Large-bandwidth filter with high adjacent band suppression

Abstract

The invention provides a high-adjacent-band suppression large-bandwidth filter which is characterized in that a plurality of narrow-band suppression curves are formed in a wide-band range needing to be suppressed by designing step-shaped band-stop filtering units with different film thicknesses; and then the LC matching network is used for connecting the plurality of stepped band-stop filtering units in series to form a large-bandwidth and extremely deep suppression curve, and meanwhile, when the matching network is a series inductor, the matching network plays a role with the series resonator, so that the series resonance point of the series resonator moves leftwards to the outside of the stop band, thereby reducing the interference to the stop band, reducing the peak in stop band suppression, and improving the suppression efficiency of the band-stop filter. And finally, the hybrid resonance network is connected to the parallel branch so as to form an extremely deep zero point at a low-frequency point.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of acoustic wave filter devices, and particularly relates to a large-bandwidth filter with high adjacent band rejection. BACKGROUND

[0002] Wireless communication technology is rapidly developing from 4G to 5G and 6G, and the demand for frequency spectrum is increasing, and the frequency spectrum is becoming more and more crowded, which makes communication face the challenge of mutual crosstalk. In addition, the communication protocol standard defines many wide frequency bands, such as N79, Wi-Fi 6E, etc., which can reach 1975MHz at most, while the transition band is only 150MHz.

[0003] LC filters based on traditional IPD and LTCC technology are suitable for large-bandwidth applications, such as 5G sub-6GHz and millimeter wave frequency bands, but these passive components are difficult to achieve high Q values due to material and process limitations, which means that several hundred megahertz of transition bands are needed, and the degree of suppression is not deep. The cavity filter has a high Q value, but its large size makes it difficult to meet the miniaturization requirements in the current radio frequency module. Acoustic filters have high Q values and good bandwidths, and bulk acoustic wave filters have achieved high-frequency filtering performance in the product end.

[0004] The patent application with the publication number CN116865714A discloses a filter for N79 frequency bands, which comprises at least one acoustic resonator and an IPD filter circuit; wherein the acoustic resonator and the IPD filter circuit are connected in series in turn, or the acoustic resonator and the IPD filter circuit are connected in series with an interval; the IPD filter circuit is used to form a passband in the N79 frequency band. The filter for N79 frequency bands adopts acoustic resonator and IPD filter circuit integration technology to achieve target requirements, both of which use semiconductor processing technology, can be processed and manufactured on the same wafer, and the circuit and structure of the filter can have the characteristics of large bandwidth and fast roll-off, and can simultaneously realize low insertion loss of N79 frequency band and high suppression of WiFi 6E. The framework displayed by the invention can only meet about 600 bandwidth, and in addition, the high suppression of the 5G frequency band of WiFi6E mentioned by the invention is also difficult to exceed 40dB.

[0005] The invention type patent application with publication number CN119788021B discloses a wideband high steepness filter embedded with a piezoelectric acoustic resonator and an LC passive circuit, which comprises a stepped filter unit and an LC resonance network. The stepped filter unit and the LC resonance network are connected in series, or the stepped filter unit and the LC resonance network are connected in series and then connected in parallel in sequence. The stepped filter unit comprises a filter series branch and a plurality of filter parallel branches. The first end of the filter series branch serves as an input end. The two ends of the filter parallel branch are connected to a ground and the series branch, respectively. At least one series hybrid resonance unit is arranged on the filter series branch. The series hybrid resonance unit is used to form a pole in the passband to expand the passband bandwidth. At least one acoustic resonator or parallel hybrid resonance unit is arranged on the filter parallel branch. The filter can realize higher bandwidth, higher out-of-band suppression and narrower transition band. However, it is difficult for the invention to realize a wider than 50dB out-of-band suppression in adjacent frequency bands, which cannot meet the increasing anti-interference demand.

