High-frequency power amplifier

Abstract

The invention provides a high-frequency power amplifier which can realize miniaturization and broadband. The input signal distributor distributes a high-frequency first input signal into a second input signal and a third input signal. A second input signal is input to the balanced amplifier. And two output ends of the balanced amplifier for outputting two amplified high-frequency signals with a phase difference of 90 degrees are respectively coupled with the first port and the second port. And the control amplifier amplifies the third input signal and outputs the amplified signal from the output end. The output of the control amplifier is coupled to the third port without via a circuit component that affects impedance matching. The balanced amplifier and the control amplifier are supplied with a common power supply voltage. The voltage level of the first input signal when the current output from the control amplifier rises is higher than the voltage level of the first input signal when the current output from the balance amplifier rises. The hybrid coupler varies a load impedance of a balanced amplifier coupled to the first and second ports in accordance with a current level of a high-frequency signal input from the control amplifier to the third port.

Description

TECHNICAL FIELD

[0001] The present application relates to a high-frequency power amplifier. BACKGROUND

[0002] As a technique for realizing a high-efficiency high-frequency power amplifier, a load-modulated balanced amplifier (LMBA) has been attracting attention (Non-Patent Literature 1). In the LMBA disclosed in Non-Patent Literature 1, a balanced amplifier is biased in AB class, and a control amplifier that modulates the load impedance of the balanced amplifier is biased in C class. Two high-frequency signals having a phase difference of 90° output from the balanced amplifier and a high-frequency signal output from the control amplifier are synthesized in a hybrid coupler and supplied to a load.

[0003] PRIOR ART DOCUMENTS

[0004] NON-PATENT LITERATURE

[0005] Non-Patent Literature 1: K. Takenaka, et al., "Load-Modulated Balanced Amplifier Design for Handset Applications", IEEE Microwave and Wireless Technology Letters, Vol. 33, No. 6, JUNE 2023 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] In the LMBA disclosed in Non-Patent Literature 1, in order to cause the balanced amplifier and the control amplifier to operate with high power-added efficiency by a single power supply, an impedance matching circuit is inserted between the control amplifier and the hybrid coupler. This impedance matching circuit becomes a major cause of hindering the miniaturization of the device and the broadbandization of the high-frequency amplifier.

[0008] An object of the present application is to provide a high-frequency power amplifier that can achieve miniaturization and broadbandization.

[0009] TECHNICAL SOLUTION FOR SOLVING THE PROBLEM

[0010] According to one aspect of the present application, there is provided a high-frequency power amplifier, comprising:

[0011] a hybrid coupler having a first port, a second port, a third port, and a fourth port connected to a load;

[0012] an input signal distributor that distributes a first input signal of a high frequency into a second input signal and a third input signal;

[0013] a balanced amplifier which is inputted with the second input signal and whose two output terminals which output two amplified high frequency signals having a phase difference of 90° from each other are coupled to the first port and the second port, respectively, and

[0014] a control amplifier which amplifies the third input signal and whose output terminal outputting the amplified third input signal is coupled to the third port without passing through a circuit member which affects impedance matching,

[0015] the balanced amplifier and the control amplifier are supplied with a common power supply voltage,

[0016] a voltage level of the first input signal when a current outputted from the control amplifier rises is higher than a voltage level of the first input signal when a current outputted from the balanced amplifier rises,

[0017] the hybrid coupler changes a load impedance of the balanced amplifier coupled to the first port and the second port in accordance with a current level of a high frequency signal inputted from the control amplifier to the third port.

[0018] Effects of the Invention

[0019] The output terminal of the balanced amplifier is coupled to the third port of the hybrid circuit without passing through a circuit member which affects impedance matching, and thus, downsizing of the device can be achieved. Also, a decrease in wideband characteristics due to insertion of an impedance matching circuit is suppressed. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a block diagram of a high frequency power amplifier of a first embodiment.

[0021] Figure 2 is a schematic equivalent circuit diagram for explaining an operation of the hybrid coupler 30.

[0022] Figure 3 is a block diagram of a high frequency power amplifier of a comparative example.

[0023] Figure 4A is a graph showing a relationship between an input voltage of a first input signal RF1 Figure 3 and currents I BA , I CSP , and I CA , Figure 4B is a graph showing a relationship between an input voltage of a first input signal RF1 and voltages V BA , V CSP , and V CA , Figure 4C is a graph showing a relationship between an input voltage and load impedances Z BA , Z CSP, Z CA a graph showing the relationship of the input voltage of the first input signal RF1

[0024] Figure 5A is a graph showing the relationship of the input voltage of the first input signal RF1 Figure 1 and the current I BA , I CSP , I CA , Figure 5B is a graph showing the relationship of the input voltage of the first input signal RF1 and the voltage V BA , V CSP , V CA , Figure 5C is a graph showing the relationship of the input voltage of the first input signal RF1 and the load impedance Z BA , Z CSP , Z CA .

