Miniaturized broadband LTCC band-pass filter
By combining a six-layer LTCC dielectric substrate with a U-shaped stripline resonator and a spiral inductor resonator, the problem of poor selectivity in existing filters is solved, and a miniaturized broadband filter design is realized, thereby improving the performance of communication systems.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-27
- Publication Date
- 2026-03-27
AI Technical Summary
Existing filters have poor selectivity for passband signals, which affects the performance of communication systems.
A six-layer LTCC dielectric substrate structure is adopted, which combines a U-shaped stripline resonator and a spiral inductor resonator to form a three-dimensional resonant structure. Three-dimensional interconnection is achieved through metallized blind vias, which expands the bandwidth and optimizes the size.
This achievement enables the miniaturization and broadband characteristics of filters, improves the selectivity of passband signals, and enhances the performance of communication systems.
Smart Images
Figure CN121748747A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of microwave communication technology, and in particular to a miniaturized broadband LTCC bandpass filter. Background Technology
[0002] Filters, as a crucial component in radio frequency (RF) front-ends, remove out-of-band noise and improve the sensitivity of circuit systems. Microstrip filters are devices used to separate microwave signals of different frequencies. Their main function is to suppress unwanted signals, preventing them from passing through the filter and allowing only the desired signals to pass. In microwave circuit systems, filter performance significantly impacts the overall system performance. Generally, the selectivity of a filter for passband signals is a critical performance indicator, and existing filters often exhibit poor selectivity, thus affecting the performance of the entire communication system. Summary of the Invention
[0003] The purpose of this invention is to provide a miniaturized broadband LTCC bandpass filter to solve the problems in the prior art.
[0004] The technical solution of the present invention is: a miniaturized broadband LTCC bandpass filter, the filter comprising a multilayer LTCC dielectric substrate, the LTCC dielectric substrate comprising six sintered dense ceramic layers arranged from top to bottom, wherein the first layer is the top layer, the second and fifth ceramic layers are respectively provided with U-shaped stripline resonators, the third and fourth ceramic layers are respectively provided with spiral inductor resonators, the sixth layer is the bottom layer, the second to fifth ceramic layers are provided with metallized blind vias, and the bottom layer is etched with an asymmetric L-shaped trench ground.
[0005] Preferably, the thickness of a single layer of the six-layer ceramic layer is 45-55 μm, and the dielectric constant is 5.5-6.5.
[0006] Preferably, the U-shaped stripline resonator and the spiral inductor resonator constitute a three-dimensional resonant structure.
[0007] Preferably, the U-shaped stripline resonator has fractal geometric edges and is a second-order Minkowski curve structure with a tortuosity factor of 1.25-1.35.
[0008] Preferably, the spiral inductor resonator is an Archimedean spiral with 3.5-4.5 turns, a line width of 60-80μm, and a turn spacing of 40-60μm.
[0009] Preferably, the top and bottom surfaces are provided with signal conductors, ground conductors, and impedance gradient transition sections.
[0010] The beneficial effects of this invention are: (1) The present invention uses a fractal geometric resonator, and the effective size is 35% of that of the traditional design; (2) A six-layer LTCC stacked structure is adopted, and the layers are interconnected in three dimensions through vertical blind holes; (3) Set up a U-shaped stripline resonator and a spiral inductor resonator to form a magnetoelectric hybrid coupling; (4) The bandwidth of the asymmetric L-shaped slotted ground is extended to about 40% of the relative bandwidth. Attached Figure Description
[0011] Figure 1 This is a schematic diagram of the structure of the present invention.
