CN117559958A - Filter, duplexer, multiplexer and communication equipment - Google Patents

Abstract

The application provides a filter, a duplexer, a multiplexer and a communication device, wherein the filter comprises an input end, an output end, one or more series resonators and one or more parallel resonators, wherein the one or more series resonators and/or at least one resonator of the one or more parallel resonators is split into two series split resonators in series, wherein a phase delay factor PDC of the series split resonators meets a predetermined range. By the processing scheme, the nonlinear characteristic of the filter is improved.

Description

Filter, duplexer, multiplexer and communication equipment

Technical Field

The invention relates to the technical field of semiconductor devices, in particular to a filter, a duplexer, a multiplexer and communication equipment.

Background

With the continuous development of mobile communication technology, the frequency spectrum complexity trend is increasingly accelerated, and the number of frequency bands used in mobile communication has been greatly increased from 4 frequency bands in the early 2000 to more than 50 frequency bands today.

The complexity of the frequency spectrum makes the requirements on the performance of the radio frequency system become more and more severe, and the good performance of the radio frequency filter can improve the transmission rate, service life and reliability of the radio frequency system, so that the continuous improvement on the performance of the filter is very urgent, and the continuous improvement on the performance of the filter is mainly characterized by lower insertion loss, higher out-of-band rejection, higher roll-off, higher power capacity and better nonlinear characteristics.

Disclosure of Invention

An object of the present application is to provide a filter, a duplexer, a multiplexer and a communication device, which at least partially solve the problems existing in the prior art.

In order to achieve the above purpose, the technical solution adopted in the embodiments of the present disclosure is as follows:

in a first aspect, embodiments of the present disclosure provide a filter, the filter comprising: an input, an output, one or more series resonators and one or more parallel resonators, wherein

At least one of the one or more series resonators and/or the one or more parallel resonators is split in series into two series split resonators, wherein a phase delay factor PDC of the series split resonators satisfies a predetermined range.

According to a specific implementation of an embodiment of the present disclosure, the phase delay factor PDC satisfies: PDC is more than or equal to 1.3 and less than or equal to 4.

According to a specific implementation of an embodiment of the present disclosure, the phase delay factor PDC satisfies: PDC is more than or equal to 1.5 and less than or equal to 3.5.

According to a specific implementation of an embodiment of the present disclosure, at least one of the first-stage series resonator and the first-stage parallel resonator near the output end is split in series into two series split resonators.

According to a specific implementation of an embodiment of the disclosure, the two series split resonators have the same area.

According to a specific implementation of an embodiment of the disclosure, the two series split resonators are identical in shape.

According to a specific implementation of an embodiment of the disclosure, the area of the two series split resonators is 2 times the area of the split resonator.

According to a specific implementation of an embodiment of the disclosure, the average resonant frequency of the two series split resonators is the same as the resonant frequency of the split resonator.

According to a specific implementation of an embodiment of the disclosure, the polarization directions of the two series split resonators are opposite.

According to a specific implementation manner of the embodiment of the disclosure, the upper electrodes of the two series split resonators are connected; or the lower electrodes of the two series split resonators are connected.

According to a specific implementation of an embodiment of the disclosure, the filter further comprises an LC matching circuit at the input and/or the output.

In a second aspect, there is provided a diplexer comprising a filter according to the first aspect of the embodiments of the present disclosure and any implementation thereof.

In a third aspect, a multiplexer is provided, the multiplexer comprising a filter according to the first aspect of the disclosure and any implementation thereof or a diplexer according to the second aspect of the disclosure.

In a fourth aspect, a communication device is provided, the communication device comprising a filter according to the first aspect of the present disclosure and any implementation thereof, or a diplexer according to the second aspect of the present disclosure, or a multiplexer according to the third aspect of the present disclosure.

The filter in the embodiment of the disclosure comprises an input end, an output end, one or more series resonators and one or more parallel resonators, wherein the one or more series resonators and/or at least one resonator of the one or more parallel resonators is split in series into two series split resonators, wherein a phase delay factor PDC of the series split resonators satisfies a predetermined range. By the processing scheme, the nonlinear characteristic of the filter is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person of ordinary skill in the art.

