1C suppresses second harmonics, thereby improving the quality and power efficiency of the transmission signal.

[0089] Furthermore, each of the power amplifier circuits 20 and 30 according to this modification is not a class F amplifier in which the load impedance of even-order harmonics is short-circuited and the load impedance of odd-order harmonics is open, but rather it is sufficient that the load impedance of the second-order harmonics is divided into inductive and capacitive, making it possible to cancel out second-order harmonics with high precision across the entire band of the wideband defined by 3GPP, for example, and ensure high transmission quality and power efficiency.

[0090] In addition, in the amplifier circuit 1C of this modified example, the first phase shift difference (90° or (+X+Y°)) obtained by subtracting the harmonic phase shift circuit 32's passing phase (-45° or (-Y°)) from the harmonic phase shift circuit 22's passing phase (+45° or (+X°)) is equal to the second phase shift difference (90° (or +Y+X°)) obtained by subtracting the harmonic phase shift circuit 33C's passing phase (-45° (or -Y°)) from the harmonic phase shift circuit 23C's passing phase (+45° (or +X°)).

[0091] As a result, the second harmonic of the first band is in phase and canceled out between input terminals 422 and 423 of transformer 42. Therefore, amplifier circuit 1C can suppress the second harmonic, thereby improving the quality and power efficiency of the transmission signal.

[0092] Furthermore, since the second harmonic of the first band only needs to have a relative phase difference of 0° (±360×m: m is a natural number) between the input terminals 422 and 423 of the transformer 42, it is possible to cancel out the second harmonic with high precision across the entire wideband band, ensuring high transmission quality and power efficiency.

[0093] In amplifier circuit 1C according to this modification, the phase difference obtained by subtracting the phase of the second harmonic of the first band at input terminal 423 from the phase of the second harmonic of the first band at input terminal 422 needs to be less than 90°.

[0094] This suppresses second harmonics in the first band compared to a conventional anti-phase synthesis type balanced amplifier that does not have a harmonic phase shift circuit added, thereby improving the quality and power efficiency of the transmitted signal.

[0095] [5. Configuration of Amplifier Circuit 1D According to Modification 4] Next, an amplifier circuit 1D according to a fourth modification of the embodiment will be described. FIG. 8A is a circuit configuration diagram of the amplifier circuit 1D according to the fourth modification of the embodiment. As shown in the figure, the amplifier circuit 1D includes a branching filter 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. Hereinafter, a description of the same configuration as the amplifier circuit 1 according to the embodiment will be omitted, and the description will focus on the different configuration.

[0096] 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), and is configured to split a fundamental wave signal of a first band transmission band input to the input terminal 101, output a first signal from the output terminal 102, and output a second signal from the output terminal 103 that has a phase of -90° relative to the first signal (delayed by 90°).

[0097] 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 duplexer 10.

[0098] 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 duplexer 10.

[0099] 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.

[0100] The power amplifier 21 amplifies the transmission signal of the first band input to the third input terminal. The power amplifier 21 is, for example, a class A (or class AB) amplifier circuit that can perform amplification operation for all power levels of the signal input to the power amplifier 21, and is capable of highly efficient amplification operation particularly in the low output and medium output ranges.

[0101] The power amplifier 31 amplifies a first-band transmission signal input to the fourth input terminal. The power amplifier 31 is, for example, a class-C amplifier circuit capable of amplifying signals input to the power amplifier 31 in a range where the power level is high. A bias current smaller than the bias current applied to the amplifying transistor of the power amplifier 21 may be applied to the amplifying transistor of the power amplifier 31. This reduces the output impedance as the power level of the signal input to the power amplifier 31 increases. This allows the power amplifier 31 to perform low-distortion amplification in a high-output range.

[0102] Since power amplifier 21 amplifies the first signal output from splitter 10 and power amplifier 31 amplifies the second signal output from splitter 10, the phase of the fundamental wave at the fourth output terminal of power amplifier 31 lags by 90° relative to the phase of the fundamental wave at the third output terminal of power amplifier 21.

[0103] The phase shift line 50 has a second input terminal and a third output terminal, the second input terminal being connected to the fourth output terminal, and the third output terminal being connected to the fifth output terminal via the output terminal 104. The phase shift line 50 is configured to delay by 90° the fundamental wave of the first output signal of the power amplifier 21 input from the second input terminal. The arrangement of the phase shift line 50 aligns the phase of the fundamental wave of the first output signal output from the power amplifier 21 with the phase of the fundamental wave of the second output signal output from the power amplifier 31. As a result, the fundamental waves of the first output signal and the second output signal are in-phase combined (current combined) at the output terminal 104. The phase shift line 50 and the output terminal 104 form a combining circuit.

[0104] The harmonic phase shift circuit 22 is an example of a first harmonic phase shift circuit, and is connected to a path connecting the fourth output terminal of the power amplifier 21 and the second input terminal of the phase shift line 50, and shifts the phase of the first band harmonics. Note that the harmonic phase shift circuit 22 hardly shifts the phase of the first band fundamental wave. In this modification, the passing phase of the second harmonic of the harmonic phase shift circuit 22 is +45°.

[0105] The harmonic phase shift circuit 32 is an example of a second harmonic phase shift circuit, and is connected to a path connecting the fifth output port of the power amplifier 31 and the output terminal 104, and shifts the phase of the harmonics of the first band. Note that the harmonic phase shift circuit 32 does not shift the phase of the fundamental wave of the first band at all. In this modification, the passing phase of the second harmonic of the harmonic phase shift circuit 32 is −45°.

[0106] The phase through which the second harmonic passes through harmonic phase shift circuit 22 may be +X° (X>0), and the phase through which the second harmonic passes through harmonic phase shift circuit 32 may be −Y° (Y>0).

[0107] 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.

[0108] According to the above configuration of amplifier circuit 1D, when a small signal is input, the output impedance of power amplifier 21 is higher than when a large signal is input. In other words, when a small signal is input, power amplifier 31 is turned off, and the output impedance of power amplifier 21 is higher, allowing amplifier circuit 1D to operate with high efficiency.

[0109] On the other hand, when a large signal is input, the power amplifiers 21 and 31 operate to output a large power signal, and the output impedance of the power amplifier 31 is reduced, making it possible to suppress signal distortion.

[0110] Furthermore, because the phase of the fundamental wave at the fifth output port of power amplifier 31 lags behind the phase of the fundamental wave at the fourth output port of power amplifier 21 by 90°, the phase of the second harmonic at the fifth output port of power amplifier 31 lags behind the phase of the second harmonic at the fourth output port of power amplifier 21 by 180°. In this modification, the phase of the second harmonic at the fourth output port of power amplifier 21 is set to +90°, and the phase of the second harmonic at the fifth output port of power amplifier 31 is set to -90°.

[0111] According to the above-described configuration of amplifier circuit 1D of this modification, 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°), and by passing through phase shift line 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°). As a result, the second harmonic of the first output signal and the second harmonic of the second output signal have a phase difference of 180° (inverse phase relationship) at output terminal 104 and are canceled out. This suppresses the second harmonic, thereby improving the quality and power efficiency of the transmission signal.

