Power amplifier circuit, power amplifier module

Abstract

The present invention comprises: a first splitter that splits an input signal into a first input signal and a second input signal; a Doherty amplifier circuit that includes a carrier amplifier and a peak amplifier, and amplifies the first input signal and outputs an output signal to an output terminal; and a control amplifier that amplifies the second input signal and outputs a control signal for controlling the load impedance of the Doherty amplifier circuit to the Doherty amplifier circuit.

Description

[Technical Field]

[0001] The present disclosure relates to a power amplifier circuit and a power amplifier module. [Background technology]

[0002] 2. Description of the Related Art An LMBA (Load Modulated Balanced Amplifier) ​​is known that includes a main amplifier including a pair of amplifiers and a control amplifier that controls the load impedance of the main amplifier (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 10,404,224 Summary of the Invention [Problem to be solved by the invention]

[0004] The LMBA described in Patent Document 1 operates a pair of amplifiers in the main amplifier in class AB, and operates the control amplifier in class AB or class C. However, with this configuration, the efficiency of the main amplifier is low at low input power, which causes a problem in that it is not possible to achieve high efficiency for signals with a high PAPR (Peak to Average Power Ratio).

[0005] Therefore, an object of the present disclosure is to provide a power amplifier circuit that can improve efficiency even at low input power. [Means for solving the problem]

[0006] A power amplifier circuit according to one aspect of the present invention includes a first divider that divides an input signal into a first input signal and a second input signal, a carrier amplifier, and a peak amplifier, a Doherty amplifier that amplifies the first input signal and outputs an output signal to an output terminal, and a control amplifier that amplifies the second input signal and outputs a control signal to the Doherty amplifier circuit to control the load impedance of the Doherty amplifier circuit. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a power amplifier circuit that can improve efficiency even at low input power. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a diagram illustrating a configuration example of a power amplifier module. [Figure 2] FIG. 1 is a diagram showing an example of the structure of a parallel plate coupler that is a combiner. [Figure 3] FIG. 1 is a diagram illustrating an example of the structure of a λ / 4 line coupler that is a combiner. [Figure 4] FIG. 1 is a diagram illustrating an example of the structure of a branch-line coupler that is a combiner. [Figure 5] FIG. 1 is a diagram illustrating an example of the structure of a lumped parameter coupler that is a combiner. [Figure 6] FIG. 1 is a diagram illustrating an example of the configuration of a communication device incorporating a power amplification module. [Figure 7] FIG. 10 is a diagram illustrating an example of a current input to a combiner. [Figure 8] 1 is a graph showing an example of the relationship between the input voltage Vin of each amplifier of a power amplifier module and the output voltage Vout of each amplifier. [Figure 9] 1 is a graph showing an example of the relationship between the output power of a power amplifier module and the output efficiency. [Figure 10] 10 is a graph showing an example of the relationship between the input voltage Vin of each amplifier and the output voltage Vout of each amplifier in a power amplifier module according to a modified example. [Figure 11] 10 is a graph showing an example of the relationship between output power and output efficiency of a power amplifier module according to a modified example. [Figure 12] FIG. 1 is a diagram illustrating an example of a configuration of a power amplifier module according to a comparative example. [Figure 13] 10 is a graph showing an example of the relationship between the input voltage Vin of each amplifier and the output voltage Vout of each amplifier in the power amplifier module according to the comparative example. [Figure 14] 10 is a graph showing an example of the relationship between output power and output efficiency of a power amplifier module according to a comparative example. [Figure 15] 10 is a graph showing an example of the relationship between the input voltage Vin of each amplifier and the output voltage Vout of each amplifier in the power amplifier module according to the comparative example. [Figure 16] 10 is a graph showing an example of the relationship between output power and output efficiency of a power amplifier module according to a comparative example. [Figure 17] FIG. 10 is a diagram illustrating an example of the configuration of a power amplifier module according to a second modification. [Figure 18] 10 is a graph showing frequency characteristics of a parallel plate coupler. [Figure 19] 10 is a graph showing the relationship between the phase of a signal input to a control amplifier and the phase of a signal input to a peak amplifier 133 in a power amplification module according to a second modification. [Figure 20] FIG. 10 is a diagram illustrating an example of the configuration of a power amplifier module according to a third modified example. [Figure 21] 10 is a graph showing the relationship between the phase of the signal output from the control amplifier and the phase of the signal output from the peak amplifier in the combiner in the third modification. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, each embodiment of the present disclosure will be described with reference to the drawings. Hereinafter, circuit elements with the same reference numerals will be referred to as the same circuit elements, and redundant description will be omitted.

[0010] ===Configuration of power amplifier module 100 according to this embodiment=== The configuration of a power amplifier module 100 will be described with reference to Fig. 1. Fig. 1 is a diagram illustrating an outline of the configuration of the power amplifier module 100. The power amplifier module 100 is mounted on, for example, a mobile communication device such as a mobile phone, amplifies the power of an input signal RFin to a level required for transmission to a base station or a terminal, and outputs the amplified power as an output signal RFout. The input signal RFin is a radio frequency (RF) signal modulated according to a predetermined communication method by, for example, an RFIC (Radio Frequency Integrated Circuit). The communication standards of the input signal RFin include, for example, 2G (second-generation mobile communication system), 3G (third-generation mobile communication system), 4G (fourth-generation mobile communication system), 5G (fifth-generation mobile communication system), LTE (Long Term Evolution)-FDD (Frequency Division Duplex), LTE-TDD (Time Division Duplex), LTE-Advanced, or LTE-Advanced Pro, and the frequency is, for example, approximately several hundred MHz to several tens of GHz. Note that the communication standards and frequencies of the input signal RFin are not limited to these.

[0011] The power amplifier module 100 includes, for example, a drive amplifier 110, a first divider 120, a Doherty amplifier circuit 130, a control amplifier 140, an impedance matching section 150, and an impedance matching section 160.

[0012] The components of the power amplifier module 100 will be described below.