FIG. 1 is a prior art design method for improving nonlinear characteristics of a filter;

fig. 2 is a schematic structural diagram of a resonator according to an embodiment of the disclosure;

FIG. 3 is a schematic diagram of an electrical sign and polarization direction of a resonator according to an embodiment of the disclosure;

FIG. 4 is a schematic diagram of a series nonlinear split provided by an embodiment of the present disclosure;

FIG. 5 is a schematic diagram of the resonant frequency of a resonator provided by an embodiment of the present disclosure;

FIG. 6 is a schematic diagram of a series nonlinear split with parasitic parameters provided by an embodiment of the present disclosure;

FIG. 7 is a top view of a resonator provided by an embodiment of the present disclosure;

FIG. 8 is a graph showing a relationship between a delay phase θ and a phase delay factor PDC generated at an output end of a resonator according to an embodiment of the present disclosure;

fig. 9 is a schematic structural diagram of a filter according to an embodiment of the disclosure;

FIG. 10 is a graph comparing nonlinear frequency characteristic curves of examples of the present disclosure and comparative examples;

fig. 11 is a schematic structural diagram of a duplexer according to an embodiment of the present disclosure.

In the figures, 11a, 11b, 11c, 11 d-series resonators; 1000-series split resonator; 12a, 12b, 12 c-parallel resonators; 104-an acoustic mirror; 106-a lower electrode; 108-a piezoelectric thin film layer; 110-upper electrode; 210-a first filter; 220-a second filter.

Detailed Description

Embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

Other advantages and effects of the present application will become apparent to those skilled in the art from the disclosure of the present application, which is described below by way of specific examples. It will be apparent that the described embodiments are only some, but not all, of the embodiments of the present application. The present application may be embodied or carried out in other specific embodiments, and the details of the present application may be modified or changed from various points of view and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments may be combined with each other without conflict. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.

It is noted that various aspects of the embodiments are described below within the scope of the following claims. It should be apparent that the aspects described herein may be embodied in a wide variety of forms and that any specific structure and/or function described herein is merely illustrative. Based on the present application, one skilled in the art will appreciate that one aspect described herein may be implemented independently of any other aspect, and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented and/or a method practiced using any number of the aspects set forth herein. In addition, such apparatus may be implemented and/or such methods practiced using other structure and/or functionality in addition to one or more of the aspects set forth herein.

It should also be noted that the illustrations provided in the following embodiments merely illustrate the basic concepts of the application by way of illustration, and only the components related to the application are shown in the illustrations, not according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complex.

In addition, in the following description, specific details are provided in order to provide a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects may be practiced without these specific details.

First, referring to fig. 1, a structure of a filter and a design method for improving nonlinear characteristics of the filter are described. In fig. 1, reference numeral RF _in Indication input end, reference sign RF _out The instruction output terminals, reference numerals 11a, 11b, 11c, and 11d denote series resonators, and reference numerals SH1, SH2, and SH3 denote parallel resonators. That is, the filter includes at least an input terminal, an output terminal, a series resonator, and a parallel resonator.

In addition, in order to improve the nonlinear characteristics of the filter, as shown in fig. 1, one of the resonators is split in series into three resonators, specifically, near the output RF _out The first series resonator 11d of the pair is split into three split resonators 1000 in series, and the second-order nonlinear harmonic components of the split resonators are mutually offset by setting the polarity and signal delay parameters of the split resonators 1000, so that the nonlinear characteristics of the filter are improved.

In the presently disclosed embodiments, the term "series split" refers to splitting one resonator into two or more resonators that are equivalent to each other in series; the term "series nonlinear splitting" refers to splitting one resonator into two or more resonators connected in series with each other in equivalent, and two resonators adjacent to each other in the two or more resonators after series splitting have opposite polarization directions.

