Radio frequency equipment second harmonic suppression circuit based on band-pass filtering

Abstract

The utility model relates to the technical field of harmonic suppression, in particular to a radio frequency equipment secondary harmonic suppression circuit based on band-pass filtering. The suppression circuit comprises: a T-type circuit comprising a first inductor (L1), a second inductor (L2) and a bridging capacitor (C1); the LC circuit comprises a third inductor (L3) and a capacitor (C2); one end of a first inductor (L1) of the T-type circuit is connected to an input end, the other end of the first inductor (L1) is connected to one end of a second inductor (L2) and one end of a bridging capacitor (C1), the other end of the second inductor (L2) is connected to an output end, and the other end of the bridging capacitor (C1) is connected to the ground. According to the utility model, through the combination of the T-type circuit and the LC circuit, the problems in the prior art are effectively solved. Specifically, by optimizing element layout and adjusting parameters, efficient impedance matching is realized, and energy loss and reflection interference in signal transmission are remarkably reduced.

Description

Technical Field

[0001] This utility model relates to the field of harmonic suppression technology, specifically a second harmonic suppression circuit for radio frequency devices based on bandpass filtering. Background Technology

[0002] In high-power devices, traditional LC resonant filter circuits have some significant limitations. First, the attenuation effect of LC resonant filters is limited, failing to achieve deep suppression within a specific frequency range, allowing some interference signals to pass through and affecting signal purity. Second, LC resonant filter circuits have poor impedance matching performance, making it difficult to achieve good matching with circuit systems of different characteristics. This not only reduces signal transmission efficiency but may also lead to output power loss. Furthermore, in high-power applications, good impedance matching also means reducing power losses related to hot spots caused by reflections and voltage standing wave ratio (VSWR), which helps protect transmission lines and equipment from damage. Utility Model Content

[0003] This invention addresses the technical problems existing in the prior art by providing a second harmonic suppression circuit for radio frequency equipment based on bandpass filtering to effectively suppress signals of specific frequencies, while improving impedance matching performance and ensuring high efficiency of signal transmission and stability of output power.

[0004] The technical solution of this utility model to solve the above-mentioned technical problems is as follows:

[0005] A second harmonic suppression circuit for radio frequency devices based on bandpass filtering is provided, the suppression circuit comprising:

[0006] The T-type circuit includes a first inductor L1, a second inductor L2, and a bridging capacitor C1;

[0007] The LC circuit includes a third inductor L3 and a capacitor C2;

[0008] One end of the first inductor L1 in the T-type circuit is connected to the input terminal, and the other end is connected to one end of the second inductor L2 and one end of the bridging capacitor C1. The other end of the second inductor L2 is connected to the output terminal, and the other end of the bridging capacitor C1 is connected to ground.

[0009] One end of the third inductor L3 is connected to the connection point of the second inductor L2 and the bridging capacitor C1, and the other end is connected to one end of the capacitor C2. The other end of the capacitor C2 is connected to ground.

[0010] The combination of the T-type circuit and the LC circuit is used to suppress the second harmonic in the 2.4G frequency band, while reducing energy loss and reflection interference in signal transmission.

[0011] Furthermore, the inductance of the first inductor L1 is 2nH; the inductance of the second inductor L2 is 3.7nH; the capacitance of the bridging capacitor C1 is 2pF; the inductance of the third inductor L3 is 1nH; the capacitance of the capacitor C2 is 1.1pF; the distance between the first inductor L1 and the second inductor L2 is 0.5mm to 2mm; the length of the connection line between the bridging capacitor C1 and ground is 0.5mm to 2mm; and the distance between the third inductor L3 and the capacitor C2 is 0.5mm to 2mm. This achieves efficient impedance matching, reducing energy loss and reflection interference during signal transmission.

[0012] Furthermore, the two-terminal impedance of the suppression circuit is 50Ω, which is suitable for the needs of Bluetooth and Wi-Fi radio frequency circuits.

[0013] Furthermore, the suppression circuit has an insertion loss of less than -0.03dB in the 2.4G band and an attenuation of more than -67.129dB in the 4.8G band, to ensure efficient signal transmission and stable output power.

[0014] Furthermore, the Smith chart impedance values ​​of the suppression circuit at the 2.465 GHz frequency point are Z0 (0.973-j0.041) for S11 and Z0 (0.002-j0.376) for S21.