[0112] Furthermore, in the amplifier circuit 1D according to this modified example, the first power amplifier circuit is an inverse class E amplifier that makes the load impedance inductive with respect to the second harmonic, and the second power amplifier circuit is an E class amplifier that makes the load impedance capacitive with respect to the second harmonic.

[0113] This makes it possible to ensure high transmission quality and power efficiency by canceling out second harmonics with high precision across the entire wide band defined by 3GPP, for example.

[0114] 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 needs to be greater than 90°.

[0115] This suppresses second harmonics in the first band compared to a conventional Doherty amplifier without a harmonic phase shift circuit, thereby improving the quality and power efficiency of the transmission signal.

[0116] [6. Configuration of Amplifier Circuit 1E According to Modification 5] Next, an amplifier circuit 1E according to a fifth modification of the embodiment will be described. FIG. 8B is a circuit configuration diagram of the amplifier circuit 1E according to the fifth modification of the embodiment. As shown in the figure, the amplifier circuit 1E includes a branching filter 10, power amplifiers 21 and 31, harmonic phase shift circuits 22 and 32, a phase shift line 51, and a transformer 43. The amplifier circuit 1E according to this modification has a different signal synthesis configuration compared to the amplifier circuit 1D according to the fourth modification. Hereinafter, a description of the same configuration as that of the amplifier circuit 1D according to the fourth modification will be omitted, and the description will focus on the different configuration.

[0117] The transformer 43 has an input terminal 432 (third input terminal) which is one end of the primary coil, an input terminal 433 (fourth input terminal) which is the other end of the primary coil, and an output terminal 431 (fourth output terminal) which is one end of the secondary coil that is electromagnetically coupled with the primary coil. The other end of the secondary coil is connected to ground. With the above configuration, the transformer 43 is configured to output from the output terminal 431 a third output signal generated by combining, in antiphase, the first output signal of the power amplifier circuit 20 input from the input terminal 432 and the second output signal of the power amplifier circuit 30 input from the input terminal 433.

[0118] The phase-shift line 51 has a second input terminal and a third output terminal, and is configured to delay by 90° the fundamental wave of the second output signal of the power amplifier 31 input from the second input terminal. Due to the arrangement of the phase-shift line 51, the phase of the fundamental wave of the first output signal output from the power amplifier 21 is opposite to the phase of the fundamental wave of the second output signal output from the power amplifier 31. As a result, the fundamental waves of the first output signal and the second output signal are anti-phase combined (voltage combined) by the transformer 43. The phase-shift line 51 and the transformer 43 form a combining circuit.

[0119] 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, with the fifth input terminal connected to the output terminal 102 of the splitter 10 and the fifth output terminal connected to the input terminal 432.

[0120] The power amplifier 31 is an example of a peak amplifier, includes an amplifying transistor, and has a sixth input terminal and a sixth output terminal, the sixth input terminal being connected to the output terminal 103 of the duplexer 10, the sixth output terminal being connected to the second input terminal, and the third output terminal being connected to the input terminal 433.

[0121] The power amplifier 21 amplifies a transmission signal of the first band input to a fifth input terminal. The power amplifier 21 is, for example, a class A (or class AB) amplifier circuit that can perform amplification operations for all power levels of signals input to the power amplifier 21, and is capable of highly efficient amplification operations particularly in the low output and medium output ranges.

[0122] The power amplifier 31 amplifies a first-band transmission signal input to the sixth input terminal. The power amplifier 31 is, for example, a class-C amplifier circuit capable of amplifying signals input to the power amplifier 31 in a range where the power level is high. A bias current smaller than the bias current applied to the amplifying transistor of the power amplifier 21 may be applied to the amplifying transistor of the power amplifier 31. This reduces the output impedance as the power level of the signal input to the power amplifier 31 increases. This allows the power amplifier 31 to perform low-distortion amplification in a high-output range.

[0123] Since power amplifier 21 amplifies the first signal output from splitter 10 and power amplifier 31 amplifies the second signal output from splitter 10, the phase of the fundamental wave at the sixth output terminal of power amplifier 31 lags by 90° relative to the phase of the fundamental wave at the fifth output terminal of power amplifier 21.

[0124] The harmonic phase shift circuit 22 is an example of a first harmonic phase shift circuit, and is connected to a path connecting the fifth output port and the input terminal 432 to shift the phase of the first band harmonics. Note that the harmonic phase shift circuit 22 does not shift the phase of the first band fundamental wave at all. In this modification, the passing phase of the second harmonic of the harmonic phase shift circuit 22 is +45°.

[0125] The harmonic phase shift circuit 32 is an example of a second harmonic phase shift circuit, and is connected to a path connecting the sixth output port and the second input port to shift the phase of the first-band harmonics. Note that the harmonic phase shift circuit 32 does not shift the phase of the first-band fundamental wave at all. In this modification, the passing phase of the second harmonic of the harmonic phase shift circuit 32 is −45°.

[0126] The phase through which the second harmonic passes through harmonic phase shift circuit 22 may be +X° (X>0), and the phase through which the second harmonic passes through harmonic phase shift circuit 32 may be −Y° (Y>0).

[0127] 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.

[0128] According to the above configuration of the amplifier circuit 1E, the output impedance of the power amplifier 21 is higher when a small signal is input than when a large signal is input. In other words, when a small signal is input, the power amplifier 31 is turned off, and the output impedance of the power amplifier 21 is higher, allowing the amplifier circuit 1E to operate with high efficiency.

[0129] On the other hand, when a large signal is input, the power amplifiers 21 and 31 operate to output a large power signal, and the output impedance of the power amplifier 31 is reduced, making it possible to suppress signal distortion.

[0130] Furthermore, because the phase of the fundamental wave at the sixth output port of power amplifier 31 lags behind the phase of the fundamental wave at the fifth output port of power amplifier 21 by 90°, the phase of the second harmonic at the sixth output port of power amplifier 31 lags behind the phase of the second harmonic at the fifth output port of power amplifier 21 by 180°. In this modification, the phase of the second harmonic at the fifth output port is set to +90°, and the phase of the second harmonic at the sixth output port is set to -90°.

[0131] According to the above-described configuration of amplifier circuit 1E of this modification, the phase of the second harmonic of the first output signal at the connection point (node ​​n1) between the fifth output terminal of power amplifier 21 and harmonic phase shift circuit 22 is +135° (or +90+X°), and the phase of the second harmonic at 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 power amplifier 31 and harmonic phase shift circuit 32 is −135° (or −90−Y°), and the phase of the second harmonic at input terminal 433 becomes −225° (or −135−Y°) after passing through phase shift line 51. As a result, the second harmonic of the first output signal and the second harmonic of the second output signal have a phase difference of 360° (become in-phase) at input terminals 432 and 433 of transformer 43, and are thus canceled out. According to this, the amplifier circuit 1E can suppress second harmonics, thereby improving the quality of the transmission signal and power efficiency.

[0132] Furthermore, in the amplifier circuit 1E according to this modified example, the first power amplifier circuit is an inverse class E amplifier that makes the load impedance inductive with respect to the second harmonic, and the second power amplifier circuit is an E class amplifier that makes the load impedance capacitive with respect to the second harmonic.

[0133] This makes it possible to ensure high transmission quality and power efficiency by canceling out second harmonics with high precision across the entire wide band defined by 3GPP, for example.

