A radio frequency power amplifier with harmonic rejection

Abstract

The application provides a harmonic suppression radio frequency power amplifier, wherein one end of an input matching circuit is connected with a radio frequency input end; the other end of the input matching circuit is connected with a base of a power amplifier tube; a collector of the power amplifier tube is connected with a power supply voltage through a first matching branch; an emitter of the power amplifier tube is connected with a first connecting point on a packaging substrate; the collector of the power amplifier tube is connected with a radio frequency output end through a second matching branch; the second matching branch is connected with the packaging substrate; a first end of a harmonic control circuit is connected with the collector of the power amplifier tube; a second end of the harmonic control circuit is connected with a second connecting point on the packaging substrate; a metal layer farthest from the power amplifier tube in a plurality of metal layers of the packaging substrate is a first metal layer; the first connecting point and the second connecting point are located on a second metal layer in the plurality of metal layers, and the first connecting point is connected with the second connecting point; and the second metal layer is a metal layer closest to the power amplifier tube in the plurality of metal layers.

Description

Technical Field

[0001] This application relates to the field of circuits, and to, but is not limited to, a harmonic-suppressing radio frequency power amplifier. Background Technology

[0002] In mobile communication systems, the efficiency and linear power of the front-end radio frequency (RF) power amplifier play a crucial role in the energy consumption and communication quality of mobile terminals. Related technologies involve RF power amplifiers comprising power amplifier transistors, harmonic control circuits, and a packaging substrate. The power amplifier transistors and harmonic control circuits are grounded via vias in the bottom substrate of the packaging substrate. Harmonic currents flowing through these vias generate harmonic voltages that are superimposed on the output voltage, causing the output voltage waveform to deviate from the ideal power amplifier waveform. To output the same power, the operating current needs to be increased, weakening the improvement in amplifier efficiency. Simultaneously, poor harmonic suppression in the harmonic control circuit leads to increased harmonic power at the RF output, failing to meet the harmonic performance requirements of communication protocols. Furthermore, under the same current, the harmonic current loop area is larger, easily generating electromagnetic radiation, thus posing a risk to the RF power amplifier's electromagnetic compatibility (EMC). Summary of the Invention

[0003] To address the aforementioned problems in the prior art, this application provides a harmonic-suppressing radio frequency power amplifier.

[0004] This application provides a harmonic suppression radio frequency power amplifier, including a power amplifier tube, a harmonic control circuit, an input matching circuit, an output matching circuit, and a packaging substrate, wherein the output matching circuit includes a first matching branch and a second matching branch;

[0005] One end of the input matching circuit is connected to the radio frequency input terminal; the other end of the input matching circuit is connected to the base of the power amplifier tube.

[0006] The collector of the power amplifier tube is connected to the power supply voltage through the first matching branch, and the emitter of the power amplifier tube is connected to the first connection point on the packaging substrate.

[0007] The collector of the power amplifier tube is connected to the RF output terminal via the second matching branch; the second matching branch is connected to the packaging substrate;

[0008] The first terminal of the harmonic control circuit is connected to the collector of the power amplifier tube, and the second terminal of the harmonic control circuit is connected to the second connection point on the packaging substrate.

[0009] The packaging substrate includes multiple parallel metal layers. The metal layer furthest from the power amplifier tube among the multiple parallel metal layers is the first metal layer. The first metal layer is grounded. A dielectric layer is disposed between two adjacent metal layers. The first connection point is connected to the first metal layer. The first connection point and the second connection point are located on the second metal layer among the multiple metal layers, and the first connection point is connected to the second connection point. The second metal layer is the metal layer closest to the power amplifier tube among the multiple metal layers. The distance between the first connection point and the second connection point is less than the target distance.

[0010] Optionally, the harmonic control circuit includes a first branch, which includes a first capacitor and a first inductor; wherein the first capacitor and the first inductor are connected in series.