[0025] Figure 6 is a graph showing the relationship of the input voltage of the first input signal RF1 and the voltage V BA , V CSP , V CA in the case where the rising point of the current I CA is changed in the high-frequency power amplifier of the first embodiment.

[0026] Figure 7 is a graph showing the relationship of the input voltage and the power addition efficiency of the high-frequency power amplifier of the first embodiment.

[0027] Figure 8 is a schematic top view of the hybrid coupler 30 used in the high-frequency power amplifier of a modification example of the first embodiment.

[0028] Figure 9 is a schematic perspective view of the hybrid coupler 30 used in the high-frequency power amplifier of another modification example of the first embodiment.

[0029] Figure 10 is an equivalent circuit diagram of the hybrid coupler 30 used in the high-frequency power amplifier of still another modification example of the first embodiment.

[0030] Figure 11 is a block diagram of the high-frequency power amplifier of the second embodiment.

[0031] Figure 12 is a block diagram of the high-frequency power amplifier of the third embodiment.

[0032] Figure 13 is a block diagram of the high-frequency power amplifier of the fourth embodiment.

[0033] Figure 14 is a block diagram of the communication device of the fifth embodiment.

[0034] Reference Signs List

[0035] 10: balance amplifier

[0036] 11: distributor

[0037] 12A, 12B: amplifier

[0038] 20: control amplifier

[0039] 30: hybrid coupler

[0040] 30A: main line

[0041] 30B: sub line

[0042] 31A, 31B, 31C, 31D: transmission line

[0043] 32A, 32B: plate

[0044] 33A, 33B: inductor

[0045] 33C, 33D: capacitor

[0046] 40: input signal distributor

[0047] 50: driver stage amplifier

[0048] 51, 53, 55: impedance matching circuit

[0049] 53A: main line

[0050] 53B: sub line

[0051] 80: transmission system

[0052] 81: high frequency power amplifier

[0053] 82: first switch

[0054] 83: filter circuit

[0055] 84: second switch

[0056] 90: transceiver IC

[0057] 91: multiplexer

[0058] 92: antenna DETAILED DESCRIPTION

[0059] [First Embodiment]

[0060] Reference Signs List Figures 1 to 5CFIG. 1 is a diagram illustrating a high-frequency power amplifier of a first embodiment.

[0061] Figure 1 FIG. 1 is a block diagram of a high-frequency power amplifier of a first embodiment. The high-frequency power amplifier of the first embodiment includes a balanced amplifier 10, a control amplifier 20, a hybrid coupler 30, and an input signal distributor 40. Hereinafter, the high-frequency power amplifier of the first embodiment and its peripheral circuit will be described.

[0062] The input terminal T in An input high-frequency signal is input to the driver stage amplifier 50 via the impedance matching circuit 51. The input high-frequency signal is a signal of a radio frequency band modulated by a prescribed communication system. A power supply voltage Vcc is supplied to the driver stage amplifier 50 via the choke coil L. The driver stage amplifier 50 amplifies the input high-frequency signal and outputs a first input signal RF1. The first input signal RF1 amplified by the driver stage amplifier 50 is input to the input signal distributor 40.

[0063] The input signal distributor 40 distributes the first input signal RF1 and outputs a second input signal RF2 and a third input signal RF3. As the input signal distributor 40, for example, a 3 dB coupler using a coupled transmission line, a Wilkinson-type distributor, or the like can be used. For example, the signal levels of the second input signal RF2 and the third input signal RF3 are each a level lowered by 3 dB from the signal level of the first input signal RF1, and the two have a phase difference of 90°. Note that the signal levels of the second input signal RF2 and the third input signal RF3 and the phase difference between the two can be other values. The second input signal RF2 is input to the balanced amplifier 10, and the third input signal RF3 is input to the control amplifier 20.

[0064] The balanced amplifier 10 includes two amplifiers 12A, 12B that amplify two high-frequency signals obtained by distributing the second input signal RF2, respectively. The amplifiers 12A, 12B are constituted by, for example, a heterojunction bipolar transistor (HBT) or the like. For example, the distributor 11 distributes the second input signal RF2 into two high-frequency signals. The two high-frequency signals have equal signal levels, and the two have a phase difference of 90°. As the distributor 11, for example, a 3 dB coupler using a coupled transmission line can be used. The amplifiers 12A, 12B are respectively given class-AB bias. A power supply voltage Vcc is supplied to the amplifiers 12A, 12B via the choke coil L, respectively.

[0065] The control amplifier 20 is given a class-C bias, and amplifies the third input signal RF3. The control amplifier 20 is constituted by, for example, a heterojunction bipolar transistor (HBT) or the like. A power supply voltage Vcc is supplied to the control amplifier 20 via the choke coil L. That is, the balanced amplifier 10 and the control amplifier 20 operate by a single power supply voltage Vcc.

