CN118017970A - Hybrid filter integrating piezoelectric acoustic wave resonator with large bandwidth and high steep drop sideband and passive microwave device - Google Patents
Hybrid filter integrating piezoelectric acoustic wave resonator with large bandwidth and high steep drop sideband and passive microwave device Download PDFInfo
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- H—ELECTRICITY
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- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
- H03H9/542—Filters comprising resonators of piezoelectric or electrostrictive material including passive elements
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
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Abstract
The invention discloses a hybrid filter integrating a piezoelectric acoustic wave resonator with a large bandwidth and a high steep drop sideband and a passive microwave device, which is characterized by comprising a low-pass part, wherein the low-pass part comprises a low-pass serial trunk circuit and a plurality of low-pass parallel branches; the low-pass serial trunk circuit comprises a plurality of LC resonance units which are sequentially connected in series; the low-pass parallel branch is connected between the low-pass serial trunk and the ground wire, at least one LC resonance unit is arranged between two adjacent low-pass parallel branches, the low-pass parallel branch comprises a low-pass capacitive element or a plurality of low-pass capacitive elements connected in series, and part or all of the low-pass capacitive elements adopt piezoelectric acoustic resonators. The hybrid filter has a large bandwidth and satisfies the narrow transition band and high adjacent band rejection.
Description
Technical Field
The invention belongs to the technical field of filtering, and particularly relates to a hybrid filter integrated by a piezoelectric acoustic wave resonator with a large bandwidth and a high steep drop sideband and a passive microwave device.
Background
The filter device is widely used in various fields such as communication systems, audio processing, industrial automation, medical fields, etc. In daily life and work, many electronic devices require the use of filters to filter out noise, interference and other unwanted signals to ensure proper operation of the device and clear transmission of the signals.
With the rapid development of communication technology, more and more frequency bands, such as WIFI6E frequency band, are put into use. With the continuous increase of the operating frequency, the conventional single filter device includes two major types, namely a passive filter and an active filter. The passive filter mainly comprises passive elements such as a resistor, a capacitor, an inductor and the like, and the working principle of the passive filter is to filter signals with specific frequencies based on the combination of the inductor, the capacitor and the resistor. The active filter includes an active element such as an amplifier in addition to the basic passive element, and can realize more complicated frequency response characteristics. However, the conventional filter formed by various piezoelectric acoustic wave resonators due to the influence of material factors such as electromechanical coupling coefficients cannot meet the performance requirement of large bandwidth.
The invention patent application CN104756403a discloses a reduction in design cost of LC filters required for making various changes in characteristics of attenuation poles formed by jump coupling. The LC filter unit (100) comprises: a ceramic laminate (10) in which a plurality of ceramic layers (11-61) are laminated, 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 circuit elements forming a jump coupling by connecting with an LC filter circuit to form an attenuation pole, mounting electrodes (64 a, 64 b) for mounting at least one of an inductor, a capacitor and a SAW resonator are formed on the surface of a ceramic laminate (10). But the Q value of the LC filter disclosed in this patent is low and cannot meet the demand.
LC filters, also known as passive filters, are conventional harmonic compensation devices. The LC filter is formed by properly combining a filter capacitor, a reactor and a resistor, is connected with a harmonic source in parallel, and not only plays a role in filtering, but also meets the requirement of reactive compensation. The most common passive filter structure that is easy to use is to connect an inductor in series with a capacitor, which can form a low impedance bypass for the main subharmonics (3, 5, 7). In addition, LC filters are also classified into single-tuned filters, high-pass filters, double-tuned filters, triple-tuned filters, and the like. Traditional LC filters such as IPD (integrated product), LTCC (low temperature co-fired ceramic) and the like cannot meet the requirements of narrow transition band and high adjacent band suppression due to the limitation of low Q value of the element. ) All the requirements have not been met.
Therefore, the piezoelectric acoustic wave resonator and the LC filter are combined to exert the advantages of the piezoelectric acoustic wave resonator and the LC filter, and the hybrid filter which not only has a large bandwidth, but also meets the requirements of narrow transition band and high adjacent band inhibition is the development direction of the current filter industry.