[0013] The drive amplifier 110 amplifies, for example, an input radio frequency RF signal (hereinafter referred to as "input signal RFin") and outputs an amplified signal (hereinafter referred to as "signal RF1"). The frequency of the signal RFin is, for example, about several GHz. The drive amplifier 110 is not particularly limited, but is configured with, for example, a bipolar transistor such as a heterojunction bipolar transistor (HBT) or a transistor such as a field effect transistor (MOSFET: Heterojunction Bipolar Transistor-oxide-semiconductor Field Effect Transistor). Note that the carrier amplifier 132, peak amplifier 133, and control amplifier 140, which will be described later, also have a similar configuration.

[0014] The first divider 120 divides, for example, the signal RF1 output from the drive amplifier 110 into a signal (hereinafter referred to as "signal RF11") to be output to the Doherty amplifier circuit 130 and a signal (hereinafter referred to as "signal RF12") to be output to the control amplifier 140. The first divider 120 may have a function of adjusting at least one of the amplitude and phase of the current in the signal RF12 based on the characteristics (e.g., frequency, amplitude, phase, etc.) of the signal RF1. The first divider 120 may be configured to include, for example, a distributed constant circuit such as a coupled-line 3 dB coupler or a Wilkinson divider. Note that the first divider 120 may each realize the function of dividing the signal RF1, the function of adjusting the amplitude of the signal RF12, and the function of adjusting the phase of the signal RF12 using separate components. Furthermore, the control amplifier 140 (described later) may be configured to realize the function of adjusting the amplitude and the phase of the current of the signal RF12.

[0015] The Doherty amplifier circuit 130 includes, for example, a second divider 131, a carrier amplifier 132, a peak amplifier 133, and a combiner 134.

[0016] The second divider 131 divides the signal RF11 divided by the first divider 120 into a signal RF11a input to a carrier amplifier 132 and a signal RF11b input to a peak amplifier 133. Here, the phase of the signal RF11a may be delayed by approximately 90 degrees relative to the phase of the signal RF11b. Approximately 90 degrees includes, for example, a range from +45 degrees to −45 degrees with 90 degrees as the center. The second divider 131 may be, for example, a distributed constant circuit such as a parallel plate coupler, a λ / 4 line coupler, a coupled line 3 dB coupler, or a Blind-in coupler, or a Wilkinson divider. The second divider 131 is electrically connected to a reference potential via a resistor 135, for example.

[0017] Carrier amplifier 132 is, for example, an amplifier that amplifies input signal RF11a and outputs an amplified signal. Carrier amplifier 132 is biased, for example, to class A, class AB, or class B. That is, carrier amplifier 132 amplifies the input signal and outputs the amplified signal regardless of the power level of the input signal, such as a small instantaneous input power.

[0018] The peak amplifier 133 is, for example, an amplifier that amplifies the input signal RF11b and outputs the amplified signal. The peak amplifier 133 is biased to class C.

[0019] The combiner 134 combines, for example, the amplified signal output from the carrier amplifier 132 and the amplified signal output from the peak amplifier 133, and outputs the output signal RFout. The combiner 134 has, for example, a characteristic impedance that is substantially equal to the load impedance of the carrier amplifier 132 and the peak amplifier 133 in a saturated state. The load impedance refers to the impedance when looking from the load side (the output terminal 102 side) of the Doherty amplifier circuit 130. The combiner 134 may be, for example, a parallel plate coupler, a λ / 4 line coupler, a coupled-line 3 dB coupler, or a branch-line coupler. In other words, by using a combiner 134 that exhibits a low characteristic impedance, the power amplifier module 100 can omit impedance matching circuits for the carrier amplifier 132 and the peak amplifier 133, thereby achieving miniaturization.

[0020] A parallel plate coupler will be described with reference to FIG. 2. FIG. 2 is a diagram showing an example of the structure of a parallel plate coupler serving as the combiner 134. As shown in FIG. 2, the parallel plate coupler is composed of one plate 134a and another plate 134b facing parallel to the plate 134a. An output terminal of the carrier amplifier 132 is electrically connected to one corner C1 of the plate 134a. An output terminal 102 is electrically connected to a corner C2 of the plate 134a diagonally opposite the corner C1, for example, via an impedance matching unit 160. A control amplifier 140 is connected to a corner C3 of the other plate 134b that overlaps with the corner C1 of the plate 134a in a direction that overlaps the corner C1 of the plate 134a. An output terminal of the peak amplifier 133 is electrically connected to a corner C4 of the plate 134b opposite the corner C3 to which the control amplifier 140 is connected. When the combiner 134 is a parallel plate coupler, the power amplifier module 100 is miniaturized.

[0021] The λ / 4 line coupler will be described with reference to Fig. 3. Fig. 3 is a diagram showing an example of the structure of a λ / 4 line coupler that is the combiner 134. As shown in Fig. 3, the λ / 4 line coupler is formed by a pair of electromagnetically coupled λ / 4 lines. One end of one of the λ / 4 lines, 134c, is electrically connected to the output terminal of the control amplifier 140, and the other end is connected to the output terminal of the peak amplifier 133. The other λ / 4 line, 134d, has one end electrically connected to the output terminal of the carrier amplifier 132, and the other end is electrically connected to the output terminal 102, for example, via an impedance matching unit 160. When the combiner 134 is a λ / 4 line coupler, low impedance can be maintained over a wide band.

[0022] The branch line coupler will be described with reference to FIG. 4. FIG. 4 is a diagram showing an example of the structure of a branch line coupler that is the combiner 134. As shown in FIG. 4, the branch line coupler is formed by arranging and coupling λ / 4 lines 134e to 134h symmetrically in the vertical and horizontal directions. The junction point between the λ / 4 line 134e and the λ / 4 line 134f is electrically connected to the output terminal of the carrier amplifier 132. The junction point between the λ / 4 line 134f and the λ / 4 line 134g is electrically connected to the output terminal 102, for example, via an impedance matching unit 160. The junction point between the λ / 4 line 134g and the λ / 4 line 134h is electrically connected to the output terminal of the control amplifier 140. The junction point between the λ / 4 line 134h and the λ / 4 line 134e is electrically connected to the output terminal of the peak amplifier 133. When the combiner 134 is a branch line coupler, low impedance can be maintained at high frequencies such as millimeter waves.