[0066] The hybrid coupler 30 is constituted by a main line 30A and a sub line 30B that are electromagnetically coupled to each other. Let the one end of the main line be referred to as a first port P1, and the other end of the main line be referred to as a fourth port P4. Let the end portion of the sub line on the first port P1 side be referred to as a third port P3, and the end portion of the sub line on the fourth port P4 side be referred to as a second port P2.

[0067] The outputs of the two amplifiers 12A, 12B are coupled to the first port P1 and the second port P2 of the hybrid coupler 30, respectively. The output of the control amplifier 20 is coupled to the third port P3 of the hybrid coupler 30. The fourth port P4 of the hybrid coupler 30 is coupled to the output terminal T out via the impedance matching circuit 53. out The load such as an antenna or the like is connected to the output terminal T

[0068] The high frequency signals input to the first port P1 and the second port P2 are synthesized and output from the fourth port P4. The high frequency signal input to the third port P3 is output from the fourth port P4. That is, the high frequency signal of a power equivalent to the sum of the powers of the high frequency signals input to the first port P1, the second port P2, and the third port P3 is output from the fourth port P4. The load impedance of the two amplifiers 12A, 12B of the balanced amplifier 10 varies in accordance with the current level of the high frequency signal input to the third port P3 from the control amplifier 20. More specifically, the load impedance of the two amplifiers 12A, 12B of the balanced amplifier 10 varies in accordance with the ratio of the current level of the high frequency signal input to the third port P3 from the control amplifier 20 to the current level of the high frequency signals input to the first port P1 and the second port P2 from the balanced amplifier 10.

[0069] Next, the operation of the hybrid coupler 30 will be described in more detail with reference to Figure 2 the equivalent circuit diagram of FIG. 6.

[0070] Figure 2 is a schematic equivalent circuit diagram for explaining the operation of the hybrid coupler 30. It is assumed that current -I BA , jI BA , and -I CSP e jφCurrent source flowing in. The current sources connected to the first port P1, the second port P2, and the third port P3 correspond to the amplifiers 12A, 12B, and the control amplifier 20 of the balanced amplifier 10, respectively Figure 1 Here, j is an imaginary unit, and φ is a phase shift.

[0071] A load RL is connected to the fourth port P4. The current flowing in from the load RL to the fourth port P4 is denoted by -I L The voltages generated at the first port P1, the second port P2, the third port P3, and the fourth port P4 are denoted by V BA2 , V BA1 , V CSP , and V L , respectively. The load impedances observed from the first port P1, the second port P2, and the third port P3 on the load side are denoted by Z BA2 , Z BA1 , and Z CSP , respectively.

[0072] The currents flowing in to the hybrid coupler 30 and the voltages generated at the ports are expressed by the following relational expressions using the impedance matrix of the hybrid coupler 30.

[0073] [Equation 1]

[0074]

[0075]

[0076] Here, Z0 is the characteristic impedance of the hybrid coupler 30.

[0077] When the expanded expression (1) is expanded, the load impedances Z BA1 , Z BA2 are expressed by the following expressions.

[0078] [Equation 2]

[0079]

[0080] The load impedance Z CSP is expressed by the following expression.

[0081] [Equation 3]

[0082]

[0083] The voltages V BA1 , V BA2 are expressed by the following expressions.

[0084] [Equation 4]

[0085]

[0086] According to equation (2), the load impedance Z BA1 Z BA2 Equal, determined by the current I input to the third port P3. CSP It is controlled by the phase offset φ. On the other hand, the load impedance Z on the load side is observed from the third port P3. CSP It is fixed.

[0087] Next, refer to Figures 3 to 4C The figure illustrates the high-frequency power amplifier of the comparative example and its operation.

[0088] Figure 3 This is a block diagram of a comparative example of a high-frequency power amplifier. In the first embodiment, the high-frequency power amplifier ( Figure 1 In the control amplifier 20, the output is directly connected to the third port P3 of the hybrid coupler 30, but in the comparative example, an impedance matching circuit 55 is inserted between the two.

[0089] and Figure 2 The currents and voltages shown are similarly labeled at each port of the hybrid coupler 30. The load impedance on the load side, as observed from the output of the control amplifier 20, is labeled Z. CA The current output from control amplifier 20 will be labeled as -I. CA e jφ The voltage at the output of the control amplifier 20 is marked as V. CA .

[0090] Figure 4A This shows the first input signal RF1 ( Figure 3 The input voltage and current I) BA I CSP I CA A diagram showing the relationship between the two. Figure 4B This shows the input voltage and voltage V of the first input signal RF1. BA V CSP V CA A diagram showing the relationship between the two. Figure 4A and Figure 4B The horizontal axis represents the input voltage as a value obtained by normalizing it to its maximum value. Figure 4A The vertical axis represents the current I. BA The value is represented by the normalized value of the maximum value. Figure 4B The vertical axis represents the voltage in terms of voltage V. BA The value is represented by the normalized value of the maximum value.

