Radio frequency power amplifier

Abstract

To provide a radio frequency power amplifier having a configuration of a sequential LMBA and capable of achieving broadband characteristics.SOLUTION: In a radio frequency power amplifier, an input signal distributer 40 distributes a first input signal RF1 at a radio frequency into two second input signals RF2a, RF2b, a peak amplifier 10 includes two first amplifiers 12A, 12B, output ends of the two first amplifiers being coupled to a first port P1 and a second port P2 of a hybrid coupler 30, respectively, and a carrier amplifier 20 includes two second amplifiers 22A, 22B and a combiner 23. The combiner combines radio frequency signals amplified by the respective two second amplifiers and outputs a combined radio frequency signal to a third port P3. The hybrid coupler combines radio frequency signals inputted to the first port and the second port and outputs a combined radio frequency signal from a fourth port, and varies a load impedance of the two first amplifiers of the peak amplifier, according to a current level of a radio frequency signal inputted to the third port from the carrier amplifier.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a high frequency power amplifier. [Background technology]

[0002] Radio frequency power amplifiers used in the transmitter section of wireless communications consume the most power in wireless communications circuits. To reduce the power consumption of wireless communications circuits, technology to improve the power added efficiency of radio frequency power amplifiers is required. The Load Modulation Balanced Amplifier (LMBA) has been proposed as a high-efficiency technology to improve power added efficiency. The LMBA includes a balanced amplifier, a control amplifier, and a hybrid coupler, and modulates the load impedance of the balanced amplifier using the output of the control amplifier.

[0003] As one type of LMBA, a sequential LMBA has been proposed (Non-Patent Document 1). In the sequential LMBA disclosed in Non-Patent Document 1, the balance amplifier operates with a class C bias, and the control amplifier operates with a class B bias. In Non-Patent Document 1, the balance amplifier is called a peak amplifier, and the control amplifier is called a carrier amplifier. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] J. Pang, "Analysis and Design of Highly Efficient Wideband RF-Input Sequential Load Modulated Balanced Power Amplifier", IEEE Trans. on Microwave Theory and Techn., Vol. 68, No. 5, pp.1741-1753, May 2020 Summary of the Invention [Problem to be solved by the invention]

[0005] If the hybrid coupler were ideal, the high-frequency signal leaking from the peak amplifier through the hybrid coupler to the output node of the carrier amplifier would be at a negligible level, and the load impedance of the carrier amplifier would not fluctuate. However, in an actual hybrid coupler, high-frequency signal leakage from the peak amplifier through the hybrid coupler to the output node of the carrier amplifier can occur. This leakage causes complex fluctuations in the load impedance of the carrier amplifier.

[0006] In a class C biased peak amplifier, the load impedance Z BA If there is leakage of high-frequency signals from the peak amplifier to the output node of the carrier amplifier, the load impedance of the carrier amplifier will fluctuate depending on frequency when the output power of the carrier amplifier approaches its saturation level. Because this fluctuation depends on frequency, it is difficult to achieve good frequency characteristics.

[0007] An object of the present invention is to provide a high frequency power amplifier having a sequential LMBA configuration and capable of achieving wideband characteristics. [Means for solving the problem]

[0008] According to one aspect of the present invention, a hybrid coupler having a first port, a second port, a third port, and a fourth port; an input signal splitter that splits a high-frequency first input signal into two second input signals; a peak amplifier including two first amplifiers that amplify two high-frequency signals obtained by dividing one of the second input signals and whose output ends are connected to the first port and the second port, respectively; a carrier amplifier including two second amplifiers that amplify two high-frequency signals obtained by dividing the other second input signal, and a combiner that combines the high-frequency signals amplified by the two second amplifiers and inputs the combined signals to the third port; Equipped with a voltage level of the first input signal at a rising edge of the output current of the peak amplifier is higher than a voltage level of the first input signal at a rising edge of the output current of the carrier amplifier; The hybrid coupler provides a radio frequency power amplifier having a configuration in which radio frequency signals input to the first port and the second port are combined and output from the fourth port, and the load impedance of the two first amplifiers of the peak amplifier changes depending on the current level of the radio frequency signal input from the carrier amplifier to the third port. [Effects of the Invention]

