A filter and a method for improving filter performance, electronic device

Abstract

The embodiment of the present application discloses a filter, which comprises an LC filter circuit composed of a capacitor and an inductor, the LC filter circuit comprises a plurality of resonance structures, at least one resonance structure is configured as a hybrid resonance structure, the hybrid resonance structure is realized by replacing the capacitor of the resonance structure at a specified position in the LC filter circuit with an acoustic resonator, so that the hybrid resonance structure can improve the left or right roll-off of the filter, wherein the specified position is determined by the inductance of the inductor and the capacitance of the capacitor of each resonance structure in the LC filter circuit, and the acoustic resonator has a predetermined resonance frequency. The embodiment of the present application also discloses a method for improving the performance of the filter. The present application can improve the roll-off of the filter while improving the design efficiency for the flexible LC filter architecture.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically, to a filter, a method for improving filter performance, and an electronic device. Background Technology

[0002] With the rapid development of communication technology and the increasing complexity of communication systems, the demand for filters has grown, as has the difficulty of filter design. Typically, the filters required by a system need low insertion loss and large bandwidth, while also requiring a rapid roll-off to prevent interference between signals in adjacent passbands. Traditional LC filters can achieve large bandwidth, but suppressing high potentials requires many stages of filtering, which increases insertion loss. While using a standalone acoustic filter can provide a rapid roll-off, its bandwidth is limited.

[0003] A hybrid filter employing both LC filters and acoustic resonators combines the advantages of both, achieving both wide bandwidth and high roll-off performance. In related technologies, when incorporating acoustic resonators into LC filters, the diverse and flexible structures of LC filters, especially complex ones, make it difficult to determine the acoustic resonator's location efficiently and simply, leading to low design efficiency and hindering the achievement of a good match between the acoustic resonator and the LC filter. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a filter and a method and electronic device for improving filter performance, which can determine the optimal match between the LC filter and the acoustic resonator in a complex LC filter architecture.

[0005] This invention provides a filter, which includes an LC filter circuit composed of a capacitor and an inductor, and the LC filter circuit includes multiple resonant structures.

[0006] At least one resonant structure is configured as a hybrid resonant structure, which is achieved by replacing the capacitor of the resonant structure at a designated location in the LC filter circuit with an acoustic resonator, such that the hybrid resonant structure can improve the left or right roll-off of the filter.

[0007] The designated position is determined by the inductance of the inductor and the capacitance of the capacitor in each resonant structure of the LC filter circuit, and the acoustic resonator has a predetermined resonant frequency.

[0008] As a further improvement of the present invention, the inductance of the inductor and the capacitance of the capacitor in the resonant structure at the specified location satisfy a preset condition.

[0009] The preset conditions include one of the following:

[0010] The inductance of the inductor and the capacitance of the capacitor satisfy the following conditions:

[0011] The inductance of the inductor and the capacitance of the capacitor satisfy the following conditions:

[0012] Where C represents the capacitance of the capacitor, L represents the inductance of the inductor, and Fp left Fp represents the frequency point at the left edge of the filter passband. right This indicates the frequency point at the right edge of the filter's passband.

[0013] As a further improvement of the present invention, the inductance value of the inductor and the capacitance value of the capacitor satisfy the following... The resonant structure is located at a first specified position in the LC filter circuit.

[0014] After the hybrid resonant structure is configured at the first designated position, the hybrid resonant structure is used to improve the left roll-off of the filter.

[0015] As a further improvement of the present invention, the inductance value of the inductor and the capacitance value of the capacitor satisfy the following... The resonant structure is located at the second specified position in the LC filter circuit.

[0016] After the hybrid resonant structure is configured at the second designated position, the hybrid resonant structure is used to improve the right roll-off of the filter.

[0017] As a further improvement of the present invention, the hybrid resonant structure is a series resonant structure in which the acoustic resonator and the inductor are connected in series, or

[0018] The parallel resonant structure is described, in which the acoustic resonator and the inductor are connected in parallel.

[0019] As a further improvement of the present invention, the filter is one of a low-pass filter, a high-pass filter, and a band-pass filter.

[0020] As a further improvement of the present invention, the acoustic resonator is a BAW resonator or a SAW resonator.

[0021] As a further improvement of the present invention, the resonant frequency of the acoustic resonator is determined by the frequency point at which the filter roll-off is to be increased.

[0022] This invention also provides a method for improving filter performance. The filter includes an LC filter circuit composed of a capacitor and an inductor, the LC filter circuit including multiple resonant structures, and the method includes:

[0023] By using the inductance values ​​of the inductors and the capacitance values ​​of the capacitors in each resonant structure of the LC filter circuit, at least one designated position is determined within the LC filter circuit.

[0024] By replacing the capacitor in the resonant structure at the specified location with an acoustic resonator, a hybrid resonant structure is formed. This hybrid resonant structure, when configured at the specified location, can improve the left or right roll-off of the filter.

[0025] The acoustic resonator has a predetermined resonant frequency.

[0026] As a further improvement of the present invention, determining at least one specified position in the LC filter circuit by using the inductance value of the inductor and the capacitance value of the capacitor in each resonant structure of the LC filter circuit includes one of the following:

[0027] When the inductance of the inductor and the capacitance of the capacitor in the resonant structure satisfy... When the resonant structure is located in the LC filter circuit, the designated position is determined.

[0028] When the inductance of the inductor and the capacitance of the capacitor in the resonant structure satisfy... When the resonant structure is located in the LC filter circuit, the designated position is determined.

[0029] Where C represents the capacitance of the capacitor, L represents the inductance of the inductor, and Fp left Fp represents the frequency point at the left edge of the filter passband. right This indicates the frequency point at the right edge of the filter's passband.

[0030] As a further improvement of the present invention, the inductance value of the inductor and the capacitance value of the capacitor satisfy the following... The resonant structure is located at a first specified position in the LC filter circuit.

[0031] The method further includes: after configuring the hybrid resonant structure at the first designated position, using the hybrid resonant structure to improve the left roll-off of the filter.

[0032] As a further improvement of the present invention, the inductance value of the inductor and the capacitance value of the capacitor satisfy the following... The resonant structure is located at the second specified position in the LC filter circuit.

[0033] The method further includes: after configuring the hybrid resonant structure at the second designated position, using the hybrid resonant structure to improve the right roll-off of the filter.

[0034] As a further improvement of the present invention, the hybrid resonant structure is a series resonant structure in which the acoustic resonator and the inductor are connected in series, or

[0035] The parallel resonant structure is described, in which the acoustic resonator and the inductor are connected in parallel.

[0036] As a further improvement of the present invention, the filter is one of a low-pass filter, a high-pass filter, and a band-pass filter.

[0037] As a further improvement of the present invention, the acoustic resonator is a BAW resonator or a SAW resonator.

[0038] As a further improvement of the present invention, the method further includes:

[0039] The resonant frequency of the acoustic resonator is determined by the frequency point to be increased by the filter roll-off.

[0040] This invention also provides an electronic device including the aforementioned filter.