[0023] The lumped parameter coupler will be described with reference to FIG. 5. FIG. 5 is a diagram showing an example of the structure of a lumped parameter coupler, which is the combiner 134. As shown in FIG. 5, the lumped parameter coupler includes a pair of magnetically coupled inductors 134i and 134j, one end of the pair of inductors 134i and 134j connected by a capacitor 134k and the other end of the pair of inductors 134i and 134j connected by a capacitor 134l. One end of the inductor 134i is electrically connected to the output terminal of the control amplifier 140. One end of the inductor 134j is electrically connected to the output terminal of the carrier amplifier 132. The other end of the inductor 134i is electrically connected to the output terminal of the peak amplifier 133. The other end of the inductor 134j is electrically connected to the output terminal 102, for example, via an impedance matching unit 160. When the combiner 134 is a lumped parameter coupler, low impedance can be maintained in the low frequency band.

[0024] The control amplifier 140 generates, for example, a control signal S for controlling the load impedance of the Doherty amplifier circuit 130. cont For example, the control amplifier 140 amplifies the signal RF12 adjusted by the first divider 120 based on the characteristics of the signal RF1, and outputs the control signal S contThe control amplifier 140 is biased, for example, in class C.

[0025] The impedance matching section 150 is a circuit that matches the load impedance of the control amplifier 140 with the input impedance of the combiner 134 of the Doherty amplifier circuit 130. The impedance matching section 150 is electrically connected between the control amplifier 140 and the Doherty amplifier circuit 130. The impedance matching section 150 may be configured with a transmission line transformer. By configuring the impedance matching circuit with a transmission line transformer, the power amplifier module 100 can achieve a wider bandwidth.

[0026] 1, the transmission line transformer of the impedance matching unit 150 includes, for example, a main line L1 and a sub-line L2. The transmission line transformer may be formed on the surface of each layer of a multilayer substrate, and the main line L1 and the sub-line L2 may be arranged so as to overlap in the stacking direction. A control signal S output from the control amplifier 140 is connected to one end of the main line L1. cont The power supply Vcc may be supplied to one end of the sub-line L2. In other words, the power supply Vcc may be electrically connected to one end of the sub-line L2 of the transmission line transformer of the impedance matching unit 150. The other end of the sub-line L2 is electrically connected to the other end of the main line L1. That is, the impedance matching unit 150 receives the control signal S converted from the other end of the main line L1 by impedance conversion due to electromagnetic coupling energy from the sub-line L2 to the main line L1. cont Output.

[0027] The impedance matching unit 160 is a circuit that matches the load impedance of the combiner 134 of the Doherty amplifier circuit 130 with the load impedance of the output terminal 102. The impedance matching unit 160 is electrically connected between the Doherty amplifier circuit 130 and the output terminal 102. The impedance matching unit 160 may be configured with a transmission line transformer. By configuring the impedance matching circuit with a transmission line transformer, the power amplifier module 100 can achieve a wider bandwidth.

[0028] As shown in FIG. 1, the transmission line transformer of the impedance matching unit 160 includes, for example, a main line L3 and a sub-line L4. The transmission line transformer may be formed on the surface of each layer of a multilayer substrate, or the main line L3 and the sub-line L4 may be arranged so that they overlap each other. One end of the main line L3 may be supplied with an output signal output from the Doherty amplifier circuit 130. One end of the sub-line L4 may be supplied with a power supply Vcc. In other words, one end of the sub-line L4 of the transmission line transformer of the impedance matching unit 160 may be electrically connected to the power supply Vcc. The other end of the sub-line L4 is electrically connected to the other end of the main line L3. That is, the impedance matching unit 160 converts impedance due to electromagnetic coupling energy from the sub-line L4 to the main line L3, and outputs a converted output signal from the other end of the main line L3.

[0029] As described above, the power amplifier module 100 may have a power supply Vcc connected to one end of a sub-line (e.g., sub-line L2, sub-line L4) of the transmission-line transformer. In this case, the transmission-line transformer has an impedance conversion function and also functions as a power supply line. This allows the power amplifier module 100 to be made smaller.

[0030] With reference to FIG. 12, the miniaturization of the power amplifier module 100 compared to the power amplifier module 1000 according to the comparative example will be described. FIG. 12 is a diagram showing an example of the configuration of the power amplifier module 1000 according to the comparative example. As shown in FIG. 12, in the power amplifier module 1000 according to the comparative example, a matching circuit 1500 (not connected to the power supply Vcc) is provided at the output terminal of the control amplifier 1400, and a matching circuit 1600 (not connected to the power supply Vcc) is also provided between the balanced amplifier circuit 1300 (for example, an amplifier circuit that operates two amplifiers in the Doherty amplifier circuit 130 of the power amplifier module 100 in class AB mode) and the output terminal 1020. Furthermore, in the power amplifier module 1000, the carrier amplifier 1320, the peak amplifier 1330, and the control amplifier 1400 are electrically connected to the power supply Vcc via inductors L10, L11, and L12, respectively.

[0031] In contrast, in the power amplifier module 100, the transmission line transformer of the impedance matching unit 150 functions as a matching circuit for matching the impedance between the control amplifier 140 and the combiner 134, and as wiring for electrically connecting each of the peak amplifier 133 and the control amplifier 140 to the power supply Vcc. Also, in the power amplifier module 100, the transmission line transformer of the impedance matching unit 160 functions as a matching circuit for matching the impedance between the Doherty amplifier circuit 130 and the output terminal 102 (load impedance), and as wiring for electrically connecting the carrier amplifier 132 to the power supply Vcc. As a result, the power amplifier module 100 has fewer components than the power amplifier module 1000, and can be made smaller.