[0009] The carrier amplifier includes two secondary amplifiers, and the high-frequency signals amplified by the two secondary amplifiers are combined and input to the hybrid coupler, making the carrier amplifier less susceptible to the effects of leakage of the output signal from the peak amplifier, enabling wideband characteristics to be achieved. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram of a high-frequency power amplifier according to a first embodiment. [Figure 2] FIG. 2 is a schematic equivalent circuit diagram for explaining the operation of the hybrid coupler 30. As shown in FIG. [Figure 3] FIG. 3A is a graph showing the relationship between the input voltage and output current of the peak amplifier 10 and the carrier amplifier 20, FIG. 3B is a graph showing the relationship between the input voltage and output voltage of the peak amplifier 10 and the carrier amplifier 20, FIG. 3C is a graph showing the relationship between the input voltage of the peak amplifier 10 and the carrier amplifier 20 and the resistance component of the load impedance, and FIG. 3D is a graph showing the relationship between input power and power-added efficiency. [Figure 4] FIG. 4 is a schematic plan view of a hybrid coupler 30 used in a radio frequency power amplifier according to a modification of the first embodiment. [Figure 5] FIG. 5 is a schematic perspective view of a hybrid coupler 30 used in a radio frequency power amplifier according to another modification of the first embodiment. [Figure 6] FIG. 6 is an equivalent circuit diagram of a hybrid coupler 30 used in a high-frequency power amplifier according to yet another modification of the first preferred embodiment. [Figure 7] FIG. 7 is a block diagram of a high-frequency power amplifier according to the second embodiment. [Figure 8] FIG. 8 is a block diagram showing a bias control state when the bias control unit 60 performs bias control in the very low power mode. [Figure 9] FIG. 9 is a block diagram showing a bias control state when the bias control unit 60 performs bias control in the first low power mode. [Figure 10] FIG. 10 is a block diagram showing a bias control state when the bias control unit 60 performs bias control in the second low power mode. [Figure 11] FIG. 11 is a schematic diagram showing the positional relationship between two first amplifiers 12A and 12B of a peak amplifier 10, two second amplifiers 22A and 22B of a carrier amplifier 20, and a drive stage amplifier 50 of a high frequency power amplifier according to the third embodiment. [Figure 12] FIG. 12 is a schematic diagram showing the positional relationship between two first amplifiers 12A and 12B of the peak amplifier 10, two second amplifiers 22A and 22B of the carrier amplifier 20, and a drive stage amplifier 50 of a high frequency power amplifier according to a comparative example. [Figure 13] FIG. 13 is a schematic diagram showing the positional relationship between two first amplifiers 12A and 12B of the peak amplifier 10, two second amplifiers 22A and 22B of the carrier amplifier 20, and a drive stage amplifier 50 of a radio frequency power amplifier according to a modification of the third embodiment. [Figure 14] FIG. 14 is a block diagram of a communication device according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] [First Example] A radio frequency power amplifier according to a first embodiment will be described with reference to FIGS. 1 to 3D.

[0012] 1 is a block diagram of a radio frequency power amplifier according to the first embodiment. The radio frequency power amplifier according to the first embodiment includes a peak amplifier 10, a carrier amplifier 20, a hybrid coupler 30, and an input signal distributor 40. The radio frequency power amplifier according to the first embodiment and its peripheral circuits will be described below.

[0013] Input terminal T in A high-frequency signal input from is input to the drive-stage amplifier 50 via an impedance matching circuit 51. This high-frequency signal is a radio frequency band signal modulated by a predetermined communication method. The drive-stage amplifier 50 amplifies the input high-frequency signal and outputs a first input signal RF1. The first input signal RF1 amplified by the drive-stage amplifier 50 is input to the input signal distributor 40.

[0014] The input signal divider 40 divides the first input signal RF1 and outputs two second input signals RF2a and RF2b. The input signal divider 40 may be, for example, a 3 dB coupler using a coupled transmission line, a Wilkinson divider, or the like. For example, the signal levels of the second input signals RF2a and RF2b are each 3 dB lower than the signal level of the first input signal, and there is a phase difference of 90° between them. One second input signal, RF2a, is input to the peak amplifier 10, and the other second input signal, RF2b, is input to the carrier amplifier 20. The phase difference between the two second input signals RF2a and RF2b may be other than 90°.

[0015] The peak amplifier 10 includes two first amplifiers 12A and 12B that amplify two high-frequency signals obtained by dividing one second input signal RF2a. The first amplifiers 12A and 12B are configured, for example, with heterojunction bipolar transistors (HBTs). For example, a first divider 11 divides the second input signal RF2a into two high-frequency signals. These two high-frequency signals have equal signal levels and a phase difference of 90°. For example, a 3 dB coupler using a coupled transmission line can be used as the first divider 11. Each of the first amplifiers 12A and 12B is biased in class C.