[0134] 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 input terminal 433 from the phase of the second harmonic of the first output signal at input terminal 432 is only required to be smaller than 90°.

[0135] This suppresses second harmonics in the first band compared to a conventional Doherty amplifier without a harmonic phase shift circuit, thereby improving the quality and power efficiency of the transmission signal.

[0136] [7. Configuration of Amplifier Circuit 1F According to Modification 6] Next, an amplifier circuit 1F according to a sixth modification of the embodiment will be described. FIG. 9 is a circuit configuration diagram of the amplifier circuit 1F according to the sixth modification of the embodiment. As shown in the figure, the amplifier circuit 1F includes a branching filter 10, power amplifier circuits 20 and 30, and a 90° combiner 44. The amplifier circuit 1F according to this modification has a different configuration from the amplifier circuit 1 according to the embodiment. Hereinafter, a description of the same configuration as the amplifier circuit 1 according to the embodiment will be omitted, and the different configuration will be mainly described.

[0137] The combining circuit according to this modification includes a 90° combiner 44 but does not include a phase shift circuit. The 90° combiner 44 has an input terminal 442 (second input terminal), an input terminal 443 (third input terminal), and an output terminal 441 (third output terminal), and is configured to output from the output terminal 441 a third output signal generated by combining the first output signal input from the input terminal 442 and a signal obtained by inputting the second output signal from the input terminal 443 and shifting its phase to +90° with respect to the first output signal.

[0138] In the amplifier circuit 1F according to this modification, the passing phase of the second harmonic in the harmonic phase shift circuit 22 is +45°, and 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 located in the inductive reactance region (inductive impedance). On the other hand, the passing phase of the second harmonic in the harmonic phase shift circuit 32 is −45°, and 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 located in the capacitive reactance region (capacitive impedance).

[0139] That is, in the amplifier circuit 1F according to this modified example, the power amplifier circuit 20 is an inverse class E amplifier that makes the load impedance inductive with respect to the second harmonic, and the power amplifier circuit 30 is an E class amplifier that makes the load impedance capacitive with respect to the second harmonic.

[0140] In other words, there is a phase difference of 90° between the phase of the impedance for the second harmonic at node n1 of the power amplifier circuit 20 and the phase of the impedance for the second harmonic at node n2 of the power amplifier circuit 30.

[0141] According to the above-described configuration of amplifier circuit 1F of this modification, the phase of the fundamental wave of the first output signal at node n1 output from power amplifier 21 is +45°, and the phase of the fundamental wave at input terminal 442 is +45°. Furthermore, the phase of the fundamental wave of the second output signal at node n2 output from power amplifier 31 is −45°, and the phase of the fundamental wave at input terminal 443 is −45°. As a result, the fundamental wave signals of the first band are in-phase combined by 90° combiner 44 and output from output terminal 441 as the third output signal. This allows amplifier circuit 1F to operate as a balanced amplifier that is resistant to load fluctuations.

[0142] On the other hand, the phase of the second harmonic of the first output signal at node n1 output from power amplifier 21 is +135°, and the phase of the second harmonic at input terminal 442 is +135°. Also, the phase of the second harmonic of the second output signal at node n2 output from power amplifier 31 is −135°, and the phase of the second harmonic at input terminal 443 is −135°. As a result, the second harmonic of the first band has a phase difference of 270° between input terminals 442 and 443, which becomes a phase difference of 180° at 90° combiner 44 and is canceled out. As a result, the amplifier circuit 1F can suppress second harmonics, thereby improving the quality and power efficiency of the transmission signal.

[0143] Furthermore, each of the power amplifier circuits 20 and 30 according to this modification is not a class F amplifier in which the load impedance of even-order harmonics is short-circuited and the load impedance of odd-order harmonics is open, but rather it is sufficient that the load impedance of the second-order harmonics is divided into inductive and capacitive, making it possible to cancel out second-order harmonics with high precision across the entire band of the wideband defined by 3GPP, for example, and ensure high transmission quality and power efficiency.

[0144] [8 Effects etc.] As described above, the amplifier circuit 1 according to the present embodiment (the amplifier circuit 1A according to the first modification and the amplifier circuit 1D according to the fourth modification) comprises a power amplifier circuit 20 (20A) including a power amplifier 21, a power amplifier circuit 30 (30A) including a power amplifier 31 whose fundamental wave at the output terminal is delayed in phase by 90° relative to the power amplifier 21, and an in-phase combining circuit 40 (phase shift line 50) configured to combine the fundamental wave of a first output signal output from the power amplifier circuit 20 (20A) and the fundamental wave of a second output signal output from the power amplifier circuit 30 (30A), wherein the power amplifier circuit 20 (20A) is inverse class E and the power amplifier circuit 30 (30A) is class E.

[0145] According to this, the power amplifier circuits 20 (20A) and 30 (30A) are not class F amplifiers in which the load impedance of even-order harmonics is short-circuited and the load impedance of odd-order harmonics is open, but rather are inverse class E amplifiers and class E amplifiers in which the load impedance of second-order harmonics is divided into inductive and capacitive, respectively, so that second-order harmonics can be canceled with high precision across the entire wide band specified by, for example, 3GPP. Therefore, it is possible to ensure high transmission quality and power efficiency while functioning as a balanced amplifier that is resistant to load fluctuations.

[0146] For example, the amplifier circuit 1 (1A) further includes a branching filter 10 having an input terminal 101 and output terminals 102 and 103, configured to branch a fundamental wave signal of a first band transmission 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 in-phase combining circuit 40 has input terminals 402, 403, and an output terminal 401, and includes an in-phase combiner 41 configured to output a third output signal from the output terminal 401, which is generated by in-phase combining a first output signal of the power amplifier circuit 20 (20A) input from the input terminal 402 and a second output signal of the power amplifier circuit 30 (30A) input from the input terminal 403; a phase shift circuit 23 connected between the power amplifier circuit 20 (20A) and the in-phase combiner 41, which is configured to phase-shift the fundamental wave and second harmonic of the first band; and a phase-shift circuit 33 connected between the first-band fundamental wave and the second harmonic wave of the first band and the in-phase combiner 41 and the power amplifier 21 (20A), and configured to phase-shift the second harmonic wave and the first-band fundamental wave so that the passing phase of the fundamental wave becomes +90° with respect to the phase-shift circuit 23. The power amplifier circuit 20 (20A) has a fourth input terminal and a fourth output terminal, and is connected to a power amplifier 21 having the fourth input terminal connected to the output terminal 102 and a path connecting the fourth output terminal and the input terminal 402, and configured to phase-shift the second harmonic wave. The power amplifier circuit 30 (30A) 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 connected to a path connecting the fifth output terminal and the input terminal 403 and configured to shift the phase of the second harmonic, and the phase 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°.

[0147] This allows for broadband suppression of second harmonics in the first band compared to conventional in-phase combining balanced amplifiers that do not include a harmonic phase shift circuit, thereby improving the quality and power efficiency of the transmitted signal.

[0148] Also, for example, in the amplifier circuit 1, a first phase 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 a second phase 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.

[0149] As a result, the second harmonic of the first band has a phase difference of 180° (inverse phase relationship) between input terminals 402 and 403 of in-phase combiner 41 and is cancelled out. Therefore, it is possible to provide amplifier circuit 1 with improved transmission signal quality and power efficiency.

