LTCC band-pass filter

Abstract

The LTCC band-pass filter comprises an LTCC porcelain body, a first inductor and a second inductor of the LTCC band-pass filter are arranged on the upper portion and the lower portion in the left side of the LTCC porcelain body respectively, the two inductors in the right side and the two inductors on the left side are symmetrically arranged, and other capacitors are correspondingly arranged. According to the utility model, the four inductors are arranged up and down and in bilateral symmetry, and the distance between the inductors at the input end and the output end can be flexibly adjusted, so that the coupling coefficient is adjusted, another two zero points are obtained by adjusting the coupling coefficient of the two inductors, the near-end suppression of the filter is optimized, and the selectivity of the filter is improved.

Description

Technical Field

[0001] This utility model relates to an LTCC bandpass filter and belongs to the technical field of LTCC bandpass filter. Background Technology

[0002] A bandpass filter is an electronic filter that allows signals in a specific frequency band to pass through while blocking signals in other frequency bands. The amplitude-frequency characteristics of bandpass filters make them widely used in audio processing, communication systems, radio modulation and demodulation, image processing, and other fields.

[0003] The reason for the arrangement of four inductors in the LTCC bandpass filter is that the original circuit has one zero on each side, resulting in low near-end suppression and a narrow suppression band. Summary of the Invention

[0004] The technical problem to be solved by this utility model is to provide an LTCC bandpass filter with low near-end suppression and a narrow suppression band.

[0005] The technical solution adopted by this utility model is as follows: An LTCC bandpass filter includes an LTCC ceramic body, a first inductor, a second inductor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, and a fifth capacitor. The first inductor and the second inductor are respectively arranged at the top and bottom of the left side of the LTCC ceramic body. The first capacitor and the second capacitor are arranged in the middle of the left side of the LTCC ceramic body near the left end. The third capacitor and the fourth capacitor are arranged at the bottom of the LTCC ceramic body. The fifth capacitor is a dual capacitor, arranged symmetrically in the middle of the LTCC ceramic body. A mirror structure symmetrical to the first inductor, the second inductor, the first capacitor, the second capacitor, the third capacitor, and the fourth capacitor is arranged in the right side of the LTCC ceramic body. The first capacitor and the first inductor are connected to the input pins provided at the left end of the LTCC ceramic body. The capacitor and inductor mirrored by the first capacitor and the first inductor are connected to the output pins provided at the right end of the LTCC ceramic body. The third capacitor and the fourth capacitor are connected to the test ground terminals provided at the front and rear sides of the LTCC ceramic body.

[0006] Furthermore, the first capacitor, the second capacitor, and the fifth capacitor share a central electrode plate. The other electrode plates of the first capacitor and the second capacitor are located on the upper and lower left sides of the central electrode plate, respectively, and the other electrode plate of the fifth capacitor is located on the upper right side of the central electrode plate.

[0007] The beneficial effects of this utility model are as follows: This utility model arranges four inductors, two at the top and two at the bottom, and symmetrically arranged left and right. The inductors at the input and output ends are located at the top, which provides a large space and allows for flexible adjustment of the spacing, thereby adjusting the coupling coefficient. By adjusting the coupling coefficient of two inductors, two additional zeros are obtained, which optimizes the near-end suppression of the filter and improves the selectivity of the filter. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the 3D structure of an LTCC bandpass filter;

[0009] Figure 2 This is a three-dimensional structural diagram of the internal electrical components of an LTCC bandpass filter.

[0010] Figure 3 This is a three-dimensional structural diagram of the internal electrical components of an LTCC bandpass filter from another perspective.

[0011] Figure 4 This is a front view schematic diagram of the internal electrical component arrangement of an LTCC bandpass filter;

[0012] Figure 5 This is a rear view schematic diagram of the internal electrical component arrangement of an LTCC bandpass filter;

[0013] Figure 6 This is a right-side view of the internal electrical component arrangement of an LTCC bandpass filter.

[0014] Figure 7 This is a top view of the internal electrical components of an LTCC bandpass filter.

[0015] Figure 8 This is a schematic diagram of an LTCC bandpass filter circuit.

[0016] Figure 9 This is an ADS simulation waveform diagram of an LTCC bandpass filter;

[0017] Figure 10 This is a front-view transparent schematic diagram of an LTCC bandpass filter (bringing the two inductors (in the black box) close together will create a second zero point, thereby improving product selectivity).