[0016] The carrier amplifier 20 includes two second amplifiers 22A and 22B that amplify two high-frequency signals obtained by dividing the other second input signal RF2b. The second amplifiers 22A and 22B are configured, for example, with heterojunction bipolar transistors (HBTs). For example, a second divider 21 divides the second input signal RF2b into two high-frequency signals. These two high-frequency signals have equal signal levels and a phase difference of 90°. For example, a 3 dB coupler using a coupled transmission line can be used as the second divider 21. Each of the second amplifiers 22A and 22B is biased in class AB. Alternatively, each of the second amplifiers 22A and 22B may be biased in class B.

[0017] The carrier amplifier 20 combines and outputs two high-frequency signals amplified by the two second amplifiers 22A and 22B. For example, a combiner 23 combines the two high-frequency signals amplified by the two second amplifiers 22A and 22B. A 3 dB coupler using a coupled transmission line can be used as the combiner 23.

[0018] The hybrid coupler 30 is composed of a main line and a secondary line that are electromagnetically coupled to each other. One end of the main line is referred to as the first port P1, and the other end is referred to as the fourth port P4. The end of the secondary line on the side of the first port P1 is referred to as the third port P3, and the end on the side of the fourth port P4 is referred to as the second port P2.

[0019] The output terminals of the two first amplifiers 12A and 12B are respectively coupled to a first port P1 and a second port P2 of the hybrid coupler 30. The output terminal of the carrier amplifier 20, i.e., the output terminal of the combiner 23, is coupled to a third port of the hybrid coupler 30 via an impedance matching circuit 52. The fourth port P4 of the hybrid coupler 30 is coupled to an output terminal T out is bonded to.

[0020] The high-frequency signals input to the first port P1 and the second port P2 are combined 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, a high-frequency signal with power equal 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 first amplifiers 12A and 12B of the peak amplifier 10 varies depending on the current level of the high-frequency signal input from the carrier amplifier 20 to the third port P3. More specifically, the load impedance of the two first amplifiers 12A and 12B of the peak amplifier 10 varies depending on the ratio between the current level of the high-frequency signal input from the carrier amplifier 20 to the current level of the high-frequency signal input from the peak amplifier 10 to the first port P1 and the second port P2.

[0021] The operation of the hybrid coupler 30 will now be described in more detail with reference to FIG. 2 is a schematic equivalent circuit diagram for explaining the operation of the hybrid coupler 30. The two first amplifiers 12A and 12B of the peak amplifier 10 are respectively connected to a current −I BA , jI BA The carrier amplifier 20 is considered as a current source that generates a current -I CSP e jφ Here, j is the imaginary unit and φ is the phase offset. Note that the current -I CSP e jφ represents the current output from the carrier amplifier 20 and passed through the impedance matching circuit 52.

[0022] A load RL is connected to the fourth port P4. The current flowing from the load RL to the fourth port P4 is defined as -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 as V BA2 , V BA1 , V CSP , V LThe load impedances of the current sources representing the first amplifiers 12A and 12B and the carrier amplifier 20 are denoted as Z BA2 , Z BA1 , Z CSP It is marked as follows.

[0023] The output current and output voltage of each current source are expressed by the following relational expressions using the impedance matrix of the hybrid coupler 30:

number

[0024] Expanding equation (1), the load impedance Z of the two first amplifiers 12A (FIG. 1) of the peak amplifier 10 is BA1 , Z BA2 is expressed by the following formula:

number

number

[0025] From equation (2), the load impedance Z of each of the two first amplifiers 12A and 12B of the peak amplifier 10 is BA1 , Z BA2 are equal, and the output current I from the carrier amplifier 20 CSP and the phase offset φ. On the other hand, the load impedance Z of the carrier amplifier 20 CSP is constant.

[0026] 3A is a graph showing the relationship between the input voltage and output current of the peak amplifier 10 and the carrier amplifier 20. The horizontal axis represents the input voltage as a normalized value, and the vertical axis represents the output current as a normalized value. Note that the normalized value of the maximum input voltage is defined as 1, and the output current I BAThe normalized maximum value of is defined as 1. The solid lines in the graph shown in FIG. 3A represent the output currents I BA The dashed line indicates the output current I of the carrier amplifier 20. CSP Hereinafter, the normalized value of the input voltage may be simply referred to as the "input voltage," and the normalized value of the output current may be simply referred to as the "output current."