[0041] The beneficial effects of this invention are as follows:

[0042] For the flexible LC filter architecture, by defining the range of inductance values ​​for the inductors and capacitance values ​​for the capacitors in the LC series or parallel resonant structures, a suitable capacitor can be selected from the LC filter to replace the acoustic resonator. This improves the filter roll-off without reducing in-band insertion loss and can even improve passband edge insertion loss. Determining the optimal match of the acoustic resonator by using the inductor and capacitor values ​​can improve filter design efficiency and achieve better filter performance. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of a filter circuit with an independently set capacitor in the series branch of an LC filter circuit in related technologies. In the diagram, 101 is the LC filter circuit, C101 is the capacitor, and R101 is the acoustic resonator.

[0045] Figure 2 To be Figure 1 A schematic diagram of the filter circuit after the independently set capacitor is replaced with an acoustic filter. In the figure, there is a 102-LC filter circuit.

[0046] Figure 3 for Figure 2 The diagram shows the effect of the filter circuit.

[0047] Figure 4 A schematic diagram comparing the impedance of a standalone acoustic resonator and an acoustic resonator connected in series with an inductor;

[0048] Figure 5 A schematic diagram showing the improvement in roll-off on different sides of the filter when an inductor is connected in series with an acoustic resonator and the equivalent resonant frequency is 5240MHz.

[0049] Figure 6 A schematic diagram comparing the impedance of a standalone acoustic resonator and an acoustic resonator connected in parallel with an inductor;

[0050] Figure 7 A schematic diagram showing the improvement in roll-off on different sides of the filter when an inductor is connected in parallel with an acoustic resonator, resulting in an equivalent resonant frequency of 1960MHz.

[0051] Figure 8 This is a schematic diagram of a filter circuit in which the capacitor of the LC series resonant structure in the series branch of the LC filter circuit is replaced with an acoustic resonator, as described in the first exemplary embodiment of the present invention. In the figure, 210 is the LC filter circuit, L210 is the inductor, and R210 is the BAW resonator.

[0052] Figure 9 for Figure 8 The diagram shows the effect of the filter circuit.

[0053] Figure 10 The diagram shows a filter circuit in which the capacitor of the LC series resonant structure in the series branch of the LC filter circuit is replaced with an acoustic resonator in a comparative embodiment of the first exemplary embodiment of the present invention. In the diagram, 220 is the LC filter circuit, L220 is the inductor, and R220 is the BAW resonator.

[0054] Figure 11 for Figure 10 The diagram shows the effect of the filter circuit, illustrating that the filter circuit does not meet the limitations of this invention.

[0055] Figure 12 This is a schematic diagram of a filter circuit in which the capacitor of the LC series resonant structure in the series branch of the LC filter circuit is replaced with an acoustic resonator, as described in the second exemplary embodiment of the present invention. In the diagram, 230 is the LC filter circuit, L230 is the inductor, and R230 is the BAW resonator.

[0056] Figure 13 for Figure 12 The diagram shows the effect of the filter circuit.

[0057] Figure 14 The diagram shows a filter circuit in which the capacitor of the LC series resonant structure in the series branch of the LC filter circuit is replaced with an acoustic resonator, which is a comparative embodiment of the second exemplary embodiment of the present invention. In the diagram, 240 is the LC filter circuit, L240 is the inductor, and R240 is the BAW resonator.

[0058] Figure 15 for Figure 14 The diagram shows the effect of the filter circuit, illustrating that the filter circuit does not meet the limitations of this invention.

[0059] Figure 16 This is a schematic diagram of a filter circuit in which the capacitor of the parallel resonant structure of the LC filter circuit is replaced with an acoustic resonator in the parallel branch of the LC filter circuit, as described in the third exemplary embodiment of the present invention. In the figure, 250 is the LC filter circuit, L250 is the inductor, and R250 is the BAW resonator.

[0060] Figure 17 for Figure 16 The diagram shows the effect of the filter circuit.

[0061] Figure 18 This is a schematic diagram of a filter circuit in which the capacitor of the parallel resonant structure of the LC filter circuit in the parallel branch is replaced with an acoustic resonator, as described in the fourth exemplary embodiment of the present invention. In the figure, 260 is the LC filter circuit, L260 is the inductor, and R260 is the BAW resonator.

[0062] Figure 19 for Figure 18 The diagram shows the effect of the filter circuit. Detailed Implementation

[0063] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0064] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0065] Furthermore, the terminology used in the description of this invention is for illustrative purposes only and is not intended to limit the scope of the invention. The terms "comprising" and / or "including" are used to specify the presence of said elements, steps, operations, and / or components, but do not exclude the presence or addition of one or more other elements, steps, operations, and / or components. The terms "first," "second," etc., may be used to describe various elements, do not represent an order, and do not limit these elements. Moreover, in the description of this invention, unless otherwise stated, "a plurality of" means two or more. These terms are used only to distinguish one element from another. These and / or other aspects become apparent in conjunction with the following drawings, and those skilled in the art will more readily understand the description of the embodiments of the invention. The drawings are used for illustrative purposes only to depict the embodiments of the invention. Those skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods shown in the invention can be employed without departing from the principles of the invention.

[0066] In related technologies, in relatively simple LC filter architectures, capacitors are typically placed separately on the series or parallel branches of the filter circuit. In this case, these capacitors can be directly replaced with acoustic resonators to enhance the filter roll-off. The maximum impedance of the acoustic resonator is at the roll-off point, while the minimum impedance is within the passband. Therefore, replacing the capacitor with an acoustic resonator will improve the roll-off while simultaneously increasing the insertion loss at the passband edge. This represents the optimal matching situation when there are independently placed capacitors on the series or parallel branches.

[0067] For example, such as Figure 1 The bandpass filter 101 shown has an independent capacitor C101 in its series branch. In this case, the capacitor C101 can be replaced with an acoustic resonator R101 to form a... Figure 2 The filter circuit 102 shown is shown. The acoustic resonator R101 and capacitor C101 have the same capacitance value in the filter passband. The parallel resonant frequency Fp of the acoustic resonator R101 forms a zero at the right roll-off edge of the filter passband to enhance the right roll-off performance of the LC filter. At the same time, the series resonant frequency Fs of the acoustic resonator R101 is within the filter passband, which can reduce the passband insertion loss at this point. Figure 3 This illustrates the effect of replacing capacitor C101 with acoustic resonator R101, where LC represents Figure 1 In the LC filter circuit, LC+BAW represents Figure 2 The replaced filter circuit shows that while the new filter strengthens the right roll-off, it does not reduce the insertion loss at the edge, which is an optimal match between an LC filter and an acoustic resonator.

[0068] However, for more complex LC filter architectures, where there are no separately installed capacitors in the series or parallel branches of the filter circuit, the above methods cannot meet the requirements of complex LC filter structures. Based on this, the present invention provides a filter that can be applied to complex LC filter architectures to improve the roll-off performance of complex LC filters while achieving wide bandwidth.

