Wave trap circuit, impedance matching circuit and radio frequency front end module

Abstract

The application provides a wave trap circuit, an impedance matching circuit and a radio frequency front end module. The wave trap circuit comprises a substrate and a first inductor, a second inductor, a first capacitor and a second capacitor arranged on the substrate. The first ends of the first capacitor and the second capacitor are connected to the first inductor through a common node, and the second ends of the first capacitor and the second capacitor are connected to the second inductor. The parasitic inductance difference generated by the wires between the first capacitor, the second capacitor and the common node is less than or equal to a preset inductance value, and the preset inductance value is less than or equal to 0.4nH. The above-mentioned mode can improve the harmonic suppression degree of the wave trap circuit.

Description

Technical Field

[0001] This application relates to the field of radio frequency technology, and in particular to a notch filter circuit, an impedance matching circuit, and a radio frequency front-end module. Background Technology

[0002] In radio frequency (RF) circuits, a trap (trap antenna) circuit is typically a resonant circuit consisting of an inductor (L) and a capacitor (C) connected in parallel. It is used to achieve multi-band antenna operation and frequency-selective isolation. The resonant point is a key parameter of the trap circuit; increasing the resonant point allows the trap circuit to more effectively block signals at the target frequency. The Q value (quality factor) of the capacitor is an important indicator of capacitor performance; a high Q value capacitor has lower losses, which improves the resonant performance and selectivity of the trap circuit.

[0003] In practical circuits, the placement and connection of capacitors have a significant impact on the performance of notch filter circuits, potentially leading to problems such as reduced harmonic suppression. Utility Model Content

[0004] The main purpose of this application is to provide a notch filter circuit, an impedance matching circuit, and an RF front-end module, which aims to solve the problem of reduced harmonic suppression in current notch filter circuits.

[0005] In a first aspect, this application provides a notch filter circuit, the notch filter circuit including a substrate and a first inductor, a second inductor, a first capacitor and a second capacitor disposed on the substrate; The first end of the first inductor serves as the input terminal of the notch filter circuit, and the second end of the first inductor serves as the output terminal of the notch filter circuit. The first terminals of the first capacitor and the second capacitor are connected to the second terminal of the first inductor through a common node. The parasitic inductance difference generated by the traces between the first terminals of the first capacitor and the second capacitor and the common node is less than or equal to a preset inductance value, which is less than or equal to 0.4nH. The second inductor is connected to the second terminal of the first capacitor and the second capacitor.

[0006] Secondly, embodiments of this application also provide a notch filter circuit, the notch filter circuit including a substrate and a first inductor, a second inductor, a first capacitor and a second capacitor disposed on the substrate; The first end of the first inductor serves as the input terminal of the notch filter circuit, and the second end of the first inductor serves as the output terminal of the notch filter circuit. The first terminals of the first capacitor and the second capacitor are connected to the second terminal of the first inductor through a common node. The parasitic inductance generated by the traces between the first terminals of the first capacitor and the second capacitor and the common node is the same, and the projections of the first capacitor and the second capacitor in the plane axis direction of the substrate at least partially overlap. The second inductor is connected to the second terminal of the first capacitor and the second capacitor.

[0007] Thirdly, embodiments of this application also provide a notch filter circuit, the notch filter circuit including a substrate and a first inductor, a second inductor, a first capacitor and a second capacitor disposed on the substrate; The first end of the first inductor serves as the input terminal of the notch filter circuit, and the second end of the first inductor serves as the output terminal of the notch filter circuit. The first terminals of the first capacitor and the second capacitor are connected to the second terminal of the first inductor through a common node, wherein the trace lengths between the first terminals of the first capacitor and the second capacitor and the common node are the same, and the projections of the first capacitor and the second capacitor in the plane axis direction of the substrate at least partially overlap. The second inductor is connected to the second terminal of the first capacitor and the second capacitor.

[0008] Fourthly, embodiments of this application also provide an impedance matching circuit, including a notch filter circuit as described in embodiments of this application.

[0009] Fifthly, embodiments of this application also provide a radio frequency front-end module, including: Notch filter circuits as described in the embodiments of this application or impedance matching circuits as described in the embodiments of this application; The power amplifier chip is connected to the notch filter circuit or the impedance matching circuit.

[0010] This application provides a notch filter circuit, an impedance matching circuit, and an RF front-end module. The notch filter circuit includes a substrate and a first inductor, a second inductor, a first capacitor, and a second capacitor disposed on the substrate. The first terminals of the first capacitor and the second capacitor are connected to the first inductor through a common node, and the second terminals of the first capacitor and the second capacitor are connected to the second inductor. The parasitic inductance difference generated by the traces between the first capacitor, the second capacitor, and the common node is less than or equal to a preset inductance value, which is less than or equal to 0.4nH. By using the common node connection method, the parasitic inductance generated by the traces between the first capacitor, the second capacitor, and the first inductor is kept basically consistent, thereby reducing the trace inductance difference between the two capacitors. This parasitic inductance difference is less than or equal to the preset inductance value (e.g., 0.4nH), which can effectively reduce or eliminate the second and third harmonics in the output signal of the notch filter circuit, thereby improving the resonance effect of the notch filter circuit for the output signal frequency. Therefore, it can effectively improve the harmonic suppression degree of the notch filter circuit, reduce the degree of resonant point deterioration, and improve the output signal quality. Attached Figure Description

[0011] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 A circuit diagram of a notch filter circuit provided for related technologies; Figure 2 A layout schematic diagram of one embodiment of a notch filter circuit provided in this application; Figure 3 A circuit diagram illustrating one embodiment of a notch filter circuit provided in this application. Figure 4 A simulation diagram of the notch filter circuit provided in the embodiments of this application; Figure 5 Another simulation diagram of the notch filter circuit provided in the embodiments of this application; Figure 6 A schematic layout diagram of one embodiment of the notch filter circuit provided in this application; Figure 7 A schematic diagram of another embodiment of the notch filter circuit provided in this application. Figure 8 A schematic layout diagram of yet another embodiment of the notch filter circuit provided in this application. Figure 9A schematic layout diagram of another embodiment of a notch filter circuit provided in this application; Figure 10 A schematic diagram of a layout of another embodiment of a notch filter circuit provided in this application. Figure 11 A schematic block diagram illustrating one embodiment of an impedance matching circuit provided in this application. Figure 12 A circuit diagram illustrating one embodiment of the impedance matching circuit provided in this application. Figure 13 A schematic block diagram of a radio frequency front-end module provided in an embodiment of this application; Figure 14 Another schematic block diagram of the radio frequency front-end module provided in the embodiments of this application.