[0027] The output current I of the class C biased peak amplifier 10 BA The voltage level of the second input signal RF2a at the rising edge of the output current I of the class AB biased carrier amplifier 20 is higher than the voltage level of the second input signal RF2b at the rising edge of the output current I of the class AB biased carrier amplifier 20. For example, CSP is the output current I of the peak amplifier 10, which is biased at class C and rises from the point when the input voltage is 0. BA starts when the input voltage is 0.5.

[0028] The carrier amplifier 20 outputs the output current I BA Therefore, when the input voltage is in the range of 0 to 0.5, the output current I CSP increases almost linearly with respect to the input voltage. When the input voltage is in the range of 0.5 to 1, the output current I CSP is almost constant.

[0029] Output current I of carrier amplifier 20 CSP Since the output current of the peak amplifier 10 rises after the peak current is saturated, the linearity of the output current of the entire high frequency power amplifier is maintained.

[0030] 3B is a graph showing the relationship between the input voltage and the output voltage of the peak amplifier 10 and the carrier amplifier 20. The horizontal axis represents the input voltage as a normalized value, and the vertical axis represents the output voltage as a normalized value. Here, the output voltage V BA The normalized value of the maximum value of is defined as 1. The solid line in the graph shown in FIG. 3B represents the output voltage V BAThe dashed line indicates the output voltage V of the carrier amplifier 20. CSP Hereinafter, the normalized value of the output voltage may be simply referred to as the "output voltage."

[0031] Output voltage V of peak amplifier 10 BA increases linearly with respect to the input voltage when the input voltage is in the range of 0 to 0.5, and increases linearly with respect to the input voltage when the input voltage is in the range of 0.5 to 1. BA The slope of the output voltage V BA The slope is gentler than that of

[0032] Carrier amplifier 20 output voltage V CSP increases linearly when the input voltage is between 0 and 0.5, and is constant when the input voltage is between 0.5 and 1.

[0033] FIG. 3C is a graph showing the relationship between the input voltage of the peak amplifier 10 and the carrier amplifier 20 and the resistance component of the load impedance. The horizontal axis represents the input voltage as a normalized value, and the vertical axis represents the resistance component of the load impedance as a normalized value. When the load impedance is equal to the characteristic impedance Z0 of the hybrid coupler 30, the normalized value is defined as 1. The solid line in the graph of FIG. 3C represents the load impedance Z BA The dashed line indicates the load impedance Z of the carrier amplifier 20. CSP shows the resistance component of

[0034] Load impedance Z of carrier amplifier 20 CSP is constant as shown in equation (3), and its normalized value is 1. The load impedance Z of the peak amplifier 10 BA is expressed by equation (2), and becomes infinite when the input voltage is 0.5, and decreases as the input voltage increases in the range of input voltage from 0.5 to 1.

[0035] 3D is a graph showing the relationship between input power and power-added efficiency. The horizontal axis represents the ratio of input power to the maximum input power (input power ratio) in dB, and the vertical axis represents power-added efficiency in %.

[0036] As with the conventional Doherty amplifier, it can be seen that high efficiency is achieved in the power back-off region where the input power ratio is around -6 dB.

[0037] Next, the excellent effects of the first embodiment will be described. In a conventional sequential LMBA (Non-Patent Document 1), the carrier amplifier 20 is not configured as a balanced amplifier. When high-frequency signals leak from the peak amplifier 10 to the carrier amplifier 20, the load impedance of the carrier amplifier 20 fluctuates in a complex manner. In particular, in a class C biased peak amplifier, the load impedance drops sharply as the input signal level increases. As a result, when the output power of the carrier amplifier approaches its saturation level, the load impedance of the carrier amplifier fluctuates depending on the frequency. Because this fluctuation depends on the frequency, it is difficult to achieve good frequency characteristics.

[0038] In the first embodiment, the carrier amplifier 20 has a balanced amplifier configuration, which suppresses fluctuations in the characteristics of the carrier amplifier 20 due to leakage of high-frequency signals from the peak amplifier 10 to the carrier amplifier 20. This makes it possible to easily obtain wideband characteristics.

[0039] 3A, the output current of the peak amplifier 10 rises after the output current of the carrier amplifier 20 is saturated, so that the linearity of the output current of the entire high-frequency power amplifier is maintained. Also, as described with reference to FIG. 3D, high efficiency is obtained in the back-off region.