[0150] For example, in the amplifier circuit 1, the phase shift circuit 23 is configured so that the passing phase of the fundamental wave and the second harmonic is -45°, the phase shift circuit 33 is configured so that the passing phase of 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°.

[0151] As a result, the second harmonic of the first band has a phase difference of 180° (inverse phase relationship) between input terminals 402 and 403 of in-phase combiner 41 and is cancelled out. Therefore, it is possible to provide amplifier circuit 1 with improved transmission signal quality and power efficiency.

[0152] 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 harmonic 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 harmonic is +Y° (Y>0), the harmonic phase shift circuit 22 is configured so that the passing phase of the harmonic is +X° (X>0), and the harmonic phase shift circuit 32 is configured so that the passing phase of the harmonic is -Y° (Y>0).

[0153] As a result, the second harmonic of the first band has a phase difference of 180° (inverse phase relationship) between input terminals 402 and 403 of in-phase combiner 41 and is cancelled out. Therefore, it is possible to provide amplifier circuit 1 with improved transmission signal quality and power efficiency.

[0154] Furthermore, for example, an amplifier circuit 1D according to a fourth modification further includes a demultiplexer 10 having an input terminal 101 and output terminals 102 and 103, and configured to demultiplex a fundamental signal of a first transmission band input to the input terminal 101, output a first signal from the output terminal 102, and output a second signal from the output terminal 103 that has a phase of −90° relative to the first signal; the combining circuit has a second input terminal and a third output terminal, and includes a phase shift line 50 configured to delay by 90° the fundamental of the first output signal of the first power amplifier circuit input from the second input terminal; the first power amplifier circuit has a third input terminal and a fourth output terminal, the third input terminal being connected to the output terminal 102, and the fourth output terminal being connected to the second input terminal and a harmonic phase shift circuit 22 connected to a path connecting the fourth output terminal and the second input terminal and configured to phase shift a second harmonic of the first band, the second power amplification circuit having a fourth input terminal and a fifth output terminal, the fourth input terminal being connected to the output terminal 103 and the fifth output terminal being connected to the third output terminal, and the harmonic phase shift circuit 32 connected to a path connecting the fifth output terminal and the third output terminal and configured to phase shift the second harmonic, wherein a 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°.

[0155] This makes it possible to suppress second harmonics in the first band with high precision compared to a conventional Doherty amplifier that does not have a harmonic phase shift circuit added, thereby improving the quality and power efficiency of the transmitted signal.

[0156] Furthermore, for example, an amplifier circuit 1E according to a fifth modification further includes a branching filter 10 having an input terminal 101 and output terminals 102 and 103, and configured to branch a fundamental wave signal of a first transmission 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 the combining circuit includes a phase-shift line 51 having a second input terminal and a third output terminal, and configured to delay the fundamental wave of the second output signal input from the second input terminal by 90°; and a transformer 43 having input terminals 432, 433 and an output terminal 432, and configured to output a third output signal from the output terminal 431, which is generated by combining, in antiphase, the first output signal input from the input terminal 432 and the second output signal input from the input terminal 433. the first power amplifier circuit includes a carrier amplifier (power amplifier 21) having a fifth input terminal and a fifth output terminal, the fifth input terminal being connected to output terminal 102 and the fifth output terminal being connected to input terminal 432, and a harmonic phase shift circuit 22 connected to a path connecting the fifth output terminal and input terminal 432 and configured to phase shift a second harmonic of the first band; the second power amplifier circuit includes a peak amplifier (power amplifier 31) having a sixth input terminal and a sixth output terminal, the sixth input terminal being connected to output terminal 103 and the sixth output terminal being connected to the second input terminal, and a harmonic phase shift circuit 32 connected to a path connecting the sixth output terminal and the second input terminal and configured to phase shift the second harmonic, and a 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°.

[0157] This makes it possible to suppress second harmonics in the first band with high precision compared to a conventional Doherty amplifier that does not have a harmonic phase shift circuit added, thereby improving the quality and power efficiency of the transmitted signal.

[0158] For example, the amplifier circuit 1C further includes a branching filter 10 having an input terminal 101 and output terminals 102 and 103, configured to branch a fundamental wave signal of a first band transmission 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 combining circuit 40C includes a transformer 42 having input terminals 422, 423, and an output terminal 421, configured to output a third output signal from the output terminal 421, which is generated by anti-phase combining the first output signal input from the input terminal 422 and the second output signal input from the input terminal 423; a phase shift circuit 23C connected between the power amplifier circuit 20 and the transformer 42 and configured to phase-shift the fundamental wave and second harmonic of the first band; the power amplifier circuit 20 has a fourth input terminal and a fourth output terminal, and includes a power amplifier 21 having the fourth input terminal connected to the output terminal 102, and a harmonic phase shift circuit 22 connected to a path connecting the fourth output terminal and the transformer 42, and configured to phase shift the second harmonic; the power amplifier circuit 30 has a fifth input terminal and a fifth output terminal, and includes a power amplifier 31 having the fifth input terminal connected to the output terminal 103, and a harmonic phase shift circuit 32 connected to a path connecting the fifth output terminal and the transformer 42, and configured to phase shift the second harmonic, and a 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 smaller than 90°.

[0159] This allows for broadband suppression of second harmonics in the first band compared to conventional anti-phase synthesis balanced amplifiers that do not include a harmonic phase shift circuit, thereby improving the quality and power efficiency of the transmitted signal.

[0160] Also, for example, in amplifier circuit 1C, the first phase difference obtained by subtracting the passing phase of the second harmonic of harmonic phase shift circuit 32 from the passing phase of the second harmonic of harmonic phase shift circuit 22 is equal to the second phase difference obtained by subtracting the passing phase of the second harmonic of phase shift circuit 33C from the passing phase of the second harmonic of phase shift circuit 23C.

[0161] As a result, the second harmonic of the first band is in phase and is cancelled out between the input terminals 422 and 423 of the transformer 42. Therefore, it is possible to provide an amplifier circuit 1C with improved transmission signal quality and power efficiency.

[0162] For example, in amplifier circuit 1C, phase shift circuit 23C is configured so that the passing phase of the fundamental wave and harmonics is +45°, phase shift circuit 33C is configured so that the passing phase of the fundamental wave and harmonics is -45°, harmonic phase shift circuit 22 is configured so that the passing phase of the harmonics is +45°, and harmonic phase shift circuit 32 is configured so that the passing phase of the harmonics is -45°.

[0163] As a result, the second harmonic of the first band is in phase and is cancelled out between the input terminals 422 and 423 of the transformer 42. Therefore, it is possible to provide an amplifier circuit 1C with improved transmission signal quality and power efficiency.

[0164] Furthermore, for example, an amplifier circuit 1F according to a sixth 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 first transmission 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 combining circuit has an input terminal 442 (second input terminal), an input terminal 443 (third input terminal), and an output terminal 441 (third output terminal), and outputs a third output signal from the output terminal 441, which is generated by combining the first output signal input from the input terminal 442 and a signal input from the input terminal 443 with a phase of the second output signal set to +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 connected to a path connecting the fourth output terminal and the input terminal 442 and configured to phase shift the second harmonic of the first 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 connected to a path connecting the fifth output terminal and the input terminal 443 and 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 443 from the phase of the second harmonic at the input terminal 442 is 90°.