[0091] Since the balanced amplifier 10 is given a Class AB bias, therefore, as Figure 4A As shown, current IBA Starting from the point where the normalized value of the input voltage is 0, the current I rises along with the rise in the input voltage. BA It increases roughly linearly. At the point where the normalized value of the input voltage reaches 1, the current I... BA The normalized value becomes 1. Since the control amplifier 20 is given a Class C bias, therefore, in the specific current I... BA When the input voltage rises to a high voltage level, for example at a time point where the normalized value of the input voltage is 0.5, the current I... CA Rise. With current I CA At the same time as the rise, the current I CSP It also rises. Current I CSP I CA It increases linearly along with the increase in input voltage level.

[0092] When the current I CSP The slope is the current I BA The slope of 2 -1 / 2 When doubled, such as Figure 4B As shown, voltage V BA It becomes fixed (refer to equation (4)). Using this relationship, the balanced amplifier 10 can be made to operate as a carrier amplifier of the Doherty amplifier.

[0093] To maximize the power-added efficiency of the high-frequency power amplifier, it is preferable that the voltage V is at its maximum value when the normalized value of the input voltage is 1 (i.e., the input voltage is at its maximum value). BA With voltage V CA Consistent. Figure 4B The figure shows the voltage V when the normalized value of the input voltage is 1. BA With voltage V CA A consistent state. Typically, the current I at this time... CA With current I CSP Inconsistent, voltage V CSP With voltage V CA Inconsistent.

[0094] Figure 4C This shows the input voltage and load impedance Z. BA Z CSP Z CA The graph shows the relationship between the input voltage and the load impedance. The horizontal axis represents the input voltage as a normalized value, and the vertical axis represents the load impedance as a normalized value obtained using the characteristic impedance Z0 of the hybrid coupler 30. In the current I... CSP Within the range of 0, the load impedance Z BA The normalized value is 1 (refer to equation (2)). Load impedance Z CSP The normalized value is also 1 (refer to formula (3)).

[0095] Due to current I CSP with I CA Inconsistent, voltage V CSP With V CA Inconsistent, therefore, the load impedance Z CA With load impedance Z CSP The difference is that, therefore, in the comparative example, an impedance matching circuit 55 must be inserted between the output of the control amplifier 20 and the third port P3 of the hybrid coupler 30. Figure 3 ).

[0096] Next, refer to Figure 5A , Figure 5B and Figure 5C The operation of the high-frequency power amplifier in the first embodiment will be explained. Figure 5A This shows the first input signal RF1 ( Figure 1 The input voltage and current I) BA I CSP I CA A diagram of the relationships. Figure 5B This shows the input voltage and voltage V of the first input signal RF1. BA V CSP V CA A diagram of the relationships. Figure 5C This shows the input voltage of the first input signal RF1 and the load impedance Z. BA Z CSP Z CA A diagram showing the relationship between the two.

[0097] In the comparative example ( Figure 4A In ), the current I CA The normalized value of the input voltage during the rise is set to 0.5, but in the first embodiment, the current I... CA The normalized value of the input voltage during the rise is set to 0.4 ( Figure 5A Current I CSP It also rises when the normalized value of the input voltage is 0.4. At this time, if the current I... CA The slope and current I CSP The slope is similarly adjusted to become the current I. BA The slope of 2 -1 / 2 If the input voltage is normalized to 1, then the voltage V... CA The normalized value reaches 1 ( Figure 5B Due to current I CSP With current I CA Consistent, therefore, voltage V CSP Also related to voltage V CA Consistent.

[0098] Due to current I CAwith I CSP Consistent, voltage V CA With V CSP Therefore, the load impedance Z is consistent. CA With Z CSP The two are identical. Therefore, in the first embodiment, the impedance matching circuit 55 inserted in the comparative example is unnecessary. Figure 3 ).

[0099] Next, the superior effects of the first embodiment will be explained.

[0100] In the first embodiment, as Figure 2 As shown, under the condition that the balanced amplifier 10 and the control amplifier 20 are driven by a single power supply voltage Vcc, such as Figure 5B As shown, the voltage V at the output terminal of the balanced amplifier 10 BA The maximum value and the voltage V at the output of the control amplifier 20 CA The maximum values ​​are roughly the same. Therefore, when the input voltage is at its maximum value, the balanced amplifier 10 and the control amplifier 20 can operate simultaneously and efficiently.

[0101] This eliminates the need for an impedance matching circuit between the control amplifier 20 and the third port P3 of the hybrid coupler 30, enabling high efficiency. Furthermore, since an impedance matching circuit can also be omitted between the output of the control amplifier 20 and the third port P3 of the hybrid coupler 30, the device can be miniaturized. Additionally, the degradation of broadband characteristics caused by the impedance matching circuit can be suppressed.

[0102] Next, a high-frequency power amplifier of a modified example of the first embodiment will be described.