[0040] Next, a radio frequency power amplifier according to a modification of the first embodiment will be described with reference to Figures 4, 5, and 6. In the first embodiment, a 3 dB coupler formed of a coupled transmission line is used as the hybrid coupler 30. In the modification described below, other couplers are used as the hybrid coupler 30.

[0041] 4 is a schematic plan view of a hybrid coupler 30 used in a radio frequency power amplifier according to a modification of Example 1. In this modification, a branch line coupler is used as the hybrid coupler 30.

[0042] This hybrid coupler 30 is composed of four transmission lines 31A, 31B, 31C, and 31D, each with a length equivalent to a quarter wavelength, arranged along the periphery of a square. As an example, the transmission lines 31A, 31B, 31C, and 31D are arranged clockwise in this order. The characteristic impedance of the transmission lines 31A and 31C is Z0, and the characteristic impedance of the transmission lines 31B and 31D is Z0 / 2. 1 / 2 is.

[0043] The connection point between transmission lines 31A and 31B corresponds to the first port P1, the connection point between transmission lines 31A and 31D corresponds to the second port P2, the connection point between transmission lines 31C and 31D corresponds to the third port P3, and the connection point between transmission lines 31B and 31C corresponds to the fourth port P4.

[0044] 5 is a schematic perspective view of a hybrid coupler 30 used in a radio frequency power amplifier according to another modification of Example 1. In this modification, a parallel plate coupler is used as the hybrid coupler 30.

[0045] This hybrid coupler 30 includes rectangular conductive flat plates 32A and 32B that face each other in parallel. One corner of one flat plate 32A corresponds to a first port P1, and the opposite corner corresponds to a fourth port P4. The corner of the other flat plate 32B that overlaps with the corner of the first port P1 corresponds to a third port P3, and the corner on the opposite side of the long side corresponds to a second port P2.

[0046] 6 is an equivalent circuit diagram of a hybrid coupler 30 used in a high-frequency power amplifier according to yet another modification of Example 1. In this modification, a lumped parameter coupler is used as the hybrid coupler 30.

[0047] This hybrid coupler 30 includes a pair of inductors 33A and 33B and capacitors 33C and 33D that are magnetically coupled to each other. One end of the inductor 33A corresponds to the third port P3, and the other end corresponds to the second port P2. The end of the other inductor 33B on the third port P3 side corresponds to the first port P1, and the opposite end corresponds to the fourth port P4. Capacitor 33C is connected between the first port P1 and the third port P3, and capacitor 33D is connected between the second port P2 and the fourth port P4.

[0048] As shown in FIGS. 4, 5, and 6, the hybrid coupler 30 may be a branch line coupler, a parallel plate coupler, a lumped parameter coupler, or the like.

[0049] [Second Example] Next, a radio frequency power amplifier according to a second embodiment will be described with reference to Figures 7 to 10. Below, a description of the configuration common to the radio frequency power amplifier according to the first embodiment described with reference to Figures 1 to 3D will be omitted.

[0050] 7 is a block diagram of a radio frequency power amplifier according to the second embodiment. In the first embodiment (FIG. 1), a class C bias is applied to the peak amplifier 10, and a class AB bias is applied to the carrier amplifier 20. In contrast, in the second embodiment, the bias control unit 60 has a plurality of control modes, and performs bias control to make the biases of the peak amplifier 10 and the carrier amplifier 20 different for each control mode. The bias control unit 60 controls the bias in one control mode selected from, for example, a very low power mode, a first low power mode, and a second low power mode. These control modes are selected by a user command.

[0051] FIG. 8 is a block diagram showing the bias control state when the bias control unit 60 performs bias control in very low power mode. When the control mode is very low power mode, the bias control unit 60 applies a class AB bias to one of the second amplifiers 22A of the carrier amplifier 20, but does not apply a bias to the other second amplifier 22B. That is, the second amplifier 22B is in a shutdown state and does not perform an amplification operation. Also, no bias is applied to either of the two first amplifiers 12A, 12B of the peak amplifier 10. That is, the peak amplifier 10 is in a shutdown state and does not perform an amplification operation. In FIG. 8, amplifiers in a shutdown state are hatched. Similarly, amplifiers in a shutdown state are hatched in FIGS. 9 and 10, which will be described below.

[0052] 9 is a block diagram showing the bias control state when the bias control unit 60 performs bias control in the first low power mode. When the control mode is the first low power mode, the bias control unit 60 applies a class AB bias to the two second amplifiers 22A of the carrier amplifier 20, and applies no bias to either of the two first amplifiers 12A, 12B of the peak amplifier 10.

