Radio frequency power amplifier and wireless signal transmitting system

Abstract

This application relates to the field of radio technology, specifically to a radio frequency (RF) power amplifier and a wireless signal transmitting system. The RF power amplifier includes: a first amplification branch, including a first transistor and a first output circuit; and a second amplification branch, including a second transistor and a second output circuit. The first output circuit includes a line with an electrical length of 50 to 90 degrees formed by capacitors and inductors, and the second output circuit includes a line with an electrical length of 120 to 180 degrees formed by capacitors and inductors. The first and second output circuits can achieve good broadband characteristics, meeting the requirements of high bandwidth. Furthermore, by forming the first and second output circuits based on inductors and capacitors, due to the characteristics of inductors and capacitors, the transmission line structure does not require a high-cost substrate or a large-area printed circuit board, thus reducing the cost and size of the RF power amplifier.

Description

Technical Field

[0001] This application relates to the field of radio technology, specifically to a radio frequency power amplifier and a wireless signal transmission system. Background Technology

[0002] Radio frequency (RF) power amplifiers are one of the most important components in RF front-end systems. Currently, base stations widely use RF power amplifiers as driver stages or final stages, and RF power amplifiers are increasingly developing towards higher power, higher efficiency, and miniaturization.

[0003] like Figure 1 As shown, Figure 1 This is a simplified circuit schematic of a conventional RF power amplifier. The broadband topology of this RF power amplifier can be based on a transmission line structure. The first amplification branch 101 includes a first transistor 1012 and a first transmission line 1011, with the drain of the first transistor 1012 connected to the first transmission line 1011. The second amplification branch 102 includes a second transistor 1022 and a second transmission line 1021, with the drain of the second transistor 1022 connected to the second transmission line 1021. The electrical length of the first transmission line 1011 can be 90 degrees, and the electrical length of the second transmission line 1021 can be 180 degrees. This RF power amplifier possesses excellent bandwidth characteristics, but it requires a high-cost substrate or a large-area printed circuit board (PCB) to implement the transmission line structure, which is not conducive to miniaturization. Summary of the Invention

[0004] To address one of the aforementioned technical deficiencies, this application provides a radio frequency power amplifier and a wireless signal transmission system, the technical solution of which is as follows:

[0005] According to a first aspect of the embodiments of this application, this application provides a radio frequency power amplifier, the radio frequency power amplifier comprising:

[0006] The first amplification branch includes a first transistor and a first output circuit. The gate of the first transistor is connected to a radio frequency output device, the drain of the first transistor is connected to a first terminal of the first output circuit, and the second terminal of the first output circuit is connected to a signal transmitting device. The second amplification branch includes a second transistor and a second output circuit. The gate of the second transistor is connected to the radio frequency output device, the drain of the second transistor is connected to a first terminal of the second output circuit, and the second terminal of the second output circuit is connected to the signal transmitting device. The first output circuit includes a line with an electrical length of 50 to 90 degrees formed by capacitors and inductors, and the second output circuit includes a line with an electrical length of 120 to 180 degrees formed by capacitors and inductors.

[0007] According to a second aspect of the embodiments of this application, this application provides a wireless signal transmitting system, the wireless signal transmitting system comprising:

[0008] The radio frequency output device and the signal transmitting device; and the aforementioned radio frequency power amplifier, wherein the radio frequency power amplifier is connected to the radio frequency output device and the signal transmitting device respectively.

[0009] Using the RF power amplifier provided in this embodiment, the first amplification branch amplifies the RF signal output by the RF output device using a first transistor, and the second amplification branch amplifies the RF signal output by the RF output device using a second transistor. The amplified RF signal then passes through a first output circuit with an electrical length of 50 to 90 degrees and a second output circuit with an electrical length of 120 to 180 degrees, respectively, to obtain good broadband characteristics, meeting the requirements of high bandwidth. Furthermore, the first and second output circuits are formed based on inductors and capacitors. Due to the characteristics of inductors and capacitors, it is not necessary to rely on high-cost substrates or large-area printed circuit boards to implement the transmission line structure, thus reducing the cost and size of the RF power amplifier. Attached Figure Description

[0010] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0011] Figure 1 This is a simplified circuit diagram of a radio frequency power amplifier in the prior art;

[0012] Figure 2 This is a simplified circuit schematic of one of the radio frequency power amplifiers in this application;

[0013] Figure 3 For having Figure 2 The circuit diagram of one of the radio frequency power amplifiers;

[0014] Figure 4 For having Figure 2 The circuit diagram of another RF power amplifier;

