Wideband filter based on thin-film bulk acoustic resonator

Abstract

This invention provides a wide passband filter based on a thin-film bulk acoustic wave (BAS) resonator, comprising a BAS resonator module and a resonant network connected in series and / or in parallel with the BAS resonator module. The BAS resonator module includes one or more BAS resonators, and the resonant network includes a series and / or parallel circuit of capacitors and inductors. This invention solves the problem of the difficulty in widening the bandwidth of conventional BAS-based filters. Multiple transmission zeros are generated through the resonant network composed of lumped elements, thereby achieving a wide passband frequency response and good out-of-band rejection. The use of resonators in the topology network of this invention solves the problem of poor passband-stopband transition steepness in conventional lumped element filters. The inherent characteristics of the resonator can effectively help the filter improve sideband steepness, thus achieving excellent bandpass filtering performance.

Description

Technical Field

[0001] This invention relates to the field of filters, and more specifically, to a wide passband filter based on a thin-film bulk acoustic resonator. Background Technology

[0002] With the rapid development of 5G communication, the market demand for miniaturized, high-performance, and high-operating-frequency filters is increasing. Existing technology includes a filter based on a bulk acoustic wave resonator (Chinese patent application number CN201710320471.4), which proposes a bulk acoustic wave resonator and connects multiple resonators in a specific manner to obtain the desired filtering response.

[0003] The shortcomings of existing technologies are as follows: conventional bulk acoustic wave (BAS) resonator-based filters have difficulty widening their bandwidth, while the filter proposed in this patent can achieve a wide passband filtering response by connecting specific lumped elements around the resonator; conventional lumped element-based filters have difficulty improving the steepness of their sidebands, while the filter proposed in this patent can significantly improve the steepness of the passband edges by appropriately using resonators; conventional BAS resonator-based filters often require separate fabrication of the resonator and lumped elements, while the IPD technology used in fabricating the lumped elements in the filter proposed in this patent is compatible with the standard photolithography process used in fabricating the resonator, which greatly... The simplified manufacturing process reduces costs. Conventional filters require the resonator to be packaged separately and then connected to the required lumped components. However, this patent proposes to process the lumped components using IPD technology and package them directly with the resonator. This greatly saves the space required for the overall filter and is conducive to the miniaturization of the integrated system. Currently, there are some filters on the market that combine resonators and IPD lumped components. However, in order to obtain better performance, the parameter values ​​and Q values ​​of capacitors and inductors are often required to be high, which greatly increases the manufacturing difficulty and cost. The capacitor and inductor values ​​required by the filter proposed in this patent are within the commonly used range, which greatly increases the feasibility and practicality of the filter. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a wideband filter based on a thin-film bulk acoustic resonator.

[0005] According to the present invention, a wide passband filter based on a thin-film bulk acoustic wave resonator includes a thin-film bulk acoustic wave resonator module and a resonant network connected in series and / or in parallel with the thin-film bulk acoustic wave resonator module. The thin-film bulk acoustic wave resonator module includes one or more thin-film bulk acoustic wave resonators, and the resonant network includes a series and / or parallel circuit of capacitors and inductors.

[0006] Preferably, the resonant network includes a plurality of first resonant networks connected in series with the thin-film bulk acoustic resonator, wherein the first resonant network includes a capacitor and an inductor connected in parallel.

[0007] Preferably, the resonant network includes a second resonant network connected in parallel to one side of the resonator. The second resonant network includes two parallel circuits, one of which includes a capacitor and an inductor connected in series, and the other circuit includes an inductor; one end of the second resonant network is grounded.

[0008] Preferably, it further includes a third resonant network connected in parallel to the other side of the resonator, the third resonant network including a capacitor and an inductor connected in series, and one end of the third resonant network being grounded.

[0009] Preferably, the thin-film bulk acoustic resonator module includes two thin-film bulk acoustic resonators connected in series.

[0010] Preferably, a fourth resonant network is provided on both sides of the thin-film bulk acoustic resonator module, and the fourth resonant network includes a capacitor and an inductor connected in series.

[0011] Preferably, it further includes a fifth resonant network disposed on both sides of the thin-film bulk acoustic resonator module. The fifth resonant network includes two thin-film bulk acoustic resonators connected in series and an inductor, and one end of the fifth resonant network is grounded.

[0012] According to the present invention, a wide passband filter based on a thin-film bulk acoustic resonator includes an intermediate network structure and a topology network disposed on both sides of the intermediate network structure. The intermediate network structure includes a series and / or parallel circuit of capacitors and inductors, and the topology network includes one or more thin-film bulk acoustic resonators.

[0013] Preferably, the intermediate network structure includes a sixth resonant network connected in series, the sixth resonant network including an inductor and a capacitor connected in series; it also includes a seventh resonant network, one end of which is grounded and the other end of which is connected to the sixth resonant network, the seventh resonant network including an inductor and a capacitor connected in parallel.