[0053] 10 is a block diagram showing the bias control state when the bias control unit 60 performs bias control in the second low power mode. When the control mode is the second low power mode, the bias control unit 60 applies a class AB bias to one second amplifier 22A of the carrier amplifier 20 and a class C bias to the other second amplifier 22B. The two second amplifiers 22A and 22B operate as Doherty amplifiers. No bias is applied to either of the two first amplifiers 12A and 12B of the peak amplifier 10.

[0054] Next, the excellent effects of the second embodiment will be described. In the second embodiment, some amplifiers are shut down depending on the control mode, which reduces the overall idle current and improves the power added efficiency. Note that which control mode to select can be determined depending on the maximum signal level of the first input signal RF1.

[0055] When the control mode is the very low power mode, the idle current reduction effect is greatest. Also, the size of the transistors constituting the carrier amplifier 20 is smaller than the size of the transistors constituting the peak amplifier 10. When the control mode is the first low power mode or the second low power mode, a significant effect of reducing the idle current can be achieved by shutting down the large-sized transistors of the peak amplifier 10.

[0056] When the control mode is the second low power mode (FIG. 10), the carrier amplifier 20 operates as a Doherty power amplifier, so that the power added efficiency can be further improved compared to the first low power mode.

[0057] [Third Example] Next, a radio frequency power amplifier according to a third embodiment will be described with reference to Fig. 11. Below, description of configurations common to the radio frequency power amplifier according to the first embodiment described with reference to Figs. 1 to 3D will be omitted.

[0058] 11 is a schematic diagram showing the positional relationship between the two first amplifiers 12A and 12B of the peak amplifier 10, the two second amplifiers 22A and 22B of the carrier amplifier 20, and the drive stage amplifier 50 of the high frequency power amplifier according to the third embodiment. In the first embodiment, there are no particular limitations on the positional relationship between these.

[0059] In the third embodiment, the two first amplifiers 12A and 12B of the peak amplifier 10, the two second amplifiers 22A and 22B of the carrier amplifier 20, and the drive stage amplifier 50 are formed on a common substrate 70. When the substrate 70 is viewed from above, the two second amplifiers 22A and 22B of the carrier amplifier 20 are disposed between the two first amplifiers 12A and 12B of the peak amplifier 10. More specifically, one first amplifier 12A, one second amplifier 22A, the other second amplifier 22B, and the other first amplifier 12B are disposed in a line in this order. Note that the order of one second amplifier 22A and the other second amplifier 22B may be reversed.

[0060] The drive stage amplifier 50 is arranged at a position separated from the rows of the first amplifiers 12A and 12B and the second amplifiers 22A and 22B in a direction intersecting the rows.

[0061] Next, the excellent effects of the third embodiment will be explained while comparing it with a comparative example shown in FIG.

[0062] 12 is a schematic diagram showing the positional relationship between the two first amplifiers 12A and 12B of the peak amplifier 10, the two second amplifiers 22A and 22B of the carrier amplifier 20, and the drive stage amplifier 50 of a high-frequency power amplifier according to a comparative example. In the comparative example, the second amplifiers 22A and 22B of the carrier amplifier 20 and the first amplifiers 12A and 12B of the peak amplifier 10 are arranged in a row in this order.

[0063] Focusing on one first amplifier 12A of the peak amplifier 10, a first amplifier 12B and a second amplifier 22B are arranged on both sides of it. Focusing on the other first amplifier 12B, the first amplifier 12A is arranged only on one side. Therefore, when the first amplifiers 12A, 12B and the second amplifiers 22A, 22B generate heat during operation of the high-frequency power amplifier, a difference in thermal influence occurs between the two first amplifiers 12A and 12B. Similarly, a difference in thermal influence occurs between the two second amplifiers 22A and 22B of the carrier amplifier 20. This difference in thermal influence can cause the high-frequency power amplifier to malfunction.

[0064] In the third embodiment, when focusing on each of the two first amplifiers 12A, 12B of the peak amplifier 10, the second amplifiers 22A, 22B are arranged on only one side. When focusing on one second amplifier 22A of the carrier amplifier 20, the first amplifier 12A is arranged on one side and the second amplifier 22B is arranged on the other side. When focusing on the other second amplifier 22B, the first amplifier 12B is arranged on one side and the second amplifier 22A is arranged on the other side.