[0013] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0014] It should be noted that the terms "first" and "second" in the specification, claims and drawings of this application are used to distinguish similar objects, rather than to describe a specific order or sequence.

[0015] It should also be noted that the methods disclosed in the embodiments of this application or the methods shown in the flowcharts include one or more steps for implementing the method. Without departing from the scope of the claims, the execution order of multiple steps can be interchanged, and some steps can also be deleted.

[0016] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0017] Figure 1 A circuit diagram of a notch filter circuit provided for related technologies. For example... Figure 1As shown, in related technologies, the Trap (Trap Antenna) circuit uses two capacitors C1 and C2 to increase the resonant point and improve the Q value of the capacitors. However, the positional difference between the two capacitors C1 and C2 at the main circuit nodes 11 and 12 leads to the generation of parasitic inductance 10, forming an equivalent ground-to-tank circuit (resonant circuit). The tank circuit consists of inductors and capacitors and has a specific resonant frequency. When the parasitic inductance 10 forms an equivalent ground-to-tank circuit with capacitors C1 and C2, it changes the resonant characteristics of the original Trap (Trap Antenna) circuit. Due to the presence of parasitic inductance 10, the equivalent ground-to-tank circuit generates additional resonant points. These resonant points may interfere with the resonant points of the original Trap circuit, leading to a deterioration in the resonant characteristics of the original Trap circuit. At the same time, this change in resonant characteristics affects the notch filter circuit's ability to suppress harmonics, reducing the harmonic suppression degree. That is, the circuit's filtering effect on harmonics deteriorates, allowing more harmonic signals to pass through the circuit, thus affecting the filtering performance of the notch filter circuit.

[0018] for Figure 1 The solution shown demonstrates that in traditional designs, using only one capacitor results in a low Q value in the trap circuit, failing to meet usage requirements. Conversely, using two capacitors in a traditional trap circuit leads to a large parasitic inductance between the two capacitors, also failing to meet performance requirements.

[0019] The following, combined with Figure 2 This application introduces a notch filter circuit provided by an embodiment of the present application. The notch filter circuit optimizes the connection points of the two capacitors C1 and C2 so that they are connected at the same node (common node 21). While ensuring the Q value of the circuit, it can also eliminate the parasitic inductance between capacitors C1 and C2, reduce or eliminate the effect of the equivalent ground tank causing the resonant point to deteriorate, and optimize the harmonic suppression degree of the notch filter circuit.

[0020] Please see Figure 2 , Figure 2 This is a schematic diagram of a notch filter circuit provided in an embodiment of this application.

[0021] like Figure 2 As shown, the notch filter circuit 100 includes a substrate 110 and a first inductor L1, a second inductor L2, a first capacitor C1 and a second capacitor C2 disposed on the substrate 110.

[0022] In this circuit, the first terminal of the first inductor L1 serves as the input terminal RFin of the notch filter circuit 100, and the second terminal of the first inductor L1 serves as the output terminal RFout of the notch filter circuit 100. The first terminals of the first capacitor C1 and the second capacitor C2 are connected to the second terminal of the first inductor L1 through a common node 21. The parasitic inductance difference generated by the traces between the first terminals of the first capacitors C1 and C2 and the common node 21 is less than or equal to a preset inductance value, which is less than or equal to 0.4nH. The second inductor L2 is connected to the second terminals of the first capacitor C1 and the second capacitor C2.

[0023] It should be noted that there are traces between the first terminals of the first capacitor C1 and the second capacitor C2 and the common node 21, and these traces will generate parasitic inductance. The common node 21 can be located between the first capacitor C1 and the second capacitor C2 in the substrate 110, or it can be located in other locations. In practical applications, due to differences in the length, width, and curvature of the traces, the parasitic inductance generated between the first capacitor C1 and the common node 21, and between the second capacitor C2 and the common node 21, may differ. When the difference in parasitic inductance is too large and the second inductor L2 is grounded, a situation similar to an equivalent ground tank circuit will be formed in the notch filter circuit 100, generating additional resonant points and reducing harmonic suppression. Therefore, it is necessary to limit the parasitic inductance difference to a small range. In this embodiment, the parasitic inductance difference is set to less than or equal to 0.4nH, thereby reducing the adverse effects caused by the parasitic inductance difference, making the resonance characteristics of the notch filter circuit 100 more stable, avoiding the notch filter circuit 100 from generating additional resonance points, and improving the harmonic suppression degree of the notch filter circuit 100.

[0024] For example, such as Figure 3 As shown, Figure 3 This is a circuit diagram of a notch filter circuit provided in an embodiment of this application. By setting a common node 21, the parasitic inductance difference generated by the traces between the first capacitor C1 and the common node 21, and between the second capacitor C2 and the common node 21, is reduced. For example, the difference in parasitic inductance between the first capacitor C1 and the second capacitor C2 can be in the range of 0-0.3nH. For instance, the difference in parasitic inductance between the first capacitor C1 and the second capacitor C2 can be 0.1nH or 0.2nH. For example, controlling the parasitic inductance generated by the traces between the first capacitor C1 and the common node 21 to be 15nH corresponds to controlling the parasitic inductance generated by the traces between the second capacitor C2 and the common node 21 to be 15.1nH, thereby ensuring that the difference in parasitic inductance between the first capacitor C1 and the second capacitor C2 is within the range of 0-0.3nH. In this way, parasitic inductance (such as...) can be reduced or eliminated. Figure 1The parasitic inductance 10 shown can effectively increase the suppression of second and third harmonics by the notch filter circuit 100, improve the harmonic suppression of the notch filter circuit 100, and reduce the deterioration of the resonant point.

