A three-channel integrated low-pass filter
By integrating a low-pass filter into an LTCC ceramic body and utilizing isolation silver pillars and inductors/capacitors, the problem of large space occupation of the low-pass filter is solved, achieving miniaturization and easy soldering integration.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- GUIYANG SUNLORD SCHINDLER ELECTRONICS CO LTD
- Filing Date
- 2025-06-16
- Publication Date
- 2026-06-26
AI Technical Summary
In existing technologies, three independent low-pass filters need to be soldered separately, which takes up a lot of space and makes it difficult to achieve miniaturization and integration.
Three low-pass filters are integrated onto a single LTCC ceramic body. By evenly arranging four rows of isolation silver pillars within the LTCC ceramic body and connecting them to ground, isolation of the low-pass filter for each channel is achieved. The arrangement of inductors and capacitors is optimized to reduce size and minimize mutual interference.
The integration of three low-pass filters has been achieved, reducing the size to 9mm*9mm and occupying only 41.8% of the space of individual components. This facilitates soldering and reduces mutual interference between channels.
Smart Images
Figure CN224418782U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to a three-channel integrated low-pass filter, belonging to the field of multi-channel low-pass filter technology. Background Technology
[0002] A typical three-channel filter consists of three independent filters, such as... Figure 1 As shown, according to the specifications, three low-pass filters with dimensions of 9mm*4mm (length*width) are required. The three independent filters need to be soldered separately, and at least 21.5mm of space is required in the width direction for soldering. Utility Model Content
[0003] The technical problem to be solved by this utility model is to provide a three-channel integrated low-pass filter that can integrate three low-pass filters, reduce size, facilitate miniaturization and integration, and make it easy to solder onto application products.
[0004] The technical solution adopted by this utility model is as follows: A three-channel integrated low-pass filter includes an LTCC ceramic body and a low-pass filter. The low-pass filter has three channels, which are evenly arranged in the front and back of the LTCC ceramic body. Four rows of isolation silver pillars are evenly arranged in the front and back of the LTCC ceramic body. The lower ends of the four rows of isolation silver pillars are connected to the large flat ground terminal set on the bottom surface of the LTCC ceramic body. The low-pass filter of each channel is located between two rows of isolation silver pillars. The left end of the LTCC ceramic body is provided with the first input terminal, the second input terminal and the third input terminal of the three-channel low-pass filter. The right end of the LTCC ceramic body is provided with the first output terminal, the second output terminal and the third output terminal of the three-channel low-pass filter.
[0005] Furthermore, the low-pass filter for each of the above channels includes a first inductor, a second inductor, a third inductor, a fourth inductor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, and a ninth capacitor. The first, second, third, and fourth inductors are evenly arranged from left to right near the top of the LTCC ceramic body. The first, second, third, fourth, fifth, sixth, seventh, eighth, and ninth capacitors are arranged near the bottom of the LTCC ceramic body. The first and sixth capacitors are located below the input terminal of the first inductor, the second capacitor is located below the input terminal of the second inductor, the seventh capacitor is located below the output terminal of the second inductor, the third capacitor is located below both the output and input terminals of the second inductor, the eighth capacitor is located below the input terminal of the third inductor, the fourth capacitor is located below the output terminal of the third inductor, and the fifth and ninth capacitors are located below the output terminal of the fourth inductor.
[0006] Furthermore, the circuit structure of the low-pass filter for each of the above channels includes a first inductor, a second inductor, a third inductor, a fourth inductor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, and a ninth capacitor. The first, second, third, and fourth inductors are connected in series. The first inductor is connected to the input terminal, and the fourth inductor is connected to the output terminal. The sixth, seventh, eighth, and ninth capacitors are connected in parallel with the first, second, third, and fourth inductors, respectively. One end of the first capacitor is connected to the input terminal, one end of the second capacitor is connected to the end where the first and second inductors are connected in series, the third capacitor is connected to the end where the second and third inductors are connected in series, the fourth capacitor is connected to the end where the third and fourth inductors are connected in series, one end of the fifth capacitor is connected to the output terminal, and the other ends of the first, second, third, fourth, and fifth capacitors are all connected to the ground terminal.