Disclosure of Invention
The 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, which has the large bandwidth and meets the requirements of narrow transition band and high adjacent band inhibition.
The embodiment of the invention provides a hybrid filter integrated by a piezoelectric acoustic wave resonator with a large bandwidth and a high steep drop sideband and a passive microwave device, which comprises the following components: a low pass portion comprising a low pass series trunk and a plurality of low pass parallel branches;
the low-pass serial trunk circuit comprises a plurality of LC resonance units which are sequentially connected in series;
The low-pass parallel branch is connected between the low-pass serial trunk and the ground wire, at least one LC resonance unit is arranged between two adjacent low-pass parallel branches, the low-pass parallel branch comprises a low-pass capacitive element or a plurality of low-pass capacitive elements connected in series, and part or all of the low-pass capacitive elements adopt piezoelectric acoustic resonators.
Therefore, compared with the IPD+BAW disclosed by the prior art, by introducing the piezoelectric acoustic wave resonator to introduce a plurality of zero points at the edge of a passband so as to improve the adjacent band rejection and the roll-off slope of a transition zone, the invention reserves an LC resonator unit on a main road so as to ensure that the passband is large and smooth, and connects one or more piezoelectric acoustic wave resonators in parallel on the branch road so as to ensure that the parallel resonance point of the parallel piezoelectric acoustic wave resonator is positioned at the passband position by parameter adjustment while introducing the transmission zero point with high Q value in the transition zone so as to improve the passband interpolation loss. Meanwhile, in the structure, the piezoelectric acoustic wave resonators are dispersed and reasonably distributed into the framework of the IPD filter, so that the piezoelectric acoustic wave filter can play a role in introducing zero points and poles and can play an impedance matching function.
The invention utilizes the LC resonance units connected in series on the low-pass serial connection trunk to ensure that the passband of the hybrid filter provided by the invention is large and gentle, and the serial resonance point of the piezoelectric acoustic wave resonator positioned on the low-pass parallel connection trunk is positioned at the transition zone position by adjusting related parameters so as to introduce the transmission zero point with high Q value of the piezoelectric acoustic wave resonator to promote the transition zone and adjacent zone inhibition, and simultaneously, the parallel resonance point of the piezoelectric acoustic wave resonator is positioned at the passband position by adjusting related parameters so as to promote the band interpolation loss.
Preferably, two adjacent low-pass parallel branches are separated by an LC resonant cell, and all low-pass capacitive elements employ piezoelectric acoustic wave resonators.
Preferably, the hybrid filter integrated by the piezoelectric acoustic wave resonator with the high bandwidth high steep drop side band and the passive microwave device further comprises a high-pass part, wherein 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;
the high-pass serial trunk circuit comprises a plurality of high-pass trunk circuit capacitive elements which are sequentially connected in series, and part or all of the high-pass trunk circuit capacitive elements adopt piezoelectric acoustic wave resonators;
the high-pass parallel branch is connected between the high-pass serial trunk and the ground wire, at least one high-pass trunk capacitive element is arranged between two adjacent high-pass parallel branches, and each high-pass parallel branch comprises an LC resonance unit or a piezoelectric acoustic wave resonator.
Compared with a single zero point which can only be provided in the prior art, the invention has the advantages that the series piezoelectric acoustic wave resonator and the parallel piezoelectric acoustic wave resonator are introduced, the zero points of the series piezoelectric acoustic wave resonator and the parallel piezoelectric acoustic wave resonator can be combined to form a band elimination effect by adjusting parameters, so that wider transition band optimization is formed, and poles are generated in the pass band of the filter through a plurality of parallel piezoelectric acoustic wave resonators, so that the effect of improving the insertion loss of the pass band is achieved.
