Large-bandwidth high-steep-drop sideband piezoelectric acoustic resonator and passive microwave device integrated hybrid filter

Abstract

The invention discloses a large-bandwidth high-steep-drop sideband piezoelectric acoustic resonator and passive microwave device integrated hybrid filter, which is characterized by comprising a low-pass part, and the low-pass part comprises a low-pass series trunk and a plurality of low-pass parallel branches; wherein the low-pass series trunk comprises a plurality of LC resonance units which are sequentially connected in series; the low-pass parallel branches are connected between the low-pass series trunk and a ground wire, at least one LC resonance unit is arranged between every two adjacent low-pass parallel branches, and each low-pass parallel branch comprises a low-pass branch capacitive element or a plurality of series low-pass branch capacitive elements. Part or all of the low-pass branch capacitive elements adopt piezoelectric acoustic resonators. The hybrid filter has a large bandwidth, and satisfies narrow transition band and high adjacent band suppression.

Description

Technical Field

[0001] The invention belongs to the technical field of filtering, and in particular relates to a hybrid filter integrating a piezoelectric acoustic wave resonator with a large bandwidth and a high steep drop sideband and a passive microwave device. Background Art

[0002] Filter components are widely used in various fields, such as communication systems, audio processing, industrial automation, medical field, etc. In daily life and work, many electronic devices need to use filters to filter out noise, interference and other unwanted signals to ensure the normal operation of the equipment and clear transmission of signals.

[0003] With the rapid development of communication technology, more and more frequency bands are being put into use, such as the WIFI6E band. As the operating frequency continues to increase, traditional single filter devices include two categories: passive filters and active filters. Passive filters are mainly composed of passive components such as resistors, capacitors and inductors. Their working principle is based on the combination of inductors, capacitors and resistors to filter out signals of specific frequencies. In addition to basic passive components, active filters also contain active components such as amplifiers, which can achieve more complex frequency response characteristics. However, the filters composed of various traditional piezoelectric acoustic resonators cannot meet the performance requirements of large bandwidths due to the influence of material factors such as their electromechanical coupling coefficients.

[0004] The invention patent application with patent number CN104756403A discloses a method for reducing the design cost of an LC filter required to make various changes to the characteristics of an attenuation pole formed by skip coupling. The LC filter unit (100) includes: a ceramic laminate (10) formed by stacking a plurality of ceramic layers (11 to 61), an LC filter circuit formed inside the ceramic laminate (10), and an input terminal, an output terminal, and a ground terminal formed on the surface of the ceramic laminate (10). As a circuit element that forms a skip coupling by connecting to the LC filter circuit to form an attenuation pole, an installation electrode (64a, 64b) for installing at least one of an inductor, a capacitor, and a SAW resonator of an external device is formed on the surface of the ceramic laminate (10). However, the Q value of the LC filter disclosed in the patent is low and cannot meet the demand.

[0005] LC filter, also known as passive filter, is a traditional harmonic compensation device. LC filter is composed of a proper combination of filter capacitor, reactor and resistor, connected in parallel with the harmonic source, in addition to filtering, it also takes into account the need for reactive power compensation. The most common and easy-to-use passive filter structure is to connect the inductor and capacitor in series, which can form a low impedance bypass for the main harmonics (3, 5, 7). In addition, LC filters are also divided into single-tuned filters, high-pass filters, double-tuned filters and triple-tuned filters. Traditional LC filters such as IPD (integrated product) and LTCC (low-temperature co-fired ceramic) cannot meet the requirements of narrow transition band and high adjacent band suppression due to the limitation of the low Q value of the component itself. It can no longer meet all requirements.

[0006] Therefore, the current development direction of the filter industry is to combine the piezoelectric acoustic wave resonator and the LC filter to give full play to the advantages of both and obtain a hybrid filter that has a large bandwidth and meets the requirements of narrow transition band and high adjacent band suppression. Summary of the invention

[0007] The present invention provides a hybrid filter integrating a piezoelectric acoustic wave resonator with a large bandwidth and a high steep drop sideband and a passive microwave device. The hybrid filter has a large bandwidth and satisfies a narrow transition band and high adjacent band suppression.