[0025] In this embodiment, by changing the connection method of the common node 21, the parasitic inductance generated by the traces between the first capacitor C1, the second capacitor C2 and the first inductor L1 is kept basically consistent, thereby reducing the difference in trace inductance between the first capacitor C1 and the second capacitor C2. This parasitic inductance difference is less than or equal to a preset inductance value (e.g., 0.4nH), which can effectively reduce or eliminate the second and third harmonics in the output signal of the notch filter circuit 100, thereby improving the resonance effect of the notch filter circuit 100 for the output signal frequency. Therefore, it can effectively improve the harmonic suppression degree of the notch filter circuit 100, reduce the degree of deterioration of the resonance point, and improve the output signal quality.

[0026] In other words, in a scenario where the notch filter circuit 100 includes two parallel capacitors C1 and C2, by readjusting the layout design, the first capacitor C1 and the second capacitor C2 are connected to the main path node as a single node, corresponding to the common node 21 in the figure, thus eliminating the dual-node configuration (e.g., Figure 1 Nodes 11 and 12 in the diagram), thereby eliminating the parasitic inductance between the two capacitors (e.g., nodes 11 and 12 in the diagram). Figure 1 This addresses the problem of parasitic inductance 10) in the notch filter circuit and avoids reduced harmonic suppression and deterioration of the resonant point. It can resolve the issue of reduced harmonic suppression in current notch filter circuits 100 that use two capacitors.

[0027] For example, such as Figure 4 As shown in Figure 21, different sizes of parasitic inductance lead to varying degrees of harmonic suppression degradation. For m30 (signal frequency freq = 6.560 GHz), as indicated by curve 21, when the parasitic inductance is small, such as in a low range (e.g., less than 0.1 nH), the impact on the harmonic suppression capability of the notch filter circuit 100 is relatively small. The resonant frequency of the notch filter circuit 100 may only experience a slight shift, and the harmonic suppression level may decrease slightly.

[0028] As shown in curve 22, as the parasitic inductance increases to a moderate level (e.g., between 0.1nH and 0.4nH), the resonant frequency shift of the notch filter circuit 100 becomes more pronounced, potentially deviating from the harmonic frequency range to be suppressed, resulting in a significant decrease in harmonic suppression. As shown in curve 23, when the parasitic inductance is large (e.g., greater than 0.4nH), the resonant characteristics of the notch filter circuit 100 are severely compromised, and the resonant frequency may deviate significantly from the harmonic frequency to be suppressed. The impedance of the notch filter circuit 100 to harmonics decreases dramatically, making it almost impossible to effectively suppress harmonic signals, and the harmonic suppression level deteriorates sharply.

[0029] Therefore, as shown in curves 21 and 22, the embodiments of this application control the parasitic inductance difference within a small range, which can effectively reduce or eliminate the problem of reduced harmonic suppression caused by parasitic inductance, better suppress harmonic signals, reduce the interference of harmonics on the output signal of the notch filter circuit 100, and improve the quality of the output signal.

[0030] For example, such as Figure 5 As shown, curve 31 characterizes the relationship between the output signal power and the third harmonic power of the notch filter circuit provided in related technologies, while curve 33 characterizes the relationship between the output signal power and the third harmonic power of the notch filter circuit 100 provided in this application embodiment. Comparing curve 31 and curve 32, it can be seen that the third harmonic power of the notch filter circuit 100 provided in this application embodiment decreases significantly under different output signal powers. Therefore, the notch filter circuit 100 provided in this application embodiment can effectively increase the degree of suppression of the third harmonic, thereby improving the harmonic suppression degree of the notch filter circuit 100 and reducing the degree of deterioration of the resonant point.

[0031] In one embodiment, the first capacitor C1 and the second capacitor C2 have the same capacitance value, and the difference in trace length between the first terminals of the first capacitor C1 and the second capacitor C2 and the common node 21 is less than or equal to a preset length. It should be noted that the preset length can be zero or close to zero, thus ensuring that, when the capacitance values ​​of the first capacitor C1 and the second capacitor C2 are the same, the trace lengths between the first terminals of the first capacitor C1 and the second capacitor C2 and the common node 21 are substantially consistent, thereby ensuring that the difference in parasitic inductance between the first capacitor C1 and the common node 21, and between the second capacitor C2 and the common node 21, is less than or equal to the preset inductance value.

[0032] For example, such as Figure 6As shown, the first capacitor C1 and the second capacitor C2 have the same capacitance value. The trace length between the first terminal of the first capacitor C1 and the common node 21 is LA, and the trace length between the first terminal of the second capacitor C2 and the common node 21 is LB. The difference between the trace lengths LA and LB is, for example, 0.1 cm, which is less than the preset length of 0.5 cm. By controlling the trace length difference to be less than or equal to the preset length, the parasitic inductance difference between the two capacitors C1 and C2 and the common node 21 can be effectively reduced, thereby making the resonance characteristics of the notch filter circuit 100 more stable and effectively reducing or eliminating the second and third harmonics in the output signal of the notch filter circuit 100. The notch filter circuit 100 can operate more accurately at the preset resonant frequency, effectively process signals of specific frequencies, and improve the selectivity and filtering effect of the notch filter circuit 100.