[0032] Furthermore, some of the components of the power amplifier module 100 may be formed on-chip (e.g., a silicon semiconductor chip or a III-V compound semiconductor chip). Specifically, for example, the drive amplifier 110, the first divider 120, the Doherty amplifier circuit 130, the control amplifier 140, and the impedance matching section 150 may be formed on-chip. This prevents unnecessary parasitic inductance from occurring in the outputs of the Doherty amplifier circuit 130 and the control amplifier 140, thereby maintaining the characteristics of the power amplifier module 100. Note that, for example, when the RF signal is in a high frequency band such as the 6 GHz band, the impedance matching section 160 may also be formed on-chip. This makes it possible to suppress deviations in impedance matching due to parasitic inductance in the impedance matching section 160. In this embodiment, for example, a circuit including components formed on-chip may also be referred to as a "power amplifier circuit."

[0033] Next, the configuration of a communication device 10 incorporating the power amplifier module 100 will be described with reference to Fig. 6. Fig. 6 is a diagram showing an example of the configuration of a communication device 10 incorporating the power amplifier module 100. As shown in Fig. 6, the communication device 10 includes, for example, the power amplifier module 100, a switch 200, a filter circuit 300, a switch 400, and a multiplexer 500.

[0034] The switches 200 and 400 each include, for example, an input terminal and a plurality of output terminals, and may be, for example, a matrix switch that can electrically connect each of the plurality of input terminals to at least one of the plurality of output terminals.

[0035] The filter circuit 300 is, for example, a circuit that attenuates signals in a predetermined frequency band, and may be, for example, a low-pass filter, a band-pass filter, a band elimination filter, or a high-pass filter.

[0036] The multiplexer 500 is, for example, a filter circuit that separates the output signal RFout of a predetermined frequency band output from the power amplifier module 100 from a signal of a predetermined frequency band received by the antenna ANT.

[0037] ===Operation of power amplifier module 100=== Next, the operation of the power amplifier module 100 will be described with reference to Fig. 1 and Fig. 7. Fig. 7 is a diagram showing an example of the current input to the combiner 134.

[0038] The drive amplifier 110 receives a signal RFin via an input terminal 101. The drive amplifier 110 amplifies the signal RFin and outputs a signal RF1 to the first divider 120. The first divider 120 divides the signal RF1 into a signal RF11 that is output to the Doherty amplifier circuit 130 and a signal RF12 that is output to the control amplifier 140. The first divider 120 may, for example, output the signal RF12 that has been adjusted based on the characteristics of the signal RF1 to the control amplifier 140.

[0039] In addition, the control signal S cont may be generated so that its power level decreases as the power level of the output signal RFout output from the power amplifier module 100 increases. cont may be input to the Doherty amplifier circuit 130 to dynamically adjust the load impedance of the Doherty amplifier circuit 130 in accordance with the power level of the output signal RFout.

[0040] Control amplifier 140 amplifies signal RF12 to generate control signal S cont The control signal S cont is input to the Doherty amplifier circuit 130 through the impedance matching section 150. The impedance matching section 150 (e.g., a conversion ratio of 12:1) matches the load impedance of the control amplifier 140 (e.g., 42.0Ω) to the impedance of the impedance matching section 160 of the Doherty amplifier circuit 130 (described later) (e.g., 3.5Ω).

[0041] In the Doherty amplifier circuit 130, the second divider 131 divides the signal RF11 into a signal RF11a to be output to the carrier amplifier 132 and a signal RF11b to be output to the peak amplifier 133. The carrier amplifier 132 amplifies the signal RF11a and outputs the amplified signal. The peak amplifier 133 amplifies the signal RF11b and outputs the amplified signal. The combiner 134 combines the amplified signals amplified by the carrier amplifier 132 and the peak amplifier 133. At this time, the combiner 134 receives a control signal S cont is input to adjust the load impedance of the Doherty amplifier circuit 130.

[0042] 7, the operation of adjusting the load impedance of the Doherty amplifier circuit 130 through interaction between the Doherty amplifier circuit 130 and the control amplifier 140 in the power amplifier module 100 will be described. In the power amplifier module 100, a signal output from the control amplifier 140 (hereinafter referred to as a "control signal S cont") to the Doherty amplifier circuit 130 to adjust the load impedance of the Doherty amplifier circuit 130. The combiner 134 shown in FIG. 7 is, for example, a 3 dB hybrid coupler. In FIG. 7, for example, V L denotes the impedance of the load, and V CA denotes the output voltage of the control amplifier 140, and V BA1 denotes the output voltage of the peak amplifier 133, and V BA2 denotes the output voltage of the carrier amplifier 132, and I CA denotes the current supplied by the control amplifier 140, and e j φ is I CA indicates the phase of I BA denotes the current supplied from the carrier amplifier 132, and jI BA indicates the current supplied from the peak amplifier 133, and Z0 indicates the characteristic impedance of the combiner 134. In the circuit shown in FIG. 7, for example, the determinant shown in equation (1) holds. Then, when equation (1) is solved, for example, the relationship shown in equation (2) holds. As shown in equation (2), in the power amplifier module 100, the control signal S output from the control amplifier 140 cont By adjusting the amplitude and phase of BA1 ,Z BA2 is adjusted.

number

number

[0043] In equation (2), Z BA1 denotes the load impedance of the carrier amplifier 132 in the Doherty amplifier circuit 130. BA2 denotes the load impedance of the peak amplifier 133 in the Doherty amplifier circuit 130. Z0 denotes the characteristic impedance of the combiner 134, and is equal to the load impedance of the control amplifier 140.

[0044] That is, the power amplifier module 100 outputs a current I CA By adjusting the amplitude and phase of the control signal S, it is possible to adjust the load impedance of the carrier amplifier 132 and the peak amplifier 133 in the saturated Doherty amplifier circuit 130 while keeping the load impedances of the carrier amplifier 132 and the peak amplifier 133 equal to each other. In other words, the power amplifier module 100 controls the saturated Doherty amplifier circuit 130 by applying the control signal S cont By inputting the above, the load impedance of the Doherty amplifier circuit 130 can be adjusted.

[0045] Here, with reference to FIGS. 8, 9, 13, and 14, it will be described how the power amplifier module 100 can improve the output efficiency even at low input power, compared to the power amplifier module 1000 according to the comparative example.

