L-band high-performance miniaturized low-pass filter
By employing an elliptic function low-pass filter structure and a high-Q capacitor, combined with a concave high-impedance transmission line, the problems of large size and low out-of-band suppression of microstrip/stripline structures are solved, thereby achieving improved out-of-band suppression and enhanced power capacity of high-performance miniaturized low-pass filters.
Patent Information
- Application Number
- CN202423224828.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-26
- Publication Date
- 2025-12-16
- Estimated Expiration
- 2034-12-26
AI Technical Summary
In existing technologies, microstrip/micro-online structures are large in size, difficult to miniaturize, have low power density, and are difficult to debug. In existing technologies, microstrip/stripline structure low-pass filters are small in size, but have low out-of-band suppression. In existing technologies, microstrip/stripline structure low-pass filters are large in size, have low power capacity, low out-of-band suppression, and are difficult to debug.
An elliptic function low-pass filter structure is adopted. By combining the series inductor in the main path, the parallel capacitor in the main path, and the capacitor to ground in the branch path, a high-performance LC structure is formed. Combined with the U-shaped high-impedance transmission line and the high-Q capacitor, miniaturization and high out-of-band rejection are achieved.
It achieves an out-of-band rejection of 60dBc@2.5GHz, a smaller size, a lower insertion loss of 0.5dB, and a power capacity of 20W for 76 hours of continuous operation, meeting the heat dissipation requirements in high-power environments.
Smart Images
Figure CN223681038U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to microwave communication electronic device technical field, concretely relates to a L wave band high performance miniaturized low pass filter applied in radar and communication field. BACKGROUND
[0002] Low pass filter is an important component of modern radar and communication electronic equipment, and has a decisive effect on the performance of system, and its working principle is that the signal lower than the cut-off frequency is passed, and the signal higher than the cut-off frequency is suppressed or weakened.According to the different structures, low pass filter can be mainly divided into cavity structure low pass filter, microstrip / band line structure low pass filter, LC structure low pass filter, and each has advantages and disadvantages in performance.Cavity structure low pass filter has large capacity power and small loss, but large volume, and it is very difficult to realize miniaturization;Microstrip / band line structure low pass filter has small volume and is easy to integrate, but has small power capacity, low out-of-band suppression and is not easy to debug;LC structure low pass filter has small loss, small volume, simple debugging and large power capacity, but is mainly limited by small out-of-band suppression.The effective combination of the low pass filters of the three structures constitutes the complete system of low pass filter in modern electronic equipment.At present, most low pass filters adopt microstrip / band line and LC structure. SUMMARY
[0003] The utility model wants to solve the technical problem of cavity structure of microstrip / band line and LC structure, which has large volume, great difficulty in miniaturization, small capacity, low out-of-band suppression and is not easy to debug, and aims at providing a L wave band high performance miniaturized low pass filter, adopts elliptic function low pass filter structure, greatly improves the out-of-band suppression of low pass filter, sets up main road series inductance, reduces the size, and through main road series transmission line inductance, main road parallel capacitor and branch to ground capacitor, a high performance LC structure low pass filter with high out-of-band suppression, small size, low insertion loss, large power capacity and simple debugging can be generated.
[0004] The utility model discloses the following technical scheme realizes:
[0005] A L wave band high performance miniaturized low pass filter, comprising: a plurality of elliptic function low pass filters in series;
[0006] The elliptic function low pass filter includes main road series transmission line inductance, main road parallel capacitor and branch to ground capacitor.
[0007] The main road series transmission line inductance and the main road parallel capacitor are connected in parallel, and then the branch to ground capacitor is connected in series after being connected in parallel, forming an elliptic function low pass filter.
[0008] Further, the main path series transmission line inductance is used for inputting radio frequency signals below a cutoff frequency to an output end, and the main path series transmission line inductance is used for cutting off radio frequency signals above the cutoff frequency.
[0009] Further, the main path series transmission line inductance adopts a concave-shaped high-impedance transmission line.
[0010] Further, the main path parallel capacitance and the branch-to-ground capacitance both adopt high-frequency capacitances.
[0011] Further, the main path series transmission line inductance and the main path series transmission line inductance are both n, and the branch-to-ground capacitance is n+1.
[0012] Further, the low-pass filter input end and the low-pass filter output end are further included:
[0013] The low-pass filter input end is connected to the low-pass filter output end in sequence through a branch-to-ground capacitance and a plurality of series-arranged elliptic function low-pass filters.
[0014] Further, the low-pass filter adopts a 50-ohm transmission line for transmission of electrical signals.
[0015] Further, the elliptic function low-pass filter is arranged on a microwave circuit sheet, and the other side of the microwave circuit sheet on which the low-pass filter is arranged is grounded.
[0016] Further, the microwave circuit sheet adopts a Roger 5880 PCB board.
[0017] Further, the microwave circuit sheet has a thickness of 0.787 mm.