[0014] Preferably, one end of the intermediate network structure is connected to an eighth resonant network, and the other end of the intermediate network structure is connected to a ninth resonant network. The eighth resonant network includes a thin-film bulk acoustic resonator and an inductor connected in series. The ninth resonant network includes a first circuit and a second circuit, wherein the first circuit includes an inductor, and the second circuit includes two thin-film bulk acoustic resonators and an inductor connected in series.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. This invention solves the problem of the difficulty in widening the bandwidth of conventional bulk acoustic resonator-based filters. By generating multiple transmission zeros through a resonant network composed of lumped elements, a wide passband frequency response and good out-of-band suppression effect are obtained.

[0017] 2. The resonator used in the topology network of this invention solves the problem of poor passband-stopband transition steepness in conventional lumped element filters. The inherent characteristics of the resonator can effectively help the filter improve sideband steepness, thereby achieving excellent bandpass filtering performance.

[0018] 3. This invention solves the problem that conventional filters require separate fabrication of acoustic resonators and lumped components by using integrated passive device (IPD) technology that is compatible with standard photolithography processes to fabricate the required lumped components, thereby effectively reducing process complexity and cost.

[0019] 4. This invention solves the problem that conventional filters require separate packaging of lumped elements and acoustic resonators by using a method of packaging the lumped elements and acoustic resonators together, thereby greatly reducing the space occupied by the overall filter and improving the system's poor stability. Attached Figure Description

[0020] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0021] Figure 1 This is a topology diagram of the first embodiment of the wide passband filter based on a thin-film bulk acoustic resonator of the present invention.

[0022] Figure 2 This is a schematic diagram of the frequency response of the topology.

[0023] Figure 3 This is a topology diagram of a second embodiment of the wide passband filter based on a thin-film bulk acoustic resonator according to the present invention.

[0024] Figure 4 This is a schematic diagram of the frequency response of the topology.

[0025] Figure 5 This is a topology diagram of the third embodiment of the wide passband filter based on a thin-film bulk acoustic resonator of the present invention.

[0026] Figure 6 This is a schematic diagram of the frequency response of the topology.

[0027] Figure 7 This is a schematic diagram of the packaging structure of a wide passband filter based on a thin-film bulk acoustic resonator.

[0028] The diagram shows:

[0029] 1-Thin-film bulk acoustic resonator

[0030] 2-Metal Electrode

[0031] 3-Integrated capacitors

[0032] 4-Integrated Inductor Detailed Implementation

[0033] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0034] like Figures 1 to 7 As shown, this invention proposes a wide passband filter based on bulk acoustic resonators. The filter consists of a series of lumped elements and several bulk acoustic resonators, and can have three topologies, each of which has superior filtering performance.

[0035] Figure 1 The diagram shows a topology for a wide passband filter based on a bulk acoustic wave resonator proposed in this patent. The filter consists of a bulk acoustic wave resonator 1 and a series of lumped capacitors and inductors. The capacitors and inductors form five resonant networks, each capable of generating a transmission zero. The parallel networks formed by L1 and C1, L2 and C2, and L3 and C3 are connected in series on both sides of the resonator. The network formed by L4 in series with C4 and then in parallel with L5 is connected in parallel in the main branch, with the other end grounded. Similarly, the network formed by C5 in series with L6 is connected in parallel on the right side of the resonator, with the other end grounded. By reasonably adjusting the values ​​of each capacitor and inductor in the circuit, the corresponding transmission zero frequencies can be shifted, thus bringing the five transmission zeros closer together around the passband, forming a wide passband filter response with good out-of-band suppression. It is worth noting that the required lumped component parameters are all within a range easily achievable in actual manufacturing. Furthermore, the filtering characteristics of the resonator itself can further help optimize the out-of-band suppression effect of the passband. Finally, through reasonable design of the lumped components and resonator, the following can be obtained: Figure 2 The high-frequency filter shown features a wide passband, high steepness, and good out-of-band suppression.

[0036] Figure 3The diagram shows another topology of the wide-passband filter based on bulk acoustic resonators proposed in this patent. This filter consists of a series of acoustic resonators and lumped elements, arranged symmetrically. The central acoustic resonator array is arranged in a π-shape, which can generate a bandpass filter response with a certain bandwidth. At the input and output ports on both sides of the resonator array, the network composed of C6 and L7 mainly serves as impedance matching. Furthermore, the inductor L8, connected in series with the resonators and grounded, mainly serves to broaden the bandwidth. By reasonably adjusting the parameter values ​​of the capacitors and inductors, the following can be obtained: Figure 4 The filter shown has a wide passband, good impedance matching, and steep sidebands.