[0015] The beneficial effects of this utility model are:

[0016] This invention effectively solves the problems existing in the prior art by combining a T-type circuit and an LC circuit. Specifically, by optimizing the component layout and parameter adjustment, this invention achieves efficient impedance matching, significantly reducing energy loss and reflection interference in signal transmission. The reasonable layout of the first inductor L1, the second inductor L2, and the bridging capacitor C1 in the T-type circuit, and the precise selection of the third inductor L3 and capacitor C2 in the LC circuit, ensure effective suppression of second harmonics in the 2.4 GHz band. Furthermore, this circuit design results in an insertion loss of less than -0.03 dB in the 2.4 GHz band and an attenuation of greater than -67.129 dB in the 4.8 GHz band, thus guaranteeing high efficiency in signal transmission and stability of output power. The circuit's two-terminal impedance is close to 50 Ω, which can adapt to the needs of most Bluetooth and Wi-Fi RF circuits, improving the overall system performance and signal quality. At the same time, the circuit structure is simple, easy to implement, and suitable for large-scale production and application, further enhancing its practicality and economy. Through these technical means, this utility model not only overcomes the limitations of traditional LC circuits and commonly used π-type LC circuits in high-power applications, but also improves the reliability and adaptability of the circuit, providing an effective second harmonic suppression solution for high-power radio frequency equipment.

[0017] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the following describes the preferred embodiments of the present invention in detail with reference to the accompanying drawings. Attached Figure Description

[0018] Figure 1 This is the circuit diagram of this utility model;

[0019] Figure 2 This is the LC S21 curve diagram of this utility model;

[0020] Figure 3 This is the Smith chart of this utility model. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this utility model and are not intended to limit this utility model.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0023] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0024] The following disclosure provides numerous different embodiments or examples for implementing various structures of the present invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention; however, those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0025] The present invention provides the following preferred embodiments:

[0026] To address the problem of insufficient second harmonic suppression in high-power radio frequency (RF) devices, this embodiment discloses a second harmonic suppression circuit for RF devices based on bandpass filtering. Specifically, this embodiment achieves effective suppression of second harmonics in the 2.4 GHz band by combining a T-type circuit and an LC circuit, while reducing energy loss and reflection interference during signal transmission.

[0027] like Figure 1 As shown, in this embodiment, the T-shaped circuit consists of a first inductor L1, a second inductor L2, and a bridging capacitor C1. One end of the first inductor L1 is connected to the input terminal, and the other end is connected to one end of the second inductor L2 and one end of the bridging capacitor C1. The other end of the second inductor L2 is connected to the output terminal, while the other end of the bridging capacitor C1 is connected to ground. This layout ensures that the second harmonic is effectively suppressed during signal transmission, while reducing energy loss and reflection interference.

[0028] Furthermore, the inductance value of the first inductor L1 is chosen to be 2nH, the inductance value of the second inductor L2 is chosen to be 3.7nH, and the capacitance value of the bridging capacitor C1 is chosen to be 2pF. These parameters were selected through precise calculations and experimental verification to ensure that the circuit exhibits excellent resonant characteristics and impedance matching performance within the target frequency range. It is important to understand that the specific values ​​of these components not only affect the resonant characteristics of the circuit but also directly influence its suppression effect on the second harmonic.

[0029] In this embodiment, the LC circuit consists of a third inductor L3 and a capacitor C2. One end of the third inductor L3 is connected to the connection point of the second inductor L2 and the bridging capacitor C1 in the T-shaped circuit, and the other end is connected to one end of the capacitor C2; the other end of the capacitor C2 is connected to ground. This layout enables the LC circuit to achieve deep suppression within a specific frequency range, thereby effectively reducing second harmonic interference.

[0030] Furthermore, the inductance value of the third inductor L3 was chosen to be 1nH, and the capacitance value of capacitor C2 was chosen to be 1.1pF. These parameters were also selected through precise calculations and experimental verification to ensure that the circuit exhibits efficient resonant characteristics and good impedance matching performance within the 2.4GHz frequency band. It is understandable that the selection of LC circuit values ​​not only affects its resonant characteristics but also has a significant impact on its attenuation effect in the high-frequency range.

[0031] In this embodiment, the combination of the T-type circuit and the LC circuit achieves efficient impedance matching through a reasonable layout and connection relationship. Specifically, the distance between the first inductor L1 and the second inductor L2 of the T-type circuit is selected between 0.5mm and 2mm, and the length of the connection line between the bridging capacitor C1 and ground is selected between 0.5mm and 2mm. The distance between the third inductor L3 and the capacitor C2 is also selected between 0.5mm and 2mm. These layout parameters are selected to ensure that the circuit can achieve optimal impedance matching and minimal energy loss in practical applications.

[0032] Furthermore, the circuit's two-terminal impedance is close to 50Ω, making it compatible with most Bluetooth and Wi-Fi RF circuits. This not only improves circuit compatibility but also ensures efficient signal transmission and stable output power. It's important to understand that impedance matching is particularly crucial for high-power RF devices, as good impedance matching significantly reduces power losses due to hot spots caused by reflections and voltage standing wave ratio (VSWR), thus protecting transmission lines and equipment from damage.