[0069] An embodiment of the present invention provides a filter comprising an LC filter circuit composed of a capacitor and an inductor, wherein the LC filter circuit includes multiple resonant structures.

[0070] At least one resonant structure is configured as a hybrid resonant structure, which is achieved by replacing the capacitor of the resonant structure at a designated location in the LC filter circuit with an acoustic resonator, such that the hybrid resonant structure can improve the left or right roll-off of the filter.

[0071] The designated position is determined by the inductance of the inductor and the capacitance of the capacitor in each resonant structure of the LC filter circuit, and the acoustic resonator has a predetermined resonant frequency.

[0072] Because LC filters have diverse and flexible structures, the impact of replacing capacitors at different locations with acoustic resonators on the overall filter performance varies, especially at the passband edges and near-band out-of-band suppression. The filter described in this invention is a combination of an LC filter and an acoustic resonator, applicable to complex LC filter structures. Based on different LC filter architectures and the varying inductor and capacitor values ​​of each resonant structure in the LC filter circuit, by analyzing the range of inductor and capacitor values, the most suitable resonant structure is selected from multiple resonant structures. Replacing the capacitors with acoustic resonators improves filter performance, particularly enhancing the roll-off of the filter sidebands, such as the left or right sideband roll-off. This achieves optimal matching between the LC filter and the acoustic resonator. Without reducing in-band insertion loss, and even improving passband edge insertion loss, the acoustic resonator significantly improves the filter roll-off. The acoustic resonator replaces the capacitor with the same capacitance value as the replaced capacitor.

[0073] It should be noted that the resonant structure in an LC filter circuit can be located on a series branch or a parallel branch. The resonant structure can be an LC series resonant structure with an inductor and a capacitor connected in series, or an LC parallel resonant structure with an inductor and a capacitor connected in parallel. Alternatively, the resonant structure can be a composite resonant structure composed of one or more capacitors, inductors, and resistors, capable of producing at least one series resonant electrical response or at least one parallel resonant electrical response. The composite resonant structure can be equivalent to a combination of one or more basic LC series resonant structures and / or LC parallel resonant structures. It is understood that multiple resonant structures can be multiple LC series resonant structures, multiple LC parallel resonant structures, or a combination of both. Multiple resonant structures can also include the aforementioned composite resonant structure that can be equivalent to one or more LC series resonant structures or LC parallel resonant structures. This invention does not specifically limit the number, location, or constituent elements of the resonant structures in an LC filter circuit.

[0074] In one optional implementation, the hybrid resonant structure is a series resonant structure in which the acoustic resonator and the inductor are connected in series, or

[0075] The parallel resonant structure is described, in which the acoustic resonator and the inductor are connected in parallel.

[0076] In more complex LC filter structures, there are no separate capacitors in the LC filter branches. In this case, it is necessary to replace the capacitors in the LC resonant structure (which can be an LC series resonant structure or an LC parallel resonant structure) of the LC filter circuit with acoustic resonators to form a hybrid resonant structure. This hybrid resonant structure can be a series resonant structure formed by replacing the capacitors in the LC series resonant structure with acoustic resonators, or a parallel resonant structure formed by replacing the capacitors in the LC parallel resonant structure with acoustic resonators.

[0077] In one optional implementation, the inductance of the inductor and the capacitance of the capacitor in the resonant structure at the designated location satisfy a preset condition.

[0078] The preset conditions include one of the following:

[0079] The inductance of the inductor and the capacitance of the capacitor satisfy the following conditions:

[0080] The inductance of the inductor and the capacitance of the capacitor satisfy the following conditions:

[0081] Where C represents the capacitance of the capacitor, L represents the inductance of the inductor, and Fp left Fp represents the frequency point at the left edge of the filter passband. rightThis indicates the frequency point at the right edge of the filter's passband.

[0082] As mentioned earlier, in more complex LC filter structures, when there is no separate capacitor in the LC filter branch or a separate capacitor is unsuitable, it is necessary to analyze the architecture of the LC filter circuit and the range of L and C values ​​for each resonant structure (LC series resonant structure and / or LC parallel resonant structure) in the filter circuit to select the optimal acoustic resonator to replace the capacitor, thereby configuring a hybrid resonant structure and achieving the best performance and optimal matching of the filter circuit. When analyzing the range of capacitor and inductor values, the focus is on each resonant structure in the LC filter circuit. When the values ​​of the capacitor and inductor in a certain resonant structure meet preset conditions, it can be determined that the capacitor in that resonant structure is the optimal replacement, achieving optimal matching. It can be understood that regardless of whether the resonant structure is an LC series resonant structure or an LC parallel resonant structure, the preset conditions that must be met when determining the optimal replacement are consistent.

[0083] In one alternative implementation, the resonant frequency of the acoustic resonator is determined by the frequency point at which the filter roll-off is to be increased.

[0084] When performing the preset condition judgment, first determine the suppression frequency of the improved filter (i.e., the frequency at which the filter roll-off needs to be improved), that is, first determine the resonant frequency of the acoustic resonator. Then, based on the above preset conditions, select a suitable resonant structure in the LC filter circuit to configure the hybrid resonant structure, achieving the optimal replacement of the acoustic resonator. This resonant frequency can be the equivalent parallel resonant frequency of the hybrid resonant structure or the equivalent series resonant frequency of the hybrid resonant structure, depending on whether the hybrid resonant structure is a parallel / series resonant structure and whether the hybrid resonant structure is connected in parallel / series in the branches of the LC filter circuit.

[0085] In one optional embodiment, the inductance of the inductor and the capacitance of the capacitor satisfy the following... The resonant structure is located at a first specified position in the LC filter circuit.

[0086] After the hybrid resonant structure is configured at the first designated position, the hybrid resonant structure is used to suppress the left roll-off of the filter.

[0087] In one optional embodiment, the inductance of the inductor and the capacitance of the capacitor satisfy the following... The resonant structure is located at the second specified position in the LC filter circuit.

[0088] After the hybrid resonant structure is configured at the second designated position, the hybrid resonant structure is used to suppress the right roll-off of the filter.

[0089] The filter described in this invention can be a low-pass filter, in which case the inductance and capacitance of the capacitor at the specified resonant structure satisfy the following conditions: At that time, the hybrid resonant structure is used to improve the right roll-off of the filter.

[0090] The filter described in this invention can be a high-pass filter, in which case the inductance and capacitance of the capacitor at the specified resonant structure satisfy the following conditions: At that time, the hybrid resonant structure is used to improve the left roll-off of the filter.

[0091] The filter described in this invention can be a bandpass filter, in which case the inductance and capacitance of the capacitor at the specified resonant structure satisfy the following conditions: At that time, the hybrid resonant structure is used to improve the right roll-off of the filter, and the inductance and capacitance of the capacitor at the specified position of the resonant structure meet the following conditions: At that time, the hybrid resonant structure is used to improve the left roll-off of the filter.

