Narrowband filter with low power and high stopband suppression

Abstract

The invention discloses a low-power high-stopband suppression narrow-band filter, which comprises a packaging body, an outer side electrode and a plurality of circuit layers arranged in the packaging body, and is characterized in that the outer side electrode comprises an input end P1, an output end P2, a first grounding end P3 and a second grounding end P4; wherein the input end P1 and the output end P2 are symmetrically arranged, and the first grounding end P3 and the second grounding end P4 are symmetrically arranged; the input end P1, the output end P2, the first grounding end P3 and the second grounding end P4 are electrically connected with a transmission line in the packaging body; a first circuit layer is arranged at the bottom of the packaging body, the first circuit layer comprises two transmission lines and a first capacitor element, the two transmission lines are electrically connected with the input end P1 and the output end P2 respectively, and the two ends of the first capacitor element are electrically connected with the first grounding end P3 and the second grounding end P4 respectively. According to the technical scheme, the problem that an existing filter cannot achieve high-stop-band suppression under the condition of low-power operation is solved, and meanwhile multi-band and multi-mode communication can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of microwave communications, and in particular to a narrowband filter with low power and high stopband suppression. Background Art

[0002] A filter is an electronic device whose main function is to selectively allow signals within a specific frequency range to pass through while blocking or attenuating signals in other frequency ranges. It is widely used in various electronic systems, such as wireless communications, audio processing, power management, etc. Types of filters include low-pass, high-pass, band-pass, and band-stop filters, which are designed to achieve specific frequency responses according to different application requirements.

[0003] High-stopband filters are particularly important in modern electronic systems because they can effectively suppress unwanted frequency components, thereby reducing signal interference and noise. Especially in wireless communications and signal processing, high-stopband filters can prevent signal interference from adjacent channels, ensuring signal clarity and integrity. In addition, high-stopband filters are essential to improving the overall performance and reliability of the system because they help protect sensitive electronic components from high-frequency noise.

[0004] General filters often have difficulty in achieving low power, mainly because the circuit design is not optimized to minimize signal loss and heat generation. These filters use more passive components, such as resistors, capacitors, and inductors, which generate additional power losses when the components are working. In addition, if the circuit design of the filter is not compact enough, the signal will encounter more impedance mismatches and reflections during transmission, resulting in additional energy loss. Therefore, ordinary filters require more energy to compensate for these losses when processing signals, resulting in higher overall power consumption. In addition, general filters often need to make a trade-off between performance and power consumption when designing. In order to achieve high stopband suppression, the filter needs to use more passive components and complex circuit structures, which will increase the total power consumption of the circuit. At the same time, in order to achieve low power requirements, the circuit design needs to be simplified, but this will limit the filter's ability in stopband suppression. Summary of the invention

[0005] The purpose of the present invention is to solve or alleviate the problem that the existing filter cannot achieve high stop-band suppression under low power operation, and to propose a low-power high stop-band suppression narrowband filter.

[0006] A low-power high-stopband suppression narrowband filter comprises a package body, an outer electrode and a plurality of circuit layers arranged inside the package body, wherein the outer electrode comprises an input terminal P1, an output terminal P2, a first ground terminal P3 and a second ground terminal P4; wherein the input terminal P1 and the output terminal P2 are symmetrically arranged, and the first ground terminal P3 and the second ground terminal P4 are symmetrically arranged; the input terminal P1, the output terminal P2, the first ground terminal P3 and the second ground terminal P4 are all electrically connected to a transmission line inside the package body; a first circuit layer is arranged at the bottom of the package body, the first circuit layer comprises two transmission lines and a first capacitor element, the two transmission lines are electrically connected to the input terminal P1 and the output terminal P2 respectively, and the two ends of the first capacitor element are electrically connected to the first ground terminal P3 and the second ground terminal P4 respectively.