[0103] In the first embodiment, as Figure 1 As shown, no impedance matching circuit is inserted between the output of the control amplifier 20 and the third port P3 of the hybrid coupler 30; the output of the control amplifier 20 is directly connected to the third port P3 of the hybrid coupler 30. Here, "direct connection" means that no circuit components that substantially affect the impedance for high-frequency signals are connected. For example, such as... Figure 1 As shown, a choke coil L, which exhibits substantially infinite impedance for high-frequency signals, can also be connected between the wiring connecting the output of the control amplifier 20 and the third port P3 of the hybrid coupler 30 and the power supply wiring. Alternatively, for example, a DC cutoff capacitor, whose impedance is substantially zero for high-frequency signals, can be inserted between the output of the control amplifier 20 and the third port P3 of the hybrid coupler 30.

[0104] Next, refer to Figure 6 and Figure 7A high-frequency power amplifier of another variation of the first embodiment will be described. In the first embodiment, as... Figure 5B As shown, in order to make the voltage V at the output terminal of the balanced amplifier 10 BA The maximum value and the voltage V at the output of the control amplifier 20 CA The maximum values ​​are roughly the same, and the current I output from the control amplifier 20 will be... CA The input voltage during the rise (first input signal RF1) Figure 1 The normalized value (hereinafter sometimes referred to as the rise point) of the voltage level of the current I is set to approximately 0.4. In the variations described below, the current I... CA The preferred range of the rising point will be explained.

[0105] Figure 6 This shows how to make the current I CA The input voltage of the first input signal RF1 and the voltage V under the condition of rising point change BA V CSP V CA A graph showing the relationship between the horizontal and vertical axes. Figure 5B The horizontal and vertical axes of the chart shown are the same. Figure 6 In the chart, solid lines a, b, and c represent the current I... CA The voltage V when the rise point is set to 0.37, 0.41, and 0.45. BA The dashed lines d, e, and f represent the current I, respectively. CA The voltage V when the rise point is set to 0.37, 0.41, and 0.45. CA V CSP .exist Figure 6 In the diagram, the parenthesized values ​​marked on the solid and dashed lines represent the current I. CA The rising point.

[0106] With the rise point set at 0.41, the voltage V BA The maximum value and voltage V CA The maximum values ​​are roughly the same. Therefore, it can be seen that high efficiency can be obtained. It should be noted that when the rise point is set to 0.37 or 0.45, the voltage V BA The maximum value and voltage V CA The maximum value produces a difference, but this difference is less than 20% relative to the normalized value of the voltage. If the deviation is of this magnitude, sufficiently high efficiency of the high-frequency power amplifier can be maintained. Therefore, to maintain high efficiency of the high-frequency power amplifier, it is preferable to reduce the current I... CA The rising point is set above 0.37 and below 0.45.

[0107] Furthermore, in order to maintain the efficiency of the high-frequency power amplifier more effectively, it is preferable to use voltage VBA the maximum value of the voltage V CA the normalized value of the difference between the maximum value of the current I CA is set to 10% or less. In order to satisfy this requirement, it is more preferable to set the rising point of the current I

[0108] Figure 7 is a graph showing the relationship between the input power and the power added efficiency of the high-frequency power amplifier of the first embodiment. The horizontal axis shows the ratio of the input power to the maximum value of the input power in units of [dB], and the vertical axis shows the power added efficiency in units of [%]. Figure 7 the solid lines g, h, i in the graph of the power added efficiency when the rising point of the current I CA is 0.37, 0.41, and 0.45, respectively. In Figure 7 , the bracketed values marked on the solid lines indicate the rising point of the current I CA .

[0109] It is known that the input power ratio at which the power added efficiency shows a peak value differs depending on the rising point of the current I CA . For example, in the case where the rising point of the current I CA is set to 0.37 in a range where the input power ratio is about -8.5 dB or less, the efficiency becomes higher than in the case where other rising points are set. In the case where the rising point of the current I CA is set to 0.45 in a range where the input power ratio is about -7 dB or more, the efficiency becomes higher than in the case where other rising points are set. In the case where the rising point of the current I CA is set to 0.41 in a range where the input power ratio is about -8.5 dB or more and -7 dB or less, the efficiency becomes higher than in the case where other rising points are set.

[0110] Thus, when the rising point of the current I CA is changed, the range of the input power ratio in which high efficiency is obtained changes.

[0111] Next, a high-frequency power amplifier of a further modified example of the first embodiment will be described with reference to Figure 8 , Figure 9 , and Figure 10 . In the first embodiment, as the hybrid coupler 30 ( Figure 1 ), a 3-dB coupler composed of a coupled transmission line is used. In the modified example described below, as the hybrid coupler 30, another coupler is used.

[0112] Figure 8 is a schematic plan view of the hybrid coupler 30 used in the high-frequency power amplifier of a modified example of the first embodiment. In this modified example, as the hybrid coupler 30, a branch-line coupler is used.

[0113] The hybrid coupler 30 is composed of four transmission lines 31A, 31B, 31C, 31D of a length corresponding to 1 / 4 wavelength arranged along the outer periphery of a square. As an example, the transmission lines 31A, 31B, 31C, 31D are arranged in this order clockwise. The characteristic impedance of the transmission lines 31A, 31C is Z0, and the characteristic impedance of the transmission lines 31B, 31D is Z0 / 2 1 / 2 .