[0092] As mentioned earlier, when configuring a hybrid resonant structure, either an LC series resonant structure or an LC parallel resonant structure in the LC filter circuit can be selected, provided that the preset conditions are the same for both. Correspondingly, after configuring and forming the hybrid resonant structure, the resulting hybrid resonant structure can be used to suppress the roll-off on the left or right side of the filter, thereby improving the filter's roll-off performance. If there is an LC series resonant structure in a branch of the LC filter circuit, satisfying... Replacing the capacitor with an acoustic resonator can effectively improve the left-side roll-off of the filter sideband, satisfying the requirements. Replacing the capacitor with an acoustic resonator can effectively improve the right-side roll-off of the filter sideband. If the LC filter circuit has an LC parallel resonant structure in its branch, it satisfies... Replacing the capacitor with an acoustic resonator can effectively improve the left-side roll-off of the filter sideband, satisfying the requirements. Replacing the capacitor with an acoustic resonator can effectively improve the right-side roll-off of the filter sideband.

[0093] When an LC series resonant structure exists in a filter circuit branch, and the capacitor in it is replaced with an acoustic resonator, it is necessary to pay attention to the changes in the equivalent series resonant frequency and the equivalent parallel resonant frequency after the acoustic resonator is connected in series with an inductor. Figure 4The diagram shows an impedance comparison between a standalone acoustic resonator and an acoustic resonator connected in series with an inductor. The gray dashed line represents the impedance curve of the standalone acoustic resonator, while the black solid line represents the impedance curve of the acoustic resonator connected in series with an inductor. It can be seen that after the acoustic resonator forms a hybrid resonant structure with an inductor, its series resonant frequency Fs shifts to a lower frequency, becoming Fs1, and an additional low-impedance point Fs2 is added. If this hybrid resonant structure is connected in series in a branch of an LC filter circuit, Fp is the frequency that forms a high rejection zero, while either Fs1 or Fs2 will fall within the filter's passband. If this hybrid resonant structure is connected in parallel in a branch of an LC filter circuit, either Fs1 or Fs2 forms a high rejection zero, while Fp and the other Fs2 or Fs1 generally fall outside the filter's passband to avoid affecting in-band performance. For example, Fs1 could be the high rejection zero frequency, with Fp and Fs2 outside the filter's passband, or Fs2 could be the high rejection zero frequency, with Fp and Fs1 outside the filter's passband. In both cases where the hybrid resonant structure is connected in series or in parallel in the branch of an LC filter circuit, the range of values ​​for the inductor and capacitor directly affects whether the replacement acoustic resonator is used to enhance the roll-off on the left or right side of the passband.

[0094] If the inductance of the inductor and the capacitance of the capacitor in this LC series resonant structure satisfy... Replacing the capacitor in the LC series resonant structure with an acoustic resonator can effectively improve the left-side roll-off of the filter's sideband. In this case, the parallel resonant frequency of the acoustic resonator in the hybrid resonant structure is to the left of the filter's passband. If the inductance of the inductor and the capacitance of the capacitor in the LC series resonant structure satisfy... Replacing the capacitor in the LC series resonant structure with an acoustic resonator can effectively improve the right-side roll-off of the filter sideband. In this case, the parallel resonant frequency of the acoustic resonator in the hybrid resonant structure is on the right side of the filter passband.

[0095] As mentioned earlier, after determining the suppression frequency of the improved filter, the resonant frequency of the acoustic resonator is also determined. Based on the aforementioned preset conditions, a certain range of inductance and capacitance values ​​(corresponding to the area of ​​the acoustic resonator if it is a BAW resonator) can be obtained. A suitable capacitor in the LC series resonant structure of the LC filter circuit can then be selected to replace the acoustic resonator. For example... Figure 5 As shown, when the resonant frequency Fp of the acoustic resonator is, for example, 5240MHz, and the value range of LC in the LC series resonant structure of the LC filter circuit is on the upper right side of the curve, this LC series resonant structure can be configured as a hybrid resonant structure and applied to improve the roll-off on the left side of the filter passband; similarly, when the value range of LC is on the lower left side of the curve, this LC series resonant structure can be configured as a hybrid resonant structure and applied to improve the roll-off on the right side of the filter passband.

[0096] When an LC parallel resonant structure exists in a filter circuit branch, and the capacitor in it is replaced with an acoustic resonator, it is necessary to pay attention to the changes in the equivalent series resonant frequency and the equivalent parallel resonant frequency after the acoustic resonator is connected in parallel with an inductor. Figure 6 The diagram shows an impedance comparison between a standalone acoustic resonator and an acoustic resonator connected in parallel with an inductor. The gray dashed line represents the impedance curve of the standalone acoustic resonator, and the black solid line represents the impedance curve of the acoustic resonator connected in parallel with an inductor. It can be seen that after the acoustic resonator forms a hybrid resonant structure with an inductor in parallel, its parallel resonant frequency Fp shifts to a higher frequency, becoming Fp2, and an additional high-impedance point Fp1 is added. If this hybrid resonant structure is connected in parallel to a branch of an LC filter circuit, Fs is the frequency that forms the rejection zero, while either Fp1 or Fp2 will fall within the filter's passband. If this hybrid resonant structure is connected in series to a branch of an LC filter circuit, Fp1 or Fp2 is the frequency that forms the high rejection zero, while Fs and the other Fp2 or Fp1 generally fall outside the filter's passband to avoid affecting in-band performance. For example, Fp1 could be the high rejection zero frequency, with Fs and Fp2 outside the filter's passband, or Fp2 could be the high rejection zero frequency, with Fs and Fp1 outside the filter's passband. In both cases where the hybrid resonant structure is connected in series or in parallel in the branch of an LC filter circuit, the range of values ​​for the inductor and capacitor directly affects whether the replacement acoustic resonator is used to enhance the roll-off on the left or right side of the passband.

[0097] If the inductance of the inductor and the capacitance of the capacitor in this LC parallel resonant structure satisfy... Replacing the capacitor in the LC series resonant structure with an acoustic resonator can effectively improve the left-side roll-off of the filter's sideband. In this case, the parallel resonant frequency of the acoustic resonator in the hybrid resonant structure is to the left of the filter's passband. If the inductance of the inductor and the capacitance of the capacitor in the LC parallel resonant structure satisfy... Replacing the capacitor in the LC series resonant structure with an acoustic resonator can effectively improve the right-side roll-off of the filter sideband. In this case, the parallel resonant frequency of the acoustic resonator in the hybrid resonant structure is on the right side of the filter passband.

[0098] As mentioned earlier, after determining the suppression frequency of the improved filter, the resonant frequency of the acoustic resonator is also determined. Based on the aforementioned preset conditions, a certain range of inductance and capacitance values ​​(corresponding to the area of ​​the acoustic resonator if it is a BAW resonator) can be obtained. A suitable capacitor in the LC parallel resonant structure of the LC filter circuit can then be selected to replace the acoustic resonator. For example... Figure 7As shown, when the resonant frequency Fp of the acoustic resonator is, for example, 1960MHz, and the value range of LC in the LC parallel resonant structure of the parallel branch of the LC filter circuit is on the upper right side of the curve, this LC parallel resonant structure can be configured as a hybrid resonant structure and applied to improve the roll-off on the left side of the filter passband; similarly, when the value range of LC is on the lower left side of the curve, this LC parallel resonant structure can be configured as a hybrid resonant structure and applied to improve the roll-off on the right side of the filter passband.