[0007] Preferably, inside the package body, above the first circuit layer, there are also a second circuit layer, a third circuit layer, a fourth circuit layer, a fifth circuit layer, a sixth circuit layer and a seventh circuit layer, and from bottom to top, the second circuit layer to the seventh circuit layer are arranged in sequence; the second circuit layer is provided with a second capacitor element, and the second capacitor element is vertically coupled with the first capacitor element; the third circuit layer is provided with a third capacitor element, a fifth capacitor element and a sixth capacitor element; wherein, a transmission line connected to each other and provided with a primary connection hole is provided between the fifth capacitor element and the sixth capacitor element; the primary connection hole is electrically connected to the second capacitor element; the third capacitor element is electrically connected to the first capacitor element through the secondary connection hole, and the fourth capacitor element is electrically connected to the first capacitor element through the third connection hole; the fourth circuit layer is provided with a seventh capacitor element and a ninth capacitor element; a transmission line connected to each other and provided with a fourth connection hole is provided between the seventh capacitor element and the ninth capacitor element, and the fourth connection hole is electrically connected to the main wave line; wherein, The seventh capacitor element is vertically coupled with the third capacitor element to form an equivalent capacitor C2; the ninth capacitor element is vertically coupled with the fifth capacitor element to form an equivalent capacitor C4; the third transmission line, the fourth transmission line, the fifth transmission line and the primary spiral conductor are provided on the fifth circuit layer; a transmission line connected to each other and provided with a sixth connection hole is provided between the fifth transmission line and the primary spiral conductor, and the sixth connection hole is electrically connected to the primary connection hole; the other end of the fifth transmission line is electrically connected to the first capacitor element through the seventh connection hole; one end of the third transmission line is connected to the fourth connection hole and is also electrically connected to the main waveguide; the fourth transmission line is electrically connected to the fifth connection hole and is also electrically connected to the auxiliary waveguide; a secondary spiral conductor is provided on the sixth circuit layer, and one end of the secondary spiral conductor is electrically connected to the intersection of the fifth transmission line and the primary spiral conductor through the eighth connection hole; a fourth spiral conductor is provided on the seventh circuit layer, and one end of the fourth spiral conductor is electrically connected to the other end of the secondary spiral conductor in the sixth circuit layer through the tenth connection hole.

[0008] Preferably, a fourth capacitor element is also provided on the third circuit layer, and the third capacitor element and the fourth capacitor element are electrically connected to the first capacitor element of the first circuit layer through the secondary connection hole and the third connection hole respectively; an eighth capacitor element and a tenth capacitor element are also provided on the fourth circuit layer, and the eighth capacitor element and the tenth capacitor element are electrically connected through a short section of transmission line, and the connection point is electrically connected to the auxiliary waveguide line through the fifth connection hole; the eighth capacitor element and the fourth capacitor element are vertically coupled to form an equivalent capacitor C3; the tenth capacitor element and the sixth capacitor element are vertically coupled to form an equivalent capacitor C5; a third spiral conductor is also provided on the sixth circuit layer, and one end of the third spiral conductor is electrically connected to the other end of the primary spiral conductor through the ninth connection hole; a fifth spiral conductor is also provided on the seventh circuit layer, and one end of the fifth spiral conductor is electrically connected to the other end of the third spiral conductor through the eleventh connection hole.

[0009] Preferably, the package is a HTCC ceramic body. HTCC ceramic body has high thermal conductivity and good thermal stability, and can effectively disperse and conduct heat, thereby improving the reliability and stability of electronic equipment in a high temperature environment.

[0010] Preferably, the U-shaped spiral wires in the fifth to seventh circuit layers are electrically connected together end to end in sequence through metal connection holes, and are equivalent to two inductor coils respectively.

[0011] Preferably, the secondary spiral wire, the fourth spiral wire, the eighth connecting hole, the tenth connecting hole, the twelfth connecting hole and the thirteenth connecting hole constitute an equivalent inductance L1.

[0012] Preferably, the third spiral wire, the fifth spiral wire, the ninth connecting hole, the eleventh connecting hole, the fourteenth connecting hole and the fifteenth connecting hole constitute an equivalent inductance L2.

[0013] Preferably, the main waveguide and the fourth connection hole together constitute an equivalent resonance line D1; the auxiliary waveguide and the fifth connection hole together constitute an equivalent resonance line D2.

[0014] Preferably, the secondary connection hole and the third connection hole are equivalent to the resonance line D3 and the resonance line D4 respectively; the fifth transmission line and the seventh connection hole together constitute the equivalent resonance line D5; the sixth connection hole and the primary connection hole together constitute the equivalent resonance line D6.