[0065] For this reason, the first amplifiers 12A and 12B of the peak amplifier 10 are affected by approximately the same thermal influence, and the two second amplifiers 22A and 22B of the carrier amplifier 20 are also affected by approximately the same thermal influence. Differences in thermal influence are unlikely to occur between the first amplifiers 12A and 12B of the peak amplifier 10, and differences in thermal influence are also unlikely to occur between the two second amplifiers 22A and 22B of the carrier amplifier 20. Therefore, malfunctions of the high-frequency power amplifier due to differences in thermal influence are unlikely to occur.

[0066] Next, a radio frequency power amplifier according to a modification of the third embodiment will be described with reference to Fig. 13. Fig. 13 is a schematic diagram showing the positional relationship between two first amplifiers 12A and 12B of a peak amplifier 10, two second amplifiers 22A and 22B of a carrier amplifier 20, and a drive stage amplifier 50 of a radio frequency power amplifier according to a modification of the third embodiment.

[0067] In the third embodiment (FIG. 11), when the substrate 70 is viewed from above, the two second amplifiers 22A and 22B of the carrier amplifier 20 are arranged at positions sandwiched between the two first amplifiers 12A and 12B of the peak amplifier 10. In contrast, in this modified example, the positional relationship between the peak amplifier 10 and the carrier amplifier 20 is reversed. That is, the two first amplifiers 12A and 12B of the peak amplifier 10 are arranged at positions sandwiched between the two second amplifiers 22A and 22B of the carrier amplifier 20.

[0068] In the modified example shown in FIG. 13, as in the third embodiment (FIG. 11), malfunctions of the high-frequency power amplifier caused by differences in thermal influences are less likely to occur.

[0069] [Fourth Example] Next, a communication device according to a fourth embodiment will be described with reference to Fig. 14. Fig. 14 is a block diagram of the communication device according to the fourth embodiment. The communication device according to the fourth embodiment includes a transceiver IC 90, multiple transmission systems 80, a multiplexer 91, and an antenna 92. Each of the multiple transmission systems 80 includes a high-frequency power amplifier 81, a first switch 82, multiple filter circuits 83, and a second switch 84. The high-frequency power amplifier 81 is the high-frequency power amplifier according to the first, second, or third embodiment.

[0070] A radio frequency signal to be transmitted is input from a transceiver IC 90 to each radio frequency power amplifier 81 of a plurality of transmission systems 80. The radio frequency signal amplified by the radio frequency power amplifier 81 is input to one filter circuit 83 selected by a first switch 82. The radio frequency signal that has passed through the filter circuit 83 is transmitted to an antenna 92 ​​via a second switch 84 and a multiplexer 91.

[0071] Next, the excellent effects of the fourth embodiment will be described. In the fourth embodiment, the high frequency power amplifier according to the first, second or third embodiment is used as the high frequency power amplifier 81, so that the linearity of the input / output characteristics is maintained and high efficiency is obtained in the back-off region. Furthermore, it is possible to easily obtain wideband characteristics.

[0072] The above-described embodiments are merely examples, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. Similar effects resulting from similar configurations of multiple embodiments will not be mentioned sequentially for each embodiment. Furthermore, the present invention is not limited to the above-described embodiments. For example, it will be obvious to those skilled in the art that various modifications, improvements, combinations, etc. are possible.

[0073] Based on the above examples described in this specification, the following invention is disclosed. <1> a hybrid coupler having a first port, a second port, a third port, and a fourth port; an input signal splitter that splits a high-frequency first input signal into two second input signals; a peak amplifier including two first amplifiers that amplify two high-frequency signals obtained by dividing one of the second input signals and whose output ends are connected to the first port and the second port, respectively; a carrier amplifier including two second amplifiers that amplify two high-frequency signals obtained by dividing the other second input signal, and a combiner that combines the high-frequency signals amplified by the two second amplifiers and inputs the combined signals to the third port; Equipped with a voltage level of the first input signal at a rising edge of the output current of the peak amplifier is higher than a voltage level of the first input signal at a rising edge of the output current of the carrier amplifier; The hybrid coupler is a radio-frequency power amplifier having a configuration in which radio-frequency signals input to the first port and the second port are combined and output from the fourth port, and the load impedance of the two first amplifiers of the peak amplifier changes depending on the current level of the radio-frequency signal input from the carrier amplifier to the third port.

[0074] <2> When the voltage level of the first input signal is increased, the output current of the carrier amplifier is saturated at the point when the output current of the peak amplifier rises. <1> The high frequency power amplifier according to claim 1.