[0099] In one alternative implementation, the acoustic resonator is a BAW resonator or a SAW resonator.

[0100] It is understood that the acoustic resonator of the present invention can be a BAW resonator, i.e., a bulk acoustic wave resonator, or a SAW resonator, i.e., a surface acoustic wave resonator. The present invention does not specifically limit the structure of the acoustic resonator.

[0101] An embodiment of the present invention provides a method for improving filter performance, wherein the filter includes an LC filter circuit composed of a capacitor and an inductor, the LC filter circuit including multiple resonant structures, and the method includes:

[0102] By using the inductance values ​​of the inductors and the capacitance values ​​of the capacitors in each resonant structure of the LC filter circuit, at least one designated position is determined within the LC filter circuit.

[0103] By replacing the capacitor in the resonant structure at the specified location with an acoustic resonator, a hybrid resonant structure is formed. This hybrid resonant structure, when configured at the specified location, can improve the left or right roll-off of the filter.

[0104] The acoustic resonator has a predetermined resonant frequency.

[0105] Because LC filters have diverse and flexible structures, the impact of replacing capacitors at different locations with acoustic resonators on the overall filter performance varies, especially at the passband edges and near-band out-of-band suppression. This invention, based on different LC filter architectures and the varying inductor and capacitor values ​​of each resonant structure in the LC filter circuit, analyzes the range of inductor and capacitor values ​​to select the most suitable resonant structure from multiple resonant structures. Replacing the capacitors in this structure with acoustic resonators improves filter performance, particularly enhancing the roll-off of the filter sidebands, such as the left or right sideband roll-off. This achieves optimal matching between the LC filter and the acoustic resonator. Without reducing in-band insertion loss, and even improving passband edge insertion loss, the acoustic resonator significantly improves the filter roll-off. The acoustic resonator replaces the capacitor with the same capacitance value as the replaced capacitor.

[0106] It should be noted that the resonant structure in an LC filter circuit can be located on a series branch or a parallel branch. The resonant structure can be an LC series resonant structure with an inductor and a capacitor connected in series, or an LC parallel resonant structure with an inductor and a capacitor connected in parallel. Alternatively, the resonant structure can be a composite resonant structure composed of one or more capacitors, inductors, and resistors, capable of producing at least one series resonant electrical response or at least one parallel resonant electrical response. The composite resonant structure can be equivalent to a combination of one or more basic LC series resonant structures and / or LC parallel resonant structures. It is understood that multiple resonant structures can be multiple LC series resonant structures, multiple LC parallel resonant structures, or a combination of both. Multiple resonant structures can also include the aforementioned composite resonant structure that can be equivalent to one or more LC series resonant structures or LC parallel resonant structures. This invention does not specifically limit the number, location, or constituent elements of the resonant structures in an LC filter circuit.

[0107] In one optional implementation, the hybrid resonant structure is a series resonant structure in which the acoustic resonator and the inductor are connected in series, or

[0108] The parallel resonant structure is described, in which the acoustic resonator and the inductor are connected in parallel.

[0109] As mentioned earlier, in more complex LC filter structures, there are no separate capacitors in the LC filter branches. In this case, it is necessary to replace the capacitors in the LC resonant structure (which can be an LC series resonant structure or an LC parallel resonant structure) of the LC filter circuit with acoustic resonators to form a hybrid resonant structure. This hybrid resonant structure can be a series resonant structure formed by replacing the capacitors in the LC series resonant structure with acoustic resonators, or a parallel resonant structure formed by replacing the capacitors in the LC parallel resonant structure with acoustic resonators.

[0110] In one optional implementation, determining at least one designated location in the LC filter circuit using the inductance value of the inductor and the capacitance value of the capacitor in each resonant structure of the LC filter circuit includes one of the following:

[0111] When the inductance of the inductor and the capacitance of the capacitor in the resonant structure satisfy... When the resonant structure is located in the LC filter circuit, the designated position is determined.

[0112] When the inductance of the inductor and the capacitance of the capacitor in the resonant structure satisfy... When the resonant structure is located in the LC filter circuit, the designated position is determined.

[0113] Where C represents the capacitance of the capacitor, L represents the inductance of the inductor, and Fp left Fp represents the frequency point at the left edge of the filter passband. right This indicates the frequency point at the right edge of the filter's passband.

[0114] As mentioned earlier, in more complex LC filter structures, when there is no separate capacitor in the LC filter branch or a separate capacitor is unsuitable, it is necessary to analyze the architecture of the LC filter circuit and the range of L and C values ​​for each resonant structure (LC series resonant structure and / or LC parallel resonant structure) in the filter circuit to select the optimal acoustic resonator to replace the capacitor, thereby configuring a hybrid resonant structure and achieving the best performance and optimal matching of the filter circuit. When analyzing the range of capacitor and inductor values, the focus is on each resonant structure in the LC filter circuit. When the values ​​of the capacitor and inductor in a certain resonant structure meet preset conditions, it can be determined that the capacitor in that resonant structure is the optimal replacement, achieving optimal matching. It can be understood that regardless of whether the resonant structure is an LC series resonant structure or an LC parallel resonant structure, the preset conditions that must be met when determining the optimal replacement are consistent.

[0115] In an optional implementation, the method further includes:

[0116] The resonant frequency of the acoustic resonator is determined by the frequency point to be increased by the filter roll-off.

[0117] When performing the preset condition judgment, first determine the suppression frequency of the improved filter, that is, first determine the resonant frequency of the acoustic resonator. Then, based on the above preset conditions, select a suitable resonant structure in the LC filter circuit to configure the hybrid resonant structure, thereby achieving the optimal replacement of the acoustic resonator. This resonant frequency can be the equivalent parallel resonant frequency of the acoustic resonator in the hybrid resonant structure, or it can be the equivalent series resonant frequency of the acoustic resonator in the hybrid resonant structure. It needs to be determined according to whether the hybrid resonant structure is a parallel / series resonant structure and whether the hybrid resonant structure is connected in parallel or series on the branch of the LC filter circuit.

[0118] In one optional implementation, the inductance of the inductor and the capacitance of the capacitor satisfy the following... The resonant structure is located at a first specified position in the LC filter circuit.

[0119] The method further includes: after configuring the hybrid resonant structure at the first designated position, using the hybrid resonant structure to improve the left roll-off of the filter.

[0120] In one optional implementation, the inductance of the inductor and the capacitance of the capacitor satisfy the following... The resonant structure is located at the second specified position in the LC filter circuit.

[0121] The method further includes: after configuring the hybrid resonant structure at the second designated position, using the hybrid resonant structure to improve the right roll-off of the filter.