[0015] Preferably, the relative dielectric constant of the HTCC ceramic material is 9.4, and the dielectric loss angle is 0.0001.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The present invention realizes low power and high stopband suppression by vertically coupling the circuit layer and the capacitor element and using the spiral wire. Specifically, the two transmission lines included in the first circuit layer are electrically connected to the input terminal P1 and the output terminal P2, and the first capacitor element is electrically connected to the ground terminals P3 and P4, forming the basic structure of the filter; by arranging multiple circuit layers inside the package, such as the second to seventh circuit layers, and arranging specific capacitor elements and spiral wires on these layers, the transmission of the signal can be effectively controlled and the signal within a specific frequency range can be suppressed; the use of the spiral wire increases the inductance effect, which helps to suppress the signal within a wider stopband range, and the vertically coupled capacitor element helps to improve the selectivity and stopband suppression capability of the filter; 2. The present invention integrates multiple circuit layers in a multi-layer ceramic substrate, and the filter can accurately control and adjust the capacitance and inductance values ​​between different layers, thereby achieving accurate filtering of multiple frequency bands. It has different filtering characteristics in different frequency bands to meet the needs of multi-band communication; secondly, by rationally utilizing structures such as vertical coupling and spiral lines, the filter achieves complex resonance and stopband suppression characteristics in a smaller volume, which helps to filter out interference in specific frequency bands, thereby supporting multi-mode communication; in addition, the circuit design of the filter also allows multiple transmission zeros to be generated in a limited space, further improving the filter's ability to suppress specific frequencies and ensuring performance stability and reliability in a multi-mode communication environment; therefore, this layered connection filter design not only improves the integration level, but also achieves effective support for multi-band and multi-mode communications through precise circuit control; 3. Since all circuit elements and connections are integrated in the ceramic package, the reliability and stability of the filter are significantly improved. Compared with the traditional discrete component design, the integrated design reduces the number of external connections and interfaces, thereby reducing the failure rate and signal loss. In addition, the use of HTCC materials also improves the heat resistance and environmental resistance of the filter, further enhancing its reliability in various application environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of the present invention, and do not constitute a limitation of the embodiments of the present invention. In the drawings: Figure 1 is an equivalent circuit diagram of the present invention; Figure 2 is a schematic diagram of a first circuit layer of the present invention; Figure 3 is a schematic diagram of a second circuit layer of the present invention; Figure 4 is a schematic diagram of a third circuit layer of the present invention; Figure 5is a schematic diagram of a fourth circuit layer of the present invention; Figure 6 is a schematic diagram of a fifth circuit layer of the present invention; Figure 7 is a schematic diagram of the sixth circuit layer of the present invention; Figure 8 is a schematic diagram of the seventh circuit layer of the present invention; Fig. 9 It is the overall structure diagram of the present invention; Fig.10 This is a schematic diagram of the third circuit layer in Embodiment 2 of the present invention; Fig.11 This is a schematic diagram of the fourth circuit layer in Embodiment 2 of the present invention; Fig.12 This is a schematic diagram of the fifth circuit layer in Embodiment 2 of the present invention; Fig.13 is an equivalent circuit diagram of embodiment 2 of the present invention; Fig.14 This is a diagram of the electromagnetic simulation results of Example 2 of the present invention.

[0018] Marks and corresponding parts names in the attached drawings: 1- auxiliary waveguide line, 10- eighth capacitor element, 11- ninth capacitor element, 12- tenth capacitor element, 13- third transmission line, 14- fourth transmission line, 15- fifth transmission line, 16- first spiral conductor, 17- second spiral conductor, 18- third spiral conductor, 19- fourth spiral conductor, 20- fifth spiral conductor, 21- sixth spiral conductor, 22- seventh spiral conductor; 2-main wave line, 23-fourth connecting hole, 24-fifth connecting hole, 25-thirteenth connecting hole, 26-fifteenth connecting hole, 27-secondary connecting hole, 28-third connecting hole, 29-seventh connecting hole; 3-first capacitor element, 30-primary connection hole, 31-sixth connection hole, 32-eighth connection hole, 33-ninth connection hole, 34-tenth connection hole, 35-eleventh connection hole, 36-twelfth connection hole, 37-fourteenth connection hole; 4- a second capacitive element; 5- a third capacitor element; 6- a fourth capacitance element; 7- a fifth capacitor element; 8-sixth capacitor element; 9-Seventh capacitor element. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and drawings. The schematic implementation modes and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention. It should be noted that the present invention is already in the actual development and use stage.

[0020] In electronic system design, it is a challenge to achieve filters with low power consumption and high stopband suppression effects because there is an inherent design trade-off between the two. Traditional filter design often requires increasing circuit complexity and using more passive components (such as capacitors and inductors) to achieve high stopband suppression, which directly leads to higher power consumption. In addition, in order to achieve stopband suppression, high-precision components and sophisticated circuit layout are required, which not only increases the design difficulty but also increases the cost. At the same time, optimizing the circuit to reduce power loss usually means sacrificing some frequency selectivity and stopband suppression capabilities, because low-power design often requires simplifying the circuit structure.

[0021] Embodiment 1: A low-power high-stopband suppression narrowband filter comprises a package body, an outer electrode and a plurality of circuit layers arranged inside the package body, wherein the outer electrode comprises an input terminal P1, an output terminal P2, a first ground terminal P3 and a second ground terminal P4; wherein the input terminal P1 and the output terminal P2 are symmetrically arranged, and the first ground terminal P3 and the second ground terminal P4 are symmetrically arranged; the input terminal P1, the output terminal P2, the first ground terminal P3 and the second ground terminal P4 are all electrically connected to a transmission line inside the package body; a first circuit layer is arranged at the bottom of the package body, the first circuit layer comprises two transmission lines and a first capacitor element 3, the two transmission lines are electrically connected to the input terminal P1 and the output terminal P2 respectively, and the two ends of the first capacitor element 3 are electrically connected to the first ground terminal P3 and the second ground terminal P4 respectively. Since the first capacitor element 3 is connected to the ground terminals of different layers, it means that the first capacitor element 3 has two independent grounding points in the circuit, which is conducive to reducing its own parasitic effects, especially the influence of parasitic capacitance. This method helps to reduce the loss of the filter in this embodiment when working at high frequencies.

