WO2021169584A1 - 调整滤波器电路的方法和滤波器、多工器、通讯设备 - Google Patents

调整滤波器电路的方法和滤波器、多工器、通讯设备 Download PDF

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WO2021169584A1
WO2021169584A1 PCT/CN2020/141270 CN2020141270W WO2021169584A1 WO 2021169584 A1 WO2021169584 A1 WO 2021169584A1 CN 2020141270 W CN2020141270 W CN 2020141270W WO 2021169584 A1 WO2021169584 A1 WO 2021169584A1
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resonator
filter
inductor
series
inductance
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PCT/CN2020/141270
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English (en)
French (fr)
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蔡华林
庞慰
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诺思(天津)微系统有限责任公司
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Publication of WO2021169584A1 publication Critical patent/WO2021169584A1/zh

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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
    • H03H9/70—Multiple-port networks for connecting several sources or loads, working on different frequencies or frequency bands, to a common load or source
    • H03H9/703—Networks using bulk acoustic wave devices
    • H03H9/706—Duplexers
    • 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

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  • the present invention relates to the technical field of filters, in particular to a method for adjusting a filter circuit, a filter, a multiplexer, and a communication device.
  • Fig. 1 is a schematic diagram of a filter topology according to the prior art.
  • the input and output ends of the filter (as shown by the black dots in the figure, the two are interchangeable) are connected in series with an inductor and 5 piezoelectric acoustic resonators (called series resonators) and Another inductor, as shown by the horizontal branch in the figure; the filter also has 4 parallel branches, as shown by the 4 vertical branches in the figure, each parallel branch contains 1 resonator (called Parallel resonator) and an inductor.
  • the specific structure is not limited to the structure shown in FIG. 1, but at least two series resonators and one parallel resonator must be included.
  • Passive devices are generally implemented on chip layouts or package substrates. Additional passive losses and irremovable unfavorable coupling will worsen loss, out-of-band suppression and isolation performance. At the same time, in order to achieve specific passive devices and avoid disadvantages Coupling, the introduction of multiple passive devices will increase the chip layout and the size of the package structure, which limits the miniaturization of the device.
  • the present invention proposes to eliminate the passive components in the filter structure in an equivalent manner, and provides a method for adjusting the filter circuit, filters, multiplexers, and communication equipment, which are helpful for the development of radio frequency communication front-ends. miniaturization.
  • a method for adjusting a filter circuit is provided.
  • the filter includes a plurality of piezoelectric acoustic wave resonators, and the method includes one or more of the following: For a filter composed of one resonator and one inductor The series body adjusts the structure of the resonator so that the specified performance index of the resonator after adjustment is close to the specified performance index of the series body according to the specified error range, and then the inductance is removed; for one resonator in the filter A parallel body composed of a capacitor, adjust the structure of the resonator so that the specified performance index of the resonator after adjustment is close to the specified performance index of the parallel body within the specified error range, and then remove the capacitor; for the filter In the two inductors with mutual inductance coupling, firstly change the two inductors into the first inductance, the second inductance, and the third inductance.
  • the first end of the third inductance is grounded, and the second end is connected to the first
  • the first end of the inductor and the second inductor, the second end of the first inductor and the second inductor are respectively connected to the first resonator and the second resonator to form a first series body and a second series body, and then the first series body and the second series body are formed respectively.
  • the adjustment structure of the resonator and the second resonator makes the adjusted specified performance index of the first resonator and the second resonator close to the specified performance of the first series body and the second series body according to the specified error range Index, then remove the first inductance and the second inductance; for the parasitic capacitance between the third resonator and the fourth resonator in the filter, adjust the structure of the third resonator and the fourth resonator to make the adjusted
  • the specified performance indicators of the third and fourth resonators are close to the specified performance indicators of the third and fourth combinations according to the specified error range, and the third resonator is directly connected to the input or output of the filter ,