[0018] Compared with the prior art, the low-pass filter has the following advantages and beneficial effects:
[0019] 1. The low-pass filter is realized by using a conventional LC low-pass filter and a main path parallel capacitance, and the out-of-band suppression of an ordinary LC filter is low, the main path parallel capacitance is used in the scheme, an elliptic function low-pass filter structure is formed, the out-of-band suppression of the low-pass filter is greatly improved, and 60dBc@2.5GHz (the cutoff frequency of the low-pass filter is 2GHz) can be achieved.
[0020] 2. The low-pass filter adopts the most advanced LC low-pass filter layout structure, compared with a conventional LC low-pass filter, the main path series inductance adopts a concave-shaped high-impedance transmission line to form a low inductance value, and through reasonable design of a circuit sheet, the size is greatly reduced.
[0021] 3, the low pass filter microwave circuit piece adopts gold plating process, the capacitor adopts high Q value capacitor, compared with the traditional LC low pass filter, the insertion loss is greatly reduced, and can reach less than 0.5db;
[0022] 4, the low pass filter adopts high thickness substrate material, high Q value high limit voltage capacitor and high power capacity microstrip line instead of small inductance value and small power capacity inductor, so that the power capacity of the low pass filter is greatly improved, and can reach 76 hours of continuous work in the environment of 20w power;
[0023] 5. The low pass filter microwave circuit piece has excellent grounding effect, the back of the circuit piece is grounded, and the front of the circuit piece is reasonably arranged through the grounding hole, which well meets the heat dissipation requirement of the low pass filter in the high power environment. BRIEF DESCRIPTION OF DRAWINGS
[0024] The drawings described herein are used to provide further understanding of the embodiments of the present application, constitute a part of the present application, and do not constitute a limitation on the embodiments of the present application. In the drawings:
[0025] Figure 1 The L band high performance miniaturized low pass filter circuit diagram in the embodiments of the present application;
[0026] Figure 2 The structure diagram of the L band high performance miniaturized low pass filter in the embodiments of the present application;
[0027] Figure 3 The S curve test result of the L band high performance miniaturized low pass filter in the embodiments of the present application.
[0028] Markings in the drawings and corresponding component names:
[0029] 1, microwave circuit piece; 2, main road series transmission line inductor; 3, main road parallel capacitor; 4, branch to ground capacitor; 5, low pass filter input end; 6, low pass filter output end. DETAILED DESCRIPTION
[0030] In order to make the purpose, technical scheme and advantages of the present application more clear, specific embodiments and drawings will be further described, the schematic embodiment and its description of the present application are only used to explain the present application, and do not limit the present application.
[0031] As a possible implementation, as Figure 1 and Figure 2As shown, the embodiment provides a kind of L wave band high-performance miniaturization low pass filter, comprising: a plurality of series arranged elliptic function low pass filter, elliptic function low pass filter includes main road series transmission line inductance 2, main road parallel capacitor 3, branch to ground capacitor 4, main road series transmission line inductance 2 and main road parallel capacitor 3 are connected in parallel, and branch to ground capacitor 4 is connected in series after being connected in parallel, form an elliptic function low pass filter, also include low pass filter input end 5 and low pass filter output end 6, low pass filter input end 5 to low pass filter output end 6 sequentially connect a branch to ground capacitor 4 and a plurality of series arranged elliptic function low pass filter.
[0032] Wherein, elliptic function low pass filter is arranged on microwave circuit piece 1, and the other side of the microwave circuit piece 1 is grounded for low pass filter.
[0033] In some possible embodiments, Figure 1 In,
[0034] C1 / C3 / C5 / C7 / C9 / C11 is branch to ground capacitor 4;
[0035] C2 / C4 / C6 / C8 / C10 is main road parallel capacitor 3;
[0036] L1 / L2 / L3 / L4 / L5 is main road series transmission line inductance 2.
[0037] In some possible embodiments, main road series transmission line inductance 2 and main road series transmission line inductance 2 are both n, and branch to ground capacitor 4 is n+1.
[0038] In some possible embodiments, main road series transmission line inductance 2 adopts concave high impedance transmission line.
[0039] In some possible embodiments, main road parallel capacitor 3 and branch to ground capacitor 4 adopt high-frequency capacitor with high Q value and high withstand voltage, which has the characteristics of large power capacity, small loss and small size, wherein main road series transmission line inductance 2 can be equivalent to replace 0.5-3nH inductance, to solve the problem of too small inductance value and no available packaged inductance for practical application.
[0040] In some possible embodiments, low pass filter adopts 50 ohm transmission line for transmission of electrical signal.
[0041] In some possible embodiments, elliptic function low pass filter is arranged on microwave circuit piece 1, and the other side of the microwave circuit piece 1 is grounded for low pass filter.
[0042] In some possible embodiments, microwave circuit piece 1 adopts Roger 5880 PCB board, and the thickness of microwave circuit piece 1 is 0.787 mm, and gold plating process is adopted, which has the characteristics of small loss and high power bearing.