[0012] In the diagram, 1 is the top layer, 2 is the second ceramic layer, 3 is the third ceramic layer, 4 is the fourth ceramic layer, 5 is the fifth ceramic layer, 6 is the bottom layer, 7 is the U-shaped stripline resonator, 8 is the spiral inductor resonator, 9 is the L-shaped slotted ground, and 10 is the metallized blind via. Detailed Implementation
[0013] A miniaturized broadband LTCC bandpass filter includes a multilayer LTCC dielectric substrate. The LTCC dielectric substrate includes six sintered dense ceramic layers arranged from top to bottom. The first layer is the top layer 1. U-shaped stripline resonators 7 are respectively disposed on the second ceramic layer 2 and the fifth ceramic layer 5. Spiral inductor resonators 8 are respectively disposed on the third ceramic layer 3 and the fourth ceramic layer 4. The sixth layer is the bottom layer 6. Metallized blind vias 10 are provided on the second to fifth ceramic layers 2 and 5. An asymmetric L-shaped trench ground 9 is etched on the bottom layer 6.
[0014] The six-layer ceramic layer 6 has a single-layer thickness of 45-55μm and a dielectric constant of 5.5-6.5.
[0015] The U-shaped stripline resonator 7 and the spiral inductor resonator 8 constitute a three-dimensional resonant structure.
[0016] The U-shaped stripline resonator 7 has fractal geometric edges and is a second-order Minkowski curve structure with a tortuosity factor of 1.25-1.35.
[0017] The spiral inductor resonator 8 is an Archimedean spiral with 3.5-4.5 turns, a line width of 60-80μm, and a turn spacing of 40-60μm.
[0018] The top layer 1 and the bottom layer 6 are provided with signal conductors, ground conductors and impedance gradient transition sections.
[0019] Metallized blind vias 10 are provided on the second to fifth ceramic layers 2 to 5 to form a vertical interconnection system. The open end of the U-shaped resonator in the second ceramic layer is connected to the starting end of the spiral resonator in the third ceramic layer; the end of the spiral resonator in the fourth ceramic layer is connected to the closed end of the U-shaped resonator in the fifth ceramic layer; the diameter of the metallized blind via 10 is 80-120μm and the spacing between the vias is 300-500μm.
[0020] In the description of this invention, it should be understood that the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.
[0021] In this invention, unless otherwise explicitly specified and limited, for example, it can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two elements or an interaction between two elements. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0022] All standard parts used in this invention can be purchased from the market, and irregular parts can be customized according to the description and drawings.
[0023] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A miniaturized broadband LTCC bandpass filter, characterized in that: The filter includes a multilayer LTCC dielectric substrate, which includes six sintered dense ceramic layers arranged from top to bottom. The first layer is the top layer (1), the second ceramic layer (2) and the fifth ceramic layer (5) are respectively provided with U-shaped stripline resonators (7), the third ceramic layer (3) and the fourth ceramic layer (4) are respectively provided with spiral inductor resonators (8), and the sixth layer is the bottom layer (6). Metallized blind vias (10) are provided on the second ceramic layer (2) to the fifth ceramic layer (5), and an asymmetric L-shaped trench ground (10) is etched on the bottom layer (6).
2. The miniaturized broadband LTCC bandpass filter according to claim 1, characterized in that: The thickness of each of the six ceramic layers is 45-55 μm, and the dielectric constant is 5.5-6.
5.
3. The miniaturized broadband LTCC bandpass filter according to claim 1, characterized in that: The U-shaped stripline resonator (7) and the spiral inductor resonator (8) constitute a three-dimensional resonant structure.
4. The miniaturized broadband LTCC bandpass filter according to claim 1, characterized in that: The U-shaped stripline resonator (7) has fractal geometric edges and is a second-order Minkowski curve structure with a tortuosity factor of 1.25-1.
35.
5. A miniaturized broadband LTCC bandpass filter according to claim 1, characterized in that: The spiral inductor resonator (8) is an Archimedean spiral with 3.5-4.5 turns, a line width of 60-80μm, and a turn spacing of 40-60μm.
6. A miniaturized broadband LTCC bandpass filter according to claim 1, characterized in that: The top layer (1) and bottom layer (6) surfaces are provided with signal conductors, ground conductors and impedance gradient transition sections.