[0006] Although the above-mentioned patent can form a very narrow transition band and a large bandwidth, the suppression of adjacent bands is still not deep enough. Therefore, there is an urgent need to design a filter circuit that can simultaneously satisfy a super large bandwidth and a very deep suppression to avoid interference in adjacent frequency bands. The present invention aims to provide a high adjacent band suppression and large bandwidth circuit. SUMMARY

[0007] The present invention provides a high adjacent band suppression and large bandwidth filter, which can provide super high suppression, fast steepness in adjacent frequency bands, and realize a large bandwidth and low insertion loss in the passband.

[0008] The present invention provides a high adjacent band suppression and large bandwidth filter, which comprises a stepped band-stop filter unit module, an LC matching unit and a hybrid resonance network. The stepped band-stop filter unit module comprises a plurality of stepped band-stop filter units connected in series, and a matching inductor connected in series between the stepped band-stop filter units. The stepped band-stop filter unit comprises a plurality of series resonators on a series branch, and a parallel resonator on a parallel branch between the series resonators. The film thickness of the series resonators of the current stepped band-stop filter unit is the same as that of the parallel resonators of the next stepped band-stop filter unit. The film thickness of the series resonators of different stepped band-stop filter units is different, and the film thickness of the parallel resonators is also different. The LC matching unit is located at the two ends of the stepped band-stop filter unit module or between different stepped band-stop filter units. The hybrid resonance network is located on the parallel branch between the stepped band-stop filter unit module and the LC matching unit.

[0009] The present application forms multiple narrow-band suppression curves in the wide-band range to be suppressed by designing different film thicknesses of the stepped band-stop filter units, and then uses LC matching networks to connect the multiple stepped band-stop filter units in series to form a large-bandwidth and extremely deep suppression curve, and when the matching network is a series inductor, it works with the series resonator, so that the series resonance point of the series resonator is shifted to the inside of the stop band with a zero point, thereby reducing the interference with the stop band and reducing the spikes formed between the band-stop filter units, and finally connecting the hybrid resonant network to the parallel branch to form an extremely deep zero point at the low frequency point.

[0010] Preferably, the stepped band-stop filter unit is provided with at least one series resonator and at least two parallel resonators to form a Π-type stepped filter unit, and the parallel resonators are respectively connected to the ground and the series main line.

[0011] Preferably, the stepped band-stop filter unit is provided with at least two series resonators and at least one parallel resonator to form a T-type stepped filter unit, and the parallel resonator is respectively connected to the ground and the series main line.

[0012] Preferably, the resonant frequency of the series resonator in the stepped band-stop filter unit is lower than the resonant frequency of the parallel resonator.

[0013] Preferably, the LC matching unit is an inductor Ls provided on the series main line or an inductor Lm provided on the parallel branch. The inductor Ls is respectively connected to different stepped band-stop filter units or one end is connected to a stepped band-stop filter unit and the other end is connected to an output or an input. The inductor Lm is connected to the series main line at one end and grounded at the other end.

[0014] The series inductor Ls provided by the present application can play the role of impedance matching between the stepped filter units, and when the series inductor Ls is connected in series with the series resonator, the position of the series resonance point fs of the series resonator can be adjusted, and an additional pole is formed at the high-frequency passband.

[0015] The parallel inductor Lm provided by the present application can play the role of impedance matching between the stepped filter units, and when the parallel inductor Lm is connected in parallel with the parallel resonator Ap, the position of the parallel resonance point fp of the parallel resonator Ap can be adjusted, and an additional pole is formed at the low frequency.

[0016] Preferably, the stepped band-stop filter unit network module comprises a stepped band-stop filter unit one and a stepped band-stop filter unit two. The stepped band-stop filter unit one comprises two series resonators As1 provided on the series main line and a parallel resonator Ap1 provided on the parallel main line between the series resonators As1. The second ladder-type band-stop filter unit includes three series resonators As2 arranged on a series arm and two parallel resonators Ap2 arranged on two parallel arms between the series resonators As2; The film thickness of the series resonator As1 is the same as that of the parallel resonator Ap2. The film thickness of the series resonator As1 is different from that of the series resonator As2. The film thickness of the parallel resonator Ap1 is different from that of the parallel resonator Ap2.