[0122] The method described in this invention can be used to improve the roll-off of low-pass filters, high-pass filters, or band-pass filters.

[0123] For a low-pass filter, when the inductance and capacitance of the capacitor at the specified resonant position meet the following conditions... At that time, the hybrid resonant structure is used to improve the right roll-off of the filter.

[0124] For a high-pass filter, when the inductance and capacitance of the capacitor at the specified resonant position satisfy... At that time, the hybrid resonant structure is used to improve the left roll-off of the filter.

[0125] For a bandpass filter, when the inductance and capacitance of the capacitor at the specified resonant position satisfy... When the hybrid resonant structure is used to improve the right roll-off of the filter, the inductance and capacitance of the capacitor at the specified position of the resonant structure meet the following conditions: Yes, the hybrid resonant structure is used to improve the left roll-off of the filter.

[0126] As mentioned earlier, when configuring a hybrid resonant structure, either an LC series resonant structure or an LC parallel resonant structure in the LC filter circuit can be selected, with the same preset conditions for both. Correspondingly, after configuring and forming the hybrid resonant structure, the resulting hybrid resonant structure can be used to improve the roll-off on the left or right side of the filter, thereby improving the filter's roll-off performance. If there is an LC series resonant structure in a branch of the LC filter circuit, satisfying... Replacing the capacitor with an acoustic resonator can effectively improve the left-side roll-off of the filter sideband, satisfying the requirements. Replacing the capacitor with an acoustic resonator can effectively improve the right-side roll-off of the filter sideband. If the LC filter circuit has an LC parallel resonant structure in its branch, it satisfies... Replacing the capacitor with an acoustic resonator can effectively improve the left-side roll-off of the filter sideband, satisfying the requirements. Replacing the capacitor with an acoustic resonator can effectively improve the right-side roll-off of the filter sideband.

[0127] When an LC series resonant structure exists in a filter circuit branch, and the capacitor in it is replaced with an acoustic resonator, it is necessary to pay attention to the changes in the equivalent series resonant frequency and the equivalent parallel resonant frequency after the acoustic resonator is connected in series with an inductor. Figure 4The diagram shows an impedance comparison between a standalone acoustic resonator and an acoustic resonator connected in series with an inductor. The gray dashed line represents the impedance curve of the standalone acoustic resonator, while the black solid line represents the impedance curve of the acoustic resonator connected in series with an inductor. It can be seen that after the acoustic resonator forms a hybrid resonant structure with an inductor, its series resonant frequency Fs shifts to a lower frequency, becoming Fs1, and an additional low-impedance point Fs2 is added. If this hybrid resonant structure is connected in series in a branch of an LC filter circuit, Fp is the frequency that forms a high rejection zero, while either Fs1 or Fs2 will fall within the filter's passband. If this hybrid resonant structure is connected in parallel in a branch of an LC filter circuit, either Fs1 or Fs2 forms a high rejection zero, while Fp and the other Fs2 or Fs1 generally fall outside the filter's passband to avoid affecting in-band performance. For example, Fs1 could be the high rejection zero frequency, with Fp and Fs2 outside the filter's passband, or Fs2 could be the high rejection zero frequency, with Fp and Fs1 outside the filter's passband. In both cases where the hybrid resonant structure is connected in series or in parallel in the branch of an LC filter circuit, the range of values ​​for the inductor and capacitor directly affects whether the replacement acoustic resonator is used to enhance the roll-off on the left or right side of the passband.

[0128] If the inductance of the inductor and the capacitance of the capacitor in this LC series resonant structure satisfy... Replacing the capacitor in the LC series resonant structure with an acoustic resonator can effectively improve the left-side roll-off of the filter's sideband. In this case, the parallel resonant frequency of the acoustic resonator in the hybrid resonant structure is to the left of the filter's passband. If the inductance of the inductor and the capacitance of the capacitor in the LC series resonant structure satisfy... Replacing the capacitor in the LC series resonant structure with an acoustic resonator can effectively improve the right-side roll-off of the filter sideband. In this case, the parallel resonant frequency of the acoustic resonator in the hybrid resonant structure is on the right side of the filter passband.

[0129] As mentioned earlier, after determining the suppression frequency of the improved filter, the resonant frequency of the acoustic resonator is also determined. Based on the aforementioned preset conditions, a certain range of inductance and capacitance values ​​(corresponding to the area of ​​the acoustic resonator if it is a BAW resonator) can be obtained. A suitable capacitor in the LC series resonant structure of the LC filter circuit can then be selected to replace the acoustic resonator. For example... Figure 5 As shown, when the resonant frequency Fp of the acoustic resonator is, for example, 5240MHz, and the value range of LC in the LC series resonant structure of the LC filter circuit is on the upper right side of the curve, this LC series resonant structure can be configured as a hybrid resonant structure and applied to improve the roll-off on the left side of the filter passband; similarly, when the value range of LC is on the lower left side of the curve, this LC series resonant structure can be configured as a hybrid resonant structure and applied to improve the roll-off on the right side of the filter passband.

[0130] When an LC parallel resonant structure exists in a filter circuit branch, and the capacitor in it is replaced with an acoustic resonator, it is necessary to pay attention to the changes in the equivalent series resonant frequency and the equivalent parallel resonant frequency after the acoustic resonator is connected in parallel with an inductor. Figure 6 The diagram shows an impedance comparison between a standalone acoustic resonator and an acoustic resonator connected in parallel with an inductor. The gray dashed line represents the impedance curve of the standalone acoustic resonator, and the black solid line represents the impedance curve of the acoustic resonator connected in parallel with an inductor. It can be seen that after the acoustic resonator forms a hybrid resonant structure with an inductor in parallel, its parallel resonant frequency Fp shifts to a higher frequency, becoming Fp2, and an additional high-impedance point Fp1 is added. If this hybrid resonant structure is connected in parallel to a branch of an LC filter circuit, Fs is the frequency that forms the rejection zero, while either Fp1 or Fp2 will fall within the filter's passband. If this hybrid resonant structure is connected in series to a branch of an LC filter circuit, Fp1 or Fp2 is the frequency that forms the high rejection zero, while Fs and the other Fp2 or Fp1 generally fall outside the filter's passband to avoid affecting in-band performance. For example, Fp1 could be the high rejection zero frequency, with Fs and Fp2 outside the filter's passband, or Fp2 could be the high rejection zero frequency, with Fs and Fp1 outside the filter's passband. In both cases where the hybrid resonant structure is connected in series or in parallel in the branch of an LC filter circuit, the range of values ​​for the inductor and capacitor directly affects whether the replacement acoustic resonator is used to enhance the roll-off on the left or right side of the passband.

[0131] If the inductance of the inductor and the capacitance of the capacitor in this LC parallel resonant structure satisfy... Replacing the capacitor in the LC series resonant structure with an acoustic resonator can effectively improve the left-side roll-off of the filter's sideband. In this case, the parallel resonant frequency of the acoustic resonator in the hybrid resonant structure is to the left of the filter's passband. If the inductance of the inductor and the capacitance of the capacitor in the LC parallel resonant structure satisfy... Replacing the capacitor in the LC series resonant structure with an acoustic resonator can effectively improve the right-side roll-off of the filter sideband. In this case, the parallel resonant frequency of the acoustic resonator in the hybrid resonant structure is on the right side of the filter passband.

