PCB structure and filter

Abstract

The PCB structure comprises an input port, a transmission line and an output port, the transmission line comprises a first main line, a second main line and a third main line which are sequentially connected in series, one end, far away from the second main line, of the first main line is connected with the input port, and the other end, far away from the third main line, of the third main line is connected with the output port. One end, away from the second main line, of the third main line is connected with the output port; the transmission line further comprises two first branch lines, one ends of the two first branch lines are connected with the joint of the first main line and the second main line and the joint of the second main line and the third main line respectively, and the other ends of the two first branch lines are grounded. The first main circuit, the second main circuit, the third main circuit and the first branch circuit are equal in length. According to the PCB structure, the signal generates frequency resonance in the first branch line so as to effectively filter interference signals, and the signal is reflected at the joint so as to reflect the interference signals back, so that the PCB structure can realize a filtering effect, reflection balance is ensured, and the filtering effect is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit boards, in particular to a PCB structure and a filter. Background Art

[0002] In high-frequency products, filters are often used to improve signal reception. Filters can effectively filter out interference from electrical signals to obtain a signal at the desired specific frequency.

[0003] Existing filters typically include LC filters and PCB hybrid filters. LC filters typically use a component-based structure, while PCB hybrid filters typically consist of a PCB inductor and discrete components. Both component structures occupy significant space on the product's circuit board, resulting in a larger overall product size and higher costs. Utility Model Content

[0004] Based on this, it is necessary to provide a PCB structure and a filter to address the above problems, so as to reduce the occupied layout space and reduce the cost.

[0005] The utility model first provides a PCB structure, including an input port, a transmission line and an output port, wherein: the transmission line includes a first main line, at least one second main line and a third main line connected in series in sequence, an end of the first main line away from the second main line is connected to the input port, and an end of the third main line away from the second main line is connected to the output port; the transmission line also includes at least two first branch lines, one end of at least two of the first branch lines is respectively connected to the connection between the first main line and the second main line and the connection between the second main line and the third main line, and the other end is grounded; the first main line, the second main line, the third main line and the first branch line are equal in length.

[0006] In the above-mentioned PCB structure, when the signal input from the input port passes through the connection between the first main line and the second main line and the connection between the second main line and the third main line, frequency resonance will be generated in the first branch line, so as to effectively filter out the interference signal in the signal, obtain a signal of the required specific frequency, and output the signal of the required specific frequency through the output port; at the same time, when the signal passes through the connection between the first main line and the second main line and the connection between the second main line and the third main line, reflection may also occur to reflect the interference signal back, so that the required specific frequency can be selected, so that the PCB structure can achieve the filtering effect without increasing the device structure, reducing the layout space occupied by the PCB structure on the product circuit board, simplifying the structure, reducing costs, and ensuring the reflection balance of the signal at the connection between the first main line and the second main line and the connection between the second main line and the third main line, so as to improve the filtering effect.

[0007] In one embodiment, the transmission line further includes two second branch lines, one end of each of the two second branch lines is respectively connected to the connection between the first main line and the input port and the connection between the third main line and the output port, and the other end of each of the two second branch lines is grounded.

[0008] With this arrangement, when the signal passes through the connection between the first main line and the input port and the connection between the third main line and the output port, frequency resonance will be generated in the second branch line, thereby further improving the filtering effect and making the required specific frequency signal more in line with the requirements.

[0009] In one embodiment, the length of the second branch line is equal to the length of the first branch line.

[0010] This setting ensures reflection balance and improves filtering effect.

[0011] In one embodiment, the length L4 of the first branch line satisfies: Wherein, F is the resonant frequency of the first branch line, and v is the transmission speed of the signal in the PCB structure.

[0012] With this configuration, the load of the first branch line is purely resistive, which produces a resonance effect, thereby enabling the first branch line to achieve efficient signal transmission and reception at a specific frequency, thereby filtering out the signal of the specific frequency from the first branch line.

[0013] In one embodiment, the resonant frequency of the first branch line is 1G, and the length of the first branch line is 1.5 inches.

[0014] In one embodiment, the impedance value of the second main line is different from the impedance value of the first main line and / or the impedance value of the third main line.

[0015] With this setting, the amplitude and phase of the reflected signal are controlled by adjusting the impedance values ​​of the first main line, the second main line and the third main line, thereby adjusting the reflection ratio and controlling the cutoff bandwidth of the signal, so that the signal has better transmission performance within the required specific frequency range; reducing the reflection ratio can also reduce the loss and distortion of the signal during transmission, thereby improving the transmission quality of the signal.

[0016] In one embodiment, the impedance value of the first main line and the impedance value of the third main line are both equal to the characteristic impedance of the transmission line.