[0037] Figure 5 The diagram shows the third topology of the wide passband filter based on a bulk acoustic wave resonator proposed in this patent. Similarly, this filter consists of a bulk acoustic wave resonator and lumped elements connected by a specific topology. Specifically, L10 and C7, C9 and L14, L11 and C8, and C10 and L15 in the middle of the filter topology form a network structure capable of wide passband filtering. On the left side of this network structure, a topology network consisting of two acoustic wave resonators and two inductors (L9, L13) is connected in series, and on the right side, a topology network consisting of an acoustic wave resonator and inductor L12 is connected in series. Both of these topologies on both sides have band-stop filtering responses, and the operating frequencies of the stopband are distributed on both sides of the entire passband of the filter. Their function is to help the filter achieve a sharp attenuation at the edges of the passband, thereby obtaining good steepness. The overall filtering response of this filter is as follows: Figure 6 As shown, the passband bandwidth and sideband steepness can be optimized by reasonably adjusting the values ​​of the lumped elements in the filter.

[0038] The lumped components required for the filter proposed in this invention can be implemented using Integrated Passive Devices (IPD) technology. IPD technology is compatible with standard photolithography processes for resonator fabrication. Through reasonable process design, the lumped components can be fabricated simultaneously with the acoustic resonator, thereby saving fabrication costs. Figure 7 As shown, the resonator is connected to a topology network consisting of an integrated capacitor 3 and an integrated inductor 4 via a metal electrode 2, resulting in a filter package device. The filter package device obtained through passive component integration technology can be perfectly integrated into a specific integrated circuit, greatly reducing the filter's footprint and manufacturing cost, and effectively improving the filter's stability.

[0039] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0040] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A wideband filter based on a thin-film bulk acoustic resonator, characterized in that, It includes a thin-film bulk acoustic wave resonator module and a resonant network connected in series and / or in parallel with the thin-film bulk acoustic wave resonator module. The thin-film bulk acoustic wave resonator module includes one or more thin-film bulk acoustic wave resonators, and the resonant network includes a series and / or parallel circuit of capacitors and inductors. The resonant network includes multiple first resonant networks connected in series with the thin-film bulk acoustic resonator. The multiple first resonant networks are connected in series on both sides of the resonator. The first resonant network includes a capacitor and an inductor connected in parallel. The resonant network includes a second resonant network connected in parallel to one side of the resonator. The second resonant network includes two parallel circuits, one of which includes a capacitor and an inductor connected in series, and the other circuit includes an inductor; one end of the second resonant network is grounded. It also includes a third resonant network connected in parallel to the other side of the resonator, the third resonant network including a capacitor and an inductor connected in series, and one end of the third resonant network being grounded.

2. A wideband filter based on a thin-film bulk acoustic resonator, characterized in that, It includes a thin-film bulk acoustic wave resonator module and a resonant network connected in series and / or in parallel with the thin-film bulk acoustic wave resonator module. The thin-film bulk acoustic wave resonator module includes one or more thin-film bulk acoustic wave resonators, and the resonant network includes a series and / or parallel circuit of capacitors and inductors. The thin-film bulk acoustic resonator module includes two thin-film bulk acoustic resonators connected in series. The thin-film bulk acoustic resonator module has an equal number of fourth resonant networks on both sides, and the fourth resonant network includes a capacitor and an inductor connected in series. It also includes an equal number of fifth resonant networks disposed on both sides of the thin-film bulk acoustic resonator module. The fifth resonant network includes two thin-film bulk acoustic resonators connected in series and an inductor, with one end of the fifth resonant network grounded.

3. A wideband filter based on a thin-film bulk acoustic resonator, characterized in that, It includes a ninth resonant network, an intermediate network structure, and an eighth resonant network connected in series. The ninth resonant network includes a ninth inductor, a thin-film bulk acoustic wave resonator module formed by connecting two first thin-film bulk acoustic wave resonators in series, and a thirteenth inductor. The eighth resonant network includes a second thin-film bulk acoustic resonator and a twelfth inductor; The intermediate network structure includes a tenth inductor, a seventh capacitor, a ninth capacitor, a fourteenth inductor, an eleventh inductor, an eighth capacitor, a tenth capacitor, and a fifteenth inductor. One end of the ninth inductor is connected to a port. The other end of the ninth inductor is connected to one end of the thin-film bulk acoustic wave resonator module and one end of the tenth inductor. The other end of the thin-film bulk acoustic wave resonator module is connected to one end of the thirteenth inductor. The other end of the thirteenth inductor is grounded. The other end of the tenth inductor is connected to one end of the seventh capacitor. The other end of the seventh capacitor is connected to one end of the ninth capacitor, one end of the fourteenth inductor, and one end of the eleventh inductor. The other end of the ninth capacitor and the other end of the fourteenth inductor are grounded. The other end of the eleventh inductor is connected to one end of the eighth capacitor. The other end of the eighth capacitor is connected to one end of the tenth capacitor, one end of the fifteenth inductor, and one end of the second thin-film bulk acoustic wave resonator. The other end of the tenth capacitor and the other end of the fifteenth inductor are grounded. The other end of the second thin-film bulk acoustic wave resonator is connected to one end of the twelfth inductor. The other end of the twelfth inductor is connected to another port.

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