The design scheme shown in fig. 1 splits 1 series resonator into 3 resonators in series, which increases the resonator area (compared with the case of not splitting, the area of the split resonator is increased to 9 times of the original resonator area), which is not beneficial to the miniaturization design of the device; in addition, the parasitic parameters have a larger influence on the nonlinear characteristics of the filter, and in the case of splitting the resonators, the more the number of split resonators (in the scheme shown in fig. 1, the number of split resonators is 3), the more and more complex the parasitic parameters are introduced, which is disadvantageous for cancellation of nonlinear harmonic components, so that it is difficult to improve the nonlinear characteristics of the filter.

In the embodiment of the disclosure, in order to realize better nonlinear characteristics of the filter, a resonator is split into two resonators, namely a first split resonator and a second split resonator in series and the shape of the resonator is defined, so that the nonlinear characteristics of the filter are improved by reducing the phase delay of a second-order nonlinear harmonic component generated by the first split resonator and transmitting the second-order nonlinear harmonic component generated by the second split resonator to an output end through the second split resonator without further increasing the area of the resonator, and the second-order nonlinear harmonic component generated by the first split resonator and the second-order nonlinear harmonic component generated by the second split resonator are offset to the greatest extent at the signal output end. Hereinafter, a scheme of improving nonlinear characteristics of a filter according to an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings.

First, referring to fig. 2, a structure of a resonator included in the filter is described, in fig. 2:

106: the lower electrode is made of metal materials such as molybdenum, gold, aluminum, magnesium, tungsten, copper, chromium and the like or alloy composed of multiple metals.

108: the piezoelectric thin film layer is made of monocrystalline aluminum nitride, polycrystalline aluminum nitride, zinc oxide, PZT and the like, and the piezoelectric material may contain rare earth elements (such as Sc) doped according to a certain atomic ratio.

110: the upper electrode is made of metal materials such as molybdenum, gold, aluminum, magnesium, tungsten, copper, chromium and the like or alloy composed of multiple metals.

For the resonator, an acoustic mirror is provided on one side of each of the upper electrode 110 and the lower electrode 108 in the thickness direction, so that the acoustic wave is confined inside the piezoelectric resonator. The acoustic mirror may be an air cavity or a bragg reflection layer or other materials having a large acoustic impedance difference from the electrode material, the method and form of forming the acoustic mirror are not limited, and the acoustic mirror may be formed by supporting other materials on the substrate. In addition, in the embodiment of the present disclosure, the region where the upper electrode 110, the piezoelectric thin film layer 108, the lower electrode 106, and the acoustic mirror overlap each other and are adjacent to each other in the lamination direction is referred to as an effective resonance region of the resonator.

Fig. 2 shows the structure of the resonators included in the filter, which for the filter includes at least one series resonator and one parallel resonator as shown in fig. 2.

In addition, the resonator shown in fig. 2 may be simplified to the resonator electrical sign shown in fig. 3. In the structure shown in fig. 3, node N1 is connected to the upper electrode 110 of the resonator and node N2 is connected to the lower electrode 106 of the resonator. Because the half wavelength of the fundamental resonance frequency of the resonator is approximately equal to the thickness of the piezoelectric film layer 108 of the resonator (i.e., half wavelength resonance). So when the upper electrode 110 is positive, the lower electrode 106 is negative, or when the upper electrode 110 is negative, the lower electrode 106 is positive, defining the polarization direction c of the resonator to be directed from the node N2 to the node N1 in the thickness direction of the resonator, i.e., from the lower electrode 106 to the upper electrode 110 in the thickness direction of the resonator.

In addition, the wavelength of the second order nonlinear harmonic is approximately equal to the thickness of the piezoelectric thin film layer 108, i.e., when the upper electrode 110 and the lower electrode 106 are positive in polarity, the center of the piezoelectric thin film layer 108 is negative in polarity, or when the upper electrode 110 and the lower electrode 106 are negative in polarity, the center of the piezoelectric thin film layer 108 is positive in polarity.