[0011] Optionally, the harmonic control circuit further includes at least one second branch, the second branch including a second capacitor and a second inductor; wherein the second capacitor and the second inductor are connected in series, and each second branch is connected in parallel with the first branch.

[0012] Optionally, the first capacitor is a variable capacitor.

[0013] Optionally, one end of the second matching branch is connected to the collector of the power amplifier tube, and the other end of the second matching branch is connected to a third connection point on the first metal layer; the output matching circuit is used to provide load impedance for the power amplifier tube.

[0014] Optionally, the first matching branch includes an inductor, and the first matching branch is used to supply power to the power amplifier tube.

[0015] Optionally, the second matching branch includes a third inductor and a third capacitor. One end of the third inductor is connected to the collector of the power amplifier tube, and the other end of the third inductor is connected to one end of the third capacitor. The other end of the third capacitor is connected to the third connection point.

[0016] Optionally, the output matching circuit further includes a third matching branch, which includes a fourth inductor and a fourth capacitor. One end of the fourth inductor is connected between the third inductor and the third capacitor, and the other end of the fourth inductor is connected to one end of the fourth capacitor. The other end of the fourth capacitor is connected to a fourth connection point on the first metal layer.

[0017] Optionally, the input matching circuit is disposed between the base of the power amplifier tube and the RF input terminal, and the input matching circuit is used to match the impedance between the components.

[0018] The technical solution provided in this application has at least the following technical effects and advantages:

[0019] 1. This application provides a harmonic-suppressive radio frequency power amplifier, comprising a power amplifier transistor, a harmonic control circuit, an input matching circuit, an output matching circuit, and a packaging substrate. The output matching circuit includes a first matching branch and a second matching branch. One end of the input matching circuit is connected to the radio frequency input terminal; the other end of the input matching circuit is connected to the base of the power amplifier transistor. The collector of the power amplifier transistor is connected to the power supply voltage via the first matching branch, and the emitter of the power amplifier transistor is connected to a first connection point on the packaging substrate. The collector of the power amplifier transistor is connected to the radio frequency output terminal via the second matching branch; the second matching branch is connected to the packaging substrate. The first end of the harmonic control circuit is connected to the collector of the power amplifier transistor, and the second end of the harmonic control circuit is connected to a second connection point on the packaging substrate. The packaging substrate includes multiple parallel-arranged... The first metal layer is the one furthest from the power amplifier tube among multiple parallel metal layers. The first metal layer is grounded. A dielectric layer is disposed between two adjacent metal layers. The first connection point is connected to the first metal layer. The first connection point and the second connection point are located on the second metal layer among the multiple metal layers, and the first connection point and the second connection point are connected. The second metal layer is the metal layer closest to the power amplifier tube among the multiple metal layers. The distance between the first connection point and the second connection point is less than the target distance. In this way, without introducing additional components, the routing between the power amplifier tube and the harmonic control circuit and the packaging substrate can be flexibly arranged, reducing the return area of ​​harmonic current, eliminating the parasitic effect of grounding inductance in the packaging substrate, improving the efficiency and linearity of the RF power amplifier, and reducing the electromagnetic radiation of the RF power amplifier.

[0020] 2. In the harmonic current loop generated by the power amplifier tube, the harmonic current passes through the low-resistance path composed of capacitors and inductors in the harmonic control circuit, and then flows back to the power amplifier tube from the emitter stage. In this way, it is not necessary to pass through the grounding inductor in the package substrate, which solves the problem of the secondary voltage component on the grounding inductor being superimposed on the output voltage, thus improving the efficiency of the power amplifier.