[0075] <3> Further, a bias control unit is provided to control biases of the carrier amplifier and the peak amplifier, The bias control unit has a plurality of control modes, and makes the bias of the carrier amplifier and the peak amplifier different for each control mode. <1> or <2> The high frequency power amplifier according to claim 1.

[0076] <4> The bias control unit operates the two second amplifiers of the carrier amplifier as Doherty amplifiers in one control mode of the plurality of control modes. <3> The high frequency power amplifier according to claim 1.

[0077] <5> The bias control unit applies a bias to the two first amplifiers of the peak amplifier in one control mode of the plurality of control modes, such that no output current is generated regardless of the voltage level of the first input signal. <3> or <4> The high frequency power amplifier according to claim 1.

[0078] <6> The bias control unit applies a bias that does not generate an output current to one of the two second amplifiers of the carrier amplifier regardless of the voltage level of the first input signal, and applies a class AB or class B bias to the other second amplifier, in one control mode of the plurality of control modes. <3> ~ <5> 10. The high-frequency power amplifier according to claim 9, wherein:

[0079] <7> the two first amplifiers of the peak amplifier and the two second amplifiers of the carrier amplifier are formed on a common substrate, The two first amplifiers and the two second amplifiers are arranged such that one of them is sandwiched between the other. <1> ~ <6> 10. The high-frequency power amplifier according to claim 9, wherein: [Explanation of symbols]

[0080] 10 Peak Amplifier 11 1st distributor 12A, 12B First amplifier 20 Carrier Amplifier 21 2nd distributor 22A, 22B Second amplifier 23 Synthesizer 30 Hybrid Coupler 31A, 31B, 31C, 31D Transmission Lines 32A, 32B flat plate 33A, 33B inductors 33C, 33D capacitors 40 Input signal distributor 50 Drive Stage Amplifier 51, 52, 53 Impedance matching circuit 60 Bias control section 70 boards 80 Transmission System 81 High frequency power amplifier 82 First Switch 83 Filter Circuit 84 Second Switch 90 Transceiver IC 91 Multiplexer 92 Antenna

Claims

1. a hybrid coupler having a first port, a second port, a third port, and a fourth port; an input signal divider that divides a high-frequency first input signal into two second input signals; a peak amplifier including two first amplifiers that amplify two high-frequency signals obtained by dividing one of the second input signals and whose output ends are connected to the first port and the second port, respectively; a carrier amplifier including two second amplifiers that amplify two high-frequency signals obtained by dividing the other second input signal, and a combiner that combines the high-frequency signals amplified by the two second amplifiers and inputs the combined signals to the third port; Equipped with a voltage level of the first input signal at a rising edge of the output current of the peak amplifier is higher than a voltage level of the first input signal at a rising edge of the output current of the carrier amplifier; The hybrid coupler is a radio frequency power amplifier having a configuration in which radio frequency signals input to the first port and the second port are combined and output from the fourth port, and the load impedance of two first amplifiers of the peak amplifier changes depending on the current level of the radio frequency signal input from the carrier amplifier to the third port.

2. 2. The radio frequency power amplifier according to claim 1, wherein, when the voltage level of the first input signal is increased, the output current of the carrier amplifier is saturated at the point when the output current of the peak amplifier rises.

3. Further, a bias control unit is provided to control biases of the carrier amplifier and the peak amplifier, 3. The radio frequency power amplifier according to claim 1, wherein the bias control section has a plurality of control modes, and the bias of the carrier amplifier and the peak amplifier is made different for each control mode.

4. The radio frequency power amplifier according to claim 3 , wherein the bias control section operates the two second amplifiers of the carrier amplifier as Doherty amplifiers in one of the plurality of control modes.

5. 4. The radio frequency power amplifier according to claim 3, wherein the bias control unit applies a bias to the two first amplifiers of the peak amplifier in one control mode of the plurality of control modes, such that no output current is generated regardless of the voltage level of the first input signal.

6. 4. The radio frequency power amplifier according to claim 3, wherein, in one control mode of the plurality of control modes, the bias control unit applies a bias that does not generate an output current to one of the two second amplifiers of the carrier amplifier regardless of the voltage level of the first input signal, and applies a class AB or class B bias to the other second amplifier.

7. the two first amplifiers of the peak amplifier and the two second amplifiers of the carrier amplifier are formed on a common substrate, 3. The high frequency power amplifier according to claim 1, wherein one of the two first amplifiers and the two second amplifiers is sandwiched between the other.

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