When the piezoelectric thin film layer 108 is symmetrical in the resonator thickness direction, the upper electrode 110 and the lower electrode 106 have the same potential, and no second-order nonlinear harmonics are generated at this time. However, in practice, the piezoelectric film layer 108 is not strictly symmetrical in the thickness direction of the resonator, and the asymmetry of the piezoelectric film layer 108 causes an uneven distribution of the electric field therein, and the uneven distribution of the electric field causes a second-order nonlinear harmonic potential difference to be generated between the upper electrode 110 and the lower electrode 106, thereby generating a second-order nonlinear harmonic.

The term "symmetrical" is used herein to mean: the piezoelectric thin film layer 108 is generally in a polycrystalline preferred orientation structure (preferred orientation means that the crystal axes of materials are arranged along the same direction in the preparation process), and when the acoustic wave propagates along the crystal axis direction, the wave velocity is maximum, and stable resonance can be obtained, but in the actual preparation process, the crystal axes are not strictly parallel to the thickness direction, but slightly inclined, so that the piezoelectric thin film layer 108 is not completely symmetrical in the thickness direction.

In the embodiment of the disclosure, in order to suppress the generation of second-order nonlinear harmonics, the resonator is split in series nonlinearity, and the shape of the split resonator is defined.

Fig. 4 shows a schematic structural diagram of serial nonlinear splitting of resonators in an electrode inversion arrangement in an embodiment of the present disclosure.

In the example of the series nonlinear split shown in fig. 4, the resonator R is equivalently split into two first and second resonators R1 and R2 connected in series with each other, wherein the areas and shapes of the first and second resonators R1 and R2 are approximately equal, and the areas of the first and second resonators R1 and R2 are 2 times the area of the resonator R. Further, the average resonance frequency of the first resonator R1 and the second resonator R2 is approximately the same as the resonance frequency of the resonator R.

In addition, the polarization direction of the first resonator R1 is opposite to the polarization direction of the second resonator R2. In fig. 4, the polarization direction c of the first resonator R1 is set opposite to the polarization direction c of the second resonator R2, and in this case, the two resonators of the first resonator R1 and the second resonator R2 may be electrically connected through the lower electrode 106, and the upper electrode 110 of the first resonator R1 is connected to the signal input terminal in, and the upper electrode 110 of the second resonator R2 is connected to the signal output terminal out.

It should be understood that the polarization direction c of the first resonator R1 may be disposed opposite to the polarization direction c of the second resonator R2 (as indicated by the dotted arrow in fig. 4), in which case the two resonators of the first resonator R1 and the second resonator R2 may be electrically connected through the upper electrode 110, and the lower electrode 106 of the first resonator R1 is connected to the signal input terminal in, and the lower electrode 106 of the second resonator R2 is connected to the signal output terminal out.

That is, in the embodiment of the present disclosure, the polarization direction c of the first resonator R1 and the second resonator R2 is opposite, that is, the polarization direction c of the first resonator R1 is set opposite to the polarization direction c of the second resonator R2 as long as it is seen from the signal input terminal in or the signal output terminal out.

The above describes the series nonlinear splitting of the resonators, but in practice, since the areas and shapes of the two resonators of the first resonator R1 and the second resonator R2 cannot be realized to be exactly equal and equal to 2 times the area of the resonator R, the average resonance frequency of the first resonator R1 and the second resonator R2 is the same as the resonance frequency of the resonator R, and thus the difference between the areas and shapes of the two resonators of the first resonator R1 and the second resonator R2 may be required to be smaller than a predetermined threshold, and the difference between the areas of the first resonator R1 and the second resonator R2 and the area of the 2 times resonator R is smaller than a predetermined threshold, and the difference between the average resonance frequency of the first resonator R1 and the second resonator R2 and the resonance frequency of the resonator R is smaller than a predetermined threshold.

Taking the area as an example, assuming that the area of the first resonator R1 is a and the area of the second resonator R2 is b after the series nonlinear splitting, the difference between the areas of the first resonator R1 and the second resonator R2 is required to be smaller than a predetermined threshold (e.g., 5%), then |a-b|/(a+b)/2) < 5% is required. In other words, in the disclosed embodiments, equal, approximately equal, may be understood as a difference of less than 5%, 3%, or other values.