[0114] The connecting portion of the transmission lines 31A and 31B corresponds to the first port P1, the connecting portion of the transmission lines 31A and 31D corresponds to the second port P2, the connecting portion of the transmission lines 31C and 31D corresponds to the third port P3, and the connecting portion of the transmission lines 31B and 31C corresponds to the fourth port P4.

[0115] Figure 9 is a perspective view of a hybrid coupler 30 used for a high-frequency power amplifier of another modification of the first embodiment. In this modification, a parallel-plate coupler is used as the hybrid coupler 30.

[0116] The hybrid coupler 30 includes electrically conductive parallel-plate-shaped plates 32A, 32B facing each other. One corner portion of one plate 32A corresponds to the first port P1, and the corner portion opposite thereto corresponds to the fourth port P4. The corner portion of the other plate 32B overlapping the corner portion of the first port P1 corresponds to the third port P3, and the corner portion on the opposite side in the longitudinal direction corresponds to the second port P2.

[0117] Figure 10 is an equivalent circuit diagram of a hybrid coupler 30 used for a high-frequency power amplifier of still another modification of the first embodiment. In this modification, a lumped parameter coupler is used as the hybrid coupler 30.

[0118] The hybrid coupler 30 includes a pair of inductors 33A, 33B and capacitors 33C, 33D magnetically coupled to each other. One end of one inductor 33A corresponds to the third port P3, and the other end corresponds to the second port P2. The end portion of the other inductor 33B on the third port P3 side corresponds to the first port P1, and the end portion on the opposite side corresponds to the fourth port P4. The capacitor 33C is connected between the first port P1 and the third port P3, and the capacitor 33D is connected between the second port P2 and the fourth port P4.

[0119] As shown in Figure 8 , Figure 9 , Figure 10 , a branch-line coupler, a parallel-plate coupler, a lumped parameter coupler, and the like can also be used as the hybrid coupler 30.

[0120] [Second Embodiment]

[0121] Next, refer to Figure 11 The high-frequency power amplifier of the second embodiment will be described below. Hereinafter, it will be discussed in relation to the referenced... Figures 1 to 5C The common structure of the high-frequency power amplifier in the first embodiment illustrated in the figure is omitted from the description.

[0122] Figure 11 This is a block diagram of the high-frequency power amplifier of the second embodiment. In the first embodiment ( Figure 1 In the balanced amplifier 10, the power supply voltage Vcc is supplied to the two amplifiers 12A and 12B and the control amplifier 20 via the choke coil L. In other words, the balanced amplifier 10 has dedicated power supply lines for the two amplifiers 12A and 12B and the control amplifier 20.

[0123] In contrast, in the high-frequency power amplifier of the second embodiment, the power supply voltage Vcc is supplied to the control amplifier 20 from the output terminal of amplifier 12B (the output terminal of the balanced amplifier 10 connected to the second port) via the secondary line 30B of the hybrid coupler 30. No dedicated power line is provided for the control amplifier 20; the power line for amplifier 12B is used as part of the power line for the control amplifier 20.

[0124] Next, the superior effects of the second embodiment will be explained.

[0125] In the second embodiment, no dedicated power supply line is required for the control amplifier 20, thus enabling miniaturization of the device.

[0126] [Third Embodiment]

[0127] Next, refer to Figure 12 The high-frequency power amplifier of the third embodiment will be described below. Hereinafter, it will be described in relation to the referenced... Figure 11 The common structure of the high-frequency power amplifier in the second embodiment described herein is omitted.

[0128] Second embodiment ( Figure 11 In the first embodiment, a 3dB coupler including a coupled transmission line is used for the hybrid coupler 30. In contrast, in the third embodiment, a branch-line coupler is used for the hybrid coupler 30. In the branch-line coupler, the first port P1, the second port P2, the third port P3, and the fourth port P4 are all short-circuited under DC conditions. Therefore, the hybrid coupler 30 can be used as part of a DC power supply line.

[0129] Second embodiment ( Figure 11In the balanced amplifier 10, dedicated power lines are provided for each of the two amplifiers 12A and 12B. In contrast, in the high-frequency power amplifier of the third embodiment, a power line is provided for only one of the two amplifiers 12A and 12B. For example, a power line is provided for one amplifier 12A, but no dedicated power line is provided for the other amplifier 12B.

[0130] A power supply voltage Vcc is supplied from the power line connected to amplifier 12A to another amplifier 12B via the first port P1 and the second port P2 of the hybrid coupler 30. Furthermore, a power supply voltage Vcc is supplied from the power line connected to amplifier 12A to the control amplifier 20 via the hybrid coupler 30.

[0131] Next, the superior effects of the third embodiment will be explained.

[0132] In the third embodiment, not only is a dedicated power line not required for the control amplifier 20, but also for one of the amplifiers 12B of the balanced amplifier 10, thus enabling further miniaturization of the device.