[0165] This allows for broadband suppression of second harmonics in the first band compared to a conventional 90° combining balanced amplifier without a harmonic phase shift circuit, thereby improving the quality and power efficiency of the transmitted signal.

[0166] Also, for example, in the amplifier circuit 1F, the harmonic phase shift circuit 22 is configured so that the phase at which harmonics pass is +45°, and the harmonic phase shift circuit 32 is configured so that the phase at which harmonics pass is −45°.

[0167] As a result, the second harmonic of the first band has a phase difference of 270° between input terminals 442 and 443 of the 90° combiner 44, and is cancelled out in opposite phase at the 90° combiner 44. Therefore, an amplifier circuit 1F with improved transmission signal quality and power efficiency can be provided.

[0168] Furthermore, amplifier circuit 1 according to the present embodiment (amplifier circuit 1A according to modified example 1 and amplifier circuit 1C according to modified example 2) includes: a demultiplexer 10 having input terminal 101 and output terminals 102 and 103, configured to demultiplex a fundamental wave signal of a first band transmission band input to input terminal 101, output a first signal from output terminal 102, and output a second signal having a phase of −90° relative to the first signal from output terminal 103; a power amplifier 21 having a fourth input terminal and a fourth output terminal, the fourth input terminal being connected to output terminal 102; a power amplifier 31 having a fifth input terminal and a fifth output terminal, the fifth input terminal being connected to output terminal 103; input terminals 402, 403 and output terminal 401, receiving a first output signal output from power amplifier 21 from input terminal 402 and a second output signal output from power amplifier 31 from input terminal 403, and combining the signals in phase; the third output signal from the input terminal 401; a phase-shift circuit 23 connected between the power amplifier 21 and the in-phase combiner 41 and configured to phase-shift the fundamental wave and second harmonic of the first band; a phase-shift circuit 33 connected between the power amplifier 31 and the in-phase combiner 41 and configured to phase-shift the fundamental wave and second harmonic of the first band so that the passing phase of the fundamental wave is +90° with respect to the phase-shift circuit 23; a harmonic phase-shift circuit 22 (22A) connected to a path connecting the fourth output terminal and the input terminal 402 and configured to phase-shift the second harmonic; and a harmonic phase-shift circuit 32 (32A) connected to a path connecting the fifth output terminal and the input terminal 403 and 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°.

[0169] This allows for more accurate suppression of second harmonics in the first band than with a conventional in-phase combining balanced amplifier that does not include a harmonic phase shift circuit, thereby improving the quality of the transmitted signal and power efficiency while functioning as a balanced amplifier that is resistant to load fluctuations.

[0170] For example, in amplifier circuit 1B, a first phase difference obtained by subtracting the passing phase of the second harmonic of harmonic phase shift circuit 32 from the passing phase of the second harmonic of harmonic phase shift circuit 22 is equal to a second phase difference obtained by subtracting the passing phase of the second harmonic of phase shift circuit 23 from the passing phase of the second harmonic of phase shift circuit 33.

[0171] As a result, the second harmonic of the first band has a phase difference of 180° (inverse phase relationship) between input terminals 402 and 403 of in-phase combiner 41 and is cancelled out. Therefore, it is possible to provide amplifier circuit 1B with improved transmission signal quality and power efficiency.

[0172] For example, in amplifier circuit 1B, phase shift circuit 23 is configured so that the passing phase of the fundamental wave and second harmonic is -45°, phase shift circuit 33 is configured so that the passing phase of the fundamental wave and 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°.

[0173] As a result, the second harmonic of the first band has a phase difference of 180° (inverse phase relationship) between input terminals 402 and 403 of in-phase combiner 41 and is cancelled out. Therefore, it is possible to provide amplifier circuit 1B with improved transmission signal quality and power efficiency.

[0174] For example, in amplifier circuit 1B, phase shift circuit 23 is configured so that the passing phase of the fundamental wave is -45° and the passing phase of the harmonic is -X° (X>0), phase shift circuit 33 is configured so that the passing phase of the fundamental wave is +45° and the passing phase of the harmonic is +Y° (Y>0), harmonic phase shift circuit 22 is configured so that the passing phase of the harmonic is +X° (X>0), and harmonic phase shift circuit 32 is configured so that the passing phase of the harmonic is -Y° (Y>0).

[0175] As a result, the second harmonic of the first band has a phase difference of 180° (inverse phase relationship) between input terminals 402 and 403 of in-phase combiner 41 and is cancelled out. Therefore, it is possible to provide amplifier circuit 1B with improved transmission signal quality and power efficiency.

[0176] For example, in the amplifier circuit 1 (1A and 1B), the phase shift circuit 23 includes an inductor 231 connected between the fourth output terminal and the input terminal 402, and a capacitor 232 connected between the path connecting the inductor 231 and the input terminal 402 and ground, and the phase shift circuit 33 includes a capacitor 331 connected between the fifth output terminal and the input terminal 403, and an inductor 332 connected between the path connecting the capacitor 331 and the input terminal 403 and ground.

[0177] With this, phase shift circuit 23 forms a low-pass filter whose passband is the fundamental wave band and second harmonic band of the first band, and can set the pass phase of the fundamental wave of the first band to -45° and the pass phase of the second harmonic to -45° (-X°: X>0).Furthermore, phase shift circuit 33 forms a high-pass filter whose passband is the fundamental wave band and second harmonic band of the first band, and can set the pass phase of the fundamental wave of the first band to +45° and the pass phase of the second harmonic to +45° (+Y°: Y>0).

[0178] For example, in the amplifier circuit 1 (1A and 1B), the harmonic phase shift circuit 22 (22A) has 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 ground, and the harmonic phase shift circuit 32 (32A) includes a capacitor 321 connected between the path connecting the fifth output terminal and the capacitor 331 and ground.

[0179] According to this, the harmonic phase shift circuit 22 (22A) forms a notch filter with the fundamental wave band of the first band as its pass band and the second harmonic band as its attenuation band, and can set the pass phase of the fundamental wave to 0° and the pass phase of the second harmonic to +45° (+X°: X>0).Furthermore, the harmonic phase shift circuit 32 (32A) forms a low-pass filter with the fundamental wave band of the first band as its pass band and the second harmonic band as its attenuation band, and can set the pass phase of the fundamental wave to 0° and the pass phase of the second harmonic to -45° (-Y°: Y>0).

[0180] Furthermore, 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.

[0181] This allows the amplifier circuit 1 (1A and 1B) to be miniaturized and the signal wiring from the power amplifiers 21 and 31 to the in-phase combiner 41 to be shortened, thereby reducing the signal transmission loss of the amplifier circuit 1 (1A and 1B).

[0182] (Other embodiments, etc.) Although the amplifier circuit according to the present invention has been described above by way of examples and modifications, the amplifier circuit according to the present invention is not limited to the above examples and modifications. The present invention also includes other embodiments realized by combining any of the components in the above examples and modifications, modifications obtained by applying various modifications to the above examples and modifications that would occur to those skilled in the art without departing from the spirit of the present invention, and various devices incorporating the above amplifier circuits.