In addition, in the above description, the "area of the resonator" refers to the area of the effective resonance region of the resonator, and as described above, the region where the upper electrode 110, the piezoelectric thin film layer 108, the lower electrode 106, and the acoustic mirror overlap each other and are adjacent to each other in the lamination direction is referred to as the effective resonance region of the resonator.

In addition, the serial nonlinear splitting requires that the areas and the shapes of the two split resonators are approximately the same, so that the acoustic characteristics of the two resonators can be approximately the same, but in the actual manufacturing process, the areas and the shapes of the two resonators cannot be completely the same due to process deviation, so that the term of approximate is added in the invention.

Fig. 5 shows the impedance frequency characteristics of the resonator, in which the frequency corresponding to the minimum impedance point is the series resonance frequency Fs, and the frequency corresponding to the maximum impedance point is the parallel resonance frequency Fp. The resonance frequency of the resonator is generally referred to as a series resonance frequency Fs, and an average value of the resonance frequency of the first resonator R1 and the resonance frequency of the second resonator R2 is an average resonance frequency.

With continued reference to fig. 4, where H-R1 is a second order nonlinear harmonic generated by the first resonator R1 at the signal output terminal out, and H-R2 is a second order nonlinear harmonic generated by the second resonator R2 at the signal output terminal out, due to the electrode inversion arrangement shown in fig. 4, ideally, the second order nonlinear harmonics H-R1 and H-R2 are opposite in phase and identical in amplitude, and therefore cancel each other, so that the second order nonlinear harmonic is not generated at the signal output terminal out.

However, in actual situations, as shown in fig. 6, an interconnection metal WL exists between the first resonator R1 and the second resonator R2 (where the interconnection metal WL is formed by the upper electrode 110 and/or the lower electrode and/or other metal materials), so, due to parasitic effects of the interconnection metal WL and the second resonator R2, after the second nonlinear harmonic H-R1 generated by the first resonator R1 passes through the interconnection metal WL and the second resonator R2, a certain delay and attenuation are generated, and the second nonlinear harmonic H-R1-d shown by a dotted line in fig. 6 is the second nonlinear harmonic generated by the first resonator R1 after passing through the interconnection metal WL and the second resonator R2.

In other words, the parasitic effects of the interconnection metal WL and the second resonator R2 themselves make the second-order nonlinear harmonic H-R2 generated by the second resonator R2 and the second-order nonlinear harmonic H-R1-d generated by the first resonator R1 not have equal amplitude and opposite phases at the signal output terminal out, and therefore, the second-order nonlinear harmonics H-R2 and H-R1-d cannot be completely cancelled, so that even if the resonators are split in series nonlinear, the second-order nonlinear harmonic component h_total is generated at the signal output terminal out.

In addition, the larger the parasitic effect (including the parasitic effect of the interconnection metal WL and the second resonator R2 itself) is within a certain delay range, the worse the cancellation effect of the second-order nonlinear harmonic wave generated by the first resonator R1 and the second resonator R2 at the signal output terminal out, that is, the worse the nonlinear characteristic is. And, at the signal output end out, the relationship between the second-order nonlinear harmonic component h_total and the delay phase θ is h_total=α (1-cos θ), where the second-order nonlinear harmonic component h_total is a harmonic component obtained by synthesizing the second-order nonlinear harmonic H-R2 and the second-order nonlinear harmonic H-R1-d, and α is the amplitude of the second-order nonlinear harmonic.

In order to reduce the second order nonlinear harmonic component due to parasitic effects, in the embodiments of the present disclosure, not only the series nonlinear splitting of the resonators but also the shape of the split resonators are defined, thereby reducing the delay phase described above.

Fig. 7 shows a top view of a resonator comprising an effective resonance area of two resonators split in series non-linearly and an upper or lower electrode of two resonators split in series non-linearly. It should be noted that the size and relative positional relationship of the upper electrode 110, the piezoelectric thin film layer 108, the lower electrode 106, and the acoustic mirror 104 are not limited in the present invention.