[0015] Figure 5 For having Figure 2 Circuit diagram of another RF power amplifier

[0016] Figure 6 This is another simplified circuit schematic of the RF power amplifier in this application;

[0017] Figure 7 For having Figure 6 The circuit diagram of one of the radio frequency power amplifiers;

[0018] Figure 8 For having Figure 6 The circuit diagram of another RF power amplifier;

[0019] Figure 9 For having Figure 6 The circuit diagram of another RF power amplifier;

[0020] Figure 10 For Figure 6 This is one of the simulation data graphs for a power amplifier;

[0021] Figure 11 For Figure 6 This is another simulation data graph for a power amplifier;

[0022] Figure 12 For Figure 6 This is another simulation data graph of the power amplifier. Detailed Implementation

[0023] To make the technical solutions and advantages of the embodiments of this application clearer, the exemplary embodiments of this application will be described in further detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not an exhaustive list of all embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0024] As a core component of wireless signal transmission systems, radio frequency power amplifiers are increasingly evolving towards higher power, higher efficiency, and miniaturization. For example... Figure 1 As shown, the RF power amplifier includes a first amplification branch 101 and a second amplification branch 102. The first amplification branch 101 includes a first transistor 1012 and a first transmission line 1011 connected to the drain of the first transistor 1012. The second amplification branch includes a second transistor 1022 and a second transmission line 1021 connected to the drain of the second transistor 1022. For example, in the RF power amplifier, the first transmission line 1011 is formed with a microstrip line and has an electrical length of 90 degrees of delay, and the second transmission line 1021 is formed with a microstrip line and has an electrical length of 180 degrees of delay, forming an inverse Doherty structure. This RF power amplifier has good broadband characteristics and can meet the high bandwidth requirements of 5G, but it requires a high-cost substrate or a large-area printed circuit board (PCB) to implement the transmission line structure, which is not conducive to miniaturization.

[0025] This application provides a radio frequency power amplifier, such as Figure 2 and Figure 6 As shown, Figure 2 This is a simplified circuit schematic of one of the radio frequency power amplifiers in this application; Figure 6This is another simplified circuit diagram of the radio frequency power amplifier of this application. The radio frequency power amplifier includes a first amplification branch 101 and a second amplification branch 102, wherein the first amplification branch 101 includes a first transistor 1012 and a first output circuit 1013, and the second amplification branch 102 includes a second transistor 1022 and a second output circuit 1023.

[0026] The gate of the first transistor 1012 can be connected to an RF output device (not shown), and the drain of the first transistor 1012 can be connected to the first terminal of the first output circuit 1013. The second terminal of the first output circuit 1013 can be connected to the signal transmitting device 103. The gate of the second transistor 1022 can be connected to an RF output device (not shown), and the drain of the second transistor 1022 can be connected to the first terminal of the second output circuit 1023. The second terminal of the second output circuit 1023 can be connected to the signal transmitting device 103. The RF output device can output RF signals to the first transistor 1012 and the second transistor 1022. After being amplified by the first transistor 1012 and the second transistor 1022, the RF signals are transmitted from the drain of the first transistor 1012 to the first output circuit 1013 and from the drain of the second transistor 1022 to the second output circuit 1023. Then, they are output from the first output circuit 1013 and the second output circuit 1023 to the signal transmitting device 103, which then transmits them to the user terminal.

[0027] The first output circuit 1013 can be based on a line with an electrical length of 50 to 90 degrees formed by capacitors and inductors, that is, the electrical length of the first output circuit 1013 includes, but is not limited to, 55, 60, 65, 70, 73, 75, 80, 85, and 88 degrees. The second output circuit 1023 can be based on a line with an electrical length of 120 to 180 degrees formed by capacitors and inductors, that is, the electrical length of the second output circuit 1023 includes, but is not limited to, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, and 177 degrees.

[0028] In the above embodiments, the first amplification branch amplifies the radio frequency (RF) signal output by the RF output device using a first transistor, and the second amplification branch amplifies the RF signal output by the RF output device using a second transistor. The amplified RF signal then passes through a first output circuit with an electrical length of 50 to 90 degrees and a second output circuit with an electrical length of 120 to 180 degrees, respectively, to obtain good broadband characteristics, meeting the requirements of high bandwidth. Furthermore, the first and second output circuits are formed based on inductors and capacitors. Due to the characteristics of inductors and capacitors, higher integration is possible, eliminating the need for high-cost substrates or large-area printed circuit boards to implement the transmission line structure, thus reducing the cost and size of the RF power amplifier.