[0018] Figure 11 This is a simulation waveform diagram of a 3D model of an LTCC bandpass filter (the waveform and the ideal circuit simulation waveform have two additional zeros). Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0020] Example 1: As Figure 1-11An LTCC bandpass filter includes an LTCC ceramic body 1, a first inductor 2, a second inductor 3, a first capacitor 4, a second capacitor 5, a third capacitor 6, a fourth capacitor 7, and a fifth capacitor 8. The first inductor 2 and the second inductor 3 are arranged vertically and horizontally on the left side of the LTCC ceramic body 1. The first capacitor 4 and the second capacitor 5 are arranged near the left end of the left side of the LTCC ceramic body 1. The third capacitor 6 and the fourth capacitor 7 are arranged at the bottom of the LTCC ceramic body 1. The fifth capacitor 8 is a dual capacitor, symmetrically arranged in the middle of the LTCC ceramic body 1. Symmetrical capacitors, corresponding to the first inductor 2, the second inductor 3, the first capacitor 4, the second capacitor 5, the third capacitor 6, and the fourth capacitor 7, are arranged on the right side of the LTCC ceramic body 1. The design employs a mirror structure, with the first capacitor 4 and the first inductor 2 connected to the input pin 9 on the left side of the LTCC ceramic body 1. A capacitor and inductor mirroring the first capacitor 4 and the first inductor 2 are connected to the output pin 10 on the right side of the LTCC ceramic body 1. The third capacitor 6 and the fourth capacitor 7 are connected to the test ground terminals 11 on the front and rear sides of the LTCC ceramic body 1. This design arranges four inductors symmetrically, with two at the top and two at the bottom, and two at the bottom. The inductors at the input and output ends are located at the top, providing ample space and allowing for flexible adjustment of the spacing, thus adjusting the coupling coefficient. By adjusting the coupling coefficients of two inductors, two additional zeros are obtained, optimizing the near-end suppression of the filter and improving its selectivity.

[0021] The first capacitor 4, the second capacitor 5, and the fifth capacitor 8 share a central electrode plate. The other electrode plates of the first capacitor 4 and the second capacitor 5 are located on the upper and lower left sides of the central electrode plate, respectively. The other electrode plate of the fifth capacitor 8 is located on the upper right side of the central electrode plate. The other electrode plate of the first capacitor 4 is connected to one end of the first inductor 2 through the first short terminal 12. The other end of the first inductor 2 is electrically connected to the other electrode plate of the second capacitor 5 through the first long terminal 13 in the middle. The lower end of the second inductor 3 is connected to the upper electrode plate of the fourth capacitor 7 through the second short terminal 15. The front side of the upper end of the second inductor 3 is electrically connected to the shared electrode plate of the first capacitor 4, the second capacitor 5, and the fifth capacitor 8, as well as the two electrode plates of the third capacitor 6, through the second long terminal 14. The electrode plate of the fifth capacitor 8 is connected to the central electrode plate of the first capacitor 4, the second capacitor 5, and the fifth capacitor 8 through the third short terminal 16.

[0022] The LTCC bandpass filter circuit consists of two cascaded bandpass filter circuits connected in series via capacitor C7 (fifth capacitor 8). The preceding bandpass filter circuit includes inductor L1 (first inductor 1). One end of inductor L1 is electrically connected to input pin 9 and one end of capacitor C3 (second capacitor 5), while the other end is electrically connected to one end of first capacitor C1 (first capacitor 4). The other end of first capacitor C1 is electrically connected to the other end of capacitor C3, capacitor C5 (fourth capacitor 7), capacitor C7 (fifth capacitor 7), and inductor L1. One end of inductor 3 (second inductor 2) and the other end of inductor L3 are electrically connected to one end of capacitor C6 (third capacitor 6). The other ends of capacitors C6 and C5 are electrically connected to test ground terminal 11. The subsequent bandpass filter circuit includes inductors L2, L4, capacitors C2, C4, C8, and C9 that are symmetrically connected to the inductors and capacitors of the preceding bandpass filter. Capacitor C2 is connected to test ground terminal 11. Inductors L2 and C4 are connected to output pin 10. Capacitor C2 is connected to capacitor C7. The remaining connections are the same as those of the preceding bandpass filter circuit.

[0023] Example 2: A method for fabricating an LTCC bandpass filter, comprising the following steps:

[0024] S1. Ingredients: Select materials with a dielectric constant of 40, and ball-mill the powder to a particle size of 0.5-1μm.