[0008] A specific embodiment of the present invention provides a hybrid filter integrating a piezoelectric acoustic wave resonator with a large bandwidth and a high steep drop sideband and a passive microwave device, comprising: a low-pass part, the low-pass part comprising a low-pass series trunk circuit and a plurality of low-pass parallel branches; Wherein, the low-pass series trunk circuit includes a plurality of LC resonance units connected in series in sequence; The low-pass parallel branch is connected between the low-pass series trunk and the ground line, and two adjacent low-pass parallel branches are separated by at least one LC resonance unit. The low-pass parallel branch includes a low-pass branch capacitive element, or multiple low-pass branch capacitive elements connected in series, and some or all of the low-pass branch capacitive elements use piezoelectric acoustic wave resonators.

[0009] Therefore, compared with the IPD+BAW disclosed in the prior art, which introduces multiple zeros at the edge of the passband by introducing piezoelectric acoustic wave resonators to improve the adjacent band suppression and the roll-off slope of the transition zone, the present invention retains the LC resonator unit on the main line to make the passband large and gentle, and connects one or more piezoelectric acoustic wave resonators in parallel on the branch line to introduce a high Q value transmission zero point in the transition band, and can also adjust the parameters so that the parallel resonance point of the parallel piezoelectric acoustic wave resonator is located at the passband position to improve the insertion loss in the passband. At the same time, in terms of structure, the present invention disperses and reasonably distributes the piezoelectric acoustic wave resonator in the framework of the IPD filter, so that it can not only play the role of introducing zeros and poles, but also play the role of impedance matching.

[0010] The present invention utilizes an LC resonance unit connected in series on a low-pass series trunk line to make the passband of the hybrid filter provided by the present invention large and flat, and by adjusting relevant parameters, the series resonance point of the piezoelectric acoustic wave resonator located on the low-pass parallel branch line is located at the transition band position, thereby introducing a high-Q transmission zero point of the piezoelectric acoustic wave resonator to improve the transition band and adjacent band suppression, and at the same time, by adjusting relevant parameters, the parallel resonance point of the piezoelectric acoustic wave resonator is located at the passband position to improve the in-band insertion loss.

[0011] Preferably, two adjacent low-pass parallel branches are separated by an LC resonance unit, and all low-pass branch capacitive elements are piezoelectric acoustic wave resonators.

[0012] Preferably, the hybrid filter integrating the piezoelectric acoustic wave resonator with large bandwidth and high steep drop sideband and the passive microwave device further comprises a high-pass part, the high-pass part is connected in series with the low-pass part, and the high-pass part comprises a high-pass series trunk circuit and a plurality of high-pass parallel branches; Wherein, the high-pass series trunk circuit includes a plurality of high-pass trunk circuit capacitive elements connected in series in sequence, and some or all of the high-pass trunk circuit capacitive elements are piezoelectric acoustic wave resonators; The high-pass parallel branch is connected between the high-pass series trunk and the ground line, at least one high-pass trunk capacitive element is spaced between two adjacent high-pass parallel branches, and the high-pass parallel branch includes an LC resonance unit or a piezoelectric acoustic wave resonator.

[0013] Compared with the prior art which can only provide a single zero point, the present invention introduces a series piezoelectric acoustic wave resonator and a parallel piezoelectric acoustic wave resonator, and adjusts the parameters so that the zero points of the two can be combined to form a band-stop effect, thereby forming a wider transition band optimization, and generates poles in the filter passband through multiple parallel piezoelectric acoustic wave resonators to achieve the effect of improving the insertion loss in the passband.

[0014] The present invention introduces a high-pass part so that the hybrid filter has a series piezoelectric acoustic wave resonator in the high-pass series trunk circuit and a parallel piezoelectric acoustic wave resonator in the low-pass parallel branch circuit. The zero points of the above two piezoelectric acoustic wave resonators can be evenly arranged on the transition band, and can also form a band-stop effect after combination, thereby supporting the optimization of a wider transition band that cannot be satisfied by the zero points generated by a single piezoelectric acoustic wave resonator.

[0015] Preferably, the high-pass trunk capacitive element that does not use the piezoelectric acoustic wave resonator uses a capacitor to maintain corresponding impedance matching.