[0029] In one or more embodiments, such as Figure 2 As shown, the first output circuit 1013 includes a first inductor L1, a second inductor L2, a third inductor L3, a first decoupling capacitor CRF1, and a second capacitor C2. The first terminal of the first inductor L1 is connected to the drain of the first transistor 1012. The first terminal of the second inductor L2 is connected to the second terminal of the first inductor L1, and the second terminal of the second inductor L2 can be connected to the signal transmitting device 103. The first terminal of the third inductor L3 is connected between the second terminals of the first inductor L1 and the first terminal of the second inductor L2, and the second terminal of the third inductor L3 is connected to the first terminal of the first decoupling capacitor CRF1, which is grounded. The first terminal of the second capacitor C2 is connected to the second terminal of the second inductor L2, and the second terminal of the second capacitor C2 is grounded. That is, the first transistor 1011, the first inductor L1 and the second inductor L2 are connected in series, the third inductor L3 and the first decoupling capacitor CRF1 are connected in series, the opposite end of the third inductor L3 and the first decoupling capacitor CRF1 is connected between the first inductor L1 and the second inductor L2, and the opposite end of the first decoupling capacitor CRF1 and the third inductor L3 is grounded; the first end of the second capacitor C2 is connected between the second end of the second inductor L2 and the signal transmitting device 103, and the second end of the second capacitor C2 is grounded.

[0030] The second output circuit 1023 includes a fourth inductor L4, a fifth inductor L5, a sixth inductor L6, a seventh inductor L7, a second decoupling capacitor CRF2, and a first capacitor C1. The first terminal of the fourth inductor L4 is connected to the drain of the second transistor 1022. The second terminal of the fourth inductor L4 is connected to the first terminal of the fifth inductor L5. The second terminal of the fifth inductor L5 is connected to the first terminal of the sixth inductor L6. The second terminal of the sixth inductor L6 is connected to the signal transmitting device 103. The first terminal of the seventh inductor L7 is connected between the second terminals of the fourth inductor L4 and the fifth inductor L5. The second terminal of the seventh inductor L7 is connected to the first terminal of the second decoupling capacitor CRF2, and the second terminal of the second decoupling capacitor CRF2 is grounded. The first terminal of the first capacitor C1 is connected between the second terminals of the fifth inductor L5 and the sixth inductor L6, and the second terminal of the first capacitor C1 is grounded. That is, the second transistor 1022, the fourth inductor L4, the fifth inductor L5 and the sixth inductor L6 are connected in series, the seventh inductor L7 and the second decoupling capacitor CRF2 are connected in series, the end of the seventh inductor L7 away from the second decoupling capacitor CRF2 is connected between the fourth inductor L4 and the fifth inductor L5, and the end of the second decoupling capacitor CRF2 away from the seventh inductor L7 is grounded; one end of the first capacitor C1 is connected between the fifth inductor L5 and the sixth inductor L6, and the other end of the first capacitor C1 is grounded.

[0031] The first transistor 1012 has a first parasitic capacitance Cds1. In the first amplification branch 101, the first parasitic capacitance Cds1, the first inductor L1, the second inductor L2, the third inductor L3, the first decoupling capacitor CRF1, and the second capacitor C2 can form a circuit with an electrical length of 50 to 90 degrees. The second transistor 1022 has a second parasitic capacitance Cds2. In the second amplification branch 102, the second parasitic capacitance Cds2, the fourth inductor L4, the fifth inductor L5, the sixth inductor L6, the seventh inductor L7, the second decoupling capacitor CRF2, and the first capacitor C1 can form a circuit with an electrical length of 120 to 180 degrees. This not only achieves good broadband characteristics to meet the demand for high bandwidth but also reduces the cost and size of the RF power amplifier. Furthermore, connecting the third inductor L3 and the seventh inductor L7 to ground increases the video bandwidth of the RF power amplifier.

[0032] In one or more embodiments, the first output circuit 1013 further includes a first resistor R1 and a third capacitor C3. The first end of the first resistor R1 is connected between the second end of the third inductor L3 and the first end of the first decoupling capacitor CRF1. The second end of the first resistor R1 is connected to the first end of the third capacitor C3, and the second end of the third capacitor C3 is grounded. The second output circuit further includes a second resistor R2 and a fourth capacitor C4. The first end of the second resistor R2 is connected between the second end of the seventh inductor L7 and the first end of the second decoupling capacitor CRF2. The second end of the second resistor R2 is connected to the first end of the fourth capacitor C4, and the second end of the fourth capacitor C4 is grounded.