[0022] There is also a better implementation method of this embodiment. Inside the package body, above the first circuit layer, there are also second circuit layers, third circuit layers, fourth circuit layers, fifth circuit layers, sixth circuit layers and seventh circuit layers. From bottom to top, the second circuit layers to the seventh circuit layers are arranged in sequence. A second capacitor element 4 is provided on the second circuit layer, and the second capacitor element 4 is vertically coupled to the first capacitor element 3; The third circuit layer is provided with a third capacitor element 5, a fifth capacitor element 7 and a sixth capacitor element 8; wherein a transmission line connected to each other and provided with a primary connection hole 30 is provided between the fifth capacitor element 7 and the sixth capacitor element 8; the primary connection hole 30 is electrically connected to the second capacitor element 4; the third capacitor element 5 is electrically connected to the first capacitor element 3 through the secondary connection hole 27, and the fourth capacitor element 6 is electrically connected to the first capacitor element 3 through the third connection hole 28; A seventh capacitor element 9 and a ninth capacitor element 11 are provided on the fourth circuit layer; a transmission line connected to each other and provided with a fourth connection hole 23 is provided between the seventh capacitor element 9 and the ninth capacitor element 11, and the fourth connection hole 23 is electrically connected to the main waveguide 2; wherein the seventh capacitor element 9 is vertically coupled with the third capacitor element 5 to form an equivalent capacitor C2; the ninth capacitor element 11 is vertically coupled with the fifth capacitor element 7 to form an equivalent capacitor C4; The fifth circuit layer is provided with a third transmission line 13, a fourth transmission line 14, a fifth transmission line 15 and a primary spiral conductor; a transmission line connected to each other and provided with a sixth connection hole 31 is provided between the fifth transmission line 15 and the primary spiral conductor, and the sixth connection hole 31 is electrically connected to the primary connection hole 30; the other end of the fifth transmission line 15 is electrically connected to the first capacitor element 3 through the seventh connection hole 29; one end of the third transmission line 13 is connected to the fourth connection hole 23 and is electrically connected to the main waveguide 2; the fourth transmission line 14 is electrically connected to the fifth connection hole 24 and is electrically connected to the auxiliary waveguide 1; A secondary spiral conductor is provided on the sixth circuit layer, and one end of the secondary spiral conductor is electrically connected to the intersection of the fifth transmission line 15 and the primary spiral conductor through the eighth connection hole 32; A fourth spiral conductor 19 is provided on the seventh circuit layer, and one end of the fourth spiral conductor 19 is electrically connected to the other end of the secondary spiral conductor in the sixth circuit layer through the tenth connecting hole 34 .

[0023] By distributing the circuit elements of the filter on multiple levels, complex circuit structures can be integrated in a smaller volume, thus achieving high integration. This not only saves space, but also facilitates integration with other electronic components, and is particularly suitable for modern compact electronic devices. The layered design allows for finer control of circuit parameters such as capacitance, inductance, and resistance values, thereby optimizing the performance of the filter. For example, by precisely adjusting the degree of coupling between the layers, more precise frequency selectivity and stopband suppression can be achieved. In a multilayer structure, the physical isolation between circuit elements helps to reduce electromagnetic interference (EMI). Each layer can act as a shielding layer to reduce crosstalk between signals and improve the stability and reliability of the filter. Layered connected filters generally have higher mechanical strength and better environmental adaptability due to their compact structure and good isolation between components, thereby improving overall reliability.

[0024] Secondly, the hierarchical structure allows for fine control of circuit parameters, such as capacitance and inductance values, to optimize the filter's frequency selectivity and stopband suppression characteristics. The filter's selectivity is improved, enabling it to effectively suppress unwanted frequency components, and the filter's stability in complex electromagnetic environments is enhanced by reducing electromagnetic interference between components and improving signal isolation. Therefore, this hierarchically connected filter achieves efficient suppression of a specific frequency range while maintaining low power consumption, making it particularly suitable for electronic systems with strict requirements on power consumption and signal quality.