[0007] The beneficial effects of this utility model are as follows: Compared with the prior art, this utility model integrates three low-pass filters into one LTCC ceramic body, which can realize the integration of three low-pass filters, reduce the size, and facilitate soldering to the application product. Integrating the three filters together can save a lot of space. The product is 9mm*9mm in length and width, and the space occupied in the width direction of the product is only 41.8% of that of three independent devices. Moreover, multiple rows of isolation silver pillars are used to isolate the low-pass filter of each channel, reducing mutual interference between channels. Attached Figure Description
[0008] Figure 1 This is a schematic diagram of the layout structure of a traditional three-channel low-pass filter;
[0009] Figure 2 This is a three-dimensional structural diagram (transparent structure) of a three-channel integrated low-pass filter.
[0010] Figure 3 This is a three-dimensional structural diagram of a three-channel integrated low-pass filter (the ceramic body is transparent).
[0011] Figure 4 This is a top view of the structure of a three-channel integrated low-pass filter (the ceramic body is transparent).
[0012] Figure 5 This is a front view schematic diagram of a three-channel integrated low-pass filter (with the ceramic body removed).
[0013] Figure 6 yes Figure 5 Schematic diagram of the cross-sectional structure of the middle AA section;
[0014] Figure 7 yes Figure 5 Schematic diagram of the cross-sectional structure of the middle BB section;
[0015] Figure 8 This is a 3D structural diagram of a three-channel integrated low-pass filter (with the ceramic body removed).
[0016] Figure 9 This is a front view schematic diagram of a three-channel integrated low-pass filter (with the ceramic body removed).
[0017] Figure 10 yes Figure 9 Schematic diagram of the cross-sectional structure of the middle AA section;
[0018] Figure 11 yes Figure 9 Schematic diagram of the cross-sectional structure of the middle BB section;
[0019] Figure 12 This is a top view of the structure of a three-channel integrated low-pass filter (with the ceramic body removed).
[0020] Figure 13 This is a schematic diagram of the low-pass filter circuit structure of the first channel of a three-channel integrated low-pass filter.
[0021] Figure 14 This is a schematic diagram of the low-pass filter circuit structure of the second channel of a three-channel integrated low-pass filter.
[0022] Figure 15 This is a schematic diagram of the low-pass filter circuit structure of the second channel of a three-channel integrated low-pass filter. Detailed Implementation
[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0024] Example 1: As Figure 2-15 As shown, a three-channel integrated low-pass filter includes an LTCC ceramic body 1 and a low-pass filter 2. The low-pass filter 2 has three channels, which are evenly arranged front and back inside the LTCC ceramic body 1. Four rows of isolation silver pillars 3 are evenly arranged front and back inside the LTCC ceramic body 1, with a spacing of 290μm between adjacent isolation pillars. The lower ends of the four rows of isolation silver pillars 3 are connected to a large flat ground terminal 4 on the bottom surface of the LTCC ceramic body 1. The low-pass filter 2 of each channel is located between two rows of isolation silver pillars 3. The left end of the LTCC ceramic body 1 is provided with the first input terminal 5, the second input terminal 6, and the third input terminal 7 of the three-channel low-pass filter 2. The right end of the LTCC ceramic body 1 is provided with the first output terminal 8, the second output terminal 9, and the third output terminal 10 of the three-channel low-pass filter 2. The upper and lower ends of the four rows of isolation silver pillars 3 are fixedly connected to the upper inner ground plane 11 and the lower inner ground plane 12, respectively. The lower inner ground plane 12 is connected to the large flat ground terminal 4 through conductive pillars 13.