[0033] The formation of video bandwidth (VBW) primarily depends on the low-frequency resonant point formed by the sum of the equivalent capacitance and equivalent inductance, measured from the drain of the first transistor. Typically, the sum of the equivalent capacitance is determined by the third capacitor C3 and the fourth capacitor C4, generally assumed to be in the microfarad (μF) range. Therefore, the main determining factor is the equivalent inductance. Thus, it is necessary to minimize the equivalent inductance by increasing the number of parallel inductors connected to ground, thereby increasing the video bandwidth. Furthermore, to avoid excessively large resonance amplitude, a first resistor R1 and a second resistor R2 are introduced to suppress the resonance amplitude.

[0034] like Figures 3 to 5 As shown, Figure 3 For having Figure 2 The circuit diagram of one of the radio frequency power amplifiers; Figure 4 For having Figure 2 The circuit diagram of another RF power amplifier; Figure 5 For having Figure 2 The circuit diagram of another RF power amplifier. Figure 3In this design, the first and second output circuits are largely implemented using a passive integrated circuit (IPD), which integrates capacitors, inductors, and other components, and is interconnected with active chips and package pins via bondwires. The first resistor R1 and the third capacitor C3, as well as the second resistor R2 and the fourth capacitor C4, are implemented on a printed circuit board (PCB) outside the package using surface-mount components. Figure 4 In this design, the first and second output circuits are implemented using a passive integrated device (IPD), which integrates components such as capacitors and inductors. These IPDs are interconnected with active chips and package pins via bondwires. The second amplification branch is implemented on the PCB board outside the package using traces and surface-mount capacitors. Figure 5 In this package, the first and second output circuits are fully implemented within the package, which can be an LGA package. It integrates surface-mount capacitors, surface-mount inductors, and surface-mount resistors, and is interconnected with active chips via bondwires and with package pins via via.

[0035] In one or more embodiments, such as Figures 3 to 5 As shown, the RF power amplifier also includes a first drain power supply circuit and a second drain power supply circuit. The first terminal of the first drain power supply circuit is connected between the first terminal of the third inductor L3 and the first terminal of the first decoupling capacitor CRF1, and the second terminal of the first drain power supply circuit is connected to the first power supply 303. The first terminal of the second drain power supply circuit is connected between the second terminal of the seventh inductor L7 and the first terminal of the second decoupling capacitor CRF2, and the second terminal of the second drain power supply circuit is connected to the second power supply 304.

[0036] In one or more embodiments, such as Figure 6 As shown, the first amplification branch also includes a first inductor L1, a second inductor L2, a fifth capacitor C5, and a second capacitor C2. The first end of the first inductor L1 is connected to the drain of the first transistor 1012, and the second end of the first inductor L1 is connected to the first end of the second inductor L2. The second end of the second inductor L2 is connected to the signal transmitting device 103. The first end of the fifth capacitor C5 is connected between the second ends of the first inductor L1 and the second inductor L2, and the second end of the fifth capacitor C5 is grounded. The first end of the second capacitor C2 is connected to the second end of the second inductor L2, and the second end of the second capacitor C2 is grounded. That is, the first transistor 1011, the first inductor L1, and the second inductor L2 are connected in series. One end of the fifth capacitor C5 is connected between the first inductor L1 and the second inductor L2, and the other end of the fifth capacitor C5 is grounded. The first end of the second capacitor C2 is connected between the second end of the second inductor L2 and the signal transmitting device 103, and the second end of the second capacitor C2 is grounded.

[0037] The second output circuit 1023 includes a fourth inductor L4, a fifth inductor L5, a sixth inductor L6, a sixth capacitor C6, and a first capacitor C1. The first terminal of the fourth inductor L4 is connected to the drain of the second transistor 1022. The second terminal of the fourth inductor L4 is connected to the first terminal of the fifth inductor L5. The second terminal of the fifth inductor L5 is connected to the first terminal of the sixth inductor L6. The second terminal of the sixth inductor L6 can be connected to the signal transmitting device 103. The first terminal of the sixth capacitor C6 is connected between the second terminals of the fourth inductor L4 and the fifth inductor L5, and the second terminal of the sixth capacitor C6 is grounded. The first terminal of the first capacitor C1 is connected between the second terminals of the fifth inductor L5 and the sixth inductor L6, and the second terminal of the first capacitor C1 is grounded. That is, the second transistor 1022, the fourth inductor L4, the fifth inductor L5 and the sixth inductor L6 are connected in series. One end of the sixth capacitor C6 is connected between the fourth inductor L4 and the fifth inductor L5, and the other end of the sixth capacitor C6 is grounded. One end of the first capacitor C1 is connected between the fifth inductor L5 and the sixth inductor L6, and the other end of the first capacitor C1 is grounded.