In fig. 7, the resonator R is split in series nonlinearity into a first resonator R1 and a second resonator R2, wherein a closed thick solid line indicates an effective resonance region of the resonator, a broken line indicates an upper electrode or a lower electrode of the resonator, the first resonator R1 and the second resonator R2 are interconnected by the upper electrode or the lower electrode, a broken arrow in the figure indicates a signal propagation direction, that is, when a two-tone signal is input from an input terminal in to a series nonlinearity split resonator group, the first resonator R1 and the second resonator R2 each generate a second order nonlinear harmonic component, and the second order nonlinear component generated by the first resonator R1 is partially cancelled by an interconnection metal WL and the second resonator R2 between the two resonators R1 and R2, and then the second order nonlinear component generated by the second resonator R2 is at an output terminal out.

Next, by studying the relationship between the phase delay factor and the delay phase θ of the second resonator R2, the phase delay factor of the resonators is defined to be within a fixed range, so that the second order nonlinear harmonic components generated by the first resonator R1 and the second resonator R2 are increased in offset amount at the signal output terminal out, thereby further improving the nonlinear characteristics. It should be noted that, although the relationship between the phase delay factor and the delay phase θ of the second resonator R2 is regarded as an object of the study in the following, since the first resonator R1 and the second resonator R2 are similar, the relationship between the corresponding phase delay factor and the delay phase θ is also applicable to the first resonator R1.

In the embodiment of the disclosure, as shown in fig. 7, a point X1 is a centroid of a closed pattern formed by an effective resonance area of the first resonator R1, a point X2 is a centroid of a closed pattern formed by an effective resonance area of the second resonator R2, a line passing through two points X1 and X2 intersects the closed pattern formed by the effective resonance area of the second resonator R2, a length of a line segment between two points a and B, A, B is a length of a line segment crossing the point X2 and making a perpendicular to the line segment between two points C and D, C, D, and the length of the line segment between the perpendicular and the closed pattern formed by the effective resonance area of the second resonator R2 is B. The phase delay factor pdc=b/a is defined, and the larger the phase delay factor PDC, the more elongated the resonator shape is in the direction perpendicular to the signal transmission direction, and at this time, the interconnect metal WL is more easily realized as short as possible in the signal transmission direction and as long as possible in the direction perpendicular to the signal transmission direction, so that the parasitic effects of the interconnect metal WL and the second resonator R2 can be reduced.

Fig. 8 shows the relationship between the phase delay factor PDC of the second resonator R2 and the delay phase of the second order nonlinear harmonic wave generated by the first resonator R1 at the signal output terminal out, wherein the horizontal axis indicates the phase delay factor PDC and the vertical axis indicates the delay phase. It can be seen from the figure that the delay phase is smaller as the phase delay factor PDC increases, and that the delay phase tends to be unchanged after the phase delay factor PDC increases to some extent.

Specifically, when the phase delay factor pdc=0.5, the phase delay is equal to 30 °, and when the phase delay factor pdc=5, the phase delay is 10 °. When the phase delay factor pdc=1.3, the phase delay is equal to 20 °, and about 6% of the second order nonlinear harmonics are not canceled, and when the phase delay factor pdc=4, the phase delay is 15 °, and about 3% of the second order nonlinear harmonics are not canceled.

In addition, when the phase delay factor PDC is larger, the resonator at this time becomes longer, and in this case, the resonator itself is more likely to generate waves of other modes, and therefore, in the embodiment of the present disclosure, the phase delay factor PDC is required to be 4 or less. Preferably, the phase delay factor PDC is required to be in the range of 1.3 to 4 in order for non-linear harmonics not to be cancelled to be less than 6% and the resonator itself not to excite more spurious modes. More preferably, the phase delay factor PDC is required to be in the range of 1.5 to 3.5.

By defining the phase delay factor PDC of the resonator after the series nonlinear split, better nonlinear characteristics can be obtained.

Next, a filter circuit including a resonator as shown in fig. 7 is described. Fig. 9 shows a circuit topology of a filter according to an embodiment of the present disclosure, which is a ladder-type filter and includes series resonators Res1, res2, res3, and Res4, and parallel resonators Res5, res6, and Res7, wherein the series resonator Res4 is equally split into two resonators Res41 and Res42 connected in series with each other, and the polarization directions of the resonators Res41 and Res42 are opposite.