[0025] There is also a better implementation of this embodiment, in which a fourth capacitor element 6 is further provided on the third circuit layer, and the third capacitor element 5 and the fourth capacitor element 6 are electrically connected to the first capacitor element 3 of the first circuit layer through the secondary connection hole 27 and the third connection hole 28 respectively; An eighth capacitor element 10 and a tenth capacitor element 12 are also provided on the fourth circuit layer. The eighth capacitor element 10 and the tenth capacitor element 12 are electrically connected through a short transmission line, and the connection is electrically connected to the auxiliary waveguide line 1 through a fifth connection hole 24; the eighth capacitor element 10 is vertically coupled with the fourth capacitor element 6 to form an equivalent capacitor C3; the tenth capacitor element 12 is vertically coupled with the sixth capacitor element 8 to form an equivalent capacitor C5; Equivalent capacitance, which helps to enhance the capacitance effect of the filter and optimize its performance. Through vertical coupling, a larger capacitance value can be achieved in a smaller physical space, which is very beneficial for reducing the size of the filter and improving the integration. In addition, this coupling method can fine-tune the frequency response of the filter, such as bandwidth and stopband suppression, thereby improving the selectivity and performance of the filter. Vertical coupling also helps to reduce parasitic parameters such as parasitic inductance and capacitance, further improving the overall performance of the filter.

[0026] A third spiral conductor 18 is also provided on the sixth circuit layer, and one end of the third spiral conductor 18 is electrically connected to the other end of the primary spiral conductor through a ninth connection hole 33; A fifth spiral conductive line 20 is further provided on the seventh circuit layer. One end of the fifth spiral conductive line 20 is electrically connected to the other end of the third spiral conductive line 18 through the eleventh connecting hole 35 .

[0027] The spiral wires can effectively increase the value of the inductance without taking up too much space, which is crucial for realizing miniaturized filters. In addition, by precisely controlling the geometric parameters of the spiral wires and the coupling between them, the resonant frequency and bandwidth of the filter can be adjusted to achieve the desired stopband suppression characteristics. This layout of the spiral wires also helps to reduce electromagnetic interference and improve the performance stability of the filter.

[0028] There is also a better implementation method for this embodiment, in which the package body is a HTCC ceramic body. The HTCC ceramic body has high thermal conductivity and good thermal stability, and can effectively disperse and conduct heat, thereby improving the reliability and stability of electronic equipment in high temperature environments. In addition, the HTCC ceramic body has high mechanical strength and can withstand physical shocks and vibrations in harsh environments, providing additional physical protection for the filter. The HTCC material also has low dielectric loss and high dielectric constant, which helps to reduce the loss of signals during transmission and improve the performance of the filter. At the same time, the HTCC ceramic body has good chemical stability and is not easily affected by chemical corrosion, ensuring reliability in long-term use.

[0029] The steps for making the HTCC ceramic substrate of the present invention are as follows: 1. Ceramic powder preparation: First select suitable ceramic powder, usually alumina or other high temperature ceramic materials.

[0030] 2. Preparation of green porcelain tape: Ceramic powder is mixed with a binder and made into a green porcelain tape with precise thickness through extrusion molding or tape casting technology.

[0031] 3. Punching and via hole formation: Use laser punching technology to form via holes on the green porcelain tape. These holes will be used in the subsequent metallization process to achieve electrical connection between layers.

[0032] 4. Micropore grouting: Fill the conductive slurry, usually silver slurry or copper slurry, in the conductive holes of the green porcelain tape to form a conductive path.

[0033] 5. Conductive pattern printing: Print conductive patterns on the surface of the green porcelain tape. These patterns will form the conductive paths, capacitors, resistors and other passive components in the circuit layer. Use screen printing or other printing techniques to accurately apply conductive paste on the green porcelain tape.

[0034] 6. Lamination and lamination: The green ceramic tapes with conductive patterns are laminated in the designed order and pressed at high temperature. This process combines the layers tightly together to form an integral multi-layer ceramic substrate.

[0035] 7. Co-firing: The laminated multilayer ceramic substrate is placed in a high-temperature furnace for co-firing. At high temperatures, the ceramic material is sintered and densified, while the metal particles in the conductive paste are sintered to form a conductive path.

[0036] 8. Post-processing: After sintering is completed, some post-processing steps may be required, such as surface treatment, cutting, drilling, etc., to form the final HTCC substrate size and shape and install necessary external connectors or terminals.

[0037] There is also a better implementation method for this embodiment. The U-shaped spiral wires in the fifth circuit layer to the seventh circuit layer are electrically connected together at the ends through metal connection holes in sequence, and are equivalent to two inductor coils. L1 and L2 interact with the capacitor element to form a resonant circuit, which helps to accurately control the cutoff frequency and bandwidth of the filter. By adjusting the inductance value, the resonant frequency can be changed, thereby adjusting the performance of the filter to meet specific application requirements.