[0183] For example, in the amplifier circuits according to the above-described embodiments and modifications, second harmonics are used as harmonics, but third or higher harmonics may also be used.

[0184] For example, in the amplifier circuits according to the above-described embodiments and modifications, other circuit elements and wiring may be inserted between the paths connecting the circuit elements and signal paths disclosed in the drawings.

[0185] The features of the amplifier circuits described based on the above embodiments will be described below.

[0186] <1> a first power amplifier circuit including a first power amplifier; a second power amplifier circuit including a second power amplifier whose output terminal has a phase delay of 90° relative to that of the first power amplifier; a combining circuit configured to combine 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, the first power amplifier circuit is an inverse class E amplifier; The second power amplifier circuit is a class E amplifier circuit.

[0187] <2> moreover, a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, configured to demultiplex a fundamental wave signal of a first transmission 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° relative to the first signal from the second output terminal; The synthesis circuit a combiner having a second input terminal, a third input terminal, and a third output terminal, configured to output a third output signal from the third output terminal, the third output signal being generated by in-phase 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 combiner and configured to phase shift a fundamental wave and a harmonic wave of the first band; a second phase shift circuit connected between the second power amplifier circuit and the combiner, and configured to phase shift the fundamental wave and harmonics of the first band so that the passing phase of the fundamental wave is +90° with respect to the first phase shift circuit; The first power amplifier circuit a first power amplifier having a fourth input and a fourth output, the fourth input connected to the first output; a first harmonic phase shift circuit connected to a path connecting the fourth output terminal and the second input terminal, and configured to phase shift the harmonic; The second power amplifier circuit a second power amplifier having a fifth input and a fifth output, the fifth input connected to the second output; a second harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third input terminal, and configured to phase shift the harmonic; a phase difference obtained by subtracting the phase of the harmonic at the third input from the phase of the harmonic at the second input is greater than 90°; <1> The amplifier circuit according to claim 1.

[0188] <3> a first phase shift difference obtained by subtracting the phase of the harmonic passing through the second harmonic phase shift circuit from the phase of the harmonic passing through the first harmonic phase shift circuit is equal to a second phase shift difference obtained by subtracting the phase of the harmonic passing through the first phase shift circuit from the phase of the harmonic passing through the second phase shift circuit; <2> The amplifier circuit according to claim 1.

[0189] <4> the first phase shift circuit is configured so that the passing phase of the fundamental wave and the harmonic wave is −45°; the second phase shift circuit is configured so that the passing phase of the fundamental wave and the harmonic wave is +45°; the first harmonic phase shift circuit is configured so that the passing phase of the harmonic is +45°; The second harmonic phase shift circuit is configured so that the passing phase of the harmonic is −45°. <3> The amplifier circuit according to claim 1.

[0190] <5> the first phase shift circuit is configured so that the fundamental wave has a passing phase of −45° and the harmonic wave has a passing phase of −X° (X>0); the second phase shift circuit is configured so that the fundamental wave has a passing phase of +45° and the harmonic wave has a passing phase of +Y° (Y>0); the first harmonic phase shift circuit is configured so that the passing phase of the harmonic is +X° (X>0); The second harmonic phase shift circuit is configured so that the passing phase of the harmonic is −Y° (Y>0). <3> The amplifier circuit according to claim 1.

[0191] <6> moreover, a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, configured to demultiplex a fundamental wave signal of a first transmission band input to the first input terminal, output a first signal from the first output terminal, and output a second signal from the second output terminal, the second signal having a phase that is −90° relative to the first signal; The synthesis circuit a phase shift line having a second input terminal and a third output terminal, the phase shift line being configured to delay the fundamental wave of the first output signal input from the second input terminal by 90°; The first power amplifier circuit a carrier amplifier having a third input terminal and a fourth output terminal, the third input terminal being connected to the first output terminal and the fourth output terminal being connected to the second input terminal; a first harmonic phase shift circuit connected to a path connecting the fourth output terminal and the second input terminal, the first harmonic phase shift circuit being configured to phase shift harmonics of the first band; The second power amplifier circuit a peak amplifier having a fourth input terminal and a fifth output terminal, the fourth input terminal being connected to the second output terminal and the fifth output terminal being connected to the third output terminal; a second harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third output terminal, and configured to phase shift the harmonic; a phase difference obtained by subtracting the phase of the harmonic input from the fifth output port to the third output port from the phase of the harmonic input from the fourth output port to the third output port is greater than 90°; <1> The amplifier circuit according to claim 1.

[0192] <7> moreover, a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, configured to demultiplex a fundamental wave signal of a first transmission band input to the first input terminal, output a first signal from the first output terminal, and output a second signal from the second output terminal, the second signal having a phase that is −90° relative to the first signal; The synthesis circuit a phase shift line having a second input terminal and a third output terminal, the phase shift line being configured to delay the fundamental wave of the second output signal input from the second input terminal by 90°; 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 combining, in antiphase, 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 a carrier amplifier having a fifth input terminal and a fifth output terminal, the fifth input terminal being connected to the first output terminal and the fifth output terminal being connected to the third input terminal; a first harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third input terminal, the first harmonic phase shift circuit being configured to phase shift harmonics of the first band; The second power amplifier circuit a peak amplifier having a sixth input terminal and a sixth output terminal, the sixth input terminal being connected to the second output terminal and the sixth output terminal being connected to the second input terminal; a second harmonic phase shift circuit connected to a path connecting the sixth output terminal and the second input terminal, the second harmonic phase shift circuit being configured to phase shift the harmonic; a phase difference obtained by subtracting the phase of the harmonic at the fourth input port from the phase of the harmonic at the third input port is less than 90°; <1> The amplifier circuit according to claim 1.

[0193] <8> moreover, a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, configured to demultiplex a fundamental wave signal of a first transmission band input to the first input terminal, output a first signal from the first output terminal, and output a second signal from the second output terminal, the second signal having a phase that is −90° relative to the first signal; The synthesis circuit 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 combining, in antiphase, 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 phase shift a fundamental wave and a harmonic wave of the first band; 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 band so that the passing phase of the fundamental wave becomes −90° relative to the first phase shift circuit; The first power amplifier circuit a first power amplifier having a fourth input and a fourth output, the fourth input connected to the first output; a first harmonic phase shift circuit connected to a path connecting the fourth output terminal and the second input terminal, and configured to phase shift the harmonic; The second power amplifier circuit a second power amplifier having a fifth input and a fifth output, the fifth input connected to the second output; a second harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third input terminal, and configured to phase shift the harmonic; a phase difference obtained by subtracting the phase of the harmonic at the third input port from the phase of the harmonic at the second input port is less than 90°; <1> The amplifier circuit according to claim 1.

[0194] <9> a first phase shift difference obtained by subtracting the phase of the harmonic passing through the second harmonic phase shift circuit from the phase of the harmonic passing through the first harmonic phase shift circuit is equal to a second phase shift difference obtained by subtracting the phase of the harmonic passing through the second phase shift circuit from the phase of the harmonic passing through the first phase shift circuit; <8> The amplifier circuit according to claim 1.

[0195] <10> the first phase shift circuit is configured so that the passing phase of the fundamental wave and the harmonic wave is +45°; the second phase shift circuit is configured so that the passing phase of the fundamental wave and the harmonic wave is −45°; the first harmonic phase shift circuit is configured so that the passing phase of the harmonic is +45°; The second harmonic phase shift circuit is configured so that the passing phase of the harmonic is −45°. <9> The amplifier circuit according to claim 1.