[0046] Fig. 8 is a graph showing an example of the relationship between the input voltage Vin of each amplifier of the power amplifier module 100 and the output voltage Vout of each amplifier. In Fig. 8, the horizontal axis represents the input voltage Vin (V), and the vertical axis represents the output voltage Vout (V). In Fig. 8, the carrier amplifier 132 is shown by the plot of "Vca," the peak amplifier 133 is shown by the plot of "Vpk," and the control amplifier 140 is shown by the plot of "Vcon."

[0047] 9 is a graph showing an example of the relationship between the output power and the output efficiency of the power amplifier module 100. In FIG. 9, the horizontal axis represents the power ratio P BO (dB), and the vertical axis represents the output efficiency E ff (%) is shown.

[0048] Fig. 13 is a graph showing an example of the relationship between the input voltage Vin of each amplifier and the output voltage Vout of each amplifier in the power amplifier module 1000 according to the comparative example. In Fig. 13, the horizontal axis represents the input voltage Vin (V), and the vertical axis represents the output voltage Vout (V). In Fig. 13, the balanced amplifier circuit 1300 is shown by the plot of "Vb," and the control amplifier 1400 is shown by the plot of "Vcon."

[0049] 14 is a graph showing an example of the relationship between the output power and the output efficiency of the power amplifier module 1000 according to the comparative example. In FIG. 14, the horizontal axis represents the power ratio P BO (dB), and the vertical axis represents the output efficiency E ff (%) is shown.

[0050] As shown in FIG. 8 , in the power amplifier module 100, the carrier amplifier 132 has an output voltage Vout that rises faster with respect to the input voltage Vin and saturates faster than the peak amplifier 133 and the control amplifier 140. For example, the carrier amplifier 132 saturates at approximately 0.23 V. The peak amplifier 133 operates in class C, and therefore has an output voltage Vout that rises slower with respect to the input voltage Vin and saturates later than the carrier amplifier 132. For example, the peak amplifier 133 saturates at approximately 0.50 V. The control amplifier 140 may be biased in class C so as to operate slower than the peak amplifier 133. In other words, the control amplifier 140 may be supplied with a bias voltage or bias current that is lower than the bias voltage or bias current of the peak amplifier 133. For example, the control amplifier 140 may be biased so as to operate at a timing when the peak amplifier 133 saturates. Specifically, the control amplifier 140 may be biased so as to operate at approximately 0.50 V.

[0051] Then, as shown in FIG. 9, in the power amplifier module 100, the carrier amplifier 132 starts up, and the output efficiency E ff is about "-12dB" and has high output efficiency E ff The carrier amplifier 132 is saturated at about "-12 dB", and the output efficiency E ff However, the peak amplifier 133 then starts up, and the output efficiency E ff Furthermore, the output efficiency E ff When the power consumption is about to decrease, the control amplifier 140 operates to provide a high power efficiency E ff can be maintained.

[0052] On the other hand, as shown in FIG. 13 , in the power amplifier module 1000 according to the comparative example, the output voltage Vout of the balanced amplifier circuit 1300 rises and saturates faster with respect to the input voltage Vin than the control amplifier 140. For example, the balanced amplifier circuit 1300 saturates at approximately 0.50 V. The control amplifier 1400 operates in class C, and therefore the output voltage Vout of the control amplifier circuit 1400 rises slower with respect to the input voltage Vin than the balanced amplifier circuit 1300. For example, the control amplifier 1400 operates at approximately 0.50 V.

[0053] As a result, as shown in FIG. 14, in the power amplifier module 1000, the balanced amplifier circuit 1300 becomes saturated at, for example, "-6 dB", and the output efficiency E ff The output efficiency E ff However, the output efficiency E ff However, as shown in Fig. 14, the power amplifier module 1000 cannot improve the efficiency at a low input voltage Vin, as compared with the power amplifier module 100.

[0054] That is, even if the Doherty amplifier circuit 130 of the power amplifier module 1000 is saturated at the same input voltage Vin as the balanced amplifier circuit 1300 of the power amplifier module 1000, the power amplifier module 1000 has a high output efficiency E ff This has an advantageous effect compared to the power amplifier module 1000, that is, it can operate at a lower power consumption.

[0055] ===Modifications of the Power Amplification Module 100=== <<First Modification>> Modifications of the power amplifier module 100 will be described with reference to FIGS. 10, 11, 15, and 16.

[0056] FIG. 10 is a graph showing an example of the relationship between the input voltage Vin of each amplifier of the power amplifier module 100 according to the modified example and the output voltage Vout of each amplifier. In FIG. 10, the horizontal axis represents the input voltage Vin (V), and the vertical axis represents the output voltage Vout (V). In FIG. 10, the carrier amplifier 132 is shown by a plot of "Vca," the peak amplifier 133 is shown by a plot of "Vpk," and the control amplifier 140 is shown by a plot of "Vcon." FIG. 11 is a graph showing an example of the relationship between the output power of the power amplifier module 100 according to the modified example and the output efficiency. In FIG. 11, the horizontal axis represents the power ratio P BO (dB), and the vertical axis represents the output efficiency E ff (%) is shown.

[0057] FIG. 15 is a graph showing an example of the relationship between the input voltage Vin of each amplifier and the output voltage Vout of each amplifier in the power amplifier module 1000 according to the comparative example. FIG. 15 shows a graph when the balanced amplifier circuit 1300 and the control amplifier 1400 of the power amplifier module 1000 all operate in class AB. In FIG. 15, the balanced amplifier circuit 1300 is shown by the plot of "Vb", and the control amplifier 1400 is shown by the plot of "Vcon". FIG. 16 is a graph showing an example of the relationship between the output power of the power amplifier module 1000 according to the comparative example and the output efficiency. In FIG. 16, the horizontal axis represents the power ratio P BO (dB), and the vertical axis represents the output efficiency E ff (%) is shown.

[0058] In the above, the control amplifier 140 is biased to class C, but in the power amplifier module 100 according to the modification, the control amplifier 140 may be biased to class AB. In this case, as shown in FIG. 10, the rise of the carrier amplifier 132 reduces the output efficiency E ff Even at a low input voltage Vin, the efficiency is high (approximately 50% at approximately -12 dB as shown in FIG. 11). After that, as shown in FIG. 10, the control amplifier 140 is saturated, but the peak amplifier 133 starts up, and the output efficiency E ff In this way, the power amplifier module 100 according to the modified example has a high output efficiency Eff It can work with.