[0133] [Fourth Embodiment]

[0134] Next, refer to Figure 13 The high-frequency power amplifier of the fourth embodiment will be described below. Hereinafter, it will be discussed in relation to the referenced... Figures 1 to 5C The common structure of the high-frequency power amplifier in the first embodiment illustrated in the figure is omitted from the description.

[0135] Figure 13 This is a block diagram of the high-frequency power amplifier in the fourth embodiment. In the first embodiment ( Figure 1 In the balanced amplifier 10, the two amplifiers 12A and 12B and the control amplifier 20 are equipped with dedicated power lines.

[0136] In contrast, in the high-frequency power amplifier of the fourth embodiment, a single power line is provided shared by the two amplifiers 12A and 12B of the balanced amplifier 10 and the control amplifier 20. An impedance matching circuit 53, connected to the fourth port P4 of the hybrid coupler 30, uses a transmission line transformer. The transmission line transformer includes a main line 53A and a secondary line 53B that are electromagnetically coupled to each other.

[0137] The input port of main line 53A is connected to the fourth port P4, and the output terminal T is connected through the port. out Connections. The isolation port of secondary line 53B is connected to the input port of primary line 53A. The coupling port of secondary line 53B is grounded via capacitor C at high frequencies and connected to the power supply wiring of power supply voltage Vcc via choke coil L at DC frequencies.

[0138] A power supply voltage Vcc is supplied to the two amplifiers 12A, 12B and the control amplifier 20 of the balanced amplifier 10 via the sub-line 53B of the impedance matching circuit 53 and the hybrid coupler 30, respectively.

[0139] Next, the excellent effects of the fourth embodiment will be described.

[0140] In the fourth embodiment, a part of the power supply line is shared among the two amplifiers 12A, 12B and the control amplifier 20 of the balanced amplifier 10, and thus, downsizing of the apparatus can be achieved.

[0141] The high-frequency power amplifier of the first embodiment can achieve high efficiency without inserting an impedance matching circuit between the output of the control amplifier 20 and the third port P3 of the hybrid coupler 30 even when operating with a single power supply voltage. Therefore, as in the second embodiment, the third embodiment, and the fourth embodiment, at least two of the two amplifiers 12A, 12B and the control amplifier 20 of the balanced amplifier 10 can share the power supply line.

[0142] [Fifth Embodiment]

[0143] Next, the excellent effects of the fifth embodiment will be described. Figure 14 The communication apparatus of the fifth embodiment will be described. Figure 14 is a block diagram of the communication apparatus of the fifth embodiment. The communication apparatus of the fifth embodiment includes a transceiver IC 90, a plurality of transmission systems 80, a multiplexer 91, and an antenna 92. The plurality of transmission systems 80 each include a high-frequency power amplifier 81, a first switch 82, a plurality of filter circuits 83, and a second switch 84. As the high-frequency power amplifier 81, the high-frequency power amplifier of the first embodiment, the second embodiment, the third embodiment, or the fourth embodiment is used.

[0144] A high-frequency signal to be transmitted is input from the transceiver IC 90 to the high-frequency power amplifier 81 of each of the plurality of transmission systems 80. The high-frequency signal amplified by the high-frequency power amplifier 81 is input to one of the filter circuits 83 selected by the first switch 82. The high-frequency signal that has passed through the filter circuit 83 is transmitted to the antenna 92 via the second switch 84 and the multiplexer 91.

[0145] Next, the excellent effects of the fifth embodiment will be described.

[0146] In the fifth embodiment, as the high-frequency power amplifier 81, the high-frequency power amplifier of the first embodiment, the second embodiment, the third embodiment, or the fourth embodiment is used, and thus, a single power supply voltage can be used, high-efficiency operation can be achieved, and a decrease in wideband characteristics can be suppressed.

[0147] The above-described embodiments are examples, and of course partial substitution or combination of the structures shown in different embodiments can be made. The same effects are produced by the same structures of the embodiments, and are not mentioned one by one for each embodiment. Also, the present application is not limited to the above-described embodiments. For example, it is obvious to those skilled in the art that various changes, improvements, combinations, and the like can be made.

[0148] Based on the above-described embodiments described in the present specification, the following inventions are disclosed.

[0149] <1>

[0150] A high-frequency power amplifier comprising:

[0151] A hybrid coupler having a first port, a second port, a third port, and a fourth port connected to a load;

[0152] An input signal distributor that distributes a first input signal of a high frequency into a second input signal and a third input signal;

[0153] A balanced amplifier that is input with the second input signal, and two output terminals of the balanced amplifier are coupled to the first port and the second port, respectively, and the two output terminals output two amplified high-frequency signals having a phase difference of 90° from each other; and

[0154] A control amplifier that amplifies the third input signal, and an output terminal of the amplified third input signal is coupled to the third port without passing through a circuit component that affects impedance matching,

[0155] The balanced amplifier and the control amplifier are supplied with a common power supply voltage,

[0156] A voltage level of the first input signal when a current output from the control amplifier rises is higher than a voltage level of the first input signal when a current output from the balanced amplifier rises,

[0157] The hybrid coupler changes a load impedance of the balanced amplifier coupled to the first port and the second port in accordance with a current level of a high-frequency signal input to the third port from the control amplifier.