[0196] <11> moreover, a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, configured to demultiplex a fundamental wave signal of a first transmission band input to the first input terminal, output a first signal from the first output terminal, and output a second signal from the second output terminal, the second signal having a phase that is −90° relative to the first signal; The synthesis circuit a combiner having a second input terminal, a third input terminal, and a third output terminal, configured to combine the first output signal input from the second input terminal with a signal input from the third input terminal, the phase of which is set to +90° with respect to the first output signal, and output the combined signal from the third output terminal; The first power amplifier circuit a first power amplifier having a fourth input and a fourth output, the fourth input connected to the first output; a first harmonic phase shift circuit connected to a path connecting the fourth output terminal and the second input terminal, the first harmonic phase shift circuit configured to phase shift a first-band harmonic; The second power amplifier circuit a second power amplifier having a fifth input and a fifth output, the fifth input connected to the second output; a second harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third input terminal, and configured to phase shift the harmonic; a phase difference obtained by subtracting the phase of the harmonic at the second input from the phase of the harmonic at the third input is 90°; <1> The amplifier circuit according to claim 1.

[0197] <12> the first harmonic phase shift circuit is configured so that the passing phase of the harmonic is +45°; The second harmonic phase shift circuit is configured so that the passing phase of the harmonic is −45°. <11> The amplifier circuit according to claim 1.

[0198] <13> a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, configured to demultiplex a fundamental wave signal of a first transmission 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° relative to the first signal from the second output terminal; a first power amplifier having a fourth input and a fourth output, the fourth input connected to the first output; a second power amplifier having a fifth input and a fifth output, the fifth input connected to the second output; a combiner having a second input terminal, a third input terminal, and a third output terminal, configured to receive a first output signal output from the first power amplifier through the second input terminal, receive a second output signal output from the second power amplifier through the third input terminal, and output an in-phase combined third output signal from the third output terminal; a first phase shift circuit connected between the first power amplifier and the combiner and configured to phase shift a fundamental wave and a harmonic wave of the first band; a second phase shift circuit connected between the second power amplifier and the combiner, configured to phase shift the fundamental wave and harmonics of the first band so that the passing phase of the fundamental wave is +90° with respect to the first phase shift circuit; a first harmonic phase shift circuit connected to a path connecting the fourth output terminal and the second input terminal, the first harmonic phase shift circuit configured to phase shift the harmonic; a second harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third input terminal and configured to phase shift the harmonic; An amplifier circuit, wherein a phase 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°.

[0199] <14> a first phase shift difference obtained by subtracting the phase of the harmonic passing through the second harmonic phase shift circuit from the phase of the harmonic passing through the first harmonic phase shift circuit is equal to a second phase shift difference obtained by subtracting the phase of the harmonic passing through the first phase shift circuit from the phase of the harmonic passing through the second phase shift circuit; <13> The amplifier circuit according to claim 1.

[0200] <15> the first phase shift circuit is configured so that the passing phase of the fundamental wave and the harmonic wave is −45°; the second phase shift circuit is configured so that the passing phase of the fundamental wave and the harmonic wave is +45°; the first harmonic phase shift circuit is configured so that the passing phase of the harmonic is +45°; The second harmonic phase shift circuit is configured so that the passing phase of the harmonic is −45°. <14> The amplifier circuit according to claim 1.

[0201] <16> the first phase shift circuit is configured so that the fundamental wave has a passing phase of −45° and the harmonic wave has a passing phase of −X° (X>0); the second phase shift circuit is configured so that the fundamental wave has a passing phase of +45° and the harmonic wave has a passing phase of +Y° (Y>0); the first harmonic phase shift circuit is configured so that the passing phase of the harmonic is +X° (X>0); The second harmonic phase shift circuit is configured so that the passing phase of the harmonic is −Y° (Y>0). <14> The amplifier circuit according to claim 1.

[0202] <17> The first phase shift circuit comprises: a first inductor connected between the fourth output terminal and the second input terminal; a first capacitor connected between a path connecting the first inductor and the second input terminal and ground; The second phase shift circuit comprises: a second capacitor connected between the fifth output terminal and the third input terminal; a second inductor connected between a path connecting the second capacitor and the third input terminal and ground; <13> ~ <16> 1. An amplifier circuit according to claim 1 .

[0203] <18> The first harmonic phase shift circuit comprises: 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 ground; The second harmonic phase shift circuit comprises: a fourth capacitor connected between a path connecting the fifth output terminal and the second capacitor and ground; <17> The amplifier circuit according to claim 1.

[0204] <19> 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; <13> ~ <18> 1. An amplifier circuit according to claim 1 . [Industrial Applicability]

[0205] The present invention can be widely used as an amplifier circuit disposed in a front end portion of communication devices such as mobile phones. [Explanation of symbols]

[0206] 1, 1A, 1B, 1C, 1D, 1E, 1F, 500 amplifier circuit 10 Duplexer 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 Inverted Phase Synthesis Circuit 41 In-phase synthesizer 42, 43 Transformer 44 90° synthesizer 50, 51 phase shift line 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. a first power amplifier circuit including a first power amplifier; a second power amplifier circuit including a second power amplifier whose output terminal has a phase delay of 90° relative to that of the first power amplifier; a combining circuit configured to combine 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, the first power amplifier circuit is an inverse class E amplifier; the second power amplifier circuit is class E; Amplification circuit.

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

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

4. the first phase shift circuit is configured so that the passing phase of the fundamental wave and the harmonic wave is −45°; the second phase shift circuit is configured so that the passing phase of the fundamental wave and the harmonic wave is +45°; the first harmonic phase shift circuit is configured so that the passing phase of the harmonic is +45°; The second harmonic phase shift circuit is configured so that the passing phase of the harmonic is −45°.

4. The amplifier circuit according to claim 3.

5. the first phase shift circuit is configured so that the fundamental wave has a passing phase of −45° and the harmonic wave has a passing phase of −X° (X>0); the second phase shift circuit is configured so that the fundamental wave has a passing phase of +45° and the harmonic wave has a passing phase of +Y° (Y>0); the first harmonic phase shift circuit is configured so that the passing phase of the harmonic is +X° (X>0); The second harmonic phase shift circuit is configured so that the passing phase of the harmonic is −Y° (Y>0).

4. The amplifier circuit according to claim 3.

6. moreover, a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, configured to demultiplex a fundamental wave signal of a first transmission band input to the first input terminal, output a first signal from the first output terminal, and output a second signal from the second output terminal, the second signal having a phase that is −90° relative to the first signal; The synthesis circuit a phase shift line having a second input terminal and a third output terminal, the phase shift line being configured to delay the fundamental wave of the first output signal input from the second input terminal by 90°; The first power amplifier circuit a carrier amplifier having a third input terminal and a fourth output terminal, the third input terminal being connected to the first output terminal and the fourth output terminal being connected to the second input terminal; a first harmonic phase shift circuit connected to a path connecting the fourth output terminal and the second input terminal, the first harmonic phase shift circuit configured to phase shift harmonics of the first band; The second power amplifier circuit a peak amplifier having a fourth input terminal and a fifth output terminal, the fourth input terminal being connected to the second output terminal and the fifth output terminal being connected to the third output terminal; a second harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third output terminal, the second harmonic phase shift circuit being configured to phase shift the harmonic; a phase difference obtained by subtracting the phase of the harmonic input from the fifth output port to the third output port from the phase of the harmonic input from the fourth output port to the third output port is greater than 90°; 2. The amplifier circuit according to claim 1.