[0038] The first transistor 1012 has a first parasitic capacitance Cds1. In the first amplification branch 101, the first parasitic capacitance Cds1, the first inductor L1, the second inductor L2, the fifth capacitor C5, and the second capacitor C2 can form a circuit with an electrical length of 50 to 90 degrees. The second transistor 1022 has a second parasitic capacitance Cds2. In the second amplification branch 102, the second parasitic capacitance Cds2, the fourth inductor L4, the fifth inductor L5, the sixth inductor L6, the sixth capacitor C6, and the first capacitor C1 can form a circuit with an electrical length of 120 to 180 degrees. This not only achieves excellent broadband characteristics to meet the requirements of a large bandwidth, but also reduces the cost and size of the RF power amplifier.

[0039] In one or more embodiments, the RF power amplifier further includes an eighth inductor L8, a third resistor R3, a third decoupling capacitor CRF3, and a seventh capacitor C7. The first terminal of the eighth inductor L8 is connected to the second terminal of the second inductor L2 and the second terminal of the sixth inductor L6, respectively. The second terminal of the eighth inductor L8 is connected to the first terminal of the third resistor R3. The second terminal of the third resistor R3 is connected to the first terminal of the seventh capacitor C7. The second terminal of the seventh capacitor C7 is grounded. The first terminal of the third decoupling capacitor CRF3 is connected between the second terminal of the eighth inductor L8 and the first terminal of the third resistor R3. The second terminal of the third decoupling capacitor CRF3 is grounded.

[0040] The video bandwidth of the RF power amplifier is increased by connecting the eighth inductor L8 to the ground; at the same time, in order to avoid excessive resonance amplitude, the third resistor R3 is introduced to suppress the resonance amplitude.

[0041] like Figures 7 to 9 As shown, Figure 7 For having Figure 6 The circuit diagram of one of the radio frequency power amplifiers; Figure 8 For having Figure 6 The circuit diagram of another RF power amplifier; Figure 9 For having Figure 6 The circuit diagram of another RF power amplifier. Figure 7 In this circuit, the first and second output circuits are largely implemented by a passive integrated device (IPD), which integrates components such as capacitors and inductors. These components are interconnected with active chips and package pins via bondwires. The first resistor R1 and the third capacitor C3, as well as the second resistor R2 and the fourth capacitor C4, are implemented on a printed circuit board outside the package using surface-mount components. Figure 8 In this design, the first and second output circuits are implemented using a passive integrated device (IPD), which integrates components such as capacitors and inductors. These components are interconnected with active chips and package pins via bondwires. The second amplification branch is implemented on the PCB board outside the package using traces and surface-mount capacitors. Figure 9 In this package, the first and second output circuits are fully implemented within the package, which can be an LGA package. It integrates surface-mount capacitors, surface-mount inductors, and surface-mount resistors, and is interconnected with active chips via bondwires and with package pins via via.

[0042] In one or more embodiments, such as Figures 7 to 9 As shown, the RF power amplifier also includes a third drain power supply circuit. The first terminal of the third drain power supply circuit is connected between the second terminal of the eighth inductor L8 and the first terminal of the third resistor R3, and the second terminal of the third drain power supply circuit is connected to the third power supply 307. The third power supply 307 supplies power to the drain of the first transistor 1012 and the drain of the second transistor 1022 through the third drain power supply circuit.

[0043] In one or more embodiments, such as Figures 3 to 5 , Figures 7 to 9 As shown, the RF power amplifier may further include a power divider 210. The input terminal of the power divider 210 is connected to the RF output device. The first output terminal of the power divider 210 is connected to the gate of the first transistor 1012, and the second output terminal of the power divider 210 is connected to the gate of the second transistor 1022. The RF output device can be connected to the RF signal input terminal 301. After outputting the RF signal, the RF signal is split at the power divider 210 to transmit the RF signal to the first amplification branch and the second amplification branch, so that the RF signal is processed in the first amplification branch and the second amplification branch, and then output to the signal transmitting device at the RF signal output terminal 302. The source of the first transistor 1012 is grounded, and the source of the second transistor 1022 is grounded.