[0033] In one embodiment, the first capacitor C1 and the second capacitor C2 have the same capacitance value, and the traces between the first terminals of the first capacitor C1 and the second capacitor C2 and the common node 21 are symmetrically distributed. It should be noted that when the first capacitor C1 and the second capacitor C2 have the same capacitance value, the traces between the first terminals of the first capacitor C1 and the second capacitor C2 and the common node 21 can be symmetrically distributed, which can ensure that the difference in parasitic inductance between the first capacitor C1 and the common node 21, and between the second capacitor C2 and the common node 21, is less than or equal to a preset inductance value.

[0034] For example, such as Figure 6 As shown, the first capacitor C1 and the second capacitor C2 have the same capacitance value. The traces between the first terminals of the first capacitor C1 and the second capacitor C2 and the common node 21 are symmetrically distributed. Symmetrical traces can generate similar electromagnetic field distributions and parasitic parameters. For example, symmetrical distribution can make the parasitic inductances generated by the two traces similar in magnitude and direction, thereby reducing the adverse effects on the circuit caused by differences in parasitic inductance of the traces. At the same time, the electromagnetic interference coupling of symmetrically distributed traces is also more similar during current transmission, which can reduce the impact of electromagnetic interference on the notch filter circuit 100.

[0035] In one embodiment, the capacitance of the first capacitor C1 is greater than the capacitance of the second capacitor C2, and the first trace length between the first end of the first capacitor C1 and the common node 21 is less than the second trace length between the first end of the second capacitor C2 and the common node 21.

[0036] It should be noted that when the capacitance of the first capacitor C1 is greater than the capacitance of the second capacitor C2, the first trace length between the first end of the first capacitor C1 and the common node 21 is less than the second trace length between the first end of the second capacitor C2 and the common node 21. This ensures that the parasitic inductance difference between the first capacitor C1 and the common node 21, and between the second capacitor C2 and the common node 21, is less than or equal to the preset inductance value.

[0037] For example, such as Figure 7 As shown, the capacitance of the first capacitor C1 is greater than that of the second capacitor C2, and the first trace length LC between the first terminal of the first capacitor C1 and the common node 21 is less than the second trace length LD between the first terminal of the second capacitor C2 and the common node 21. Reasonable capacitance values ​​and trace length settings can control the parasitic inductance difference generated by the traces between the first capacitor C1, the second capacitor C2, and the common node 21, which helps improve the harmonic suppression capability of the notch filter circuit 100. This allows the circuit to better suppress the second and third harmonics at specific frequencies, improving the harmonic suppression degree of the notch filter circuit 100 and reducing the deterioration of the resonant point.

[0038] Furthermore, by varying the capacitance values ​​of the first capacitor C1 and the second capacitor C2, as well as the differences in trace lengths, the resonant frequency of the notch filter circuit 100 can be adjusted more precisely. For example, the first capacitor C1 provides basic energy storage and a stable resonant foundation, while the second capacitor C2, with its small capacitance and large parasitic inductance, fine-tunes the resonant frequency, enabling the notch filter circuit 100 to operate more accurately at the desired resonant frequency and improving its resonant accuracy.

[0039] Understandably, the capacitance values ​​of the first capacitor C1 and the second capacitor C2 can be flexibly adjusted according to actual conditions. For example, the capacitance values ​​of the first capacitor C1 and the second capacitor C2 can be adjusted according to layout requirements. The distance between the first terminals of the first capacitor C1 and the second capacitor C2 and the common node 21 can also be flexibly adjusted. For example, this distance can be set based on the capacitance values ​​of the first capacitor C1 and the second capacitor C2. That is to say, if the capacitance values ​​of the first capacitor C1 and the second capacitor C2 are the same, the distance between the first terminals of the first capacitor C1 and the second capacitor C2 and the common node 21 should be close to avoid excessive distance leading to excessive inductance difference, and large difference in resonant points causing a bulge between the two resonant points, resulting in harmonic deterioration. Furthermore, in this embodiment, when setting the first capacitor C1 and the second capacitor C2, the distance between the first end of the first capacitor C1 and the second capacitor C2 and the common node 21 can be set according to requirements. The corresponding capacitance values ​​of the first capacitor C1 and the second capacitor C2 are also set according to requirements. In order to keep the resonant frequency points close when setting the distance values ​​and corresponding capacitance values, in this embodiment, a larger capacitor can be connected to a smaller inductor. That is, the shorter the distance, the larger the inductor needs to be connected to, i.e., the longer the distance.

[0040] In one embodiment, such as Figure 8 As shown, the input terminal RFin of the notch filter circuit 100 is used to connect to the power amplifier chip 20, and the distance between the common node 21 and the power amplifier chip 20 is greater than or equal to 300µm. It should be noted that the power amplifier chip 20 can be disposed on the substrate 110 or on other substrates (not shown in the figure). The first inductor L1 and the second inductor L2 are formed by traces on the substrate 110, and the distance between the common node 21 and the power amplifier chip 20 can refer to the shortest distance. By setting the distance between the common node 21 and the power amplifier chip 20 to be greater than or equal to 300µm, the impact of electromagnetic interference from the power amplifier chip 20 on the notch filter circuit 100 can be effectively reduced, improving the harmonic suppression, selectivity, and other performance indicators of the notch filter circuit 100, and ensuring the signal processing quality of the notch filter circuit 100.

[0041] For example, such as Figure 8 As shown, the distance between the common node 21 and the power amplifier chip 20 is between 300-400µm. Alternatively, the distance between the first capacitor C1, the second capacitor C2 and the power amplifier chip 20 is between 300-400µm, to avoid electromagnetic interference from the power amplifier chip 20 to the first capacitor C1 and the second capacitor C2, thereby improving the reliability of the notch filter circuit 100.

[0042] In one embodiment, the trace between the first end of the first capacitor C1 and the common node 21 is called the first trace, and the trace between the first end of the second capacitor C2 and the common node 21 is called the second trace. The first trace and the second trace are located in the same metal layer of the substrate 110.