[0021] 3. The harmonic short-circuit circuit composed of capacitors and inductors in the harmonic control circuit does not need to be connected to the ground equivalent inductor in the package substrate. In this way, the equivalent inductance of the inductor in the resonant control circuit and the ground equivalent inductor in the package substrate in series is equal to the inductor in the resonant control circuit. This ensures that the quality factor of the equivalent inductor after series connection is equal to the quality factor of the inductor in the resonant control circuit. In addition, the equivalent impedance of the harmonic short-circuit resistance is reduced, the harmonic suppression is better, and the harmonic power output at the output terminal is reduced, which meets the harmonic performance requirements of the communication protocol for the RF power amplifier. Attached Figure Description

[0022] Figure 1 An optional circuit diagram of a harmonic suppression radio frequency power amplifier provided in an embodiment of this application;

[0023] Figure 2 Another optional circuit diagram for a harmonic-suppressing radio frequency power amplifier provided in an embodiment of this application;

[0024] Figure 3 Another optional circuit diagram for a harmonic-suppressing radio frequency power amplifier provided in the embodiments of this application;

[0025] Figure 4 An optional circuit diagram of a harmonic-suppressing radio frequency power amplifier provided in another embodiment of this application;

[0026] Figure 5 Another alternative circuit diagram of a harmonic-suppressing radio frequency power amplifier provided for another embodiment of this application. Detailed Implementation

[0027] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0028] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0029] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0030] Currently, in mobile communication systems, the efficiency and linear power of the front-end RF power amplifier directly affect the power consumption and communication quality of the mobile terminal. The Adjacent Channel Leakage Ratio (ACLR) of the uplink modulated signal amplified by the front-end power amplifier must meet the requirements of various mobile communication protocols. RF power amplifiers can be classified into Class A, Class AB, Class B, and Class C, and also into Class D, Class E, Class F, and inverse Class F, etc., based on their DC bias point and output waveform control method.

[0031] To balance efficiency, linearity, and engineering feasibility, most terminal devices in related technologies use Class F RF power amplifiers. An ideal Class F RF power amplifier typically has its final stage power transistors biased at Class AB or Class B. The output node of the power transistors has a harmonic control circuit to ensure that even-order harmonic voltages (2f0, 4f0, ..., nf0, where n is even and f0 is the fundamental frequency, i.e., the operating frequency) are short-circuited, odd-order harmonic voltages (3f0, 5f0, ..., mf0, where m is odd) have high impedance or are open-circuited, even-order harmonic voltage amplitudes are zero, odd-order harmonic voltage amplitudes are appropriate, and the output node voltage Vout waveform is a square wave. From the Fourier expansion of a square wave, we know that the fundamental frequency voltage Vf0 of a Class F power amplifier is 4 / π compared to the DC voltage Vdc, while the Vf0 / Vdc ratio of a Class AB power amplifier without harmonic control is 1. Therefore, for the same output power, the load impedance of a Class F power amplifier can be selected to be higher than that of a traditional Class AB power amplifier, resulting in lower operating current and better efficiency. Considering the chip area occupied by the harmonic control circuit and engineering feasibility, the output node of a practical Class F RF power amplifier typically only has a 2f0 harmonic control circuit.

[0032] However, in related technologies, RF power amplifiers include power amplifier transistors, harmonic control circuits, and packaging substrates. The power amplifier transistors and harmonic control circuits are grounded via vias in the bottom substrate of the packaging substrate. Harmonic currents flowing through these vias generate harmonic voltages that are superimposed on the output voltage, causing the output voltage waveform to deviate from the waveform of an ideal power amplifier. To output the same power, the operating current needs to be increased, weakening the improvement in amplifier efficiency. Simultaneously, the harmonic suppression in the harmonic control circuit is poor, resulting in increased harmonic power at the RF output terminal, failing to meet the harmonic performance requirements of communication protocols for power amplifiers. Furthermore, under the same current, the loop area of ​​the harmonic current is larger, easily generating electromagnetic radiation, thus posing EMC risks to the RF power amplifier.