[0017] The parallel resonant point of the series resonator As2 and the series resonant point of the parallel resonator Ap2 provide deep zero points for the second filter unit, the parallel resonant point of the series resonator As1 and the series resonant point of the parallel resonator Ap1 provide deep zero points for the first filter unit, the deep zero points form deep stop bands in the corresponding frequency ranges, and the stop bands formed by the first filter unit and the second filter unit are adjacent.

[0018] Preferably, the LC matching unit is located on the series arm or the parallel arm.

[0019] Preferably, the LC matching unit is a single inductor. The single inductor as the LC matching unit can increase the resonator Kt while generating additional zero-pole points when adjusting the resonator frequency.

[0020] The single inductor provided by the present application is a matching inductor Ls located on the series arm, which can form more poles with the series resonator As, and at the same time, shift the series resonant frequency fs of the series resonator As to the left to the required frequency range, thereby achieving better suppression.

[0021] The single inductor provided by the present application is a parallel inductor Lm located on the parallel arm, which can form additional poles at low frequencies when connected in parallel with the parallel resonator Ap, and at the same time, shift the parallel resonant point fp of the parallel resonator Ap to the required frequency, thereby achieving better suppression.

[0022] Preferably, the hybrid resonant network is grounded at one end and connected to the series arm at the other end, and includes a series unit of a first capacitor and a first inductor in series, and a second capacitor connected in parallel with the series unit. The hybrid resonant network can provide deep zero points at low frequencies of the filter curve.

[0023] Further preferably, the first capacitor and the second capacitor are replaced by a bulk acoustic wave resonator. In order to provide more deep zero points at low frequencies.

[0024] Compared with the prior art, the present application has the following advantages: The present application connects multiple ladder-type band-stop filter units in series to generate multiple band-stops between adjacent frequency bands, and by making the film thickness of the series resonator of the current ladder-type band-stop filter unit the same as the parallel resonator of the next ladder-type band-stop filter unit, the adjacent band-stops are generated, and the series resonance points of the parallel resonator and the series resonator are made to substantially coincide, so that a suitable band-stop bandwidth is obtained, and then the multiple band-stop networks are superimposed in the adjacent frequency band range to achieve a wide and deep suppression width and height, and at the same time, a super large bandwidth is achieved in the required passband frequency range.

[0025] If the film thickness of the parallel resonator of the next ladder-type band-stop filter unit is thicker than the film thickness of the series resonator of the current ladder-type band-stop filter unit, the series resonance point of the parallel resonator is lower than the series resonance point of the series resonator, and then the band-stop bandwidth of the next ladder-type band-stop filter unit is narrowed, and the series resonance point of the series resonator may not fall within the stop band range, affecting the suppression effect.

[0026] If the film thickness of the parallel resonator of the next ladder-type band-stop filter unit is thinner than the film thickness of the series resonator of the current ladder-type band-stop filter unit, the series resonance point of the parallel resonator is higher than the series resonance point of the series resonator, and then the band-stop bandwidth of the next ladder-type band-stop filter unit is widened, and the series resonance point of the series resonator can fall within the stop band, but the suppression depth of the next ladder-type band-stop filter unit is not enough.

[0027] The present application moves the series resonance point of the series resonator, that is, the pole of the filter, to the stop band range with deep suppression by connecting a matching inductor in series between the ladder-type band-stop filter units, prevents the formation of protruding peaks between the stop bands formed by the series connected ladder-type band-stop filter units, and further realizes impedance matching of each ladder-type band-stop filter unit through the inductor. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The present application provides a ladder-type band-stop filter unit composed of acoustic resonators.

[0029] Figure 2 The present application provides a filter circuit formed by two ladder-type band-stop filter units connected in series.

[0030] Figure 3 The present application provides an S21 parameter curve and a resonator impedance curve schematic diagram of two ladder-type band-stop filter units connected in series.