[0016] Preferably, all the capacitive elements of the low-pass branch are piezoelectric acoustic wave resonators to obtain more zero points and improve the optimization effect of the transition band.

[0017] Preferably, the capacitive element of the low-pass branch that does not use the piezoelectric acoustic wave resonator uses a capacitor to maintain corresponding impedance matching.

[0018] Preferably, at least one piezoelectric acoustic wave resonator is spaced between the high-pass portion and the low-pass portion.

[0019] Preferably, the transmission zeros generated by the self-resonance of the piezoelectric acoustic wave resonators in the high-pass part and the low-pass part are distributed in the adjacent band range of the edge of the low-frequency end of the passband.

[0020] Preferably, the piezoelectric acoustic wave resonators in the low-pass parallel branch and the high-pass parallel branch both generate poles within the passband range.

[0021] Preferably, the piezoelectric acoustic wave resonator may be selected from a bulk acoustic wave resonator, a surface acoustic wave resonator, a Lamb wave resonator, but is not limited thereto.

[0022] Compared with the prior art, the present invention has the following beneficial effects: The present invention retains part of the LC resonator unit so that the hybrid filter has a large and gentle passband, and introduces a piezoelectric acoustic wave resonator on the low-pass parallel branch. By adjusting the parameters of the piezoelectric acoustic wave resonator, the transmission zero point generated by the piezoelectric acoustic wave resonator is located within the tie range at the edge of the low-frequency end of the passband, thereby improving the adjacent band suppression and roll-off slope. In addition, since the piezoelectric acoustic wave resonator generates a pole in the passband range, the insertion loss in the band is improved. At the same time, in terms of structure, the present invention reasonably distributes the piezoelectric acoustic wave resonators one by one in the framework of the IPD filter, so that it can not only play the role of introducing zero points and poles, but also play the role of impedance matching. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the structure of a hybrid filter provided in Embodiment 1 of the present invention; Figure 2 This is an S parameter simulation diagram of the hybrid filter provided in Example 1 of the present invention; Figure 3 A schematic diagram of the structure of a hybrid filter provided in Embodiment 2 of the present invention; Figure 4 This is an S parameter simulation diagram of the hybrid filter provided in Example 2 of the present invention; Figure 5 A schematic diagram of the structure of a hybrid filter provided in Embodiment 3 of the present invention; Figure 6 This is an S parameter simulation diagram of the hybrid filter provided in Example 3 of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the accompanying drawings.

[0025] The present invention is described in detail below in conjunction with specific embodiments and drawings. For the convenience of description, the structures shown in the drawings are only the relevant parts of the present invention, not all structures. For the convenience of description and understanding, some typical embodiments are provided below. The present invention includes but is not limited to the listed embodiments, and is applicable to LC filters of various forms and orders and various types of piezoelectric acoustic resonators.

[0026] Example 1: Figure 1 As shown, this example provides a hybrid filter integrating a piezoelectric acoustic wave resonator with a large bandwidth and a high steep drop sideband and a passive microwave device, including: The low-pass part provided in this embodiment includes a low-pass series trunk and a plurality of low-pass parallel branches; the low-pass series trunk includes an LC resonance unit 204 and an LC resonance unit 205 connected in series between the input end and the output end, and a plurality of low-pass parallel branches are respectively connected between the LC resonance unit 204 and the input end, between the LC resonance unit 204 and the LC resonance unit 205, and between the LC resonance unit 205 and the output end. Figure 1 The three low-pass parallel branches respectively include piezoelectric acoustic wave resonator 104, piezoelectric acoustic wave resonator 105, and piezoelectric acoustic wave resonator 106. It can be understood that in this embodiment, more LC resonance units and piezoelectric acoustic wave resonators can be cascaded on the basis of the three low-pass parallel branches in parallel, so as to achieve the desired target performance.