[0033] Furthermore, to verify the effectiveness of this embodiment, detailed experiments and tests were conducted, such as... Figure 2 and Figure 3 As shown in Table 1:

[0034] Table 1 Parameter Comparison Table

[0035]

[0036] Experimental results show that the circuit exhibits an insertion loss of less than -0.03 dB in the 2.4 GHz band and an attenuation of greater than -67.129 dB in the 4.8 GHz band. These data fully demonstrate the circuit's high suppression capability and excellent impedance matching performance within the target frequency range.

[0037] Furthermore, such as Figure 3As shown, the Smith chart impedance values ​​of this invention at the 2.465 GHz frequency point are Z0 (0.973-j0.041) for S11 and Z0 (0.002-j0.376) for S21. These data indicate that the suppression circuit of this invention exhibits excellent impedance matching performance in practical applications, ensuring high efficiency of signal transmission and stability of output power.

[0038] In this embodiment, the circuit has a simple structure, is easy to implement, and is suitable for large-scale production and application. This design not only improves the reliability and adaptability of the circuit but also reduces production costs, making it more economical. Furthermore, this circuit is suitable for high-power radio frequency devices, effectively suppressing second harmonics and improving the overall system performance and signal quality.

[0039] Furthermore, this embodiment can also consider adding some additional features, such as introducing a temperature compensation circuit, to ensure the stability and reliability of the circuit under different ambient temperatures. The temperature compensation circuit can be implemented using a temperature sensor and an adjustable resistor, automatically adjusting the circuit parameters according to changes in ambient temperature, thereby maintaining the circuit's optimal operating state. It is understood that the introduction of a temperature compensation circuit will further improve the stability and reliability of the circuit, enabling it to maintain good performance in various complex environments.

[0040] The advantage of this embodiment lies in its effective suppression of second harmonics within the 2.4 GHz band through the combination of a T-type circuit and an LC circuit, while simultaneously reducing energy loss and reflection interference during signal transmission. The circuit's impedance at both ends is close to 50Ω, making it compatible with the requirements of most Bluetooth and Wi-Fi RF circuits, thus improving the overall system performance and signal quality. This embodiment not only overcomes the limitations of traditional LC circuits and commonly used π-type LC circuits in high-power applications but also improves the circuit's reliability and adaptability, providing an effective second harmonic suppression solution for high-power RF devices.

[0041] This embodiment solves the problems existing in the prior art, improves the efficiency and stability of signal transmission, and provides a reliable second harmonic suppression scheme for high-power radio frequency equipment.

[0042] The beneficial effects of this utility model are specifically reflected in the fact that the above description is only a preferred embodiment of this utility model and is not intended to limit this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A bandpass filter based second harmonic rejection circuit for radio frequency devices, characterized by, The suppression circuit includes: The T-type circuit includes a first inductor (L1), a second inductor (L2), and a bridging capacitor (C1); An LC circuit, including a third inductor (L3) and a capacitor (C2); One end of the first inductor (L1) of the T-type circuit is connected to the input terminal, and the other end is connected to one end of the second inductor (L2) and one end of the bridging capacitor (C1). The other end of the second inductor (L2) is connected to the output terminal, and the other end of the bridging capacitor (C1) is connected to ground. One end of the third inductor (L3) is connected to the connection point of the second inductor (L2) and the bridging capacitor (C1), and the other end is connected to one end of the capacitor (C2), the other end of the capacitor (C2) is connected to ground; The combination of the T-type circuit and the LC circuit is used to suppress the second harmonic in the 2.4G frequency band, while reducing energy loss and reflection interference in signal transmission.

2. The bandpass-filter-based second harmonic rejection circuit for radio frequency devices of claim 1, wherein, The first inductor (L1) has an inductance of 2nH; the second inductor (L2) has an inductance of 3.7nH; the bridging capacitor (C1) has a capacitance of 2pF; the third inductor (L3) has an inductance of 1nH; the capacitor (C2) has a capacitance of 1.1pF; the distance between the first inductor (L1) and the second inductor (L2) is 0.5mm to 2mm; the length of the connection line between the bridging capacitor (C1) and ground is 0.5mm to 2mm; the distance between the third inductor (L3) and the capacitor (C2) is 0.5mm to 2mm; in order to achieve efficient impedance matching and reduce energy loss and reflection interference in signal transmission.

3. The bandpass-filter-based second harmonic rejection circuit for radio frequency devices of claim 1, wherein, The suppression circuit has a two-terminal impedance of 50Ω, which is suitable for Bluetooth and WIFI radio frequency circuits.

4. The bandpass-filter-based second harmonic rejection circuit for radio frequency devices of claim 1, wherein, The suppression circuit has an insertion loss of less than -0.03dB in the 2.4G band and an attenuation of more than -67.129dB in the 4.8G band, to ensure efficient signal transmission and stable output power.

5. The bandpass-filter-based second harmonic rejection circuit for radio frequency devices of claim 1, wherein, The Smith chart impedance values ​​of the suppression circuit at the 2.465 GHz frequency point are Z0 (0.973-j0.041) for S11 and Z0 (0.002-j0.376) for S21.

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