[0038] There is also a better implementation method of this embodiment, the secondary spiral wire, the fourth spiral wire 19, the eighth connection hole 32, the tenth connection hole 34, the twelfth connection hole 36 and the thirteenth connection hole 25 constitute an equivalent inductance L1.

[0039] There is also a better implementation method for this embodiment, the third spiral conductor 18, the fifth spiral conductor 20, the ninth connecting hole 33, the eleventh connecting hole 35, the fourteenth connecting hole 37 and the fifteenth connecting hole 26 constitute an equivalent inductance L2; the main waveguide line 2 and the fourth connecting hole 23 together constitute an equivalent resonant line D1; the auxiliary waveguide line 1 and the fifth connecting hole 24 together constitute an equivalent resonant line D2.

[0040] There is a better implementation method for this embodiment. The secondary connection hole 27 and the third connection hole 28 are equivalent to the resonance line D3 and the resonance line D4 respectively; the fifth transmission line 15 and the seventh connection hole 29 together constitute the equivalent resonance line D5; the sixth connection hole 31 and the primary connection hole 30 together constitute the equivalent resonance line D6.

[0041] There is a better implementation of this embodiment. The relative dielectric constant of the HTCC ceramic material is 9.4, and the dielectric loss angle is 0.0001.

[0042] The present invention proposes an innovative filter circuit design method, that is, by integrating lumped elements and distributed elements, a "semi-lumped resonant circuit" is constructed. This design strategy effectively combines the precise control characteristics of lumped elements and the wide-band advantages of distributed elements. In this way, not only the influence of parasitic parameters that may be introduced by lumped elements is significantly reduced, but also several precise transmission zeros are successfully realized in a limited physical space. These transmission zeros are crucial to the performance of the filter because they can be accurately positioned at specific frequency points, thereby achieving a strong suppression effect on the signal at these frequency points. As a result, this design not only improves the stopband suppression characteristics of the filter, but also ensures high selectivity and low insertion loss of the filter within the required frequency band while maintaining circuit miniaturization. Therefore, the filter circuit design of the present invention not only optimizes the performance, but also meets the requirements of modern electronic devices for miniaturization and high integration.

[0043] Figure 1In the figure, L1 and C4 are connected in parallel to form the first resonance unit; C5 and L2 are connected in parallel to form the second resonance unit, wherein the first resonance unit and the second resonance unit are connected in parallel to each other, C2 and D3 are connected in series to form the third resonance unit, C3 and D4 are connected in series to form the fourth resonance unit, and C1 and D6 are connected in series to form the fifth resonance unit. The first resonance unit and the second resonance unit determine the cutoff frequency of the filter, and the third resonance unit, the fourth resonance unit and the fifth resonance unit determine the position of the transmission zero point.

[0044] Embodiment 2: This embodiment only describes the parts that are different from the embodiment 1. Specifically, in the design process of the embodiment 1, since the width of the transmission line is almost equal to the inductance, and the length is almost equal to the side length of the capacitors C1 and C2, according to the equivalent circuit model of the transmission line, the transmission line will introduce parasitic capacitance to ground and parasitic series inductance at the same time, and these two parasitic effects cannot be completely eliminated. The longer the length of the transmission line, the greater the parasitic inductance introduced. In the technical solution of the embodiment 1, although the problem that the existing filter cannot achieve high stopband suppression under low power operation is solved or alleviated, in this embodiment, there are still the following optimization options, more specifically: As attached Fig.10 , which is a schematic diagram of an improved solution for the third circuit layer, wherein an alternative solution for the third circuit layer includes a metal sheet H1, a metal sheet H2 and a plurality of vias; As attached Fig.11 , which is a schematic diagram of an improved solution for the fourth circuit layer, wherein the alternative solution for the fourth circuit layer includes a metal sheet H3, a metal sheet H4, a metal sheet H5 and a plurality of vias; As attached Fig.12 , which is a schematic diagram of an improved solution for the fifth circuit layer, wherein an alternative solution for the fifth circuit layer includes a metal sheet H6, a metal sheet H7 and a plurality of vias.

[0045] More specifically, in the alternative solution of the third circuit layer, the metal sheet H1 is vertically coupled with the second capacitor element (4) in the second circuit layer to form an equivalent capacitor C11; More specifically, in the alternative of the third circuit layer, the metal sheet H2 is vertically coupled with the second capacitor element (4) in the second circuit layer to form an equivalent capacitor C41; More specifically, in the alternative solution of the fourth circuit layer, the metal sheet H3 is vertically coupled with the metal sheets H4 and H6 respectively to form equivalent capacitors C21 and C22; More specifically, in the alternative solution of the fourth circuit layer, the metal sheet H3 is vertically coupled with the metal sheets H5 and H7 respectively to form equivalent capacitors C31 and C32; More specifically, in the alternative of the fifth circuit layer, the metal sheet H6 is vertically coupled with the sixth capacitor element (8) in the sixth circuit layer to form an equivalent capacitor C12; More specifically, in the alternative of the fifth circuit layer, the metal sheet H7 is vertically coupled with the sixth capacitor element (8) in the sixth circuit layer to form an equivalent capacitor C42.