[0027] The hybrid filter provided in this embodiment is obtained by optimizing a traditional LC low-pass filter. The traditional LC low-pass filter is Figure 1 The piezoelectric acoustic wave resonator shown is replaced by an LC resonator. The components of the resonant unit part of the hybrid filter provided in this embodiment retain the part of the LC low-pass filter circuit to maintain the excellent performance of the LC filter, that is, the passband is large and flat, and the components of the non-resonant unit part are composed of various piezoelectric acoustic wave resonators to adjust the relevant parameters on the basis of the LC filter circuit so that the series resonance point of the parallel piezoelectric acoustic wave resonator located in the low-pass parallel branch is located at the transition band position, thereby introducing a high-Q transmission zero point of the piezoelectric acoustic wave resonator to improve the transition band and adjacent band suppression, and at the same time, by adjusting the relevant parameters, the parallel resonance point of the parallel piezoelectric acoustic wave resonator is located at the passband position to improve the in-band insertion loss.

[0028] like Figure 2As shown, curve 01 is the frequency response curve of the hybrid low-pass filter circuit provided in this embodiment, curve 02 is the frequency response curve of the traditional LC low-pass filter compared with the hybrid low-pass filter circuit curve provided in this embodiment, and curve 03 is the impedance curve of the parallel resonator located on the low-pass parallel branch. It can be seen that due to the effect of the parallel resonator, curve 01 has two additional extremely narrow transmission zero points on the basis of curve 02, so that the insertion loss in this area drops rapidly; at the same time, it can be seen from curve 03 that the parallel resonance point of the parallel resonator is located at 5.1GHz, and the pole generated therein increases the passband insertion loss of the filter by a part.

[0029] Example 2: Figure 3 As shown, this example provides a hybrid filter integrating a piezoelectric acoustic wave resonator with a large bandwidth and a high steep drop sideband and a passive microwave device, including a low-pass part and a high-pass part, wherein the high-pass part is connected in series with the low-pass part.

[0030] The low-pass part provided in this embodiment includes a low-pass series trunk and a plurality of low-pass parallel branches; the low-pass series trunk includes an LC resonance unit 209 and an LC resonance unit 210 connected in series between one end of the high-pass part and the output end, and a plurality of low-pass parallel branches are respectively connected between the LC resonance unit 209 and one end of the high-pass part, between the LC resonance unit 210 and the LC resonance unit 209, and between the LC resonance unit 210 and the output end. Figure 3 3 shows three low-pass parallel branches, which respectively include a piezoelectric acoustic wave resonator 110 , a piezoelectric acoustic wave resonator 111 , and a piezoelectric acoustic wave resonator 112 .

[0031] The high-pass part provided in this embodiment includes a high-pass series main circuit and multiple high-pass parallel branches. The high-pass series main circuit includes a piezoelectric acoustic wave resonator 107, a capacitor C1, a capacitor C2 and a piezoelectric acoustic wave resonator 108 connected in series between the input end and one end of the low-pass part. The high-pass parallel branch connected in parallel between the input end and the piezoelectric acoustic wave resonator 107 includes a piezoelectric acoustic wave resonator 109. The high-pass parallel branches respectively connected in parallel between the piezoelectric acoustic wave resonator 107 and the capacitor C1, between the capacitor C1 and the capacitor C2, and between the capacitor C2 and the piezoelectric acoustic wave resonator 108 include corresponding LC resonance units 206, LC resonance units 207 and LC resonance units 208.

[0032] In the hybrid filter provided in this embodiment, each resonant unit supports the characteristics of a large bandwidth, and the piezoelectric acoustic wave resonator 107, the piezoelectric acoustic wave resonator 108, the piezoelectric acoustic wave resonator 109, the piezoelectric acoustic wave resonator 110, the piezoelectric acoustic wave resonator 111, and the piezoelectric acoustic wave resonator 112 can all self-resonate to generate a transmission zero with a high Q value. The transmission zero is moved by adjusting the material parameters of the piezoelectric acoustic wave resonator, and is distributed on the adjacent band at the edge of the low-frequency end of the passband to achieve the effect of improving the adjacent band suppression and the roll-off slope. At the same time, since there are both series piezoelectric acoustic wave resonators and parallel piezoelectric acoustic wave resonators in the overall circuit, the zero point combination of the two can form a band-stop effect, thereby supporting the optimization of a wider transition band that cannot be satisfied by a single zero point; the piezoelectric acoustic wave resonator 109, the piezoelectric acoustic wave resonator 110, the piezoelectric acoustic wave resonator 111, and the piezoelectric acoustic wave resonator 112 can all generate poles in the filter passband to achieve the effect of improving the insertion loss in the passband. Improve filtering performance.