[0025] Furthermore, the low-pass filter 2 of each channel includes a first inductor 201, a second inductor 202, a third inductor 203, a fourth inductor 204, a first capacitor 205, a second capacitor 206, a third capacitor 207, a fourth capacitor 208, a fifth capacitor 209, a sixth capacitor 210, a seventh capacitor 211, an eighth capacitor 212, and a ninth capacitor 213. The first inductor 201, the second inductor 202, the third inductor 203, and the fourth inductor 204 are evenly arranged from left to right near the top of the LTCC ceramic body 1, while the first capacitor 205, the second capacitor 206, the third capacitor 207, the fourth capacitor 208, the fifth capacitor 209, the sixth capacitor 210, the seventh capacitor 211, the eighth capacitor 212, and the ninth capacitor 213 are arranged near the bottom of the LTCC ceramic body 1. The first capacitor 205 and the sixth capacitor 210 are located below the input terminal of the first inductor 201. The second capacitor 206 is located below the input terminal of the second inductor 202. The seventh capacitor 211 is located below the output terminal of the second inductor 202. The third capacitor 207 is located below the output terminal of the second inductor 202 and the input terminal of the third inductor 203. The eighth capacitor 212 is located below the input terminal of the third inductor 203. The fourth capacitor 208 is located below the output terminal of the third inductor 203. The fifth capacitor 209 and the ninth capacitor 213 are located below the output terminal of the fourth inductor 204. The inductors are placed on top, at the same height, and the spacing between each layer is the same, which can reduce the number of inductor layers.
[0026] like Figure 13-15 The low-pass filter circuit structures for the three channels corresponding to 30-43MHz, 43-62MHz, and 62-88MHz are identical. The circuit structure for each channel's low-pass filter includes a first inductor L1, a second inductor L2, a third inductor L3, a fourth inductor L4, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, and a ninth capacitor C9. The first inductor L1, the second inductor L2, the third inductor L3, and the fourth inductor L4 are connected in series. The first inductor L1 is connected to the input terminal, and the fourth inductor L4 is connected to the output terminal. The sixth capacitor C6, the seventh capacitor C7, the eighth capacitor C8, and the ninth capacitor C9 are connected in parallel with the first inductor L1, the second inductor L2, the third inductor L3, and the fourth inductor L4, respectively. One end of the first capacitor C1 is connected to the input terminal. One end of the second capacitor C2 is connected to the end of the series connection between the first inductor L1 and the second inductor L2. The third capacitor C3 is connected to the end of the series connection between the second inductor L2 and the third inductor L3. The fourth capacitor C4 is connected to the end of the series connection between the third inductor L3 and the fourth inductor L4. One end of the fifth capacitor C5 is connected to the output terminal. The other ends of the first capacitor C1, the second capacitor C2, the third capacitor C3, the fourth capacitor C4, and the fifth capacitor C5 are all connected to the ground terminal.
[0027] Example 2: A method for fabricating a three-channel integrated low-pass filter includes the following steps:
[0028] S1. Ingredients: The product uses M-LG01 material with a dielectric constant of 6.5. The powder is ball-milled to a particle size of 0.5-2μm.
[0029] S2, Casting: The ball-milled ingredients are prepared into a slurry, and casting technology is used to obtain green ceramic tapes of different thicknesses (different thicknesses are obtained according to the film thickness of the design model); only with accurate green ceramic tape thickness can the interlayer thickness of the model be better reproduced, and only then can the electrical performance indicators of the product meet the requirements.
[0030] S3. Cutting: Cut the green ceramic strip into strips of a set size (usually 6 inches) and various thicknesses, using a 6-inch process platform;
[0031] S4. Opening: Opening holes in the green ceramic tape where holes are required. The holes are filled with conductive material to allow electrical connection between adjacent layers, thus achieving interconnection between layers and forming a circuit.
[0032] S5. Printing: The printing method is screen printing. The design graphic is prepared on film, exposed and transferred to a 400-mesh and 500-mesh steel wire mesh covered with photosensitive emulsion to form a printing fixture. By controlling the thickness of the photosensitive emulsion coating: 32μm~55μm; printing GAP value: 0.5mm~3mm; printing squeegee pressure: 0.05MPa~0.20MPa; squeegee stepping speed: 0.01m / s~0.10m / s; each layer of the design model is printed on a green ceramic tape of corresponding thickness. The thickness of the large-area capacitor layer silver layer is controlled at 6-8μm to prevent cracking after sintering due to excessive silver layer thickness.