[0043] In some possible embodiments, the L-band high-performance miniaturized low-pass filter provided by the present embodiment combines the traditional LC low-pass filter with the main path parallel capacitor 3 to form an elliptic function low-pass filter, achieving an LC structure low-pass filter with high out-of-band suppression;
[0044] The design is based on the latest LC low-pass filter concept, and the main path series inductance is replaced by a concave high-impedance transmission line, effectively solving the problem of too small inductance value, and miniaturizing the LC structure low-pass filter;
[0045] The low-loss circuit sheet is combined with high-Q, low-loss high-frequency capacitors to achieve a low-loss LC structure low-pass filter.
[0046] In some possible embodiments, the main working principle of the L-band high-performance miniaturized low-pass filter provided by the present embodiment is as follows: a wideband signal enters from the common low-pass filter input end 5, radio frequency signals below the cutoff frequency flow to the output end through the main path series transmission line inductance 2, and the signals are blocked by the branch-to-ground capacitor 4 at the same time. Radio frequency signals above the cutoff frequency are blocked by the main path series transmission line inductance 2 and cannot flow to the output end, and the signals flow to the ground through the branch-to-ground capacitor 4, and at the same time the main path parallel capacitor 3 can resonate at the out-of-band to form a transmission zero point, greatly improving the out-of-band suppression. The base material 1 of the microwave circuit sheet 1 is composed of Roger 5880, with a thickness of 0.787 mm. The circuit sheet adopts a gold plating process, and the circuit sheet structure layout is as shown in Figure 2 The main path series transmission line inductance 2 is composed of a concave high-impedance transmission line, effectively solving the problem of too small inductance value, and at the same time having the advantages of small size and low loss. The main path parallel capacitor 3 is a high-frequency capacitor with high Q value and high withstand voltage, which has the characteristics of high out-of-band suppression, low loss, large power capacity, and small size. The branch-to-ground capacitor 4 is a high-frequency capacitor with high Q value and high withstand voltage, which has the characteristics of small loss, large power capacity, and small size. The input / low-pass filter output end 6 is a standard transmission line with a resistance of 50 ohms.
[0047] The L-band high-performance miniaturized low-pass filter of the present embodiment was tested for electrical performance using a vector network analyzer, and the test results are shown in Figure 3 The frequency range is set to 10MHz-8000MHz. For power capacity testing: the input end 5 of the L-band high-performance miniaturized low-pass filter is filled with a continuous wave with a frequency of 1GHz and a power of 20W, the output end is connected to a spectrum analyzer, and the power capacity displayed on the spectrum analyzer is observed after continuous operation for 1 hour. The test results are shown in Table 1:
[0048] Table 1
[0049]
[0050] The above detailed description of the specific embodiments of the present application has further explained the purpose, technical solutions and beneficial effects of the present application, and it should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.
Claims
1. An L-band high-performance miniaturized low-pass filter, characterized by, The utility model relates to a low pass filter, including: a plurality of elliptic function low pass filters arranged in series; the elliptic function low pass filter includes main road series transmission line inductance (2), main road shunt capacitor (3), branch to ground capacitor (4); the main road series transmission line inductance (2) and main road shunt capacitor (3) are parallelly connected, and after parallel connection, branch to ground capacitor (4) is connected in series, and an elliptic function low pass filter is formed.
2. The L-band high-performance miniaturized low-pass filter according to claim 1, characterized in that, the main road series transmission line inductance (2) is used to input radio frequency signal below cut-off frequency to output end, and the main road series transmission line inductance (2) is used to cut off radio frequency signal higher than cut-off frequency.
3. The L-band high performance miniaturized low pass filter according to claim 1, characterized in that, the main road series transmission line inductance (2) adopts concave high impedance transmission line.
4. The L-band high performance miniaturized low pass filter according to claim 1, characterized in that, the main road shunt capacitor (3) and branch to ground capacitor (4) all adopt high-frequency capacitor.
5. The L-band high performance miniaturized low pass filter according to claim 1, characterized in that, the main road series transmission line inductance (2) and main road series transmission line inductance (2) are all n, and branch to ground capacitor (4) is n+1.
6. The L-band high-performance miniaturized low-pass filter according to claim 5, characterized in that, It also includes low pass filter input end (5) and low pass filter output end (6): low pass filter input end (5) to low pass filter output end (6) is connected with a branch to ground capacitor (4) and a plurality of elliptic function low pass filters arranged in series in turn.
7. The L-band high performance miniaturized low pass filter according to claim 6, characterized in that, the low pass filter adopts 50 ohm transmission line to transmit electric signal.
8. The L-band high performance miniaturized low pass filter according to claim 1, characterized in that, the elliptic function low pass filter is arranged on microwave circuit piece (1), and the other side of the microwave circuit piece (1) is grounded to arrange low pass filter.
9. The L-band high performance miniaturized low pass filter according to claim 8, characterized in that, the microwave circuit piece (1) adopts Roger 5880 PCB board.
10. The L-band high performance miniaturized low pass filter according to claim 8, characterized in that, the thickness of the microwave circuit piece (1) is 0.787mm.