According to the invention, the high-pass part is introduced, so that the hybrid filter is provided with the series piezoelectric acoustic wave resonator on a high-pass series trunk circuit, and is also provided with the parallel piezoelectric acoustic wave resonator on a low-pass parallel branch circuit, the zero points of the two piezoelectric acoustic wave resonators can be uniformly distributed on the transition band, and the band-stop effect can be formed after the two piezoelectric acoustic wave resonators are combined, so that the optimization of a wider transition band which cannot be met by the zero point generated by a single piezoelectric acoustic wave resonator can be supported.
Preferably, the high pass dry-circuit capacitive element that does not employ a piezoelectric acoustic wave resonator employs a capacitance to maintain a corresponding impedance match.
Preferably, the low-pass branch capacitive elements all adopt piezoelectric acoustic wave resonators to obtain more zero points, so that the optimization effect of the transition zone is improved.
Preferably, the low-pass capacitive element, which does not employ a piezoelectric acoustic wave resonator, employs a capacitance to maintain a corresponding impedance match.
Preferably, at least one piezoelectric acoustic wave resonator is spaced between the high pass portion and the low pass portion.
Preferably, transmission zeros generated by self-resonance of the piezoelectric acoustic wave resonators in the high-pass portion and the low-pass portion are distributed in a vicinity of the edge of the low-frequency end of the pass band.
Preferably, the piezoelectric acoustic wave resonators on both the low-pass parallel leg and the high-pass parallel leg produce poles in the passband range.
Preferably, the piezoelectric acoustic wave resonator is a bulk acoustic wave resonator, a surface acoustic wave resonator, a lamb wave resonator, and is not limited thereto.
Compared with the prior art, the invention has the beneficial effects that:
According to the invention, the mixed filter has a large and gentle passband by keeping part of LC resonator units, the piezoelectric acoustic wave resonator is introduced on the low-pass parallel branch, and the transmission zero point generated by the piezoelectric acoustic wave resonator is positioned in the tie range of the edge of the low-frequency end of the passband by adjusting the parameters of the piezoelectric acoustic wave resonator, so that the adjacent band inhibition and roll off slope are improved, and the piezoelectric acoustic wave resonator generates a pole in the passband range, so that the effect of improving the band interpolation loss is achieved. Meanwhile, in the structure, the piezoelectric acoustic wave resonators are reasonably distributed into the framework of the IPD filter one by one, so that the piezoelectric acoustic wave resonator can play a role in introducing zero points and poles and can play an impedance matching function.
Drawings
Fig. 1 is a schematic structural diagram of a hybrid filter according to embodiment 1 of the present invention;
Fig. 2 is an S-parameter simulation diagram of the hybrid filter according to embodiment 1 of the present invention;
fig. 3 is a schematic structural diagram of a hybrid filter according to embodiment 2 of the present invention;
Fig. 4 is an S-parameter simulation diagram of the hybrid filter according to embodiment 2 of the present invention;
fig. 5 is a schematic structural diagram of a hybrid filter according to embodiment 3 of the present invention;
fig. 6 is an S-parameter simulation diagram of the hybrid filter according to embodiment 3 of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
The present invention will be described in detail with reference to specific embodiments and drawings. For convenience of description, the structures shown in the drawings are only relevant to the invention, and not all the structures. For ease of description and understanding, some exemplary embodiments are provided below, including but not limited to the embodiments listed, as applicable to various forms and orders of LC filters and various types of piezoelectric acoustic wave resonators.
Example 1
As shown in fig. 1, the present example provides a hybrid filter in which a piezoelectric acoustic wave resonator with a large bandwidth and a high steep drop sideband is integrated with a passive microwave device, comprising:
The low-pass part provided by the embodiment comprises a low-pass serial trunk circuit and a plurality of low-pass parallel branches; the low-pass series trunk circuit comprises an LC resonance unit 204 and an LC resonance unit 205 which are connected in series between an input end and an output end, wherein a plurality of low-pass parallel branches are respectively connected between the LC resonance unit 204 and the LC resonance unit 205 and between the LC resonance unit 205 and the output end, and three low-pass parallel branches are shown in fig. 1 to respectively comprise a piezoelectric acoustic wave resonator 104, a piezoelectric acoustic wave resonator 105 and a piezoelectric acoustic wave resonator 106. It can be appreciated that this embodiment can cascade more LC resonant cells and piezoelectric acoustic wave resonators on the basis of three low-pass parallel branches in parallel, thereby achieving the desired target performance.