[0043] It should be noted that the first and second traces are located on the same metal layer, ensuring consistency in electrical characteristics and parasitic parameters. This allows the first capacitor C1 and the second capacitor C2 to operate more stably in the notch filter circuit 100, improving the filtering effect and selectivity of the notch filter circuit 100 and reducing performance fluctuations caused by trace differences. Simultaneously, the trace layout on the same metal layer helps reduce the impact of electromagnetic interference, improves the electromagnetic compatibility of the notch filter circuit 100, and enhances its resistance to external electromagnetic interference.

[0044] In one embodiment, the trace between the first end of the first capacitor C1 and the common node 21 is called the first trace, and the trace between the first end of the second capacitor C2 and the common node 21 is called the second trace. The first trace and the second trace are located in different metal layers of the substrate 110.

[0045] It should be noted that due to the electromagnetic isolation between different metal layers, electromagnetic interference between the first and second traces can be greatly reduced, enabling the first capacitor C1 and the second capacitor C2 to operate more stably. This reduces problems such as decreased harmonic suppression capability and signal distortion caused by electromagnetic interference, thus improving the overall stability and reliability of the notch filter circuit 100. Simultaneously, utilizing the wiring space of different metal layers allows for more flexible planning of the first and second traces, avoiding design limitations caused by trace crossings and overlaps. This makes the layout of the notch filter circuit 100 more compact and rational, accommodating more components and complex connections, improving the space utilization of the substrate 110, and also facilitating subsequent expansion and modification of the notch filter circuit 100.

[0046] In one embodiment, the trace between the first end of the first capacitor C1 and the common node 21 is called the first trace, and the trace between the first end of the second capacitor C2 and the common node 21 is called the second trace. A portion of the first trace and the second trace are located in the same metal layer of the substrate 110.

[0047] It should be noted that a portion of the traces in the first trace and the second trace reside on the same metal layer, ensuring the consistency of the electrical characteristics of this portion of the traces. This makes the operation of the first capacitor C1 and the second capacitor C2 more stable in the notch filter circuit 100. While avoiding excessive interference, this improves the response of the notch filter circuit 100 to specific frequency signals, enhancing its filtering effect and selectivity. Simultaneously, the design of a portion of the traces sharing the same metal layer reduces the crossing and overlap between traces, improving the space utilization of the substrate 110, providing layout space for more components and connections, and reducing design difficulty and cost.

[0048] In one embodiment, the trace between the first end of the first capacitor C1 and the common node 21 is called the first trace, and the trace between the first end of the second capacitor C2 and the common node 21 is called the second trace. A portion of the first trace and a portion of the second trace are located in the same metal layer of the substrate 110.

[0049] It should be noted that a portion of the first trace and a portion of the second trace are located on the same metal layer, which brings about synergistic electrical characteristics, making the resonant characteristics of the notch filter circuit 100 more stable. The first capacitor C1 and the second capacitor C2 can process specific frequency signals more precisely, improving the filtering effect and selectivity of the notch filter circuit 100, reducing harmonic interference, and ensuring the quality of the output signal. At the same time, it can improve the space utilization of the substrate 110, making the notch filter circuit 100 design more compact, which helps to achieve the integration and miniaturization of the notch filter circuit 100, meeting the stringent size and performance requirements of modern electronic devices.

[0050] The notch filter circuit 100 of the above embodiment includes a substrate 110 and a first inductor L1, a second inductor L2, a first capacitor C1, and a second capacitor C2 disposed on the substrate 110. The first terminals of the first capacitor C1 and the second capacitor C2 are connected to the first inductor L1 through a common node 21, and the second terminals of the first capacitor C1 and the second capacitor C2 are connected to the second inductor L2. The parasitic inductance difference generated by the traces between the first capacitor C1, the second capacitor C2, and the common node 21 is less than or equal to a preset inductance value, which is less than or equal to 0.4nH. By connecting the common node 21, the parasitic inductance generated by the traces between the first capacitor C1, the second capacitor C2 and the first inductor L1 is kept basically consistent, thereby reducing the difference in trace inductance between the two capacitors. This parasitic inductance difference is less than or equal to a preset inductance value (e.g., 0.4nH), which can effectively reduce or eliminate the second and third harmonics in the output signal of the notch filter circuit 100. This can improve the resonance effect of the notch filter circuit 100 for the output signal frequency, thus effectively improving the harmonic suppression of the notch filter circuit 100 using two capacitors, reducing the degree of deterioration of the resonance point, and improving the output signal quality.

[0051] Please refer to Figure 9 , Figure 9 A circuit diagram of another notch filter circuit provided for an embodiment of this application.

[0052] like Figure 9 As shown, the notch filter circuit 200 includes a substrate 210 and a first inductor L1, a second inductor L2, a first capacitor C1 and a second capacitor C2 disposed on the substrate 210.

[0053] In this circuit, the first end of the first inductor L1 serves as the input terminal RFin of the notch filter circuit 200, and the second end of the first inductor L1 serves as the output terminal RFout of the notch filter circuit 200. The first ends of the first capacitor C1 and the second capacitor C2 are connected to the second end of the first inductor L1 through a common node 21. The parasitic inductance generated by the traces between the first ends of the first capacitor C1 and the second capacitor C2 and the common node 21 is the same, and the projections of the first capacitor C1 and the second capacitor C2 onto the plane axis of the substrate 210 at least partially overlap. The second inductor L2 is connected to the second ends of the first capacitor C1 and the second capacitor C2.

[0054] It should be noted that by setting a common node 21, the parasitic inductances of the traces corresponding to the first capacitor C1 and the second capacitor C2 are the same. That is, the difference in parasitic inductance between the traces of the first capacitor C1 and the common node 21, and between the second capacitor C2 and the common node 21, is zero or close to zero. This allows the effects on the resonant frequency to cancel each other out or synergize, thereby effectively increasing the suppression degree of the notch filter circuit 100 for the second and third harmonics, improving the harmonic suppression degree of the notch filter circuit 100, and reducing the deterioration of the resonant point. The projections of the first capacitor C1 and the second capacitor C2 onto the plane axis (including the horizontal or vertical axis) of the substrate 210 at least partially overlap. The positions of the first capacitor C1 and the second capacitor C2 on the substrate 210 can be close, which facilitates the setting of the position of the common node 21, thereby facilitating the control of the trace lengths between the first capacitor C1 and the common node 21, and between the second capacitor C2 and the common node 21.