[0031] Figure 4 The present application provides a schematic diagram of an LC matching network located in a parallel branch.

[0032] Figure 5 The LC matching network provided by the embodiment of the present application is located in the schematic diagram of the series transmission line.

[0033] Figure 6 The LC matching network provided by the embodiment of the present application is located in the schematic diagram of the series transmission line.

[0034] Figure 7 The LC matching network provided by the embodiment of the present application is located in the schematic diagram of the series transmission line.

[0035] Figure 8 The LC matching network provided by the embodiment of the present application is located in the schematic diagram of the series transmission line.

[0036] Figure 9 The LC matching network provided by the embodiment of the present application is located in the schematic diagram of the series transmission line.

[0037] Figure 10 The LC matching network provided by the embodiment of the present application is located in the schematic diagram of the series transmission line.

[0038] Figure 11 The LC matching network provided by the embodiment of the present application is located in the schematic diagram of the series transmission line.

[0039] Figure 12 The LC matching network provided by the embodiment of the present application is located in the schematic diagram of the series transmission line.

[0040] Figure 13 The LC matching network provided by the embodiment of the present application is located in the schematic diagram of the series transmission line.

[0041] Figure 14 The LC matching network provided by the embodiment of the present application is located in the schematic diagram of the series transmission line. Figure 14 The LC matching network provided by the embodiment of the present application is located in the schematic diagram of the series transmission line. Figure 14 The LC matching network provided by the embodiment of the present application is located in the schematic diagram of the series transmission line.

[0042] Figure 15 The LC matching network provided by the embodiment of the present application is located in the schematic diagram of the series transmission line. Figure 15(a) in the figure is an actual manufacturing path diagram, Figure 15 (b) in the figure is a high adjacent band suppression large bandwidth filter architecture physical diagram. DETAILED DESCRIPTION

[0043] The following will be described in detail in combination with specific implementation examples. The following examples are only related parts of the present application, and the examples will help relevant personnel understand the principles of the present application, and do not limit the present application. It should be noted that on the basis of the concept of the present application, corresponding structural adjustments and changes can be made, and such changes belong to the protection scope of the present application.

[0044] 5.15-5.85GHz frequency band and 5.925-7.125GHz are two extremely important frequency bands for WiFi and 6G communication, both of which have super large bandwidth, but are adjacent and easy to interfere. In order to realize the passband in one of the frequency bands and the wide and deep suppression in the other frequency band, the step type acoustic band stop filter unit is connected through the LC matching network in the specific embodiment of the present application, the narrow band stop suppression is realized by transverse and longitudinal superposition, and the wide and deep band stop suppression is obtained, and the mixed resonance network is connected to form the required extremely deep zero point at the low frequency.

[0045] The specific embodiment of the present application provides a step type band stop filter unit composed of acoustic resonators. Since the design frequency band selected by the present application is a high frequency band, the network is composed of two or more series resonators As and one or more parallel resonators Ap to form a T-type step filter unit, wherein one end of the parallel resonator is connected in the middle of two adjacent series resonators, and one end includes but is not limited to ground. The transmission zero point and the transmission pole generated by the acoustic resonator of the filter unit can obtain the band stop filtering effect with fast transition and deep suppression, and at the same time, the passband effect is displayed at high frequency or low frequency.

[0046] In a specific embodiment, as shown in Figure 1 The T-type step filter unit one provided by the embodiment includes two series resonators As1 and one parallel resonator Ap1 on the parallel branch between the two series resonators As1.

[0047] As shown in Figure 2 The other T-type step filter unit two provided by the embodiment includes three series resonators As2 and two parallel resonators Ap2. The resonator thickness of the two T-type step filter units one and filter unit two is designed in the embodiment, and the filter circuit has a wide band stop. Among them, the series resonators As1 of the step type band stop filter unit one have consistent thickness, the parallel resonators Ap1 of the step type band stop filter unit one have thinner thickness than the series resonators As1, and the series resonators As2 of the filter unit two have consistent thickness, and the parallel resonators Ap2 of the filter unit two have consistent thickness with the series resonators As1 of the step type band stop filter unit one.