[0059] On the other hand, in the power amplifier module 1000 according to the comparative example shown in Fig. 12, when the balanced amplifier circuit 1300 and the control amplifier 1400 operate in class AB, both the balanced amplifier circuit 1300 and the control amplifier 1400 rise, as shown in Fig. 15. In this case, as shown in Fig. 16, the power amplifier module 1000 exhibits lower efficiency at a low input voltage Vin compared to the power amplifier module 100 according to the modified example (approximately "30%" at approximately "-12 dB" as shown in Fig. 16).

[0060] That is, the power amplifier module 100 has a higher output efficiency E than the power amplifier module 1000 at a lower input voltage Vin, even when its control amplifier 140 operates in class AB. ff This has an advantageous effect compared to the power amplifier module 1000, that is, it can operate at a lower power consumption.

[0061] <<Second Modification>> A power amplifier module 100a according to a second modification will be described with reference to FIGS. 17, 18, and 19. FIG. 17 is a diagram illustrating an example configuration of the power amplifier module 100a according to the second modification. FIG. 18 is a graph illustrating the frequency characteristics of a parallel plate coupler. In FIG. 18, the horizontal axis represents normalized frequency, and the vertical axis represents the phase difference between two signals. FIG. 19 is a graph illustrating the relationship between the phase of a signal input to the control amplifier 140 and the phase of a signal input to the peak amplifier 133 in the power amplifier module 100a according to the second modification. In FIG. 19, the horizontal axis represents normalized frequency, and the vertical axis represents the phase difference between the two signals.

[0062] As shown in FIG. 17, the control amplifier 140 in the power amplifier module 100a is biased to class AB. Compared to the power amplifier module 100, the first divider 120a in the power amplifier module 100a includes a divider 121a, a capacitor 122a, an inductor 123a, an inductor 124a, and a capacitor 125a. In the power amplifier module 100a, the combiner 134 is configured as a parallel plate coupler. It is preferable that the second divider 131 in the power amplifier module 100a is configured as a parallel plate coupler. The "plates" (for example, one plate 134a and the other plate 134b facing parallel to the plate 134a shown in FIG. 2) that face each other and form the parallel plate coupler refer to plates whose main surface facing the other plate has a larger area than the side surface that does not face the other plate.

[0063] The dividing unit 121a divides the signal RF1 into a signal RF11 (first input signal) and a signal RF12 (second input signal). The dividing unit 121a is configured as a parallel plate coupler formed of a pair of flat plates arranged in parallel facing each other. Note that the dividing unit 121a may be a λ / 4 line coupler, but is preferably a parallel plate coupler from the viewpoint of miniaturization.

[0064] Capacitor 122a is connected in series to one of the plates of divider 121a and passes signal RF11 to second divider 131. Inductor 123a is shunt-connected to one of the plates. In other words, inductor 123a is connected in series between one of the plates and the reference potential.

[0065] Inductor 124a is connected in series with the other plate of divider section 121 and passes signal RF12 to control amplifier 140. Capacitor 125a is shunt-connected to the other plate. In other words, capacitor 125a is connected in series between the other plate and the reference potential.

[0066] As shown in Fig. 18, a parallel plate coupler can split into two signals with a phase difference of approximately 90 degrees regardless of frequency. As shown in Fig. 18, it can be seen that the parallel plate coupler (dashed line) has better frequency characteristics than the branch line coupler (chain double-dashed line).

[0067] That is, in the power amplifier module 100a, two signals that have been phase-adjusted and divided by the parallel plate coupler, capacitor, and inductor are combined by the parallel plate coupler of the combiner 134. As a result, as shown in Fig. 19, the power amplifier module 100a can adjust the phase difference between the signal (RF12) input to the control amplifier 140 and the signal (RF11a) input to the peak amplifier 133 to be approximately 45 degrees (solid line) regardless of frequency, so as to optimally control the load impedance of the Doherty amplifier circuit 130 with respect to the phase difference of 90 degrees (dashed line) between the signals (RF11a, RF11b) input to the peak amplifier 133.

[0068] As shown in equation (2), the power amplifier module 100a receives the current I CA By adjusting the phase of the input signal, the load impedance of the Doherty amplifier circuit 130 can be optimally controlled.

[0069] <<Third Modification>> A power amplifier module 100b according to a third modification will be described with reference to Fig. 20 and Fig. 21. Fig. 20 is a diagram showing an example configuration of the power amplifier module 100b according to the third modification. Fig. 21 is a graph showing the relationship between the phase of the signal input to the control amplifier 140 and the phase of the signal input to the peak amplifier 133 in the power amplifier module 100b according to the third modification. In Fig. 21, the horizontal axis represents normalized frequency, and the vertical axis represents the phase difference between the two signals.

[0070] 20, the control amplifier 140 in the power amplifier module 100b is biased to class C, unlike the power amplifier module 100a according to the second modification. The first divider 120b in the power amplifier module 100b includes a divider 121b, an inductor 122b, a capacitor 123b, a capacitor 124b, and an inductor 125b. The combiner 134 in the power amplifier module 100b is configured as a parallel plate coupler. The second divider 131 in the power amplifier module 100b is preferably configured as a parallel plate coupler.

[0071] The distributor 121b is similar to the distributor 121a, and therefore a description thereof will be omitted.

[0072] Inductor 122b is connected in series to one of the plates of divider 121b and passes signal RF11 to second divider 131. Capacitor 123b is shunt-connected to one of the plates. In other words, capacitor 123b is connected in series between one of the plates and the reference potential.

[0073] Capacitor 124b is connected in series to the other plate of divider 121 and passes signal RF12 to control amplifier 140. Inductor 125b is shunt-connected to the other plate. In other words, inductor 125b is connected in series between the other plate and the reference potential.