[0033] Example 1

[0034] like Figure 1The diagram shown is an optional circuit diagram of a harmonic suppression radio frequency power amplifier provided in an embodiment of this application. The radio frequency power amplifier 10 includes a power amplifier transistor 101, a harmonic control circuit 102, an input matching circuit 107, an output matching circuit 106, and a package substrate 103. The output matching circuit 106 includes a first matching branch and a second matching branch. The output matching circuit 106 is used to provide a load impedance for the power amplifier transistor 101.

[0035] One end of the input matching circuit 107 is connected to the RF input terminal 104; the other end of the input matching circuit 107 is connected to the base of the power amplifier tube 101.

[0036] The collector of the power amplifier tube 101 is connected to the power supply voltage Vcc through the first matching branch, and the emitter of the power amplifier tube 101 is connected to the first connection point on the packaging substrate 103; the first connection point can also be called the first through hole.

[0037] The collector of the power amplifier tube 101 is connected to the RF output terminal 105 via the second matching branch; the second matching branch is connected to the packaging substrate 103.

[0038] The first terminal of the harmonic control circuit 102 is connected to the collector of the power amplifier tube 101, and the second terminal of the harmonic control circuit 102 is connected to the second connection point on the packaging substrate 103.

[0039] The packaging substrate 103 includes multiple parallel metal layers. The metal layer furthest from the power amplifier transistor 101 is the first metal layer, which is grounded. A dielectric layer is disposed between adjacent metal layers. A first connection point is connected to the first metal layer. The first and second connection points are located on the second metal layer, and are connected to each other. The second metal layer, being the closest to the power amplifier transistor, is also called the top metal layer of the packaging substrate. Thus, the emitter of the power amplifier transistor is connected through the first connection point on the packaging substrate, and the emitter is connected to the first metal layer via the packaging substrate. The second terminal of the harmonic control circuit is connected through the second connection point on the packaging substrate. The first and second connection points are connected, and are located on the second metal layer of the packaging substrate, ensuring that the current return path of the harmonic current does not need to pass through the first metal layer on the packaging substrate for return.

[0040] It should be noted that the distance between the first connection point and the second connection point is less than the target distance. Ideally, the first connection point and the second connection point are the same point on the top metal layer of the package substrate. In this way, the grounding hole of the power amplifier tube 101 is shared with the grounding hole of the second harmonic short-circuit circuit and connected through the top metal layer of the package substrate 103. The current return path of the second harmonic becomes through the harmonic control circuit to the top metal layer trace and then back to the power amplifier tube 101. The loop path of the second harmonic circuit avoids the influence of grounding inductance and greatly improves the electromagnetic compatibility performance of the RF power amplifier 10.

[0041] In some cases, other electronic components may be disposed on the top metal of the packaging substrate, so that a certain distance is formed between the first connection point and the second connection point. In the embodiments of this application, it is ensured that the distance between the first connection point and the second connection point is less than the target distance, which is a sufficiently small distance.

[0042] Other embodiments of this application provide a harmonic suppression radio frequency power amplifier in which a first connection point and a second connection point are located at two relatively close connection points on a second metal layer, and the first connection point and the second connection point are connected through the second metal layer. Thus, a shorter metal trace is cleverly used to connect the first connection point and the second connection point, achieving a short-circuit connection between them.