[0132] As mentioned earlier, after determining the suppression frequency of the improved filter, the resonant frequency of the acoustic resonator is also determined. Based on the aforementioned preset conditions, a certain range of inductance and capacitance values ​​(corresponding to the area of ​​the acoustic resonator if it is a BAW resonator) can be obtained. A suitable capacitor in the LC parallel resonant structure of the LC filter circuit can then be selected to replace the acoustic resonator. For example... Figure 7As shown, when the resonant frequency Fp of the acoustic resonator is, for example, 1960MHz, and the value range of LC in the LC parallel resonant structure of the parallel branch of the LC filter circuit is on the upper right side of the curve, this LC parallel resonant structure can be configured as a hybrid resonant structure and applied to improve the roll-off on the left side of the filter passband; similarly, when the value range of LC is on the lower left side of the curve, this LC parallel resonant structure can be configured as a hybrid resonant structure and applied to improve the roll-off on the right side of the filter passband.

[0133] In one alternative implementation, the acoustic resonator is a BAW resonator or a SAW resonator.

[0134] As mentioned above, the acoustic resonator of the present invention can be a BAW resonator, i.e., a bulk acoustic wave resonator, or a SAW resonator, i.e., a surface acoustic wave resonator. The present invention does not specifically limit the structure of the acoustic resonator.

[0135] This disclosure also relates to an electronic device including the filter described in the foregoing embodiments.

[0136] The present invention will now be described using several specific embodiments.

[0137] Example 1

[0138] In this embodiment, an LC series resonant structure exists in the series branch of the LC filter circuit. The capacitor in this LC series resonant structure is replaced with a BAW resonator. The resulting filter circuit is as follows: Figure 8 As shown. In the LC filter circuit 210, R210 is a BAW resonator that replaces the capacitor, with a capacitance of 0.5pF, while L210 is an inductor connected in series with it, with an inductance of 0.66nH. Calculations show... The filter has a passband of 3.2-5.8 GHz, and the resonant frequency Fp of the replaced BAW resonator is 6 GHz. Therefore, the hybrid resonant structure formed by the BAW resonator R210 in series with the inductor L210 is suitable for improving the right-side roll-off of the filter. For example... Figure 9 The diagram shows the impedance curve of the BAW resonator R210 connected in series with the inductor L210, and a comparison of the insertion loss before and after replacing the capacitor with the BAW resonator R210. The solid black line represents the original LC series resonant structure, and the dashed gray line represents the hybrid resonant structure. Figure 9 It can be seen that replacing the BAW resonator R210 not only improved the right roll-off of the filter, but also improved the insertion loss of the right sideband. The results show that the BAW resonator and the LC filter circuit achieved good matching.

[0139] Comparative Example 1

[0140] In this comparative embodiment, an LC series resonant structure exists in the series branch of the LC filter circuit. The capacitor in this LC series resonant structure is replaced with a BAW resonator. The resulting filter circuit is as follows: Figure 10 As shown. In the LC filter circuit 220, R220 is a BAW resonator that replaces the capacitor, with a capacitance of 0.51pF, while L220 is an inductor connected in series with it, with an inductance of 2.76nH. The passband of the filter is 3.2-5.8GHz, which does not meet the requirements. Figure 11 The diagram shows the impedance curve of the BAW resonator R220 connected in series with inductor 220, and a comparison of the insertion loss before and after replacing the capacitor with the BAW resonator R220. The solid black line represents the original LC series resonant structure, and the dashed gray line represents the hybrid resonant structure. Figure 11 It can be seen that after replacing the BAW resonator R220, the right sideband suppression effect of the filter is poor, with a high spike, and the insertion loss in the passband is also correspondingly worsened.

[0141] Example 2

[0142] In this embodiment, an LC series resonant structure exists in the series branch of the LC filter circuit. The capacitor in this LC series resonant structure is replaced with a BAW resonator. The resulting filter circuit is as follows: Figure 12 As shown. In the LC filter circuit 230, R230 is a BAW resonator that replaces the capacitor, with a capacitance of 0.86pF, while L230 is an inductor connected in series with it, with an inductance of 11.3nH. Calculations show... The filter has a passband of 2-2.8 GHz, and the resonant frequency Fp of the replaced BAW resonator is 1.92 GHz. Therefore, the hybrid resonant structure formed by the BAW resonator R230 and the inductor L230 is suitable for improving the left roll-off of the filter. Figure 13 The diagram shows the impedance curve of the BAW resonator R230 connected in series with the inductor L230, and a comparison of the insertion loss before and after replacing the capacitor with the BAW resonator R230. The solid black line represents the original LC series resonant structure, and the dashed gray line represents the hybrid resonant structure. Figure 13 It can be seen that replacing the BAW resonator R230 not only improved the left roll-off of the filter, but also improved the insertion loss of the left sideband. The results show that the BAW resonator and the LC filter circuit achieved good matching.

[0143] Comparative Example 2

[0144] In this comparative embodiment, an LC series resonant structure exists in the series branch of the LC filter circuit. The capacitor in this LC series resonant structure is replaced with a BAW resonator. The resulting filter circuit is as follows: Figure 14 As shown. In the LC filter circuit 240, R240 is a BAW resonator that replaces the capacitor, with a capacitance of 0.83pF, while L240 is an inductor connected in series with it, with an inductance of 3.5nH. The passband of the filter is 2-2.8GHz, which does not meet the requirements. Figure 15 The diagram shows the impedance curve of the BAW resonator R240 connected in series with the inductor 240, and a comparison of the insertion loss before and after replacing the capacitor with the BAW resonator R240. The solid black line represents the original LC series resonant structure, and the dashed gray line represents the hybrid resonant structure. Figure 15 It can be seen that after replacing the BAW resonator R240, the left sideband suppression effect of the filter is poor, and the insertion loss in the passband is also correspondingly worsened.

[0145] Example 3

[0146] In this embodiment, an LC parallel resonant structure exists in the parallel branch of the LC filter circuit. The capacitor in this LC parallel resonant structure is replaced with a BAW resonator. The resulting filter circuit is as follows: Figure 16 As shown. In the LC filter circuit 250, R250 is a BAW resonator that replaces the capacitor, with a capacitance of 0.29pF, while L250 is an inductor connected in parallel with it, with an inductance of 1.5nH. Calculations show... The filter has a passband of 4.7-5.3 GHz, and the resonant frequency Fs of the replaced BAW resonator is 5.57 GHz. Therefore, the BAW resonator R250 connected in parallel with the inductor L250 forms a specified resonant mechanism, suitable for improving the right-side roll-off of this filter. For example... Figure 17 The diagram shows the impedance curve of the BAW resonator R250 connected in parallel with the inductor L250, and a comparison of the insertion loss before and after replacing the capacitor with the BAW resonator R250. The solid black line represents the original LC series resonant structure, and the dashed gray line represents the hybrid resonant structure. Figure 17 It can be seen that replacing the BAW resonator R250 significantly improved the right-side roll-off of the filter, indicating that the BAW resonator achieved a good match with the LC filter circuit.