[0048] like Figure 3 As shown, by Figure 2 The S-parameter curves obtained by connecting two stepped band-stop filter units in series are shown. The frequency range of f2-f3 is band-stopped by filter unit two, and the frequency range of f4-f5 is band-stopped by filter unit one. Although the two are superimposed to obtain a wide stopband, there is a bulge in the middle of the stopband, the suppression is not deep enough, and the performance of the passband frequency band curve is poor.

[0049] The zero point at frequency f2 is provided by the parallel resonant point fp of the series resonator As2; The zero point at frequency f3 is provided by the series resonant point fs of the parallel resonator Ap2; The zero point at frequency f4 is provided by the parallel resonant point fp of the series resonator As1; The zero point at frequency f5 is provided by the series resonant point fs of the parallel resonator Ap1; The series resonator As1 and the parallel resonator Ap2 have the same film thickness, meaning they have the same frequency.

[0050] like Figure 4 As shown in the figure, a specific embodiment of the present invention provides a filter circuit in which an LC matching network and a stepped band-stop filter unit are connected in parallel, wherein the LC matching network is an inductor Lm.

[0051] In a specific embodiment of this invention, when the LC matching network is in a parallel branch, one end is connected to the series main circuit, and the other end is connected to the ground wire. Compared with the prior art, when the parallel inductor Lm mentioned in this invention is located in the parallel branch and connected in parallel with the parallel resonator Ap1, it can form an additional pole at low frequencies, and at the same time shift the parallel resonant point fp of the parallel resonator Ap1 to the desired frequency, thereby achieving better suppression.

[0052] like Figure 5 As shown in the figure, a specific embodiment of the present invention provides an LC matching network connected to a stepped band-stop filter unit, wherein the LC matching network is an inductor Ls.

[0053] When the LC matching network in a specific embodiment of the present invention is in the series trunk, the series inductor Ls not only has the function of impedance matching, but also can move the series resonant point fs of the series resonator to the left, so that the pole formed by the series resonant point is located outside the stopband to be suppressed, or moved to the zero position of the filter unit, thereby eliminating the stopband bump generated by the pole, and thus obtaining a wide and deep band-stop performance.

[0054] In a specific embodiment of the present invention, the LC matching network can be located at both ends of the stepped band-stop filter unit, acting as a bridge for the stepped band-stop filter unit.

[0055] In a specific embodiment of the present invention, the LC matching network can be located at the input and output ends, serving as input-output matching.

[0056] like Figure 6 As shown in the figure, a specific embodiment of the present invention provides a filter circuit composed of a stepped band-stop filter unit and an LC matching network. The stepped band-stop filter unit includes filter unit one, filter unit two, etc. The stepped band-stop filter units in this circuit are connected in series with matching inductors at intervals, and the input and output terminals are impedance matched by parallel inductors Lm. The series matching inductor Ls moves the series resonant point of the series resonator, which is also the pole of the filter, to a stopband range with deep suppression, preventing spikes from forming between the stopbands of the series stepped band-stop filter units. Furthermore, this inductor also achieves impedance matching between the individual stepped band-stop filter units.

[0057] like Figure 7 As shown in the figure, a specific embodiment of the present invention provides a hybrid resonant unit, which is composed of two capacitors and one inductor, wherein the capacitor Cp and the inductor Lp are connected in series, and the capacitor C0 is connected in parallel with the series unit formed by Cp and Lp.

[0058] A specific embodiment of the present invention provides a hybrid resonant unit in which the capacitor can be replaced with an acoustic resonator, thereby obtaining a resonant unit with multiple zeros.