[0043] This application provides a harmonic suppression radio frequency power amplifier, including a power amplifier transistor, a harmonic control circuit, and a packaging substrate. The output matching circuit includes a first matching branch and a second matching branch. One end of the input matching circuit is connected to the radio frequency input terminal; the other end of the input matching circuit is connected to the base of the power amplifier transistor. The collector of the power amplifier transistor is connected to the power supply voltage via the first matching branch, and the emitter of the power amplifier transistor is connected to a first connection point on the packaging substrate. The collector of the power amplifier transistor is connected to the radio frequency output terminal via the second matching branch; the second matching branch is connected to the packaging substrate. The first end of the harmonic control circuit is connected to the collector of the power amplifier transistor, and the second end of the harmonic control circuit is connected to a second connection point on the packaging substrate. The packaging substrate includes multiple parallel metal layers, with the metal layer furthest from the power amplifier transistor being the first metal layer, which is grounded. A dielectric material is disposed between adjacent metal layers. The first connection point is connected to the first metal layer. The first connection point and the second connection point are located on the second metal layer among multiple metal layers, and the first connection point and the second connection point are connected. The second metal layer is the metal layer closest to the power amplifier tube among multiple metal layers. The distance between the first connection point and the second connection point is less than the target distance. In this way, firstly, without introducing additional components, the parasitic influence of the grounding inductance between the power amplifier tube and the harmonic control circuit and the packaging substrate is flexibly set, which improves the efficiency and linearity of the RF power amplifier and reduces the electromagnetic radiation of the RF power amplifier. Secondly, the harmonic current generated by the power amplifier tube passes through the low-impedance path composed of capacitors and inductors in the harmonic control circuit, and then flows back to the power amplifier tube from the emitter stage. In this way, it is not necessary to pass through the grounding inductance in the packaging substrate, which solves the problem of the secondary voltage component on the grounding inductance being superimposed on the output voltage, thus improving the output efficiency of the power amplifier. Finally, the harmonic short-circuit circuit composed of capacitors and inductors in the harmonic control circuit does not need to be connected to the ground equivalent inductor in the package substrate. In this way, the equivalent inductance of the inductor in the resonant control circuit and the ground equivalent inductor in the package substrate connected in series is equal to the inductor in the resonant control circuit. This ensures that the quality factor of the equivalent inductor after series connection is equal to the quality factor of the inductor in the resonant control circuit. Furthermore, the equivalent impedance of the harmonic short-circuit resistor is reduced, the harmonic suppression is better, and the harmonic power output at the output terminal is reduced, which meets the harmonic performance requirements of the communication protocol for the RF power amplifier.

[0044] Example 2

[0045] like Figure 2 The diagram shown is an optional circuit diagram of a harmonic suppression radio frequency power amplifier provided in an embodiment of this application. The radio frequency power amplifier 10 includes a power amplifier tube 101, a harmonic control circuit 102, a package substrate 103, an output matching circuit 106, and an input matching circuit 107.

[0046] The harmonic control circuit 102 includes a first branch 1021, which includes a first capacitor C1 and a first inductor L1; wherein the first capacitor C1 and the first inductor L1 are connected in series.

[0047] The output matching circuit 106 includes a first matching branch 1061 and a second matching branch 1062; one end of the first matching branch 1061 is connected to the power supply voltage Vcc, and the other end of the first matching branch 1061 is connected to the collector of the power amplifier transistor 101; one end of the second matching branch 1062 is connected to the collector of the power amplifier transistor 101, and the other end of the second matching branch 1062 is connected to a third connection point on the first metal layer; the output matching circuit 106 is used to provide load impedance for the power amplifier transistor; the third connection point can also be called a third via.

[0048] The first matching branch 1061 includes an inductor L CHOKE The first matching branch 1061 is used to supply power to the power amplifier tube 101.

[0049] The second matching branch 1062 includes a third inductor L2 and a third capacitor C2. One end of the third inductor L2 is connected to the collector of the power amplifier tube, and the other end of the third inductor L2 is connected to one end of the third capacitor C2. The other end of the third capacitor C2 is connected to the third connection point.

[0050] The output matching circuit 106 further includes a third matching branch 1063, which includes a fourth inductor L3 and a fourth capacitor C3. One end of the fourth inductor L3 is connected between the third inductor L2 and the third capacitor C2, and the other end of the fourth inductor L3 is connected to one end of the fourth capacitor C3. The other end of the fourth capacitor C3 is connected to a fourth connection point on the first metal layer; the fourth connection point can also be called a fourth via.

[0051] The input matching circuit 107 is located between the base of the power amplifier tube 101 and the RF input terminal 104. The input matching circuit 107 is used to match the impedance between the components.