[0017] Such an arrangement enables the signal to be transmitted more stably when passing through the first main line and the third main line, thereby improving the transmission quality of the signal.

[0018] In one embodiment, the width of the second main line is different from the width of the first main line and / or the width of the third main line.

[0019] With this arrangement, the impedance value is adjusted by adjusting the wiring width of the second main line, making the adjustment method simpler.

[0020] In one embodiment, the first branch line is configured as a stub antenna.

[0021] With this setup, there is no need for complex circuit design and debugging. It is only necessary to select a suitable length based on the impedance of the signal source and the characteristic impedance of the transmission line to transmit signals of a specific frequency.

[0022] The utility model also provides a filter, comprising the PCB structure as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 This is a schematic diagram of a PCB structure according to one embodiment of the present invention.

[0025] Reference numerals: 1. input port; 2. transmission line; 21. first main line; 22. second main line; 23. third main line; 24. first branch line; 25. second branch line; 3. output port. DETAILED DESCRIPTION

[0026] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0027] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it may be directly on the other component or there may be a central component. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may be a central component at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in the specification of this application are for illustrative purposes only and do not represent the only implementation method.

[0028] 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 the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0029] In this application, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it can mean that the first feature is directly in contact with the second feature, or the first feature and the second feature are indirectly in contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it can mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is higher in level than the second feature. When a first feature is "below," "below," or "below" a second feature, it can mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is lower in level than the second feature.

[0030] Unless otherwise defined, all technical and scientific terms used in the specification of this application have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in the specification of this application includes any and all combinations of one or more of the relevant listed items.

[0031] In high-frequency products, filters are often required to improve signal reception. Filters effectively filter out interference signals from electrical signals to obtain a signal at a specific desired frequency. This interference signal can be at or near the specific frequency. Existing filters typically include LC filters and PCB hybrid filters. LC filters typically have a component-based structure, while PCB hybrid filters typically consist of a PCB inductor and discrete components. Both component structures occupy a significant amount of layout space on the product's circuit board, resulting in a larger overall product size and higher cost.

[0032] In order to solve the above problems, Figure 1As shown, the present invention first provides a PCB structure to reduce the occupied layout space and lower the cost.

[0033] Specifically, the PCB structure includes an input port 1, a transmission line 2, and an output port 3. The transmission line 2 includes a first main line 21, at least one second main line 22, and a third main line 23 connected in series. The end of the first main line 21 remote from the second main line 22 is connected to the input port 1, and the end of the third main line 23 remote from the second main line 22 is connected to the output port 3. The transmission line 2 also includes at least two first branch lines 24, one end of each of the at least two first branch lines 24 being connected to the connection between the first main line 21 and the second main line 22 and the connection between the second main line 22 and the third main line 23, respectively, and the other end of each being grounded. The first main line 21, the second main line 22, the third main line 23, and the first branch lines 24 are of equal length. The length of the first main line 21 is defined as L1, the length of the second main line 22 is defined as L2, the length of the third main line 23 is defined as L3, and the length of the first branch line 24 is defined as L4, satisfying the following equation: L1 = L2 = L3 = L4.

[0034] Among them, input port 1 is used to connect to the signal source, and output port 3 is used to connect to the load.

[0035] In the PCB structure provided by the embodiment of the present invention, the signal source can input the electrical signal into the PCB structure through the input port 1 and transmit it in the direction of the first main line 21, the second main line 22 and the third main line 23. Since the connection between the first main line 21 and the second main line 22 and the connection between the second main line 22 and the third main line 23 are both connected to the first branch line 24, when the signal passes through the connection between the first main line 21 and the second main line 22 and the connection between the second main line 22 and the third main line 23, a frequency resonance is generated in the first branch line 24, so as to effectively filter out the interference signal in the signal, obtain a signal of a required specific frequency, and output the signal of the required specific frequency to the load through the output port 3; at the same time, since the first main line 21. The impedance values ​​of the second main line 22 and the third main line 23 may not match the impedance value of the signal source or the impedance value of the load. Therefore, the signal may be reflected when passing through the connection between the first main line 21 and the second main line 22 and the connection between the second main line 22 and the third main line 23, so as to reflect the interference signal back, so as to further select the required specific frequency, so that the PCB structure can achieve the filtering effect without increasing the device structure, reduce the layout space occupied by the PCB structure on the product circuit board, have a simple structure, and reduce costs. In addition, L1=L2=L3=L4 can ensure that the signal reflection is balanced at the connection between the first main line 21 and the second main line 22 and the connection between the second main line 22 and the third main line 23, so as to improve the filtering effect.