[0055] It should be noted that the identical parasitic inductance of the traces ensures the balanced electrical characteristics of the first capacitor C1 and the second capacitor C2 in the notch filter circuit 200. This makes the resonant characteristics of the notch filter circuit 200 more stable, reduces the resonant frequency shift and performance fluctuations of the notch filter circuit 200 caused by differences in parasitic inductance, and improves the reliability and stability of the notch filter circuit 200. The at least partial overlap of the projections of the first capacitor C1 and the second capacitor C2 enhances the electromagnetic coupling between the capacitors, enabling the notch filter circuit 200 to achieve more complex filtering characteristics. Through the synergistic work of the two capacitors, harmonic signals (such as second and third harmonics) can be suppressed more effectively, improving the transmission capability of useful signals, thereby optimizing the filtering effect of the notch filter circuit 200, improving the harmonic suppression degree and reducing the deterioration of the resonant point, and improving the quality of the output signal.

[0056] In one embodiment, the first capacitor C1 and the second capacitor C2 are arranged side by side in the horizontal or vertical direction of the substrate 210. For example... Figure 9 As shown, the first capacitor C1 and the second capacitor C2 can be arranged side by side along the horizontal axis (X-axis) of the substrate 210. In other examples, the first capacitor C1 and the second capacitor C2 can also be arranged side by side along the vertical axis (Y-axis) of the substrate 210.

[0057] It should be noted that the electromagnetic coupling generated by the side-by-side arrangement of the first capacitor C1 and the second capacitor C2 along the horizontal or vertical axis can optimize the resonant characteristics of the notch filter circuit 200. For example, by adjusting the relative position and coupling degree between the capacitors, the notch filter circuit 200 can operate more accurately at the preset resonant frequency, improving the filtering effect and selectivity for specific frequency signals, reducing harmonic interference, and ensuring the quality of the output signal. Simultaneously, the signal delay and distortion during transmission are smaller, allowing for more accurate transmission to other parts of the notch filter circuit 200, ensuring its normal operation.

[0058] For example, such as Figure 9 As shown, the common node 21 is positioned between the first capacitor C1 and the second capacitor C2, which are arranged side-by-side. It should be noted that the centrally located common node 21 makes the layout of the notch filter circuit 200 more symmetrical. Symmetrical connections and signal transmission allow current and signal to pass evenly through the two capacitors, avoiding performance instability issues caused by uneven current distribution or signal transmission differences. Simultaneously, this layout makes more efficient use of the substrate 210 space, resulting in a more compact and orderly arrangement of capacitors and other components of the notch filter circuit 200. Within the limited area of ​​the substrate 210, more components and connections can be accommodated, improving the space utilization of the substrate 210.

[0059] In one embodiment, the first inductor L1 includes a first trace, which is C-shaped or arc-shaped. It should be noted that when the first trace is C-shaped or arc-shaped, the current flowing through the trace will generate a magnetic field surrounding it. This shape of the trace allows the magnetic field to be more concentrated within the area enclosed by the trace, reducing the diffusion of the magnetic field into the surrounding space. This helps reduce the impact of electromagnetic interference generated by the first inductor L1 on other components of the notch filter circuit 200, improving the electromagnetic compatibility of the notch filter circuit 200. Simultaneously, by rationally designing the dimensions of the C-shape or arc (such as radius and arc length), the inductance value can be precisely adjusted, thereby adjusting the resonant frequency of the notch filter circuit 200, enabling the notch filter circuit 200 to operate more accurately at the preset resonant frequency and improving the filtering effect on signals of a specific frequency.

[0060] The notch filter circuit 200 of the above embodiment includes a substrate 210 and a first inductor L1, a second inductor L2, a first capacitor C1, and a second capacitor C2 disposed on the substrate 210. The first terminals of the first capacitor C1 and the second capacitor C2 are connected to the first inductor L1 through a common node 21, and the second terminals of the first capacitor C1 and the second capacitor C2 are connected to the second inductor L2. The parasitic inductance generated by the traces between the first capacitor C1, the second capacitor C2, and the common node 21 is the same, and the projections of the first capacitor C1 and the second capacitor C2 in the plane axial direction of the substrate 210 at least partially overlap. By connecting the common node 21, the parasitic inductance generated by the traces between the first capacitor C1, the second capacitor C2 and the first inductor L1 is the same, thereby reducing the difference in trace inductance between the two capacitors. This can effectively reduce or eliminate the second and third harmonics in the output signal of the notch filter circuit 200, thereby improving the resonance effect of the notch filter circuit 200 at the output signal frequency. Therefore, it can effectively improve the harmonic suppression degree of the notch filter circuit 200 using two capacitors, reduce the degree of deterioration of the resonance point, and improve the output signal quality.

[0061] Please refer to Figure 10 , Figure 10 A circuit diagram of yet another notch filter circuit provided for an embodiment of this application.

[0062] like Figure 10 As shown, the notch filter circuit 300 includes a substrate 310 and a first inductor L1, a second inductor L2, a first capacitor C1 and a second capacitor C2 disposed on the substrate 310.

[0063] In this circuit, the first end of the first inductor L1 serves as the input terminal RFin of the notch filter circuit 300, and the second end of the first inductor L1 serves as the output terminal RFout of the notch filter circuit 300. The first ends of the first capacitor C1 and the second capacitor C2 are connected to the second end of the first inductor L1 through a common node 21. The trace lengths between the first ends of the first capacitor C1 and the second capacitor C2 and the common node 21 are the same, and the projections of the first capacitor C1 and the second capacitor C2 onto the plane axis of the substrate 310 at least partially overlap. The second inductor L2 is connected to the second ends of the first capacitor C1 and the second capacitor C2.