[0059] like Figure 8 As shown in the figure, a specific embodiment of the present invention provides an ultra-wide bandwidth filter architecture with high adjacent band rejection. The architecture includes a stepped band-stop filter unit, an LC matching unit, and a hybrid resonant network. The stepped band-stop filter unit module includes multiple stepped band-stop filter units connected in series. Matching inductors Ls are connected in series between the stepped band-stop filter units. The stepped band-stop filter unit is a T-shaped stepped filter unit such as filter unit one and filter unit two. The LC matching unit is disposed on the parallel branch at both ends of the stepped band-stop filter unit module. The LC matching unit is a single inductor Lm. The hybrid resonant network is disposed between the LC matching unit and the stepped band-stop filter unit module. One end of the hybrid resonant network is grounded, and the other end is connected to the series trunk. The hybrid resonant network includes a series unit consisting of a first capacitor and a first inductor connected in series, and a second capacitor connected in parallel with the series unit.

[0060] like Figure 9 As shown, a specific embodiment of the present invention also provides an ultra-wideband filter architecture with high adjacent band suppression, which is similar to... Figure 8 Unlike the ultra-wideband filter architecture shown, the LC matching unit is a single inductor Ls set in the series trunk, which is connected in series with the stepped band-stop filter unit.

[0061] like Figure 10As shown, it is from Figure 9 The circuit shown is derived from a specific circuit topology with three stepped band-stop filter units. In this circuit topology, filter unit one, filter unit two, and filter unit three are connected in sequence through a series matching inductor. The three band-stop frequency bands are superimposed to form a band-stop interval with wide and deep suppression, and a passband with low insertion loss and large bandwidth is formed at high frequencies.

[0062] like Figure 11 and 12 as well as Figure 13 The following is a specific embodiment of the present invention. Figure 10 The filter S-parameter diagram shows that f2-f3 form a stepped band-stop filter unit two, f4-f5 form a stepped band-stop filter unit one, and f6-f7 form a stepped band-stop filter unit three. These three stepped band-stop filter units are connected in series through an LC matching network to achieve a 700MHz bandwidth stopband with 55dB suppression, while simultaneously achieving a passband range of 5.925GHz-7.125GHz. The minimum insertion loss within the band is 1.4dB. By introducing a hybrid resonant network, an extremely deep zero is formed at f1, resulting in suppression of over 55dB at 2.4GHz. This effectively achieves a 6GHz passband for Wi-Fi while significantly minimizing interference from low-frequency Wi-Fi bands.

[0063] To verify the feasibility of the theory behind this invention, electromagnetic simulation studies and actual chip manufacturing were conducted. For example... Figure 14 As shown, Figure 14 (a) in the figure is based on the present invention. Figure 10 Electromagnetic simulation model of a high adjacent-band suppression filter circuit topology. Figure 14 (b) shows a comparison of the S-parameters of the electromagnetic simulation model and the schematic circuit, which are basically identical.

[0064] Figure 15 (a) in the middle shows Figure 10 The actual fabrication of the chip structure is illustrated, showing a chip including independent resonators, capacitors, and inductors; a hybrid filter constructed from multiple chips; and a bonding diagram of different chips. Specifically, the capacitor chip is gold-bonded to the resonator chip, and the resulting chip is then flip-chip bonded to the inductor chip, thereby obtaining the high adjacent-bandgap rejection, wide-bandwidth filter provided in this specific embodiment of the invention. Figure 15 As shown in (b) in the figure, it can be observed in the fixture.

[0065] In a specific embodiment of this invention, a stepped band-stop filter unit composed of acoustic resonators and a hybrid resonator unit are organically cascaded through an LC matching network. This cleverly utilizes the series superposition characteristics of the band-stop filter units. By designing the film thickness of the band-stop filter resonators, multiple band-stop filter unit networks form a wide and deep stopband suppression. Simultaneously, a series inductor is used to shift the series resonant frequency of the series resonators to the desired position, avoiding pole interference. Furthermore, the interaction between the matching network and the band-stop filter units creates low impedance and mutual impedance matching at high frequencies (5.925-7.125 GHz), resulting in a low insertion loss and flat passband. The properly embedded hybrid resonator unit can introduce extremely deep zeros at low frequencies, thus achieving suppression. The filter circuit obtained through these steps can achieve an ultra-wide bandwidth of 1200 MHz at high frequencies, while suppressing adjacent band signals to over 50 dB and possessing an extremely fast transition band. This provides an excellent solution to the challenges brought by the development of WIFI 6 / 7 and 5G / 6G, effectively solving signal interference problems.