[0036] like Figure 1 As shown, in the illustrated embodiment, there is one second main line 22, the first main line 21, the second main line 22, and the third main line 23 are connected in series, and there are two first branch lines 24, one end of each of which is connected to the connection between the first main line 21 and the second main line 22, and the connection between the second main line 22 and the third main line 23. This ensures filtering effects while minimizing the layout space occupied by the PCB structure.

[0037] Of course, in other embodiments, the number of second main lines 22 can also be two, three or more, and multiple second main lines 22 are connected in series in sequence. The last two second main lines 22 are respectively connected to the first main line 21 and the third main line 23. The number of first branch lines 24 is one more than the number of second main lines 22, wherein one end of two first branch lines 24 is respectively connected to the connection between the first main line 21 and the second main line 22 and the connection between the second main line 22 and the third main line 23, and one end of the remaining first branch lines 24 is respectively connected to the connection between two adjacent second main lines 22.

[0038] like Figure 1 As shown, the transmission line 2 also includes two second branch lines 25. One end of each of the two second branch lines 25 is connected to the connection between the first main line 21 and the input port 1, and the connection between the third main line 23 and the output port 3, respectively, and the other end of each is grounded. When the signal passes through the connection between the first main line 21 and the input port 1, and the connection between the third main line 23 and the output port 3, frequency resonance is generated in the second branch lines 25. This can filter out interference signals when the signal is first transmitted from the input port 1 to the transmission line 2, and finally when it is transmitted from the transmission line 2 to the output port 3, further improving the filtering effect, so that the obtained signal of the required specific frequency better meets the requirements.

[0039] The length of the second branch line 25 is equal to that of the first branch line 24. The length of the second branch line 25 is defined as L5, satisfying L1 = L2 = L3 = L4 = L5. This ensures balanced reflections at the connection between the first main line 21 and input port 1 and at the connection between the third main line 23 and output port 3, further improving filtering effectiveness.

[0040] In one embodiment, the length L4 of the first branch line 24 satisfies: Wherein, F is the resonant frequency of the first branch line 24, and v is the transmission speed of the signal in the PCB structure. therefore That is, the length L4 of the first branch line 24 is 1 / 4 wavelength λ. Furthermore, the first branch line 24 is an open circuit. A 1 / 4 wavelength open circuit is equivalent to a series resonant circuit. Therefore, the load of the first branch line 24 is purely resistive, which produces a resonance effect. This enables the first branch line 24 to achieve efficient signal transmission and reception at a specific frequency, thereby filtering out the signal of the specific frequency from the first branch line 24. The specific frequency is the frequency of the interference signal to be filtered out. Similarly, the length L5 of the second branch line 25 also satisfies:

[0041] For example, when the interference signal to be filtered out has a frequency of 1 GHz, the resonant frequency of the first branch line 24 is 1 GHz, the signal routing delay within transmission line 2 is 0.25 ns, and the length of the first branch line 24 is 1.5 in. In other words, L1 = L2 = L3 = L4 = L5 = 1.5 in. The routing delay is related to L1, L2, L3, L4, L5, and v.

[0042] Specifically, after determining the frequency of the interference signal to be filtered, the length L1 of the first main line 21, the length L2 of the second main line 22, the length L3 of the third main line 23, the length L4 of the first branch line 24, and the length L5 of the second branch line 25 can be calculated according to the above formula.

[0043] In one embodiment, the impedance of the second main line 22 is different from at least one of the impedance of the first main line 21 and the impedance of the third main line 23. The impedance of the first main line 21 and the impedance of the third main line 23 may be equal or different. When the impedance of the transmission line 2 does not match the impedance of the signal source or the impedance of the load, the signal will be reflected. The amplitude and phase of the reflected signal are related to the amplitude and phase of the incident signal and the impedance of the transmission line 2. Therefore, the amplitude and phase of the reflected signal, and thus the reflection ratio, can be controlled by adjusting the impedance of the first main line 21, the second main line 22, and the third main line 23. Changes in the reflection ratio affect the frequency response characteristics of the signal. Therefore, by adjusting the reflection ratio, the signal cutoff bandwidth can be controlled, resulting in better transmission performance within a specific desired frequency range. Furthermore, reducing the reflection ratio can reduce signal loss and distortion during transmission, thereby improving signal transmission quality. Moreover, by adjusting the impedance values ​​of the first main line 21, the second main line 22 and the third main line 23, the impedance value of the transmission line 2 can be matched with the impedance value of the signal source and the impedance value of the load, further reducing reflection loss and improving signal transmission efficiency.