[0052] The input matching circuit 107 includes a fifth inductor L4 and a fifth capacitor C4. One end of the fifth inductor L4 is connected to the RF input terminal 104, and the other end of the fifth inductor L4 is connected to the fifth capacitor C4. The other end of the fifth capacitor C4 is connected to the base of the power amplifier transistor 101. The fifth capacitor C4 is a DC blocking capacitor. In a device's output current, there is both AC and DC current. If only the AC current needs to be input to the next stage device, a DC blocking capacitor can be connected between the two stages of the circuit. In this way, the AC current reaches the next stage device through the capacitor, while the DC current remains in the previous stage device. The input matching circuit is used to match the impedance between components to avoid power loss of the RF signal during transmission.

[0053] In practical applications, the packaging substrate has at least two metal layers, with a dielectric spacer between each pair of adjacent metal layers. The dielectric between any two adjacent metal layers can be the same or different. The dielectric material can be a common flame-retardant material such as FR4, or an epoxy board material such as FR5; this application does not impose specific limitations. Furthermore, due to the thickness of the metal plates and the spaces between them, the second metal layer, the closest metal layer to the power amplifier in the packaging substrate, connects to the first metal layer in the packaging substrate through a via. This via generates impedance, which can be understood as an equivalent inductance, such as... Figure 3 As shown.

[0054] Example 4

[0055] Based on the foregoing embodiments, an optional circuit diagram of the harmonic suppression radio frequency power amplifier provided in this application is as follows: Figure 4 As shown, the first capacitor C1 in the first branch 1021 of the harmonic control circuit 102 is a variable capacitor.

[0056] An optional circuit diagram of a harmonic-suppressing radio frequency power amplifier provided in this application embodiment is as follows: Figure 5 As shown, the harmonic control circuit 102 further includes at least one second branch 1022, which includes a second capacitor C12 and a second inductor L12; wherein the second capacitor C12 and the second inductor L12 are connected in series, and each second branch 1022 is connected in parallel with the first branch 1021.

[0057] In practical applications, the harmonic control circuit has a first branch and at least one second branch, which can make the harmonic control circuit resonate at different resonant points, that is, resonate at different operating frequencies. For example, if the operating frequency of the first branch is 2f0, the resonant control circuit can also resonate at the third-order operating frequency, that is, at the 3f0 operating frequency. It can also resonate at the Kth-order operating frequency, that is, at K times the f0 frequency, where K>3 and K is an integer.

[0058] Example 5

[0059] Based on the foregoing embodiments, the harmonic suppression radio frequency power amplifier provided in this application will be further described as follows:

[0060] like Figure 2 As shown, the RF power amplifier includes the power amplification transistor M1, the output matching circuit, the second-order harmonic control circuit, and the packaging substrate.

[0061] Among them, the power amplifier transistor M1 is the core component used to realize power amplification, which is powered by the power supply Vcc through the inductor L. CHOKE The power amplifier transistor M1 is generally integrated on the chip die. The power amplifier transistor M1 can be a FET, HBT transistor, or BJT transistor. This application does not limit the power amplifier transistor M1.

[0062] The output matching circuit consists of inductors L2, L3, and L4. CHOKE Together with capacitors C2 and C3, it provides a suitable load impedance for power amplifier transistor M1.