[0064] It should be noted that the trace lengths between the first terminals of the first capacitor C1 and the second capacitor C2 and the common node 21 are the same. This ensures the consistency of the parasitic parameters of the first capacitor C1 and the second capacitor C2, making the resonant characteristics of the notch filter circuit 300 more stable, improving the filtering effect and selectivity of the notch filter circuit 300, reducing harmonic interference, and ensuring the quality of the output signal. At the same time, this design method of identical trace lengths and overlapping capacitor projections provides more flexibility in the design of the notch filter circuit 300. Designers can adjust the trace lengths and the degree of capacitor projection overlap according to the specific requirements of the notch filter circuit 300 to control parasitic parameters and electromagnetic coupling, thereby optimizing the performance of the notch filter circuit 300 and meeting the requirements of different application scenarios. For example, it can effectively improve the harmonic suppression of the notch filter circuit 300, reduce the deterioration of the resonant point, and improve the quality of the output signal.

[0065] In one embodiment, such as Figure 10 As shown, the first capacitor C1 and the second capacitor C2 are symmetrically arranged with respect to the center line of the common node 21. It should be noted that the symmetrical arrangement of the first capacitor C1 and the second capacitor C2 with respect to the center line of the common node 21 makes the resonant characteristics of the notch filter circuit 300 more stable. The two capacitors can work together to ensure that the notch filter circuit 300 operates accurately at the preset resonant frequency, reducing the resonant frequency offset and thus improving the reliability of the notch filter circuit 300.

[0066] Meanwhile, the symmetrical arrangement of the first capacitor C1 and the second capacitor C2 relative to the center line of the common node 21 reduces electromagnetic interference, giving the notch filter circuit 300 stronger anti-interference capabilities. In complex electromagnetic environments, the notch filter circuit 300 can better resist external interference, ensuring stable signal transmission and improving reliability and stability. The symmetrical arrangement of the first capacitor C1 and the second capacitor C2 relative to the center line of the common node 21 makes the layout of the notch filter circuit 300 more symmetrical and regular, simplifying the design process. Designers can more easily plan and lay out the notch filter circuit 300, reducing design difficulty and the possibility of errors.

[0067] The notch filter circuit 300 of the above embodiment includes a substrate 310 and a first inductor L1, a second inductor L2, a first capacitor C1, and a second capacitor C2 disposed on the substrate 310. The first terminals of the first capacitor C1 and the second capacitor C2 are connected to the first inductor L1 through a common node 21, and the second terminals of the first capacitor C1 and the second capacitor C2 are connected to the second inductor L2. The trace lengths between the first capacitor C1, the second capacitor C2, and the common node 21 are the same, and the projections of the first capacitor C1 and the second capacitor C2 in the plane axial direction of the substrate 310 at least partially overlap. By using the connection method of the common node 21, the parasitic inductance generated by the traces between the first capacitor C1, the second capacitor C2 and the first inductor L1 is kept basically consistent, thereby reducing the difference in trace inductance between the two capacitors. This parasitic inductance difference is less than or equal to the preset inductance value (e.g., 0.4nH), which can effectively reduce or eliminate the second and third harmonics in the output signal of the notch filter circuit 300. This can improve the resonance effect of the notch filter circuit 300 for the output signal frequency, thus effectively improving the harmonic suppression degree of the notch filter circuit 300 using two capacitors, reducing the degree of deterioration of the resonance point, and improving the output signal quality.

[0068] Please refer to Figure 11 , Figure 11 A circuit diagram of an impedance matching circuit provided for an embodiment of this application.

[0069] like Figure 11 As shown, the impedance matching circuit 400 includes a notch filter circuit 410. The notch filter circuit 410 can be the notch filter circuit 100, notch filter circuit 200, or notch filter circuit 300 described in the above embodiments.

[0070] In one embodiment, the impedance matching circuit 400 includes an LCCL circuit or an LCLCC circuit. The LCCL circuit mainly consists of two inductors (L) and two capacitors (C), such as... Figure 12 As shown, an LCLCC circuit can contain three inductors and two capacitors. Compared to an LCCL circuit, it has one more inductor.

[0071] It should be noted that the impedance matching circuit 400 can be used in low-band, medium-band, and high-band applications. When the impedance matching circuit 400 is a CLLC circuit, the parallel capacitor value is usually small, and the notch filter circuit 410, which includes two capacitors, is usually unnecessary. Through the impedance matching circuit 400, signals can be transmitted more efficiently, reducing power loss. That is, with the same input power, the load can obtain more useful power, improving signal transmission efficiency. This is of great significance for applications with high signal power requirements, such as the transmitting and receiving circuits in wireless communication.

[0072] For example, the impedance matching circuit 400 can achieve good impedance matching in different frequency bands (LB, MB, HB) by adjusting the component parameters in the circuit. In the low-frequency band, the low-frequency characteristics of inductors and capacitors can be utilized to compensate for impedance differences in signal transmission by adjusting the component values. In the mid-frequency band, efficient impedance matching can be achieved while ensuring signal bandwidth. In the high-frequency band, precise impedance matching can be achieved through precise component design and layout. For example, when the impedance matching circuit 400 is used for HB, the circuit structure is an LCCL circuit, with a series matching inductor Lse of approximately 0.35nH, a parallel matching capacitor Csh of approximately 6pF, a series matching capacitor Cse of 2.5pF, and a parallel matching inductor Lsh of 1.5nH.

[0073] Please refer to Figure 13 and Figure 14 , Figure 13 and Figure 14 This is a schematic block diagram of a radio frequency front-end module provided in an embodiment of this application.

[0074] like Figure 13 As shown, the RF front-end module 500 includes a power amplifier chip 510 and a notch filter circuit 520 as described in the above embodiment, wherein the power amplifier chip 510 is connected to the notch filter circuit 520.