The hybrid filter provided in this embodiment is optimized by a conventional LC low-pass filter obtained by replacing the piezoelectric acoustic wave resonator shown in fig. 1 with an LC resonator. The elements of the resonance unit part of the hybrid filter provided in this embodiment reserve a part of the LC low-pass filter circuit to maintain the excellent performance of the LC filter, that is, the passband is large and gentle, and the elements of the non-resonance unit part are formed by respective piezoelectric acoustic wave resonators to enable the series resonance point of the parallel piezoelectric acoustic wave resonator located in the low-pass parallel branch to be located at the transition band position on the basis of the LC filter circuit by adjusting the relevant parameters so as to introduce the transmission zero point of the high Q value of the piezoelectric acoustic wave resonator to promote the transition band and the adjacent band suppression, and enable the parallel resonance point of the parallel piezoelectric acoustic wave resonator to be located at the passband position by adjusting the relevant parameters so as to promote the band interpolation loss.
As shown in fig. 2, a curve 01 is a frequency response curve of the hybrid low-pass filter circuit provided in this embodiment, a curve 02 is a frequency response curve of a conventional LC low-pass filter compared with the hybrid low-pass filter circuit provided in this embodiment, and a curve 03 is an impedance curve of a parallel resonator located on a low-pass parallel branch. It can be seen that, due to the effect of the parallel resonator, the curve 01 additionally obtains two extremely narrow transmission zero points on the basis of the curve 02, so that the insertion loss of the area is rapidly reduced; meanwhile, as can be seen from the curve 03, the parallel resonance point of the parallel resonator is located at 5.1GHz, and the pole generated at the point increases the passband insertion loss of the filter by a part.
Example 2
As shown in fig. 3, the present example provides a hybrid filter in which a piezoelectric acoustic wave resonator of a large bandwidth high steep drop side band is integrated with a passive microwave device, including a low-pass portion and a high-pass portion connected in series with the low-pass portion.
The low-pass part provided by the embodiment comprises a low-pass serial trunk circuit and a plurality of low-pass parallel branches; the low-pass series trunk circuit comprises an LC resonance unit 209 and an LC resonance unit 210 connected in series between one end of the high-pass portion 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 portion, between the LC resonance unit 210 and the LC resonance unit 209, and between the LC resonance unit 210 and the output end, three low-pass parallel branches are shown in fig. 3, and each of the three low-pass parallel branches comprises a piezoelectric acoustic wave resonator 110, a piezoelectric acoustic wave resonator 111, and a piezoelectric acoustic wave resonator 112.
The high-pass section provided in this embodiment includes a high-pass serial trunk and a plurality of high-pass parallel branches, the high-pass serial trunk includes a piezoelectric acoustic wave resonator 107, a capacitor C1, a capacitor C2 and a piezoelectric acoustic wave resonator 108 connected in series between an input end and one end of the low-pass section, 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, and the high-pass parallel branch 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 includes a corresponding LC resonance unit 206, LC resonance unit 207 and LC resonance unit 208.
In the hybrid filter provided in this embodiment, the characteristics of large bandwidth are supported by each resonant unit, and the piezoelectric acoustic resonator 107, the piezoelectric acoustic resonator 108, the piezoelectric acoustic resonator 109, the piezoelectric acoustic resonator 110, the piezoelectric acoustic resonator 111, and the piezoelectric acoustic resonator 112 can generate transmission zero points with high Q values by self-resonance, and the transmission zero points are distributed on adjacent bands at the edge of the low-frequency end of the passband by adjusting material parameters of the piezoelectric acoustic resonators to move the transmission zero points, so as to achieve the effect of improving adjacent band suppression and roll off slope, and meanwhile, because the series piezoelectric acoustic resonators and the parallel piezoelectric acoustic resonators exist in the whole circuit, the combination of the zero points of the two can form a band-stop effect so as to support the optimization of a wider transition band which 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 generate poles in the pass band of the filter to achieve the effect of improving the insertion loss of the pass band. And the filtering performance is improved.