In addition, T1 is a filter signal input end, T2 is a filter signal output end, L1 and L2 are respectively a filter signal input end T1 series inductance and a filter signal output end T2 series inductance, L3, L4 and L5 are respectively a filter parallel branch series grounding inductance, that is, parallel resonators Res5, res6 and Res7 are respectively grounded through series grounding inductances L3, L4 and L5.

To achieve a better matching, LC matching circuits may be included at the signal input T1 and/or the signal output T2. The filter structure shown in fig. 9 is only an example, and the invention is not limited to the ladder-type structure filter stage number, the matching mode and the parallel branch grounding mode.

In addition, in the example shown in fig. 9, at least one of the first-stage resonators (including the first series resonator and the first parallel resonator near the signal output terminal T2) near the signal output terminal T2 is split in series nonlinearity, and the phase delay factor PDC of the split resonators in series nonlinearity can be made to satisfy a specific range, thereby improving the nonlinear characteristics of the filter. Specifically, the first series resonator and/or the first parallel resonator near the signal output terminal T2 may be split in series non-linearity, and the phase delay factor PDC of the resonator requiring the split in series non-linearity satisfies a specific range. In the example shown in fig. 9, the first series resonator Res4 near the signal output terminal T2 is subjected to series nonlinear splitting, and the phase delay factor PDC of the resonator requiring series nonlinear splitting ranges from 1.3 to 4. More preferably, the phase delay factor PDC is required to be in the range of 1.5 to 3.5. In this way, by splitting at least one of the first-stage series resonator and the first-stage parallel resonator near the output end in series into two series split resonators, the nonlinear characteristics of the filter can be further improved.

Fig. 10 shows a nonlinear frequency characteristic curve of an embodiment of the present disclosure and a comparative example, in which the horizontal axis indicates frequency and the vertical axis indicates second order nonlinear harmonics at the output terminal out. Wherein pdc=2.0 for resonators Res4-1 and Res4-2 in the examples of the present disclosure, and pdc=0.8 for resonators Res4-1 and Res4-2 in the comparative examples. In fig. 10, the line with the triangle mark indicates the second order nonlinear harmonic of the comparative example (pdc=0.8 of resonator Res 4-2), and the line with the circle mark indicates the second order nonlinear harmonic of the embodiment of the present disclosure (pdc=2 of resonator Res 4-2).

As can be seen from the figure, the second order nonlinear harmonic components generated by the resonator Res4-1 and the resonator Res4-2 at the output out in the embodiment of the present disclosure are smaller than the second order nonlinear harmonic components generated by the resonator Res4-1 and the resonator Res4-2 at the output out in the comparative example, and in particular, the nonlinear harmonic components of the embodiment of the present disclosure are about 5dB smaller on average than the nonlinear harmonic components of the comparative example. In other words, when the range of the phase delay factor PDC is not within the range (comparative example), the second order nonlinear harmonic cancellation effect produced by the resonators Res4-1 and Res4-2 is worse than in the case where the range of the phase delay factor PDC is 1.3 to 4 (the presently disclosed embodiment). Thus, in the disclosed embodiments, better second order nonlinearity is achieved by limiting the range of the phase delay factor PDC.

A filter circuit including a resonator of an embodiment of the present disclosure is described above with reference to fig. 9, and the embodiment of the present disclosure further provides a duplexer as shown in fig. 11, in which a first filter 210 is connected between an antenna port Ant and a first port T1, and a second filter 220 is connected between the antenna port Ant and a second port T2. The pass bands of the first filter 210 and the second filter 220 are not overlapped, the first filter 210 can suppress signals of other frequencies through signals of corresponding pass band frequencies, and the second filter 220 can suppress signals of other frequencies through signals of corresponding pass band frequencies.