[0033] S6. Lamination: The printed green ceramic tapes are laminated in the design order using a fully automatic alignment and lamination machine. Precise alignment can reduce interlayer misalignment, accurately restore the model capacitance value, and ensure that the through-holes are accurately aligned to avoid the formation of weak points and reduce power loss.
[0034] S7. Isostatic pressing: The laminated membrane is subjected to final pressing using isostatic pressing; maximum isostatic pressing temperature: 70℃~75℃; holding time: 600s~900s; holding pressure: 5100psi~8300psi, forming a Bar block;
[0035] S8. Cutting: Divide the Bar block into 17.07mm*13.29mm segments to form independent product units (single products).
[0036] S9. De-gumming: De-gumming operation is performed on the divided product units for 60 hours according to the de-gumming curve (originally 30 hours). The inventors found that the product units of this utility model are large in size, and the 30-hour de-gumming is not thorough. During sintering, gas is released from the product, causing abnormal cracking.
[0037] S10. Sintering: The product after debinding is sintered in a tunnel furnace; there are 8 to 10 sintering temperature zones, sintering temperature: 850℃ to 900℃, and holding time: 80 min to 100 min.
[0038] S11. Electroplating: Electroplating nickel, tin, and lead onto the sintered product to form the final product. The nickel plating serves as a protective layer, while the tin and lead plating increases the product's solderability.
[0039] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.
Claims
1. A three-channel integrated low-pass filter, characterized by, It includes an LTCC ceramic body and a low-pass filter. The low-pass filter has three channels, which are evenly arranged in the front and back of the LTCC ceramic body. There are four rows of isolation silver pillars evenly arranged in the front and back of the LTCC ceramic body. The lower ends of the four rows of isolation silver pillars are connected to the large flat ground terminal on the bottom surface of the LTCC ceramic body. The low-pass filter of each channel is located between two rows of isolation silver pillars. The left end of the LTCC ceramic body is provided with the first input terminal, the second input terminal and the third input terminal of the three-channel low-pass filter. The right end of the LTCC ceramic body is provided with the first output terminal, the second output terminal and the third output terminal of the three-channel low-pass filter.
2. A three-channel integrated low-pass filter according to claim 1, characterized in that, Each channel's low-pass filter includes a first inductor, a second inductor, a third inductor, a fourth inductor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, and a ninth capacitor. The first, second, third, and fourth inductors are evenly arranged from left to right near the top of the LTCC ceramic body. The first, second, third, fourth, fifth, sixth, seventh, eighth, and ninth capacitors are arranged near the bottom of the LTCC ceramic body. The first and sixth capacitors are located below the input terminal of the first inductor, the second capacitor is located below the input terminal of the second inductor, the seventh capacitor is located below the output terminal of the second inductor, the third capacitor is located below both the output and input terminals of the second inductor, the eighth capacitor is located below the input terminal of the third inductor, the fourth capacitor is located below the output terminal of the third inductor, and the fifth and ninth capacitors are located below the output terminal of the fourth inductor.
3. A three-channel integrated low-pass filter according to claim 1, characterized in that, The circuit structure of the low-pass filter for each channel includes a first inductor, a second inductor, a third inductor, a fourth inductor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, and a ninth capacitor. The first, second, third, and fourth inductors are connected in series. The first inductor is connected to the input terminal, and the fourth inductor is connected to the output terminal. The sixth, seventh, eighth, and ninth capacitors are connected in parallel with the first, second, third, and fourth inductors, respectively. One end of the first capacitor is connected to the input terminal, one end of the second capacitor is connected to the end of the series connection between the first and second inductors, the third capacitor is connected to the end of the series connection between the second and third inductors, the fourth capacitor is connected to the end of the series connection between the third and fourth inductors, and one end of the fifth capacitor is connected to the output terminal. The other ends of the first, second, third, fourth, and fifth capacitors are all connected to the ground terminal.