[0046] Reference Fig.13 On the basis of the above improvement scheme, L1 is designed as two parallel sub-inductors to increase the size of the small inductor and reduce the parasitic effect; the main parts of L1 are placed on the fifth and sixth layers respectively, and these two parts are connected to the ground of the first and fifth layers through vias; the preferred structure of L2 and L3 in this embodiment is a planar zigzag inductor to adapt to increasing the inductance value of the inductor in a limited space; L2 is adjacent to C2, and L3 is adjacent to C3, and they are both placed directly next to the corresponding capacitors; since the value of C1 is much larger than that of C2 and C3, L2 and L3 can be placed directly next to C2 and C3 without introducing additional parasitic capacitance to the ground; L4 is similar to L1, L2 and L3 in structure, and is also an inductor composed of metal strips and metal vias, which will not be repeated here. Based on the above content, the parasitic capacitance of the inductor can be fully utilized, and the capacitor does not introduce additional parasitic effects. This is partly because adjacent components share the same plate, which can greatly reduce the use of transmission lines. Since no transmission lines are required, the structure of this capacitor is very compact, thereby reducing the parasitic effects introduced by the transmission lines.

[0047] It can also be understood that in a multilayer dielectric structure filter, the frequency response of the LC resonator mainly depends on the product of capacitance and inductance. If the product of capacitance and inductance is guaranteed to be constant, when the capacitance and inductance values ​​change within a certain range, the performance of the resonator remains basically unchanged. This characteristic means that even if there are parasitic effects, as long as the product of capacitance and inductance is controlled well, the performance of the filter can be maintained, thereby utilizing the parasitic effects instead of being affected by them. Based on the above characteristics, the improved scheme in this embodiment can place components that may produce coupling on different layers, and even use the ground to isolate multiple components, thereby reducing parasitic coupling between components, and divide L1 into two parallel sub-inductors, whose main parts are placed on the fifth and sixth layers respectively, and use metal vias to connect them to the ground of the fourth and seventh layers respectively. In this way, the size of L1 can be doubled in theory, and the parasitic capacitance between L1 and the ground can be utilized by the resonator, thereby reducing the size of C1.

[0048] Combined with Fig.14 , which is the electromagnetic simulation result of the filter. It is not difficult to see that it is in very good agreement with the circuit simulation result, and no parasitic passband appears at the second and third frequencies, which once again verifies the advantage of stacked plate capacitors in reducing parasitic effects.

[0049] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A low-power high-stopband suppression narrowband filter, comprising a package, an outer electrode and a plurality of circuit layers arranged inside the package, characterized in that: The outer electrode includes an input terminal P1, an output terminal P2, a first ground terminal P3 and a second ground terminal P4; wherein the input terminal P1 and the output terminal P2 are symmetrically arranged, and the first ground terminal P3 and the second ground terminal P4 are symmetrically arranged; The input terminal P1, the output terminal P2, the first ground terminal P3 and the second ground terminal P4 are all electrically connected to the transmission line inside the package; A first circuit layer is provided at the bottom of the package body, the first circuit layer comprising two transmission lines and a first capacitor element (3), the two transmission lines are electrically connected to the input end P1 and the output end P2 respectively, and the two ends of the first capacitor element (3) are electrically connected to the first ground end P3 and the second ground end P4 respectively.