[0074] In the power amplifier module 100b, the two signals that have been phase-adjusted and divided by the parallel plate coupler, capacitor, and inductor are combined by the parallel plate coupler of the combiner 134. As a result, as shown in Fig. 21, the power amplifier module 100b can adjust the phase difference between the signal (RF12) input to the control amplifier 140 and the signal (RF11a) input to the peak amplifier 133 to be approximately 135 degrees (solid line) regardless of frequency, so as to optimally control the load impedance of the Doherty amplifier circuit 130 with respect to the phase difference of 90 degrees (dashed line) between the signals (RF11a, RF11b) input to the peak amplifier 133.

[0075] In this way, as shown in equation (2), the power amplifier module 100b receives the current I CA By adjusting the phase of the power amplifier 100b, it is possible to optimally control the load impedance of the Doherty amplifier circuit 130. As a result, the power amplifier module 100b can improve the output efficiency by widening the band.

[0076] ===Summary=== Hereinafter, as an example, it will be explicitly stated that in the power amplifier module 100, the signal RF11 corresponds to the "first input signal" in the claims, the signal RF12 corresponds to the "second input signal" in the claims, the main line L1 corresponds to the "first main line" in the claims, the sub-line L2 corresponds to the "first sub-line" in the claims, the impedance matching section 150 corresponds to the "first impedance matching section" in the claims, the impedance matching section 160 corresponds to the "second impedance matching section" in the claims, the main line L3 corresponds to the "second main line" in the claims, the sub-line L4 corresponds to the "second sub-line" in the claims, the signal RF11a corresponds to the "first signal" in the claims, and the signal RF11b corresponds to the "second signal" in the claims.

[0077] The power amplifier module 100 according to an exemplary embodiment of the present disclosure includes a first divider 120 that divides an input signal (here, a signal RF1) into a signal RF11 and a signal RF12, a carrier amplifier 132, and a peak amplifier 133, and includes a Doherty amplifier circuit 130 that amplifies the signal RF11 and outputs an output signal RFout to an output terminal 102, and a control signal S cont and a control amplifier 140 that outputs the output voltage to the Doherty amplifier circuit 130. This allows the power amplifier module 100 to improve efficiency even at low input power.

[0078] Furthermore, in the power amplifier module 100, the Doherty amplifier circuit 130 includes a second divider 131 that divides the signal RF11 into signals RF11a and RF11b, a carrier amplifier 132 that operates in class A or class AB and amplifies the signal RF11a to output a first amplified signal, a peak amplifier 133 that operates in class C and amplifies the signal RF11b to output a second amplified signal, and a combiner 134 that combines the first amplified signal and the second amplified signal to output an output signal RFout to the output terminal 102, and the combiner 134 controls a control signal S cont is input. This allows the power amplifier module 100 to improve efficiency even at low input power.

[0079] Furthermore, the control amplifier 140 of the power amplifier module 100 is an amplifier that operates in class C. This allows the power amplifier module 100 to improve efficiency even at low input power.

[0080] Furthermore, the control amplifier 140 of the power amplifier module 100 is an amplifier that operates in class AB, which allows the power amplifier module 100 to improve efficiency even at low input power.

[0081] Furthermore, the combiner 134 of the power amplifier module 100 is configured with a parallel plate coupler formed by a pair of plates arranged in parallel facing each other, thereby making the power amplifier module 100 more compact.

[0082] Furthermore, the combiner 134 of the power amplifier module 100 is configured with a λ / 4 line coupler formed with wiring having a line length of one-fourth the wavelength at the frequency of the input signal, thereby making it possible to maintain low impedance over a wide band.

[0083] Furthermore, the combiner 134 of the power amplifier module 100 is configured with a branch line coupler, which allows low impedance to be maintained at high frequencies such as millimeter waves.

[0084] The power amplifier module 100 further includes an impedance matching section 150 electrically connected in series between the Doherty amplifier circuit 130 and the control amplifier 140, and the impedance matching section 150 includes a transmission line transformer, thereby widening the bandwidth and improving output efficiency.

[0085] Furthermore, the transmission line transformer of the impedance matching section 150 of the power amplifier module 100 includes a main line L1 and a sub-line L2, the main line L1 being electrically connected in series between the Doherty amplifier circuit 130 and the control amplifier 140, and one end of the sub-line L2 being electrically connected to one end of the main line L1 and the other end being electrically connected to a power supply Vcc. This eliminates the need to provide wiring (inductors) between the power supply Vcc and each amplifier in addition to the transmission line transformer for impedance matching, thereby reducing the size of the power amplifier module 100.

[0086] The power amplifier module 100 further includes an impedance matching section 160 electrically connected in series between the Doherty amplifier circuit 130 and the output terminal 102, and the impedance matching section 160 includes a transmission line transformer. This makes it possible to widen the bandwidth and improve output efficiency.

[0087] Furthermore, the transmission line transformer of the impedance matching section 160 of the power amplifier module 100 includes a main line L3 and a sub-line L4, the main line L3 being electrically connected in series between the Doherty amplifier circuit 130 and the output terminal 102, and one end of the sub-line L4 being electrically connected to one end of the main line L3 and the other end being electrically connected to a power supply Vcc. This eliminates the need to provide wiring (inductors) between the power supply Vcc and each amplifier in addition to the transmission line transformer for impedance matching, thereby reducing the size of the power amplifier module 100.

[0088] Furthermore, the first divider 120, the Doherty amplifier circuit 130, the control amplifier 140, and the impedance matching section 150 of the power amplifier module 100 are formed on the same chip. This makes it possible to suppress deviations in impedance matching due to parasitic inductance in the impedance matching section 160 and the like in the power amplifier module 100.

[0089] In the power amplifier module 100a, the first divider 120a includes a divider 121a configured by a parallel plate coupler formed of a pair of plates arranged in parallel facing each other, which divides a signal RF1 (input signal) into a signal RF11 (first input signal) and a signal RF12 (second input signal), a capacitor 122a (first capacitor) connected in series to one of the plates of the divider 121a, which passes the signal RF11 (first input signal) to the Doherty amplifier circuit 130, and a The divider 134 is configured with an inductor 123a (first inductor) shunt-connected to one of the plates, an inductor 124 (second inductor) connected in series to the other plate of the divider 121a and allowing the signal RF12 (second input signal) to pass to the control amplifier 140 (biased to class AB), and a capacitor 125a (second capacitor) shunt-connected to the other plate, and the combiner 134 is configured with a parallel plate coupler formed by a pair of plates arranged facing each other in parallel. This makes it possible to widen the band and improve output efficiency.