As shown in fig. 4, curve 04 is a frequency response curve of the hybrid band-pass filter provided in this embodiment, curve 05 is a frequency response curve of a conventional band-pass filter compared with the hybrid band-pass filter circuit provided in this embodiment, and the filter structure corresponding to the conventional band-pass filter frequency response curve is obtained by replacing the piezoelectric acoustic wave resonator in the hybrid band-pass filter provided in this embodiment with an LC resonator, and curve 06 is an impedance curve of the parallel resonator located on the high-pass parallel branch or on the low-pass parallel branch.
In curve 04, the sharp transmission zeros in the 4.4 GHz-5 GHz interval are generated by the piezoelectric acoustic wave resonator, and several additional transmission zeros generated by the piezoelectric acoustic wave resonator are all located on the adjacent band at the edge of the low-frequency end of the passband, so that the transition band and the adjacent band suppression of the bandpass filter circuit are improved, and the filter performance is improved. Compared with curve 05, the transition zone of the filter shown in curve 04 is reduced from approximately 750MHz to 150MHz due to the action of a sharp transmission zero in the 4.4 GHz-5 GHz interval; meanwhile, as can be seen from curve 06, the parallel resonance point of the parallel resonator is located in the left region within the passband, and the pole generated in this region causes the in-band insertion loss to be improved to the left of the passband of the filter.
As shown in fig. 4, the curve 04 passband is in the range of 5.15-7.15 GHz, the passband reaches 2GHz, and the in-band insertion loss is within-1.5 dB (the minimum in-band insertion loss is-1.24 dB). The parallel resonance points of the piezoelectric acoustic wave resonator 107 and the piezoelectric acoustic wave resonator 108 are positioned on the adjacent band of the edge of the low-frequency end of the passband, and noise signals with frequencies within the adjacent band range are blocked; the series resonance points of the piezoelectric acoustic resonator 109, the piezoelectric acoustic resonator 110, the piezoelectric acoustic resonator 111 and the piezoelectric acoustic resonator 112 are located on the adjacent band at the edge of the low-frequency end of the passband, so as to block noise signals with frequencies in the adjacent band range, and the parallel resonance point is located on the left side in the passband, so that the in-band interpolation loss of the filter is improved, and the filtering performance is improved. As shown in curve 04, on the premise of ensuring that the passband is in the range of 5.15-7.15 GHz (the filtering circuit formed by a single piezoelectric acoustic resonator cannot achieve the performance), the transition area of the edge of the low-frequency end of the passband is maintained within 150MHz (the single LC filtering circuit cannot meet the performance), the whole out-of-band rejection is maintained below-30 dB, the roll off slope and the adjacent-band rejection are greatly improved, and compared with the traditional band-pass filter, the in-band insertion loss is also improved.
Example 3
As shown in fig. 5, the present example provides a hybrid filter in which a piezoelectric acoustic wave resonator of a large bandwidth high steep drop side band is integrated with a passive microwave device, comprising: the present example provides a hybrid filter with a large bandwidth high-drop sideband piezoelectric acoustic resonator integrated with a passive microwave device, including a low-pass portion and a high-pass portion connected in series with the low-pass portion.
The low-pass part provided by the embodiment comprises a low-pass serial trunk circuit and a plurality of low-pass parallel branches: the low-pass series trunk circuit comprises an LC resonance unit 214 and an LC resonance unit 215 which are connected in series between one end of the high-pass part and the output end, a low-pass parallel branch circuit comprising a piezoelectric acoustic wave resonator 116 and a piezoelectric acoustic wave resonator 117 which are connected in series is connected between the LC resonance unit 214 and one end of the high-pass part, a low-pass parallel branch circuit comprising 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 circuit comprising a capacitor C5 is respectively connected between the LC resonance unit 215 and the output end.