[0033] like Figure 4 As shown, curve 04 is the frequency response curve of the hybrid bandpass filter provided in this embodiment, curve 05 is the frequency response curve of the traditional bandpass filter compared with the hybrid bandpass filter circuit curve provided in this embodiment, and the filter structure corresponding to the frequency response curve of the traditional bandpass filter is obtained by replacing the piezoelectric acoustic wave resonator in the hybrid bandpass filter provided in this embodiment with an LC resonator, and curve 06 is the impedance curve of the parallel resonator located on the high-pass parallel branch or the low-pass parallel branch.

[0034] In curve 04, the sharp transmission zeros in the 4.4GHz~5GHz range are all generated by the piezoelectric acoustic wave resonator, and the several additional transmission zeros generated by the piezoelectric acoustic wave resonator are all located in the adjacent band at the edge of the low-frequency end of the passband, so as to improve the transition band and adjacent band suppression of the bandpass filter circuit and enhance the filtering performance. Compared with curve 05, due to the effect of the sharp transmission zeros in the 4.4GHz~5GHz range, the transition band of the filter shown in curve 04 is reduced from nearly 750MHz to 150MHz; at the same time, it can be seen from curve 06 that the parallel resonance point of the parallel resonator is located in the left area of ​​the passband, and the poles generated in this area increase the in-band insertion loss on the left side of the filter passband.

[0035] like Figure 4As shown, the passband of curve 04 is in the range of 5.15~7.15GHz, the passband reaches 2GHz, and the in-band insertion loss is within -1.5dB (the minimum in-band insertion loss is -1.24dB). The parallel resonance point of piezoelectric acoustic wave resonator 107 and piezoelectric acoustic wave resonator 108 is located in the adjacent band of the low-frequency end edge of the passband, blocking the noise signal with a frequency within the adjacent band range; the series resonance point of piezoelectric acoustic wave resonator 109, piezoelectric acoustic wave resonator 110, piezoelectric acoustic wave resonator 111 and piezoelectric acoustic wave resonator 112 is located in the adjacent band of the low-frequency end edge of the passband, blocking the noise signal with a frequency within the adjacent band range, and its parallel resonance point is located on the left side of the passband, which improves the in-band insertion loss of the filter, thereby improving the filtering performance. As shown in curve 04, under the premise of ensuring that the passband is within the range of 5.15~7.15GHz (a filter circuit composed of a single piezoelectric acoustic resonator cannot achieve this performance), the transition region at the edge of the low-frequency end of the passband is maintained within 150MHz (a single LC filter circuit cannot meet this performance) and the overall out-of-band suppression is maintained below -30dB, which greatly improves the roll-off slope and adjacent-band suppression. Compared with traditional bandpass filters, its in-band insertion loss is also improved.

[0036] Example 3: Figure 5 As shown, this example provides a hybrid filter integrating a piezoelectric acoustic wave resonator with a large bandwidth and a high steep drop sideband and a passive microwave device, including: This example provides a hybrid filter integrating a piezoelectric acoustic wave resonator with a large bandwidth and a high steep drop sideband and a passive microwave device, including a low-pass part and a high-pass part, and the high-pass part is connected in series with the low-pass part.

[0037] The low-pass part provided in this embodiment includes a low-pass series main circuit and multiple low-pass parallel branches: the low-pass series main circuit includes an LC resonance unit 214 and an LC resonance unit 215 connected in series between one end of the high-pass part and the output end, a low-pass parallel branch including a piezoelectric acoustic wave resonator 116 and a piezoelectric acoustic wave resonator 117 connected in series is connected between the LC resonance unit 214 and one end of the high-pass part, a low-pass parallel branch including a piezoelectric acoustic wave resonator 118 is connected between the LC resonance unit 214 and the LC resonance unit 215, and a low-pass parallel branch including a capacitor C5 is connected between the LC resonance unit 215 and the output end.