[0025] S2, Casting: The ball-milled ingredients are prepared into a slurry, and casting technology is used to obtain green ceramic tapes with thicknesses of 43μm, 50μm, and 38μm.

[0026] S3. Cutting: Cut the green ceramic strip into green ceramic strips of various thicknesses, each 6 inches in diameter;

[0027] S4. Hole making: According to the pre-made hole making pattern, use a laser hole making machine to make holes on the green ceramic tape that needs to be made;

[0028] S5. Printing: The printing method is screen printing. The design graphic is prepared on film, and after exposure, the inductance is transferred to a 400 and 500 mesh steel wire mesh covered with photosensitive emulsion to form a printing fixture. The large area G layer uses 500 mesh. The photosensitive emulsion coating thickness is controlled as follows: 37μm~43μm; printing GAP value: 1mm~2mm; printing squeegee pressure: 0.05MPa~0.10MPa; squeegee stepping speed: 0.05m / s~0.10m / s. Each layer of the design model is printed on a green ceramic tape of corresponding thickness. The printed inductor linewidth error is within 2μm, and the inductor thickness is 12-15μm. The printed capacitor length and width error is within 5μm, and the capacitor thickness is 8-10μm.

[0029] S6. Lamination: The printed ceramic tapes are laminated in the design order using a fully automatic alignment and lamination machine.

[0030] S7. Isostatic pressing: The laminated membrane is subjected to final pressing using isostatic pressing; maximum isostatic pressing temperature: 70℃±5℃; holding time: 800s~900s; holding pressure: 5100psi~8300psi, forming a Bar block;

[0031] S8. Cutting: Divide the Bar block into independent product units of 3.87mm*1.93mm with an error of ±0.1mm;

[0032] S9. De-glue removal: Perform a 36-hour de-glue removal operation on the segmented products according to the de-glue removal curve for a material with a dielectric constant of 40.

[0033] S10. Sintering: The product after debinding is sintered in a tunnel furnace; the tunnel furnace has 12 sintering temperature zones with a belt speed of 45mm / min, a sintering temperature of 900℃, and a holding time of 50min~60min.

[0034] S11. Chamfering: Chamfer the sintered product. Use a roller to chamfer for 6 hours, using 2600ml of grinding media and adding 2250-2350ml of water.

[0035] S12, Silver coating: Apply silver coating to the external electrodes of the product after chamfering using a fully automatic end electrode silver coating machine;

[0036] S13, Silvering: Silvering process is performed on the silver-plated products; silvering is performed using a tunnel furnace; there are 6 sintering temperature zones, sintering temperature: 715℃, holding time: 20min~25min;

[0037] S14. Electroplating: Electroplating nickel, tin, and lead onto the product after silver burning to form the final product.

[0038] 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. An LTCC bandpass filter, characterized by, The utility model relates to a kind of LTCC ceramic body (1), first inductance (2), second inductance (3), first capacitor (4), second capacitor (5), third capacitor (6), fourth capacitor (7) and fifth capacitor (8), LTCC ceramic body (1) left side inner upper and lower are respectively arranged with first inductance (2) and second inductance (3), first capacitor (4) and second capacitor (5) are arranged in LTCC ceramic body (1) left side middle part close to left end, LTCC ceramic body (1) bottom is arranged in third capacitor (6) and fourth capacitor (7), fifth capacitor (8) is double capacitor, and it is arranged in LTCC ceramic body (1) middle part axially symmetric, LTCC ceramic body (1) right side inner is arranged with mirror image structure symmetrical with first inductance (2), second inductance (3), first capacitor (4), second capacitor (5), third capacitor (6) and fourth capacitor (7), first capacitor (4) and first inductance (2) are connected to the input pin (9) of the left end of LTCC ceramic body (1) setting, and the capacitor inductance of mirror image with first capacitor (4) and first inductance (2) is connected to the output pin (10) of the right end of LTCC ceramic body (1) setting, third capacitor (6) and fourth capacitor (7) are connected to the test ground terminal (11) of the front side and rear side of LTCC ceramic body (1) setting.

2. The LTCC bandpass filter according to claim 1, characterized in that First capacitor (4), second capacitor (5) and fifth capacitor (8) share a middle electrode plate, and the other electrode plate of first capacitor (4) and second capacitor (5) is respectively located on the upper side and lower side of the left end of the middle electrode plate, and the other electrode plate of fifth capacitor (8) is located on the upper part of the right end of the middle electrode plate.

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