7. moreover, a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, configured to demultiplex a fundamental wave signal of a first transmission band input to the first input terminal, output a first signal from the first output terminal, and output a second signal from the second output terminal, the second signal having a phase that is −90° relative to the first signal; The synthesis circuit a phase shift line having a second input terminal and a third output terminal, the phase shift line being configured to delay by 90° the fundamental wave of the second output signal input from the second input terminal; 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 anti-phase synthesis of 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 a carrier amplifier having a fifth input terminal and a fifth output terminal, the fifth input terminal being connected to the first output terminal and the fifth output terminal being connected to the third input terminal; a first harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third input terminal, the first harmonic phase shift circuit being configured to phase shift harmonics of the first band; The second power amplifier circuit a peak amplifier having a sixth input terminal and a sixth output terminal, the sixth input terminal being connected to the second output terminal and the sixth output terminal being connected to the second input terminal; a second harmonic phase shift circuit connected to a path connecting the sixth output terminal and the second input terminal, the second harmonic phase shift circuit being configured to phase shift the harmonic; a phase 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°; 2. The amplifier circuit according to claim 1.

8. moreover, a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, configured to demultiplex a fundamental wave signal of a first transmission band input to the first input terminal, output a first signal from the first output terminal, and output a second signal from the second output terminal, the second signal having a phase that is −90° relative to the first signal; The synthesis circuit 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 combining, in antiphase, 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 phase shift a fundamental wave and a harmonic wave of the first band; 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 band so that the passing phase of the fundamental wave becomes −90° relative to the first phase shift circuit; The first power amplifier circuit a first power amplifier having a fourth input and a fourth output, the fourth input connected to the first output; a first harmonic phase shift circuit connected to a path connecting the fourth output terminal and the second input terminal, the first harmonic phase shift circuit being configured to phase shift the harmonic; The second power amplifier circuit a second power amplifier having a fifth input and a fifth output, the fifth input connected to the second output; a second harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third input terminal, the second harmonic phase shift circuit being configured to phase shift the harmonic; a phase difference obtained by subtracting the phase of the harmonic at the third input from the phase of the harmonic at the second input is less than 90°; 2. The amplifier circuit according to claim 1.

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

10. the first phase shift circuit is configured so that the passing phase of the fundamental wave and the harmonic wave is +45°; the second phase shift circuit is configured so that the passing phase of the fundamental wave and the harmonic wave is −45°; the first harmonic phase shift circuit is configured so that the passing phase of the harmonic is +45°; The second harmonic phase shift circuit is configured so that the passing phase of the harmonic is −45°.

10. The amplifier circuit according to claim 9.

11. moreover, a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, configured to demultiplex a fundamental wave signal of a first transmission band input to the first input terminal, output a first signal from the first output terminal, and output a second signal from the second output terminal, the second signal having a phase that is −90° relative to the first signal; The synthesis circuit a combiner having a second input terminal, a third input terminal, and a third output terminal, configured to combine the first output signal input from the second input terminal with a signal input from the third input terminal, the phase of which is set to +90° with respect to the first output signal, and output a third output signal from the third output terminal; The first power amplifier circuit a first power amplifier having a fourth input and a fourth output, the fourth input connected to the first output; a first harmonic phase shift circuit connected to a path connecting the fourth output terminal and the second input terminal, the first harmonic phase shift circuit being configured to phase shift harmonics of a first band; The second power amplifier circuit a second power amplifier having a fifth input and a fifth output, the fifth input connected to the second output; a second harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third input terminal, the second harmonic phase shift circuit being configured to phase shift the harmonic; a phase 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°; 2. The amplifier circuit according to claim 1.

12. the first harmonic phase shift circuit is configured so that the passing phase of the harmonic is +45°; The second harmonic phase shift circuit is configured so that the passing phase of the harmonic is −45°.

12. The amplifier circuit of claim 11.

13. a demultiplexer having a first input terminal, a first output terminal, and a second output terminal, configured to demultiplex a fundamental wave signal of a first transmission 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° relative to the first signal from the second output terminal; a first power amplifier having a fourth input and a fourth output, the fourth input connected to the first output; a second power amplifier having a fifth input and a fifth output, the fifth input connected to the second output; a combiner having a second input terminal, a third input terminal, and a third output terminal, configured to receive a first output signal output from the first power amplifier through the second input terminal, receive a second output signal output from the second power amplifier through the third input terminal, and output an in-phase combined third output signal from the third output terminal; a first phase shift circuit connected between the first power amplifier and the combiner and configured to phase shift a fundamental wave and a harmonic wave of the first band; a second phase shift circuit connected between the second power amplifier and the combiner, configured to phase shift the fundamental wave and harmonics of the first band so that the passing phase of the fundamental wave is +90° with respect to the first phase shift circuit; a first harmonic phase shift circuit connected to a path connecting the fourth output terminal and the second input terminal, the first harmonic phase shift circuit configured to phase shift the harmonic; a second harmonic phase shift circuit connected to a path connecting the fifth output terminal and the third input terminal and configured to phase shift the harmonic; a phase difference obtained by subtracting the phase of the harmonic at the third input from the phase of the harmonic at the second input is greater than 90°; Amplification circuit.

14. a first phase shift difference obtained by subtracting the phase of the harmonic passing through the second harmonic phase shift circuit from the phase of the harmonic passing through the first harmonic phase shift circuit is equal to a second phase shift difference obtained by subtracting the phase of the harmonic passing through the first phase shift circuit from the phase of the harmonic passing through the second phase shift circuit; 14. The amplifier circuit of claim 13.

15. the first phase shift circuit is configured so that the passing phase of the fundamental wave and the harmonic wave is −45°; the second phase shift circuit is configured so that the passing phase of the fundamental wave and the harmonic wave is +45°; the first harmonic phase shift circuit is configured so that the passing phase of the harmonic is +45°; The second harmonic phase shift circuit is configured so that the passing phase of the harmonic is −45°.

15. The amplifier circuit of claim 14.

16. the first phase shift circuit is configured so that the fundamental wave has a passing phase of −45° and the harmonic wave has a passing phase of −X° (X>0); the second phase shift circuit is configured so that the fundamental wave has a passing phase of +45° and the harmonic wave has a passing phase of +Y° (Y>0); the first harmonic phase shift circuit is configured so that the passing phase of the harmonic is +X° (X>0); The second harmonic phase shift circuit is configured so that the passing phase of the harmonic is −Y° (Y>0).

15. The amplifier circuit of claim 14.

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

18. The first harmonic phase shift circuit comprises: 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 ground; The second harmonic phase shift circuit comprises: a fourth capacitor connected between a path connecting the fifth output terminal and the second capacitor and ground; 18. The amplifier circuit of claim 17.

19. 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; The amplifier circuit according to any one of claims 13 to 16.

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