[0038] The high-pass part provided in this embodiment includes a high-pass series main circuit and multiple high-pass parallel branches. The high-pass series main circuit includes a piezoelectric acoustic wave resonator 114, a capacitor C3, a capacitor C4 and a piezoelectric acoustic wave resonator 113 connected in series between the input end and one end of the low-pass part. The high-pass parallel branch connected in parallel between the input end and the piezoelectric acoustic wave resonator 113 includes a piezoelectric acoustic wave resonator 115. The high-pass parallel branches respectively connected in parallel between the piezoelectric acoustic wave resonator 113 and the capacitor C3, between the capacitor C3 and the capacitor C4, and between the capacitor C4 and the piezoelectric acoustic wave resonator 114 include corresponding LC resonance units 211, LC resonance units 212 and LC resonance units 213.

[0039] The hybrid filter provided in this embodiment still supports the characteristics of large bandwidth by each resonant unit. Piezoelectric acoustic wave resonator 113, piezoelectric acoustic wave resonator 114, piezoelectric acoustic wave resonator 115, piezoelectric acoustic wave resonator 116, piezoelectric acoustic wave resonator 117, and piezoelectric acoustic wave resonator 118 can all self-resonate to generate transmission zeros with high Q values. By adjusting the material parameters of the piezoelectric acoustic wave resonator to move the transmission zeros, it is distributed on the adjacent band at the edge of the low-frequency end of the passband to achieve the effect of improving adjacent band suppression and roll-off slope, thereby improving filtering performance. At the same time, since there are both series piezoelectric acoustic wave resonators and parallel piezoelectric acoustic wave resonators in the overall circuit, the zero point combination of the two can form a band-stop effect, thereby supporting the optimization of a wider transition band that cannot be satisfied by a single zero point; piezoelectric acoustic wave resonator 116, piezoelectric acoustic wave resonator 117, and piezoelectric acoustic wave resonator 118 can all generate poles in the filter passband to achieve the effect of improving the insertion loss in the band. It is worth noting that the piezoelectric acoustic wave resonator 116 and the piezoelectric acoustic wave resonator 117 are connected in series in the same parallel branch. Due to the limitation of its area and process, the equivalent capacitance of a single piezoelectric acoustic wave resonator has a minimum value. Connecting two or more piezoelectric acoustic wave resonators in series in the same branch can break through the minimum capacitance value due to process limitations and obtain a smaller equivalent capacitance.

[0040] like Figure 6As shown, curve 08 is the frequency response curve of the hybrid filter provided in this embodiment, and curve 09 is the frequency response curve of the traditional bandpass filter compared with the hybrid filter curve provided in this embodiment. The structure of the traditional bandpass filter is obtained by replacing the piezoelectric acoustic wave resonator in the hybrid bandpass filter provided in this embodiment with a capacitor element. Curve 10 is the impedance curve of the parallel resonator located on the high-pass parallel branch or the low-pass parallel branch. In curve 08, the sharp transmission zeros in the range of 4.4GHz to 5GHz are all generated by the piezoelectric acoustic wave resonator. These additional transmission zeros are all located on the adjacent band at the edge of the low-frequency end of the passband, so as to improve the transition band and adjacent band suppression of the bandpass filter circuit and enhance the filtering performance. Compared with curve 09, due to the effect of the sharp transmission zeros in the range of 4.4GHz to 5GHz, the transition band of the filter shown in curve 08 is reduced from nearly 650MHz to 150MHz; at the same time, it can be seen from curve 10 that the parallel resonance point of the parallel resonator is located in the left area of ​​the passband, and the poles generated in this area increase the in-band insertion loss of the filter passband.

[0041] like Figure 6 As shown, the passband of curve 08 is in the range of 5.15~5.9GHz, the passband reaches 750MHz, and the in-band insertion loss is within -2dB (the minimum in-band insertion loss is -1.80dB); the parallel resonance point of piezoelectric acoustic wave resonator 113 and piezoelectric acoustic wave resonator 114 is located in the adjacent band of the edge of the low-frequency end of the passband, and the noise signal with a frequency within the adjacent band is blocked; the series resonance point of piezoelectric acoustic wave resonator 115, piezoelectric acoustic wave resonator 116, piezoelectric acoustic wave resonator 117 and piezoelectric acoustic wave resonator 118 is located in the adjacent band of the edge of the low-frequency end of the passband, and the noise signal with a frequency within the adjacent band is blocked, and its parallel resonance point is located on the left side of the passband, thereby improving the in-band insertion loss of the filter and improving the filtering performance. As shown in curve 08, under the premise of ensuring that the passband is within the range of 5.15~5.9GHz (a filter circuit composed of a single piezoelectric acoustic wave resonator cannot achieve this performance), the transition region at the edge of the low-frequency end of the passband is maintained within 150MHz (a single LC filter circuit cannot meet this performance) and the overall out-of-band suppression is maintained below -30dB, which greatly improves the roll-off slope and adjacent-band suppression, and compared with traditional bandpass filters, its in-band insertion loss is also improved.