Claims

1. A wide-bandwidth filter with high adjacent-band suppression, characterized in that, include: Stepped band-stop filter module, LC matching unit and hybrid resonant network; The stepped band-stop filter unit module includes multiple stepped band-stop filter units connected in series, and matching inductors connected in series between the stepped band-stop filter units. Each stepped band-stop filter unit includes multiple series resonators on the main series circuit and parallel resonators on the parallel branches between the series resonators. The film thickness of the series resonator of the current stepped band-stop filter unit is the same as that of the parallel resonator of the next stepped band-stop filter unit. The film thickness of the series resonators of different stepped band-stop filter units is different, and the film thickness of the parallel resonators is also different. The LC matching unit is located at both ends of the stepped band-stop filter unit module or between different stepped band-stop filter units. The hybrid resonant network is located on the parallel branch between the stepped band-stop filter unit module and the LC matching unit.

2. The high adjacent-bandwidth suppression, wide-bandwidth filter according to claim 1, characterized in that, The stepped band-stop filter unit is provided with at least one series resonator and at least two parallel resonators to form a Π-type stepped filter unit. The two ends of the parallel resonators are respectively connected to the ground wire and the series trunk.

3. The high adjacent-bandwidth suppression, wide-bandwidth filter according to claim 1, characterized in that, The stepped band-stop filter unit is provided with at least two series resonators and at least one parallel resonator to form a T-shaped stepped filter unit. The two ends of the parallel resonator are respectively connected to the ground wire and the series trunk.

4. The high adjacent-bandwidth suppression, wide-bandwidth filter according to claim 1, characterized in that, In the stepped band-stop filter unit, the resonant frequency of the series resonator is lower than that of the parallel resonator.

5. The high adjacent-bandwidth suppression, wide-bandwidth filter according to claim 1, characterized in that, The LC matching unit is an inductor Ls installed in the series trunk or an inductor Lm installed in the parallel branch; The inductor Ls is connected to different stepped band-stop filter units at both ends, or one end is connected to a stepped band-stop filter unit and the other end is connected to the output or input terminal. One end of the inductor Lm is connected to the series main circuit, and the other end is grounded.

6. The wide-bandwidth filter with high adjacent-band suppression according to claim 1, characterized in that, The stepped band-stop filter unit network module includes a stepped band-stop filter unit one and a stepped band-stop filter unit two. The stepped band-stop filter unit includes two series resonators As1 arranged in the series trunk and a parallel resonator Ap1 in the parallel trunk between the series resonators As1. The stepped band-stop filter unit 2 includes three series resonators As2 arranged on the series trunk line and parallel resonators Ap2 arranged on two parallel trunk lines between the series resonators As2. The film thickness of the series resonator As1 is the same as that of the parallel resonator Ap2. The film thicknesses of the series resonators As1 and As2 are different. The parallel resonators Ap1 and Ap2 have different film thicknesses.

7. The high adjacent-bandwidth suppression, wide-bandwidth filter according to claim 1, characterized in that, The LC matching unit is a single inductor.

8. The high adjacent-bandwidth suppression, wide-bandwidth filter according to claim 1, characterized in that, The hybrid resonant network is grounded at one end and connected to a series trunk at the other end. The hybrid resonant network includes a series unit consisting of a first capacitor and a first inductor connected in series, and a second capacitor connected in parallel with the series unit. The hybrid resonant network can provide a deep zero at the low frequency of the filter curve.

9. The high adjacent-bandwidth filter with high adjacent-band suppression according to claim 8, characterized in that, Replace the layer acoustic resonator with the first and second capacitors.

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