The high-pass section provided in this embodiment includes a high-pass serial trunk and a plurality of high-pass parallel branches, the high-pass serial trunk includes a piezoelectric acoustic wave resonator 114, a capacitor C3, a capacitor C4 and a piezoelectric acoustic wave resonator 113 connected in series between an input end and one end of the low-pass section, 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, and the high-pass parallel branch 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 includes a corresponding LC resonance unit 211, LC resonance unit 212 and LC resonance unit 213.
The hybrid filter provided by the present embodiment still supports the characteristic of large bandwidth by each resonance unit. The piezoelectric acoustic wave resonator 113, the piezoelectric acoustic wave resonator 114, the piezoelectric acoustic wave resonator 115, the piezoelectric acoustic wave resonator 116, the piezoelectric acoustic wave resonator 117 and the piezoelectric acoustic wave resonator 118 can generate a transmission zero point with a high Q value by self-resonance, the transmission zero point is distributed on an adjacent band at the edge of a low-frequency end of a passband by adjusting material parameters of the piezoelectric acoustic wave resonator so as to achieve the effects of improving adjacent band inhibition and roll off slope, filtering performance is improved, and meanwhile, the zero point combination of the piezoelectric acoustic wave resonator and the piezoelectric acoustic wave resonator can form a band-stop effect due to the fact that the piezoelectric acoustic wave resonator is connected in series and the piezoelectric acoustic wave resonator is connected in parallel in the whole circuit, so that optimization of a wider transition band which cannot be met by a single zero point is supported; the piezoelectric acoustic wave resonator 116, the piezoelectric acoustic wave resonator 117 and the piezoelectric acoustic wave resonator 118 can generate poles in the pass band of the filter to achieve the effect of increasing the band interpolation loss. It is noted that the piezoelectric acoustic wave resonator 116 and the piezoelectric acoustic wave resonator 117 are connected in series in the same parallel branch. The single piezoelectric acoustic wave resonator has a minimum value of equivalent capacitance due to the limitation of the area technology, and two or more piezoelectric acoustic wave resonators connected in series in the same branch can break through the minimum capacitance value due to the technology limitation, so that smaller equivalent capacitance is obtained.
As shown in fig. 6, curve 08 is a frequency response curve of the hybrid filter provided in this embodiment, curve 09 is a frequency response curve of a conventional band-pass filter compared with the hybrid filter curve provided in this embodiment, the conventional band-pass filter is configured by replacing a piezoelectric acoustic wave resonator in the hybrid band-pass filter provided in this embodiment with a capacitive element, and curve 10 is an impedance curve of a parallel resonator located on a high-pass parallel branch or a low-pass parallel branch. In curve 08, the sharp transmission zeros in the 4.4 GHz-5 GHz interval are generated by the piezoelectric acoustic wave resonator, and the extra transmission zeros are all located on the adjacent bands of the edges of the low-frequency ends of the pass band, so that the transition band and the adjacent band inhibition of the band-pass filter circuit are improved, and the filter performance is improved. Compared with curve 09, the transition zone of the filter shown in curve 08 is reduced from approximately 650MHz to 150MHz due to the action of sharp transmission zero in the 4.4 GHz-5 GHz interval; meanwhile, as can be seen from curve 10, the parallel resonance point of the parallel resonator is located in the left region within the passband, and its pole generated in this region causes the in-band loss of the filter passband to be improved.