The first filter 210 and/or the second filter 220 in the duplexer shown in fig. 11 may be a ladder filter shown in fig. 9, and may be other types of filters as well, and the filters include an input terminal, an output terminal, one or more series resonators, and one or more parallel resonators, wherein at least one resonator of the one or more series resonators and/or the one or more parallel resonators is split in series into two series split resonators, wherein a phase delay factor PDC of the series split resonators satisfies a predetermined range.

The duplexer of the present invention is only used as an example, and is not limited thereto, and the structure of the present invention can be applied to multiplexers such as triplexer, quad-multiplexer, etc., or electronic devices including the above-mentioned filters or multiplexers.

In addition, the embodiment of the disclosure further provides a communication device, where the communication device includes a filter, a duplexer, or a multiplexer as described above with reference to the drawings, and details thereof are not described herein again.

Accordingly, embodiments of the present disclosure provide the following:

1. a filter, the filter comprising: an input, an output, one or more series resonators and one or more parallel resonators, wherein

At least one of the one or more series resonators and/or the one or more parallel resonators is split in series into two series split resonators, wherein a phase delay factor PDC of the series split resonators satisfies a predetermined range.

2. The filter according to 1, the phase delay factor PDC satisfying: PDC is more than or equal to 1.3 and less than or equal to 4.

3. The filter according to 1, the phase delay factor PDC satisfying: PDC is more than or equal to 1.5 and less than or equal to 3.5.

4. The filter of claim 1, wherein at least one of the first-stage series resonator and the first-stage parallel resonator near the output end is split in series into two series split resonators.

5. The filter of 1, the two series split resonators having the same area.

6. The filter of 1, the two series split resonators being identical in shape.

7. The filter of claim 1, the two series split resonators having an area that is 2 times the area of the split resonator.

8. The filter of claim 1, wherein the average resonant frequency of the two series split resonators is the same as the resonant frequency of the split resonator.

9. The filter of claim 1, the two series split resonators having opposite polarization directions.

10. The filter of 9, the upper electrodes of the two series split resonators being connected; or the lower electrodes of the two series split resonators are connected.

11. The filter of 1, further comprising an LC matching circuit at the input and/or the output.

12. A diplexer comprising a filter according to any one of claims 1-11.

13. A multiplexer comprising a filter according to any one of claims 1-11 or a diplexer according to claim 12.

14. A communication device comprising a filter according to any one of claims 1-11 or a diplexer according to 12 or a multiplexer according to 13.

The foregoing description is only of the preferred embodiments of the present application and is not intended to limit the same, but rather, various modifications and variations may be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims (14)

1. A filter, the filter comprising: an input, an output, one or more series resonators and one or more parallel resonators, wherein

At least one of the one or more series resonators and/or the one or more parallel resonators is split in series into two series split resonators, wherein a phase delay factor PDC of the series split resonators satisfies a predetermined range.

2. The filter of claim 1, wherein the phase delay factor PDC satisfies: PDC is more than or equal to 1.3 and less than or equal to 4.

3. The filter of claim 1, wherein the phase delay factor PDC satisfies: PDC is more than or equal to 1.5 and less than or equal to 3.5.

4. The filter of claim 1, wherein at least one of the first stage series resonator and the first stage parallel resonator near the output is split in series into two series split resonators.

5. The filter of claim 1, wherein the two series split resonators are the same area.

6. The filter of claim 1, wherein the two series split resonators are identical in shape.

7. The filter of claim 1, wherein the two series split resonators have an area that is 2 times the area of the split resonator.

8. The filter of claim 1, wherein the average resonant frequency of the two series split resonators is the same as the resonant frequency of the split resonator.

9. The filter of claim 1, wherein the polarization directions of the two series split resonators are opposite.

10. The filter of claim 9, wherein upper electrodes of the two series split resonators are connected; or the lower electrodes of the two series split resonators are connected.

11. The filter of claim 1, further comprising an LC matching circuit at the input and/or the output.

12. A diplexer comprising a filter according to any one of claims 1-11.

13. A multiplexer comprising a filter according to any one of claims 1-11 or a diplexer according to claim 12.

14. A communication device comprising a filter according to any of claims 1-11 or a diplexer according to claim 12 or a multiplexer according to claim 13.