Claims

1. A hybrid filter integrating a piezoelectric acoustic wave resonator with a wide bandwidth and high steep drop sideband and a passive microwave device, characterized in that: It includes a low-pass part, which includes a low-pass series trunk circuit and a plurality of low-pass parallel branches; Wherein, the low-pass series trunk circuit includes a plurality of LC resonance units connected in series in sequence; The low-pass parallel branch is connected between the low-pass series trunk and the ground line, and two adjacent low-pass parallel branches are separated by at least one LC resonance unit. The low-pass parallel branch includes a low-pass branch capacitive element, or multiple low-pass branch capacitive elements connected in series, and some or all of the low-pass branch capacitive elements use piezoelectric acoustic wave resonators.

2. The hybrid filter of the piezoelectric acoustic wave resonator with large bandwidth and high steep drop sideband and integrated with passive microwave devices according to claim 1 is characterized in that: Two adjacent low-pass parallel branches are separated by an LC resonance unit, and all low-pass branch capacitive elements adopt piezoelectric acoustic wave resonators.

3. The hybrid filter integrating a piezoelectric acoustic wave resonator with a wide bandwidth and a high steep drop sideband and a passive microwave device according to claim 1 is characterized in that: It also includes a high-pass part, the high-pass part is connected in series with the low-pass part, and the high-pass part includes a high-pass series trunk circuit and a plurality of high-pass parallel branches; Wherein, the high-pass series trunk circuit includes a plurality of high-pass trunk circuit capacitive elements connected in series in sequence, and some or all of the high-pass trunk circuit capacitive elements are piezoelectric acoustic wave resonators; The high-pass parallel branch is connected between the high-pass series trunk and the ground line, at least one high-pass trunk capacitive element is spaced between two adjacent high-pass parallel branches, and the high-pass parallel branch includes an LC resonance unit or a piezoelectric acoustic wave resonator.

4. The hybrid filter integrating a piezoelectric acoustic wave resonator with a wide bandwidth and a high steep drop sideband and a passive microwave device according to claim 3 is characterized in that: The capacitive element of the high-pass trunk path that does not use the piezoelectric acoustic wave resonator uses a capacitor.

5. The hybrid filter integrating a piezoelectric acoustic wave resonator with a wide bandwidth and a high steep drop sideband and a passive microwave device according to claim 3 is characterized in that: The low-pass branch capacitive elements all adopt piezoelectric acoustic wave resonators.

6. The hybrid filter integrating a piezoelectric acoustic wave resonator with a wide bandwidth and a high steep drop sideband and a passive microwave device according to claim 3 is characterized in that: The capacitive element of the low-pass branch where the piezoelectric acoustic wave resonator is not used adopts a capacitor.

7. The hybrid filter integrating a piezoelectric acoustic wave resonator with a wide bandwidth and a high steep drop sideband and a passive microwave device according to claim 3 is characterized in that: At least one piezoelectric acoustic wave resonator is spaced between the high-pass portion and the low-pass portion.

8. The hybrid filter integrating a piezoelectric acoustic wave resonator with a wide bandwidth and a high steep drop sideband and a passive microwave device according to claim 3 is characterized in that: The transmission zeros generated by the self-resonance of the piezoelectric acoustic wave resonator in the high-pass part and the low-pass part are distributed in the adjacent band range of the edge of the low-frequency end of the passband.

9. The hybrid filter integrating a piezoelectric acoustic wave resonator with a wide bandwidth and a high steep drop sideband and a passive microwave device according to claim 3, characterized in that: The piezoelectric acoustic wave resonators in both the low-pass parallel branch and the high-pass parallel branch generate poles within the passband range.

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