[0044] In one embodiment, the impedance value of the first main line 21 and the impedance value of the third main line 23 are both equal to the characteristic impedance of the transmission line 2. The impedance value of the second main line 22 is different from the impedance value of the first main line 21 and the impedance value of the third main line 23, that is, the impedance value of the second main line 22 is different from the characteristic impedance of the transmission line 2. This allows the signal to be transmitted more stably when passing through the first main line 21 and the third main line 23, further improving the signal transmission quality. Moreover, simply adjusting the impedance value of the second main line 22 can enable the signal to be transmitted within different required specific frequency ranges, making the PCB structure suitable for different scenarios, with a wide range of applications, simple adjustment methods, and low cost.

[0045] In one embodiment, the width of the second main line 22 is different from the width of the first main line 21 and the width of the third main line 23. The impedance value can be adjusted by adjusting the routing width of the first main line 21, the second main line 22, and the third main line 23. When the impedance value of the first main line 21 and the impedance value of the third main line 23 are both equal to the characteristic impedance of the transmission line 2, only the routing width of the second main line 22 needs to be adjusted, thereby simplifying the adjustment method. Of course, in other embodiments, the impedance values ​​of the first main line 21, the second main line 22, and the third main line 23 can also be adjusted by adjusting other parameters such as the thickness of the PCB structure and the dielectric constant.

[0046] Specifically, pre-simulation software can be used to calculate the impedance values ​​of the first, second, and third main lines 21, 22, and 23, along with the corresponding trace widths, board structure, and other relevant values, for later design considerations. Once the lengths and widths of each section of transmission line 2 are determined, a three-dimensional electromagnetic simulation model of the PCB structure can be constructed using the electromagnetic field simulation software HFSS, and the relevant characteristics of the PCB structure can be obtained using the pre-simulation software.

[0047] In one embodiment, the first branch line 24 is configured as a short stub antenna. This stub antenna does not require complex circuit design and debugging; it can be used to transmit signals of a specific frequency simply by selecting an appropriate length based on the impedance of the signal source and the characteristic impedance of the transmission line 2. Of course, in other embodiments, the first branch line 24 can also be configured as other similar short antenna structures, and this embodiment of the utility model is not specifically limited thereto.

[0048] The embodiment of the present invention further provides a filter, comprising the above-mentioned PCB structure, so that the overall volume of the filter is small and the cost is low.

[0049] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0050] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of patent protection for the present application shall be determined by the appended claims.

Claims

1. A PCB structure, characterized in that: It includes an input port (1), a transmission line (2) and an output port (3), wherein: The transmission line (2) comprises a first main line (21), at least one second main line (22) and a third main line (23) which are connected in series in sequence, wherein an end of the first main line (21) away from the second main line (22) is connected to the input port (1), and an end of the third main line (23) away from the second main line (22) is connected to the output port (3); The transmission line (2) further comprises at least two first branch lines (24), one end of the at least two first branch lines (24) being respectively connected to the connection point between the first main line (21) and the second main line (22) and the connection point between the second main line (22) and the third main line (23), and the other end of each of the at least two first branch lines (24) being grounded; The first main line (21), the second main line (22), the third main line (23) and the first branch line (24) are of equal length.

2. The PCB structure according to claim 1, characterized in that: The transmission line (2) further comprises two second branch lines (25), one end of each of the two second branch lines (25) being respectively connected to a connection point between the first main line (21) and the input port (1) and a connection point between the third main line (23) and the output port (3), and the other end of each of the two second branch lines (25) being grounded.

3. The PCB structure according to claim 2, characterized in that: The length of the second branch line (25) is equal to the length of the first branch line (24).

4. The PCB structure according to claim 1, characterized in that: The length L4 of the first branch line (24) satisfies: Wherein, F is the resonant frequency of the first branch line (24), and v is the transmission speed of the signal in the PCB structure.

5. The PCB structure according to claim 4, characterized in that: The resonance frequency of the first branch line (24) is 1G, and the length of the first branch line (24) is 1.5 inches.

6. The PCB structure according to claim 1, characterized in that: The impedance value of the second main line (22) is not equal to the impedance value of the first main line (21) and / or the impedance value of the third main line (23).

7. The PCB structure according to claim 6, characterized in that: The impedance value of the first main line (21) and the impedance value of the third main line (23) are both equal to the characteristic impedance of the transmission line (2).

8. The PCB structure according to claim 6, characterized in that: The width of the second main line (22) is different from the width of the first main line (21) and / or the width of the third main line (23).

9. The PCB structure according to any one of claims 1 to 8, characterized in that: The first branch line (24) is configured as a stub antenna.

10. A filter, characterized in that: Comprising a PCB structure as described in any one of claims 1-9.

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