[0063] The harmonic control circuit consists of capacitor C1 and inductor L1, with a resonant frequency at the second harmonic. The resonant equivalent resistance is Rres. At the third harmonic frequency, this circuit is equivalent to an inductor Lequ1, and the third-order impedance is matched to a high impedance, providing the necessary harmonic impedance for the power amplifier transistor M1 to operate in Class F. As circuit theory shows, the higher the equivalent quality factor Q of capacitor C1 and / or inductor L1, the smaller the short-circuit resistance for achieving the second harmonic, the closer the second harmonic voltage amplitude is to zero, and the closer the output voltage Vout is to an ideal square wave, resulting in a more significant improvement in power amplifier efficiency. Capacitor C1 is typically powered by a die. The capacitance (C1) and Q value are typically above 100. The inductor (L1) is usually implemented using a wide M1 trace or multiple bond wires, with a Q value typically designed to be around 40-50. Furthermore, the capacitor (C1) is usually larger, while the inductor (L1) is smaller, ensuring that the second harmonics exhibit sufficiently low impedance within a certain frequency range. This allows the power amplifier to perform well in a specific operating frequency band. For example, in a power amplifier operating in the 1700MHz-2700MHz band, the capacitor (C1) is typically 4-5pF, and the inductor (L1) is typically 0.3-0.5nH. Capacitors C1, C2, and C3 can be surface-mount devices (SMD) or die-mounted capacitors. Inductors L1, Lchoke, L2, and L3 can be substrate windings, bond wires, or SMD devices.

[0064] The number of metal layers in the packaging substrate circuit board can be any number greater than or equal to 2. Here, combined with... Figures 2-5As shown, taking a 4-layer metal packaging substrate as an example, this application provides a schematic diagram of the substrate packaging in an RF power amplifier; layers M1, M2, M3, and M4 are metal trace layers (M1 metal trace layer is equivalent to the second metal layer, and M4 metal trace layer is equivalent to the first metal layer), and each adjacent pair of layers is separated by dielectric 1, dielectric 2, and dielectric 3 respectively; the materials of dielectric 1, dielectric 2, and dielectric 3 can be the same or different, and this application does not make specific limitations; the material of the dielectric can be common FR4 or other dielectric materials. Via1 is a via from metal layer M1 to metal layer M2, Via2 is a via from metal layer M2 to metal layer M3, and Via3 is a via from metal layer M3 to metal layer M4, enabling electrical connections between the chip die, SMD devices, and substrate traces. The height of M1 to M4 is the substrate thickness, which is typically around 220um. The equivalent inductances of a single via from the first to the fourth layer are Lpara1, Lpara3, and Lpara4, respectively, with inductance typically ranging from 0.8 to 0.1nH and a Q value of approximately 30.

[0065] The harmonic control circuit is connected to the second connection point of the M1 metal trace layer via a through-hole in the substrate, which is the top metal layer of the package substrate. The emitter of the power amplifier transistor is also connected to the first connection point of the M1 metal trace layer, and the first connection point is also connected to the M4 metal trace layer. In the output matching circuit, capacitor C2 is connected to the M4 metal trace layer via a third connection point, and capacitor C3 is connected to the M4 metal trace layer via a fourth connection point.

[0066] The technical solution provided in this application has at least the following technical effects and advantages:

[0067] 1. This application provides a harmonic suppression radio frequency power amplifier. The second harmonic current generated by the power amplifier tube M1 passes through a low-impedance path composed of capacitor C1 and inductor L1, and then flows back to the power amplifier tube M1 from the emitter stage. In this way, it is not necessary to pass through the ground inductor Lpara1 in the package substrate, which solves the problem of the secondary voltage component on the ground inductor Lpara1 being superimposed on the output voltage Vout, thereby improving the efficiency of the power amplifier.

[0068] 2. The harmonic short-circuit circuit composed of capacitor C1 and inductor L1 in the harmonic control circuit does not need to be connected to the ground equivalent inductance Lpara2 in the package substrate (not shown in the figure). In this way, the equivalent inductance Lequ2 after the series connection of inductor L1 in the resonant circuit and the ground equivalent inductance Lpara2 in the package substrate is equal to the inductor L1 in the resonant control circuit, that is, Lequ2 = L1. This ensures that the quality factor Q of the series equivalent inductance Lequ2 is equal to the quality factor Q of the inductor in the resonant control circuit, and the equivalent Rres of the second harmonic short-circuit resistance is reduced, resulting in better second harmonic suppression and a smaller second harmonic power output at the output terminal, which meets the second harmonic performance requirements of the communication protocol for the RF power amplifier.