[0147] Example 4

[0148] In this embodiment, an LC parallel resonant structure exists in the parallel branch of the LC filter circuit. The capacitor in this LC parallel resonant structure is replaced with a BAW resonator. The resulting filter circuit is as follows: Figure 18As shown. In the LC filter circuit 260, R260 is a BAW resonator that replaces the capacitor, with a capacitance of 0.3pF, while L260 is an inductor connected in parallel with it, with an inductance of 4nH. Calculations show... The passband of this filter is 4.7-5.4 GHz, and the resonant frequency Fs of the replaced BAW resonator is 4.6 GHz. Therefore, the BAW resonator R260 connected in parallel with the inductor L260 forms a specified resonant structure, suitable for improving the left roll-off of this filter. For example... Figure 19 The diagram shows the impedance curve of the BAW resonator R260 connected in parallel with the inductor L260, and a comparison of the insertion loss before and after replacing the capacitor with the BAW resonator R260. The solid black line represents the original LC series resonant structure, and the dashed gray line represents the hybrid resonant structure. Figure 19 It can be seen that replacing the BAW resonator R260 not only improved the left roll-off of the filter, but also improved the insertion loss of the left sideband. The results show that the BAW resonator and the LC filter circuit achieved good matching.

[0149] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0150] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features but not others included in other embodiments, combinations of features from different embodiments are intended to be within the scope of the invention and form different embodiments. For example, in the claims, any of the claimed embodiments can be used in any combination.

[0151] Those skilled in the art will understand that although the invention has been described with reference to exemplary embodiments, various changes may be made and its elements may be substituted with equivalents without departing from the scope of the invention. Furthermore, many modifications may be made to adapt particular situations or materials to the teachings of the invention without departing from the essential scope of the invention. Therefore, the invention is not limited to the specific embodiments disclosed, but rather the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A filter, characterized in that, The filter includes an LC filter circuit composed of capacitors and inductors. The LC filter circuit includes multiple resonant structures, at least one of which is configured as a hybrid resonant structure. The hybrid resonant structure is achieved by replacing the capacitors of the resonant structures at a specified position in the LC filter circuit with acoustic resonators, so that the hybrid resonant structure can improve the left or right roll-off of the filter. The specified position is determined by the inductance value of the inductor and the capacitance value of the capacitor of each resonant structure in the LC filter circuit. The acoustic resonator has a predetermined resonant frequency. The inductance of the inductor and the capacitance of the capacitor in the resonant structure at the specified location meet a preset condition, which includes one of the following: The inductance of the inductor and the capacitance of the capacitor satisfy the following conditions: The inductance of the inductor and the capacitance of the capacitor satisfy the following conditions: Where C represents the capacitance of the capacitor, and L represents the inductance of the inductor. This indicates the frequency point at the left edge of the filter's passband. This indicates the frequency point at the right edge of the filter's passband.

2. The filter as claimed in claim 1, wherein, The inductance of the inductor and the capacitance of the capacitor satisfy the following conditions: The resonant structure is located at a first designated position in the LC filter circuit. After the hybrid resonant structure is configured at the first designated position, the hybrid resonant structure is used to improve the left roll-off of the filter.

3. The filter as described in claim 1, wherein, The inductance of the inductor and the capacitance of the capacitor satisfy the following conditions: The resonant structure is located at a second specified position in the LC filter circuit. After the hybrid resonant structure is configured at the second specified position, the hybrid resonant structure is used to improve the right roll-off of the filter.

4. The filter according to any one of claims 1-3, wherein, The hybrid resonant structure is either a series resonant structure in which the acoustic resonator and the inductor are connected in series, or a parallel resonant structure in which the acoustic resonator and the inductor are connected in parallel.

5. The filter according to any one of claims 1-3, wherein, The filter is one of a low-pass filter, a high-pass filter, and a band-pass filter.

6. The filter as claimed in claim 1, wherein, The acoustic resonator is a BAW resonator or a SAW resonator.

7. The filter as claimed in claim 1, wherein, The resonant frequency of the acoustic resonator is determined by the frequency point at which the roll-off of the filter is to be increased.

8. A method for improving filter performance, characterized in that, The filter includes an LC filter circuit composed of capacitors and inductors, the LC filter circuit including multiple resonant structures, the method including: determining at least one designated position in the LC filter circuit by the inductance value of the inductor and the capacitance value of the capacitor in each resonant structure in the LC filter circuit, replacing the capacitor of the resonant structure at the designated position with an acoustic resonator, configuring to form a hybrid resonant structure, such that after configuring the hybrid resonant structure at the designated position, the hybrid resonant structure can improve the left or right roll-off of the filter, wherein the acoustic resonator has a predetermined resonant frequency; Specifically, determining at least one designated position in the LC filter circuit by using the inductance value of the inductor and the capacitance value of the capacitor in each resonant structure includes one of the following: when the inductance value of the inductor and the capacitance value of the capacitor in the resonant structure satisfy... When the resonant structure is located in the LC filter circuit, the designated position is determined. When the inductance of the inductor and the capacitance of the capacitor in the resonant structure satisfy... When the resonant structure is located in the LC filter circuit, the designated position is determined. Where C represents the capacitance of the capacitor, and L represents the inductance of the inductor. This indicates the frequency point at the left edge of the filter's passband. This indicates the frequency point at the right edge of the filter's passband.

9. The method of claim 8, wherein, The inductance of the inductor and the capacitance of the capacitor satisfy the following conditions: The resonant structure is located at a first specified position in the LC filter circuit. The method further includes: after configuring the hybrid resonant structure at the first specified position, using the hybrid resonant structure to improve the left roll-off of the filter.

10. The method of claim 8, wherein, The inductance of the inductor and the capacitance of the capacitor satisfy the following conditions: The resonant structure is located at a second specified position in the LC filter circuit, and the method further includes: after configuring the hybrid resonant structure at the second specified position, using the hybrid resonant structure to improve the right roll-off of the filter.

11. The method according to any one of claims 8-10, wherein, The hybrid resonant structure is either a series resonant structure in which the acoustic resonator and the inductor are connected in series, or a parallel resonant structure in which the acoustic resonator and the inductor are connected in parallel.

12. The method according to any one of claims 8-10, wherein, The filter is one of a low-pass filter, a high-pass filter, and a band-pass filter.

13. The method of claim 8, wherein, The acoustic resonator is a BAW resonator or a SAW resonator.

14. The method of claim 8, wherein, The method further includes determining the resonant frequency of the acoustic resonator by using the frequency point to be increased by the filter roll-off.

15. An electronic device comprising a filter as claimed in any one of claims 1-7.

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