[0044] In one or more embodiments, such as Figures 3 to 5 , Figures 7 to 9 As shown, the RF power amplifier also includes a first gate bias circuit and a second gate bias circuit. The first terminal of the first gate bias circuit is connected to the gate of the first transistor 1012, and the second terminal of the first gate bias circuit is connected to a fourth power supply 305. The first terminal of the second gate bias circuit is connected to the gate of the second transistor 1022, and the second terminal of the second gate bias circuit is connected to a fifth power supply 306. The fourth power supply 305 can provide voltage to the gate of the first transistor 1012 through the first gate bias circuit, and the fifth power supply 306 can provide voltage to the gate of the second transistor 1022 through the second gate bias circuit.

[0045] In one or more embodiments, such as Figures 3 to 5 , Figures 7 to 9 As shown, the RF power amplifier also includes a first DC blocking capacitor 201 and a second DC blocking capacitor 202. The first end of the first DC blocking capacitor 201 is connected to the first output terminal of the power divider 210, and the second end of the first DC blocking capacitor 201 is connected to the gate of the first transistor 1012 and the first terminal of the first gate bias circuit, respectively. The first end of the second DC blocking capacitor 202 is connected to the second output terminal of the power divider 210, and the second end of the second DC blocking capacitor 202 is connected to the gate of the second transistor 1022 and the first terminal of the second gate bias circuit, respectively. Since the fourth power supply 305 supplies power to the gate of the first transistor 1012 and the fifth power supply 306 supplies power to the gate of the second transistor 1022, this may cause interference through the power divider 210. Therefore, the first DC blocking capacitor 201 and / or the second DC blocking capacitor 202 can achieve isolation between different gate voltages.

[0046] In one or more embodiments, such as Figure 5 and Figure 9 As shown, the first gate bias circuit includes a ninth inductor 2031 and a fourth resistor 2032. One end of the ninth inductor 2031 is connected to the fourth power supply 305, and the other end of the ninth inductor 2031 is connected to one end of the fourth resistor 2032. The other end of the fourth resistor 2032 is connected to the gate of the first transistor 1012. The second gate bias circuit includes a tenth inductor 2041 and a fifth resistor 2042. One end of the tenth inductor 2041 is connected to the fifth power supply 306, and the other end of the tenth inductor 2041 is connected to one end of the fifth resistor 2042. The other end of the fifth resistor 2042 is connected to the gate of the second transistor 1022.

[0047] The following is based on Figure 6 The technical effects of this application are illustrated using the chip structure shown and a DHT amplifier with a center frequency of 860MHz as an example. Figure 10 As shown, Figure 10 For Figure 6 This is a simulation data graph of a power amplifier; the dashed line represents the high-impedance insertion loss of the main circuit, i.e., the insertion loss of the first amplification branch in the back-off state. The lower the insertion loss, the larger the bandwidth. The solid line represents the high-impedance return loss of the main circuit, i.e., the return loss of the first amplification branch in the back-off state. The lower the return loss, the better the matching quality and the larger the bandwidth. Therefore, it can be seen that... Figure 6 The chip structure shown can have good bandwidth characteristics.

[0048] For example Figure 11 As shown, Figure 11 For Figure 6 This is another simulation data graph for a power amplifier. The solid line represents the main path saturation return loss, i.e., the return loss of the first amplification branch in saturation; the dashed line represents the auxiliary path saturation return loss, i.e., the return loss of the second amplification branch in saturation. A smaller value indicates better matching quality and a larger bandwidth. Therefore, it can be seen that… Figure 6 The chip structure shown can have good bandwidth characteristics.

[0049] In such Figure 12 As shown, Figure 12 For Figure 6 This is another simulation data graph for the power amplifier. The dashed line represents the VBW impedance increase with a VBW (video bandwidth) enhancement network, while the dashed line represents the VBW impedance increase without a VBW enhancement network. Figure 12 It can be seen that after adding the VBW enhancement network, the frequency response below 400MHz is very flat, indicating that the VBW impedance response is very consistent.

[0050] The following design example uses a Doherty amplifier with a first output circuit electrical length of 90 degrees and a second output circuit electrical length of 180 degrees:

[0051] 1. The drain voltage of the first and second transistors is VDD, and their knee voltage is Vknee. These two factors determine the voltage swing of the process. The power-normalized drain-source capacitance is also defined, let's call it Cds_per_W. Simultaneously, for a specific application scenario, its saturation power is defined, let's call it Psat, and its operating frequency is also defined, let's call it fo. Therefore, for the Doherty amplifier, the optimal load at its combining point can be calculated:

[0052]

[0053] 2. Assuming the saturated power ratio of the first and second amplification branches is α, the optimal loads under saturated conditions for both branches, as well as the high-resistance load under the retraction condition of the first amplification branch, can be calculated as follows:

[0054] R opt_M =R L ·(1+α)

[0055]

[0056] R RHL_M =R L ·(1+α) 2

[0057] 3. The second output circuit includes a first sub-output circuit and a second sub-output circuit. Therefore, the characteristic impedances of the first output circuit TL1 in the first amplification branch and the first sub-output circuit TL2 and the second sub-output circuit TL3 in the second amplification branch can be obtained as follows:

[0058] Z TL1 =R opt_M

[0059] Z TL2 =Z TL3 =R opt_P

[0060] 4. Based on the saturated power Psat, power ratio α, and power-normalized drain-source capacitance Cds_per_W, the parasitic capacitance Cds values ​​of the first and second amplification branches can be calculated as follows:

[0061]

[0062]

[0063] 5. With the corresponding parasitic capacitance Cds and characteristic impedance Z... TL Then, the conversion of each output circuit segment can begin; Figure 2 In the first output circuit, whether the connection between the first inductor L1 and the second inductor L2 is a capacitor or an inductor depends on Q1 = 2π·fo·Z. TL1 CdsM determines that when the value of Q1 is less than 1, it is a capacitor, and when Q1 is greater than 1, it is an inductor. Figure 6 In the second sub-output circuit, whether the connection between the fourth inductor L4 and the fifth inductor L5 is a capacitor or an inductor depends on Q2 = 2π·fo·Z. TL1 The CdsP value determines whether a value of Q2 is less than 1 and whether it is an inductor.

[0064] From the following expansion—Q1 of the first amplification branch and Q2 of the second amplification branch—it can be seen that the connection between the first inductor L1 and the second inductor L2 is the same as that between the fourth inductor L4 and the fifth inductor L5.

[0065] Q1 = 2π·fo·ZTL1 ·CdsM=2π·fo·(VDD-Vknee) 2 ·Cds_per_W

[0066] Q2=2π·fo·Z TL2 ·CdsP=2π·fo·(VDD-Vknee) 2 ·Cds_per_W

[0067] but Figure 2 The components are as follows:

[0068]

[0069]

[0070]

[0071] Cds1=CdsM

[0072]

[0073]

[0074]

[0075]

[0076] Cds2=CdsP

[0077] but Figure 6 The components are as follows:

[0078]

[0079]

[0080]

[0081] Cds1=CdsM

[0082]

[0083]

[0084]

[0085]

[0086]

[0087] Cds2=CdsP

[0088] This application also provides a wireless signal transmission system, which includes the aforementioned radio frequency power amplifier, radio frequency output device (not shown), and signal transmission device. The radio frequency power amplifier is connected to the radio frequency output device and the signal transmission device respectively. The radio frequency output device outputs a radio frequency signal to the radio frequency power amplifier, which amplifies the received signal and then outputs it to the signal transmission device, which transmits the signal to the user terminal.