[0075] like Figure 14 As shown, the RF front-end module 500 includes a power amplifier chip 510 and an impedance matching circuit 530 as described in the above embodiment, wherein the power amplifier chip 510 is connected to the impedance matching circuit 530.

[0076] In this embodiment, the power amplifier chip 510 can be the power amplifier chip 20 described above, and the notch filter circuit 520 can be the notch filter circuit 100, notch filter circuit 200, or notch filter circuit 300 described above. The impedance matching circuit 530 can be the impedance matching circuit 400 described above.

[0077] It is understood that the beneficial effects that the RF front-end module provided in this application embodiment can achieve can be referred to the beneficial effects of the notch filter circuit or impedance matching circuit in the corresponding embodiment provided above, and will not be repeated here.

[0078] This embodiment provides a radio frequency (RF) front-end module. An RF front-end module is a component that integrates two or more discrete devices, such as RF switches, low-noise amplifiers, filters, duplexers, power amplifiers, and transformers, into a single independent module. This improves the integration and hardware performance of the RF front-end module and reduces its size. Specifically, the RF front-end module can be applied to 4G and 5G communication devices such as smartphones, tablets, and smartwatches.

[0079] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application.

Claims

1. A notch filter circuit, characterized in that, The notch filter circuit includes a substrate and a first inductor, a second inductor, a first capacitor, and a second capacitor disposed on the substrate. The first end of the first inductor serves as the input terminal of the notch filter circuit, and the second end of the first inductor serves as the output terminal of the notch filter circuit. The first terminals of the first capacitor and the second capacitor are connected to the second terminal of the first inductor through a common node. The parasitic inductance difference generated by the traces between the first terminals of the first capacitor and the second capacitor and the common node is less than or equal to a preset inductance value, which is less than or equal to 0.4nH. The second inductor is connected to the second terminal of the first capacitor and the second capacitor.

2. The notch filter circuit according to claim 1, characterized in that, The first capacitor and the second capacitor have the same capacitance value, and the difference in trace length between the first terminal of the first capacitor and the second capacitor and the common node is less than or equal to a preset length.

3. The notch filter circuit according to claim 1, characterized in that, The first capacitor and the second capacitor have the same capacitance value, and the traces between the first terminals of the first capacitor and the second capacitor and the common node are symmetrically distributed.

4. The notch filter circuit according to claim 1, characterized in that, The capacitance of the first capacitor is greater than that of the second capacitor, and the first trace length between the first terminal of the first capacitor and the common node is less than the second trace length between the first terminal of the second capacitor and the common node.

5. The notch filter circuit according to claim 1, characterized in that, The difference between the parasitic inductances corresponding to the first capacitor and the second capacitor is in the range of 0-0.3nH.

6. The notch filter circuit according to claim 1, characterized in that, The input terminal of the notch filter circuit is used to connect to the power amplifier chip, and the distance between the common node and the power amplifier chip is greater than or equal to 300um.

7. The notch filter circuit according to claim 6, characterized in that, The distance between the common node and the power amplifier chip is between 300-400um.

8. The notch filter circuit according to claim 1, characterized in that, The trace between the first terminal of the first capacitor and the common node is designated as the first trace, and the trace between the first terminal of the second capacitor and the common node is designated as the second trace; wherein: The first trace and the second trace are located in the same metal layer of the substrate; or... The first trace and the second trace are located in different metal layers of the substrate; or... A portion of the first trace and the second trace are located in the same metal layer of the substrate; or... A portion of the first trace and a portion of the second trace are located in the same metal layer of the substrate.

9. A notch filter circuit, characterized in that, The notch filter circuit includes a substrate and a first inductor, a second inductor, a first capacitor, and a second capacitor disposed on the substrate. The first end of the first inductor serves as the input terminal of the notch filter circuit, and the second end of the first inductor serves as the output terminal of the notch filter circuit. The first terminals of the first capacitor and the second capacitor are connected to the second terminal of the first inductor through a common node. The parasitic inductance generated by the traces between the first terminals of the first capacitor and the second capacitor and the common node is the same, and the projections of the first capacitor and the second capacitor in the plane axis direction of the substrate at least partially overlap. The second inductor is connected to the second terminal of the first capacitor and the second capacitor.

10. The notch filter circuit according to claim 9, characterized in that, The first capacitor and the second capacitor are arranged side by side in the horizontal or vertical direction of the substrate.

11. The notch filter circuit according to claim 10, characterized in that, The common node is located in the middle of the first capacitor and the second capacitor, which are side by side.

12. The notch filter circuit according to claim 9, characterized in that, The first inductor includes a first trace, which is C-shaped or arc-shaped.

13. A notch filter circuit, characterized in that, The notch filter circuit includes a substrate and a first inductor, a second inductor, a first capacitor, and a second capacitor disposed on the substrate. The first end of the first inductor serves as the input terminal of the notch filter circuit, and the second end of the first inductor serves as the output terminal of the notch filter circuit. The first terminals of the first capacitor and the second capacitor are connected to the second terminal of the first inductor through a common node, wherein the trace lengths between the first terminals of the first capacitor and the second capacitor and the common node are the same, and the projections of the first capacitor and the second capacitor in the plane axis direction of the substrate at least partially overlap. The second inductor is connected to the second terminal of the first capacitor and the second capacitor.

14. The notch filter circuit according to claim 13, characterized in that, The first capacitor and the second capacitor are symmetrically arranged with respect to the center line of the common node.

15. An impedance matching circuit, characterized in that, Includes the notch filter circuit as described in any one of claims 1-12.

16. The impedance matching circuit according to claim 15, characterized in that, The impedance matching circuit includes an LCCL circuit or an LCLCC circuit.

17. A radio frequency front-end module, characterized in that, include: The notch filter circuit as described in any one of claims 1-14 or the impedance matching circuit as described in any one of claims 15-16; The power amplifier chip is connected to the notch filter circuit or the impedance matching circuit.

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