2. A low-power high-stopband suppression narrowband filter according to claim 1, characterized in that: Inside the package, above the first circuit layer, there are also second circuit layers, third circuit layers, fourth circuit layers, fifth circuit layers, sixth circuit layers and seventh circuit layers, and from bottom to top, the second circuit layers to the seventh circuit layers are arranged in sequence; A second capacitor element (4) is provided on the second circuit layer, and the second capacitor element (4) is vertically coupled to the first capacitor element (3); A third capacitor element (5), a fifth capacitor element (7) and a sixth capacitor element (8) are provided on the third circuit layer; wherein a transmission line is provided between the fifth capacitor element (7) and the sixth capacitor element (8) and is connected to each other and is provided with a primary connection hole (30); the primary connection hole (30) is electrically connected to the second capacitor element (4); the third capacitor element (5) is electrically connected to the first capacitor element (3) via the secondary connection hole (27), and the fourth capacitor element (6) is electrically connected to the first capacitor element (3) via the third connection hole (28); A seventh capacitor element (9) and a ninth capacitor element (11) are provided on the fourth circuit layer; a transmission line connected to each other and provided with a fourth connection hole (23) is provided between the seventh capacitor element (9) and the ninth capacitor element (11); the fourth connection hole (23) is electrically connected to the main waveguide (2); wherein the seventh capacitor element (9) is vertically coupled to the third capacitor element (5); and the ninth capacitor element (11) is vertically coupled to the fifth capacitor element (7); A third transmission line (13), a fourth transmission line (14), a fifth transmission line (15) and a primary spiral conductor are provided on the fifth circuit layer; a transmission line connected to each other and provided with a sixth connection hole (31) is provided between the fifth transmission line (15) and the primary spiral conductor, and the sixth connection hole (31) is electrically connected to the primary connection hole (30); the other end of the fifth transmission line (15) is electrically connected to the first capacitor element (3) through the seventh connection hole (29); one end of the third transmission line (13) is connected to the fourth connection hole (23) and is also electrically connected to the main waveguide (2); the fourth transmission line (14) is electrically connected to the fifth connection hole (24) and is also electrically connected to the auxiliary waveguide (1); A secondary spiral conductor is provided on the sixth circuit layer, and one end of the secondary spiral conductor is electrically connected to the intersection of the fifth transmission line (15) and the primary spiral conductor through an eighth connection hole (32); A fourth spiral conductor (19) is provided on the seventh circuit layer, and one end of the fourth spiral conductor (19) is electrically connected to the other end of the secondary spiral conductor in the sixth circuit layer through a tenth connection hole (34).

3. A low-power high-stopband suppression narrowband filter according to claim 2, characterized in that: A fourth capacitor element (6) is also provided on the third circuit layer, and the third capacitor element (5) and the fourth capacitor element (6) are electrically connected to the first capacitor element (3) of the first circuit layer through the secondary connection hole (27) and the third connection hole (28), respectively; An eighth capacitor element (10) and a tenth capacitor element (12) are also provided on the fourth circuit layer. The eighth capacitor element (10) and the tenth capacitor element (12) are electrically connected via a short transmission line, and the connection is electrically connected to the auxiliary waveguide line (1) via a fifth connection hole (24); the eighth capacitor element (10) and the fourth capacitor element (6) are vertically coupled to form an equivalent capacitor C3; the tenth capacitor element (12) and the sixth capacitor element (8) are vertically coupled to form an equivalent capacitor C5; A third spiral conductor (18) is also provided on the sixth circuit layer, and one end of the third spiral conductor (18) is electrically connected to the other end of the primary spiral conductor via a ninth connection hole (33); A fifth spiral conductor (20) is also provided on the seventh circuit layer, and one end of the fifth spiral conductor (20) is electrically connected to the other end of the third spiral conductor (18) through an eleventh connection hole (35).

4. A low-power high-stopband suppression narrowband filter according to claim 1, characterized in that: The package body is a HTCC ceramic body.

5. A low-power high-stopband suppression narrowband filter according to claim 2, characterized in that: The U-shaped spiral wires in the fifth circuit layer to the seventh circuit layer are electrically connected together end to end through metal connection holes in sequence, and are equivalent to two inductor coils respectively.

6. A low-power high-stopband suppression narrowband filter according to claim 5, characterized in that: The secondary spiral conductor, the fourth spiral conductor (19), the eighth connection hole (32), the tenth connection hole (34), the twelfth connection hole (36) and the thirteenth connection hole (25) constitute an equivalent inductance L1.

7. A low-power high-stopband suppression narrowband filter according to claim 3, characterized in that: The third spiral conductor (18), the fifth spiral conductor (20), the ninth connecting hole (33), the eleventh connecting hole (35), the fourteenth connecting hole (37) and the fifteenth connecting hole (26) constitute an equivalent inductance L2.

8. A low-power high-stopband suppression narrowband filter according to claim 7, characterized in that: The main waveguide line (2) and the fourth connection hole (23) together form an equivalent resonance line D1; the auxiliary waveguide line (1) and the fifth connection hole (24) together form an equivalent resonance line D2.

9. A low-power high-stopband suppression narrowband filter according to claim 8, characterized in that: The secondary connection hole (27) and the third connection hole (28) are equivalent to the resonance line D3 and the resonance line D4 respectively; the fifth transmission line (15) and the seventh connection hole (29) together constitute the equivalent resonance line D5; and the sixth connection hole (31) and the primary connection hole (30) together constitute the equivalent resonance line D6.

10. A low-power high-stopband suppression narrowband filter according to claim 4, characterized in that: The relative dielectric constant of the HTCC ceramic material is 9.4, and the dielectric loss angle is 0.0001.

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