[0089] In the description of this application, it should be understood that the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0090] In this application, unless otherwise expressly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0091] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A radio frequency power amplifier, characterized in that, include: The first amplification branch includes a first transistor and a first output circuit. The gate of the first transistor is used to connect to an RF output device, the drain of the first transistor is connected to a first terminal of the first output circuit, and the second terminal of the first output circuit is used to connect to a signal transmitting device. The second amplification branch includes a second transistor and a second output circuit. The gate of the second transistor is connected to the radio frequency output device, and the drain of the second transistor is connected to a first terminal of the second output circuit. The second terminal of the second output circuit is connected to the signal transmitting device. The first output circuit includes a line with an electrical length of 50 to 90 degrees formed by capacitors and inductors, and the second output circuit includes a line with an electrical length of 120 to 180 degrees formed by capacitors and inductors. Both the first and second output circuits include at least one of the following two structures: First structure: The first output circuit includes: a first inductor, with its first end connected to the drain of the first transistor; a second inductor, with its first end connected to the second end of the first inductor, the second end being used to connect to the signal transmitting device; a third inductor, with its first end connected between the second end of the first inductor and the first end of the second inductor; a first decoupling capacitor, with its first end connected to the second end of the third inductor and its second end grounded; a second capacitor, with its first end connected to the second end of the second inductor and its second end grounded; and / or, The second output circuit includes: a fourth inductor, the first end of which is connected to the drain of the second transistor; a fifth inductor, the first end of which is connected to the second end of the fourth inductor; a sixth inductor, the first end of which is connected to the second end of the fifth inductor, and the second end of which is used to connect to the signal transmitting device; a seventh inductor, the first end of which is connected between the second end of the fourth inductor and the first end of the fifth inductor; a second decoupling capacitor, the first end of which is connected to the second end of the seventh inductor, and the second end of which is grounded; and a first capacitor, the first end of which is connected between the second end of the fifth inductor and the first end of the sixth inductor, and the second end of which is grounded. The second structure: The first output circuit includes: a first inductor, a second inductor, a fifth capacitor, and a second capacitor, wherein a first terminal of the first inductor is connected to the drain of a first transistor, a second terminal of the first inductor is connected to a first terminal of the second inductor, a second terminal of the second inductor is connected to a signal transmitting device, a first terminal of the fifth capacitor is connected between the second terminals of the first and second inductors, and a second terminal of the fifth capacitor is grounded; a first terminal of the second capacitor is connected to a second terminal of the second inductor, and a second terminal of the second capacitor is grounded; and / or, The second output circuit includes: a fourth inductor, a fifth inductor, a sixth inductor, a sixth capacitor, an eighth inductor, a third resistor, a third decoupling capacitor, a seventh capacitor, and a first capacitor. The first terminal of the fourth inductor is connected to the drain of the second transistor. The second terminal of the fourth inductor is connected to the first terminal of the fifth inductor. The second terminal of the fifth inductor is connected to the first terminal of the sixth inductor. The second terminal of the sixth inductor can be connected to a signal transmitting device. The first terminal of the sixth capacitor is connected between the second terminals of the fourth and fifth inductors and is grounded. The first terminal of the first capacitor is connected between the second terminals of the fifth and sixth inductors and is grounded. The first terminal of the eighth inductor is connected to the second terminals of the second and sixth inductors, respectively. The first terminal of the third resistor is connected to the second terminal of the eighth inductor. The first terminal of the third decoupling capacitor is connected between the second terminal of the eighth inductor and the first terminal of the third resistor and is grounded. The first terminal of the seventh capacitor is connected to the second terminal of the third resistor and is grounded. The first transistor includes a first parasitic capacitance, and the second transistor includes a second parasitic capacitance.

2. The radio frequency power amplifier according to claim 1, characterized in that, The first output circuit further includes: The first resistor has its first end connected between the second end of the third inductor and the first end of the first decoupling capacitor. The third capacitor has its first terminal connected to the second terminal of the first resistor, and its second terminal grounded. The second output circuit also includes: The first end of the second resistor is connected between the second end of the seventh inductor and the first end of the second decoupling capacitor. The fourth capacitor has its first terminal connected to the second terminal of the second resistor, and its second terminal grounded.

3. The radio frequency power amplifier according to claim 1, characterized in that, The radio frequency power amplifier also includes: The first drain power supply circuit has a first terminal connected between the second terminal of the third inductor and the first terminal of the first decoupling capacitor, and the second terminal is used to connect to the first power supply. The second drain power supply circuit has its first end connected between the second end of the seventh inductor and the first end of the second decoupling capacitor, and its second end is used to connect to the second power supply.

4. The radio frequency power amplifier according to claim 1, characterized in that, The radio frequency power amplifier also includes: The third drain power supply circuit has its first end connected between the second end of the eighth inductor and the first end of the third resistor, and its second end is used to connect to the third power supply.

5. The radio frequency power amplifier according to any one of claims 1 to 4, characterized in that, The radio frequency power amplifier also includes, The power divider has an input terminal connected to the RF output device, a first output terminal connected to the gate of the first transistor, and a second output terminal connected to the gate of the second transistor.

6. The radio frequency power amplifier according to claim 5, characterized in that, The RF power amplifier also includes: The first gate bias circuit has a first end connected to the gate of the first transistor and a second end used to connect to a fourth power supply. The second gate bias circuit has a first end connected to the gate of the second transistor and a second end used to connect to the fifth power supply.

7. The radio frequency power amplifier according to claim 6, characterized in that, The radio frequency power amplifier also includes: The first DC blocking capacitor has its first end connected to the first output terminal of the power divider, and its second end connected to the gate of the first transistor and the first terminal of the first gate bias circuit, respectively. And / or, the second DC blocking capacitor, with its first end connected to the second output terminal of the power divider, and its second end connected to the gate of the second transistor and the first terminal of the second gate bias circuit, respectively.

8. A wireless signal transmission system, characterized in that, The wireless signal transmission system includes: Radio frequency output devices and signal transmitting devices; The radio frequency power amplifier as described in any one of claims 1 to 7, wherein the radio frequency power amplifier is connected to the radio frequency output device and the signal transmitting device respectively.

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