[0158] <2>

[0159] The high-frequency power amplifier according to <1>, wherein

[0160] A load impedance of the balanced amplifier in a state where a current from the control amplifier does not rise is equal to a load impedance of the control amplifier in a state where a current from the control amplifier rises.

[0161] <3>

[0162] The high-frequency power amplifier according to any one of <1> to <3>, wherein

[0163] The balanced amplifier, the control amplifier, and the hybrid coupler are configured such that, when the voltage level of the first input signal is increased, the voltage level of the output terminal of the balanced amplifier becomes fixed after the current from the control amplifier rises,

[0164] When the maximum value of the voltage level of the first input signal is set to 1, the voltage level of the first input signal at the time of the rise of the current from the control amplifier is 0.37 or more and 0.45 or less.

[0165] <4>

[0166] The high-frequency power amplifier according to any one of <1> to <3>, wherein

[0167] The hybrid coupler includes a coupled transmission line including a main line having the first port and the fourth port as both ends, and a sub line having the third port and the second port as both ends,

[0168] A power supply voltage is supplied from the output terminal of the balanced amplifier connected to the second port to the control amplifier via the sub line of the hybrid coupler.

[0169] <5>

[0170] The high-frequency power amplifier according to any one of <1> to <3>, wherein

[0171] The hybrid coupler is a branch line coupler,

[0172] A power supply voltage is supplied from the output terminal of one of the balanced amplifiers to the other of the balanced amplifiers and the control amplifier via the branch line coupler.

[0173] <6>

[0174] The high-frequency power amplifier according to any one of <1> to <3>, wherein

[0175] The high-frequency power amplifier further includes a transmission line transformer disposed between the fourth port and a load,

[0176] The hybrid coupler is a branch line coupler,

[0177] A power supply voltage is supplied to the balanced amplifier and the control amplifier via the transmission line transformer and the hybrid coupler.

Claims

1. A high-frequency power amplifier comprising: a hybrid coupler having a first port, a second port, a third port, and a fourth port connected to a load; an input signal distributor that distributes a high-frequency first input signal into a second input signal and a third input signal; a balanced amplifier that is input with the second input signal, and that has two output terminals coupled to the first port and the second port, respectively, the two output terminals outputting two amplified high-frequency signals having a phase difference of 90° from each other; and a control amplifier that amplifies the third input signal, an output terminal outputting the amplified third input signal being coupled to the third port without passing through a circuit component that affects impedance matching, the balanced amplifier and the control amplifier being supplied with a common power supply voltage, a voltage level of the first input signal when a current output from the control amplifier rises being higher than a voltage level of the first input signal when a current output from the balanced amplifier rises, and the hybrid coupler varying a load impedance of the balanced amplifier coupled to the first port and the second port in accordance with a current level of a high-frequency signal input to the third port from the control amplifier.

2. The high-frequency power amplifier according to claim 1, wherein a load impedance of the balanced amplifier in a state where a current from the control amplifier does not rise is equal to a load impedance of the control amplifier in a state where a current from the control amplifier rises.

3. The high-frequency power amplifier according to claim 1 or 2, wherein the balanced amplifier, the control amplifier, and the hybrid coupler are configured so that, when a voltage level of the first input signal is increased, a voltage level of the output terminal of the balanced amplifier becomes fixed after a current from the control amplifier rises, and when a maximum value of the voltage level of the first input signal is set to 1, the voltage level of the first input signal when the current from the control amplifier rises is 0.37 or more and 0.45 or less.

4. The high-frequency power amplifier according to any one of claims 1 to 3, wherein the hybrid coupler includes a coupled transmission line including a main line having the first port and the fourth port as both ends, and a sub line having the third port and the second port as both ends, and a power supply voltage is supplied to the control amplifier from the output terminal of the balanced amplifier connected to the second port via the sub line of the hybrid coupler.

5. The high-frequency power amplifier according to any one of claims 1 to 3, wherein the hybrid coupler is a branch line coupler, and a power supply voltage is supplied to the other amplifier of the balanced amplifier and the control amplifier from the output terminal of one amplifier of the balanced amplifier via the branch line coupler.

6. The high-frequency power amplifier according to any one of claims 1 to 3, wherein the high-frequency power amplifier further includes a transmission line transformer disposed between the fourth port and a load, the hybrid coupler is a branch line coupler, and a power supply voltage is supplied to the control amplifier from the output terminal of the balanced amplifier connected to the second port via the sub line of the hybrid coupler. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ A power supply voltage is supplied to the balanced amplifier and the control amplifier via the transmission line transformer and the hybrid coupler.

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