[0090] In the power amplifier module 100b, the first divider 120b includes a divider 121b formed of a pair of flat plates arranged parallel to each other and configured as a parallel plate coupler that divides a signal RF1 (input signal) into a signal RF11 (first input signal) and a signal RF12 (second input signal), an inductor 122b (third inductor) that is connected in series to one of the flat plates of the divider 121b and that passes the signal RF11 (first input signal) to the Doherty amplifier circuit 130, and a The divider 134 is made up of a capacitor 123b (third capacitor) shunt-connected to one of the plates, a capacitor 124b (fourth capacitor) connected in series to the other plate of the divider 121b and passing the signal RF12 (second input signal) to the control amplifier 140 (biased to class C), and an inductor 125b (fourth inductor) shunt-connected to the other plate, and the combiner 134 is made up of a parallel plate coupler formed by a pair of plates arranged facing each other in parallel. This makes it possible to widen the band and improve the output efficiency.

[0091] The above-described embodiments are intended to facilitate understanding of the present disclosure and are not intended to limit the present disclosure. The present disclosure may be modified or improved without departing from its spirit, and equivalents thereof are also included in the present disclosure. In other words, designs modified by a person skilled in the art as appropriate are also included within the scope of the present disclosure as long as they comprise the features of the present disclosure. The elements and their arrangements included in the embodiments are not limited to those exemplified and can be modified as appropriate. [Explanation of symbols]

[0092] 100, 100a, 100b...power amplifier module, 110...drive amplifier, 120, 120a, 120b...first divider, 130...Doherty amplifier circuit, 131...second divider, 132...carrier amplifier, 133...peak amplifier, 134...combiner, 140...control amplifier, 150...impedance matching section, 160...impedance matching section.

Claims

1. a first divider that divides an input signal into a first input signal and a second input signal; a Doherty amplifier circuit including a carrier amplifier and a peak amplifier, amplifying the first input signal and outputting an output signal to an output terminal; a control amplifier that amplifies the second input signal and outputs a control signal to the Doherty amplifier circuit to control a load impedance of the Doherty amplifier circuit; A power amplifier circuit comprising:

2. The Doherty amplifier circuit a second divider that divides the first input signal into a first signal and a second signal; the carrier amplifier operating in class A or class AB, amplifying the first signal and outputting a first amplified signal; the peak amplifier operating in class C to amplify the second signal and output a second amplified signal; a combiner that combines the first amplified signal and the second amplified signal to output the output signal to the output terminal; Equipped with The control signal is input to the combiner.

2. The power amplifier circuit according to claim 1.

3. The control amplifier is an amplifier operating in class C.

3. The power amplifier circuit according to claim 2.

4. The control amplifier is an amplifier operating in class AB.

3. The power amplifier circuit according to claim 2.

5. The combiner is configured by a parallel plate coupler formed by a pair of plates arranged in parallel facing each other.

5. The power amplifier circuit according to claim 2.

6. the combiner is configured with a λ / 4 line coupler formed with wiring having a line length that is a quarter of the wavelength at the frequency of the input signal, 5. The power amplifier circuit according to claim 2.

7. The combiner is composed of a branch-line coupler.

5. The power amplifier circuit according to claim 2.

8. a first impedance matching unit electrically connected in series between the Doherty amplifier circuit and the control amplifier; the first impedance matching unit includes a transmission line transformer, 2. The power amplifier circuit according to claim 1.

9. the transmission line transformer of the first impedance matching unit includes a first main line and a first sub-line, the first main line is electrically connected in series between the Doherty amplifier circuit and the control amplifier; one end of the first sub-line is electrically connected to one end of the first main line, and the other end is electrically connected to a power source; 9. The power amplifier circuit according to claim 8.

10. a second impedance matching unit electrically connected in series between the Doherty amplifier circuit and the output terminal; the second impedance matching unit includes a transmission line transformer, 2. The power amplifier circuit according to claim 1.

11. the transmission line transformer of the second impedance matching unit includes a second main line and a second sub-line, the second main line is electrically connected in series between the Doherty amplifier circuit and the output terminal; one end of the second sub-line is electrically connected to one end of the second main line, and the other end is electrically connected to a power source; The power amplifier circuit according to claim 10.

12. 10. A power amplifier module including the power amplifier circuit according to claim 8, wherein the first divider, the Doherty amplifier circuit, the control amplifier, and the first impedance matching unit are formed on the same chip.

13. The first distributor is a splitter configured by a parallel plate coupler formed of a pair of plates arranged in parallel facing each other, which splits the input signal into the first input signal and the second input signal; a first capacitor connected in series to one of the flat plates of the dividing unit, the first capacitor passing the first input signal to the Doherty amplifier circuit; and a first inductor connected in shunt to the one of the flat plates. a second inductor connected in series to the other plate of the dividing section, for passing the second input signal to the control amplifier; and a second capacitor connected in shunt to the other plate. It consists of The combiner is configured by a parallel plate coupler formed by a pair of plates arranged in parallel facing each other.

5. The power amplifier circuit according to claim 4.

14. The first distributor is a splitter configured as a parallel plate coupler formed of a pair of plates arranged parallel to each other and facing each other, which splits the input signal into the first input signal and the second input signal; a third inductor connected in series to one of the flat plates of the dividing unit, the third inductor passing the first input signal to the Doherty amplifier circuit; and a third capacitor shunt-connected to the one of the flat plates. a fourth capacitor connected in series to the other plate of the dividing section, for passing the second input signal to the control amplifier; and a fourth inductor connected in shunt to the other plate. It consists of The combiner is configured by a parallel plate coupler formed by a pair of plates arranged in parallel facing each other.

4. The power amplifier circuit according to claim 3.

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