[0069] 3. According to electromagnetic field theory, without introducing additional components, flexibly setting the connection method between the power amplifier tube M1 and the harmonic control circuit and the packaging substrate can significantly reduce the area of ​​harmonic current return and greatly improve the electromagnetic compatibility (EMC) of the RF power amplifier.

[0070] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0071] In the several embodiments provided in this application, it should be understood that the disclosed apparatus can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of the units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical or other forms.

[0072] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0073] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A harmonic-suppressed radio frequency power amplifier, characterized in that, It includes a power amplifier tube, a harmonic control circuit, an input matching circuit, an output matching circuit, and a packaging substrate, wherein the output matching circuit includes a first matching branch and a second matching branch; One end of the input matching circuit is connected to the radio frequency input terminal; the other end of the input matching circuit is connected to the base of the power amplifier tube. The collector of the power amplifier tube is connected to the power supply voltage through the first matching branch, and the emitter of the power amplifier tube is connected to the first connection point on the packaging substrate. The collector of the power amplifier tube is connected to the RF output terminal via the second matching branch; the second matching branch is connected to the packaging substrate. The first terminal of the harmonic control circuit is connected to the collector of the power amplifier tube, and the second terminal of the harmonic control circuit is connected to the second connection point on the packaging substrate. The packaging substrate includes multiple parallel metal layers. The metal layer furthest from the power amplifier tube among the multiple parallel metal layers is the first metal layer. The first metal layer is grounded. A dielectric layer is disposed between two adjacent metal layers. The first connection point is electrically connected to the first metal layer through a through-hole disposed in the multiple parallel metal layers. The first connection point and the second connection point are located on the second metal layer among the multiple metal layers, and the first connection point is connected to the second connection point. The second metal layer is the metal layer closest to the power amplifier tube among the multiple metal layers. The distance between the first connection point and the second connection point is less than the target distance.

2. The harmonic suppression radio frequency power amplifier according to claim 1, characterized in that, The harmonic control circuit includes a first branch, which includes a first capacitor and a first inductor; wherein the first capacitor and the first inductor are connected in series.

3. The harmonic-suppressed radio frequency power amplifier according to claim 2, characterized in that, The harmonic control circuit further includes at least one second branch, which includes a second capacitor and a second inductor; wherein the second capacitor and the second inductor are connected in series, and each second branch is connected in parallel with the first branch.

4. The harmonic-suppressed radio frequency power amplifier according to claim 2 or 3, characterized in that, The first capacitor is a variable capacitor.

5. The harmonic-suppressing radio frequency power amplifier according to claim 1, characterized in that, One end of the second matching branch is connected to the collector of the power amplifier tube, and the other end of the second matching branch is connected to the third connection point on the first metal layer; the output matching circuit is used to provide load impedance for the power amplifier tube.

6. The harmonic-suppressed radio frequency power amplifier according to claim 5, characterized in that, The first matching branch includes an inductor and is used to supply power to the power amplifier tube.

7. The harmonic-suppressed radio frequency power amplifier according to claim 6, characterized in that, The second matching branch includes a third inductor and a third capacitor. One end of the third inductor is connected to the collector of the power amplifier tube, and the other end of the third inductor is connected to one end of the third capacitor. The other end of the third capacitor is connected to the third connection point.

8. The harmonic-suppressed radio frequency power amplifier according to claim 7, characterized in that, The output matching circuit further includes a third matching branch, which includes a fourth inductor and a fourth capacitor. One end of the fourth inductor is connected between the third inductor and the third capacitor, and the other end of the fourth inductor is connected to one end of the fourth capacitor. The other end of the fourth capacitor is connected to a fourth connection point on the first metal layer.

9. The harmonic-suppressed radio frequency power amplifier according to claim 1, characterized in that, The input matching circuit is disposed between the base of the power amplifier tube and the RF input terminal, and is used to match the impedance between the components.

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