As shown in fig. 6, the curve 08 passband is in the range of 5.15-5.9 GHz, the passband reaches 750MHz, the in-band insertion loss is within-2 dB (the minimum in-band insertion loss is-1.80 dB); the parallel resonance points of the piezoelectric acoustic wave resonator 113 and the piezoelectric acoustic wave resonator 114 are positioned on the adjacent band of the edge of the low-frequency end of the passband, and noise signals with frequencies within the adjacent band range are blocked; the series resonance points of the piezoelectric acoustic resonator 115, the piezoelectric acoustic resonator 116, the piezoelectric acoustic resonator 117 and the piezoelectric acoustic resonator 118 are positioned on the adjacent band at the edge of the low-frequency end of the passband to block noise signals with frequencies in the adjacent band range, and the parallel resonance point is positioned at the left side in the passband to improve the in-band interpolation loss of the filter and the filtering performance. As shown in curve 08, on the premise of ensuring that the passband is in the range of 5.15-5.9 GHz (the filtering circuit formed by a single piezoelectric acoustic resonator cannot achieve the performance), the transition area of the edge of the low-frequency end of the passband is maintained within 150MHz (the single LC filtering circuit cannot meet the performance), the whole out-of-band rejection is maintained below-30 dB, the roll off slope and the adjacent-band rejection are greatly improved, and compared with the traditional band-pass filter, the in-band interpolation loss is also improved.
Claims (9)
1. The hybrid filter integrated by the piezoelectric acoustic wave resonator with the large bandwidth and the high steep drop side band and the passive microwave device is characterized by comprising a low-pass part, wherein the low-pass part comprises a low-pass serial trunk circuit and a plurality of low-pass parallel branches;
the low-pass serial trunk circuit comprises a plurality of LC resonance units which are sequentially connected in series;
The low-pass parallel branch is connected between the low-pass serial trunk and the ground wire, at least one LC resonance unit is arranged between two adjacent low-pass parallel branches, the low-pass parallel branch comprises a low-pass capacitive element or a plurality of low-pass capacitive elements connected in series, and part or all of the low-pass capacitive elements adopt piezoelectric acoustic resonators.
2. The hybrid filter of claim 1 wherein the piezoelectric acoustic resonator of the high bandwidth high drop sideband is integrated with a passive microwave device, wherein two adjacent low pass parallel branches are separated by an LC resonant cell, and wherein all low pass capacitive elements are piezoelectric acoustic resonators.
3. The hybrid filter of claim 1, further comprising a high pass portion in series with the low pass portion, the high pass portion comprising a high pass series trunk and a plurality of high pass parallel branches;
the high-pass serial trunk circuit comprises a plurality of high-pass trunk circuit capacitive elements which are sequentially connected in series, and part or all of the high-pass trunk circuit capacitive elements adopt piezoelectric acoustic wave resonators;
the high-pass parallel branch is connected between the high-pass serial trunk and the ground wire, at least one high-pass trunk capacitive element is arranged between two adjacent high-pass parallel branches, and each high-pass parallel branch comprises an LC resonance unit or a piezoelectric acoustic wave resonator.
4. A hybrid filter with a high bandwidth high drop sideband piezoelectric acoustic resonator integrated with a passive microwave device as claimed in claim 3, wherein the high pass capacitive element without the piezoelectric acoustic resonator uses a capacitor.
5. A hybrid filter with large bandwidth high drop sideband piezoelectric acoustic resonator integrated with a passive microwave device as recited in claim 3, wherein the low pass capacitive elements all employ piezoelectric acoustic resonators.
6. A hybrid filter with a large bandwidth high drop sideband piezoelectric acoustic resonator integrated with a passive microwave device as claimed in claim 3, wherein the low pass capacitive element without piezoelectric acoustic resonator uses capacitance.
7. A hybrid filter with a large bandwidth high drop sideband piezoelectric acoustic resonator integrated with a passive microwave device as recited in claim 3, wherein said high pass portion is separated from said low pass portion by at least one piezoelectric acoustic resonator.
8. A hybrid filter with large bandwidth high steep drop side band piezoelectric acoustic wave resonator integrated with passive microwave device according to claim 3, characterized in that transmission zeroes generated by self-resonance of the piezoelectric acoustic wave resonators in the high pass section and the low pass section are distributed in the adjacent band range of the low frequency end edge of the pass band.
9. A hybrid filter with large bandwidth high drop sideband piezoelectric acoustic wave resonator integrated with passive microwave device as claimed in claim 3, wherein the piezoelectric acoustic wave resonators on both the low pass parallel leg and the high pass parallel leg create poles in the passband range.
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2024
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