  • the fourth resonator is directly grounded, where the third resonator is a series resonator and is connected with a third inductor before adjustment, the fourth resonator is a parallel resonator and is connected with a fourth inductor before adjustment, and the third combination Contains the third inductance and the
  • the fourth assembly includes the fourth inductance and the fourth network and the fourth resonator before the adjustment.
  • the third network and the fourth network are used for equivalent As for the parasitic capacitance, one end of the third network is located at the connection point of the third resonator and the third inductor, the other end is grounded, one end of the fourth network is located at the connection point of the fourth resonator and the fourth inductor, and the other end is grounded.
  • the step of adjusting the structure includes one or more of the following: changing the thickness of one or more of the following in the resonator: piezoelectric layer, upper electrode and its auxiliary structure, lower electrode and its auxiliary structure, lining Bottom, and other selected layers; change the structure of one or more of the following in the resonator: piezoelectric layer, upper electrode and its auxiliary structure, lower electrode and its auxiliary structure, substrate, and other selected layers; change resonance The boundary or internal structure of the filter; when the resonator of the adjusted structure is located on the first wafer of the filter and the other resonators of the filter are located on the second wafer of the filter, change the first crystal The thickness of the piezoelectric layer of the circular resonator.
  • the specified performance index includes a series resonance frequency, a parallel resonance frequency and an electromechanical coupling coefficient.
  • the specified error range is: the series resonance frequency and the parallel resonance frequency error is ⁇ 5M, preferably ⁇ 2M, and the electromechanical coupling coefficient error is ⁇ 0.5%, preferably ⁇ 0.2%.
  • the specified performance index further includes impedance.
  • the specified error range further includes: an impedance error of ⁇ 50%, preferably ⁇ 20%.
  • the third network and the fourth network have the same structure, and both include a first capacitor, a second capacitor, a first inductor, and a first resistor, wherein the latter three are connected in parallel and the first terminal is connected to the first capacitor , The second end is grounded.
  • the filter includes 5 series resonators and 4 parallel resonators, the first end of each parallel resonator is located at the connection point of adjacent series resonators, and the second end is grounded via an inductor; the third The resonator is directly connected to the input end of the filter, and there are two series resonators between the first end of the fourth resonator and the third resonator; or, the third resonator is connected to the The output end of the filter is connected, and there are two series resonators between the first end of the fourth resonator and the third resonator.
  • a filter including a plurality of piezoelectric acoustic resonators, and the circuit of the filter is obtained after adjusting the circuit according to the method of the present invention.
  • the passive components of the filter are completely or partially eliminated after the circuit is adjusted.
  • a multiplexer including a plurality of filters of the present invention.
  • a communication device including the filter of the present invention.
  • Fig. 1 is a schematic diagram of a filter topology according to the prior art
  • Figure 2 is an equivalent circuit of an acoustic wave resonator in the prior art
  • FIG. 4 is a circuit diagram of a filter after removing series inductance according to an embodiment of the present invention.
  • Figure 6 is a partial enlarged view of Figure 5 at 2.43-2.46 GHz;
  • FIG. 7 is the insertion loss curve of the series body and the resonator after adjusting the structure according to the embodiment of the present invention.
  • Figure 8 is a circuit diagram of a filter, in which some of the resonators are connected in parallel with capacitors;
  • FIG. 9 is a circuit diagram of a filter that eliminates the capacitor in FIG. 8;
  • Figure 11 is an enlarged view of Figure 10 at 2.49-2.51 GHz;
  • FIG. 12 is the insertion loss curve of the parallel body and the resonator after adjusting the structure according to the embodiment of the present invention.
  • FIG. 13 is an out-of-band suppression curve of the parallel body and the resonator after adjusting the structure according to the embodiment of the present invention.
  • Figure 14 is a schematic diagram of the mutual inductance generated between the inductances of the filter, where the inductances in the two parallel branches produce the mutual inductance M;
  • FIG. 15 is a circuit after decoupling the coupled inductor in FIG. 14;
  • Figure 16 is a circuit diagram of a filter, which shows the parasitic coupling capacitance
  • Figure 17 is a schematic diagram of replacing parasitic coupling capacitors with an equivalent network in a filter.
  • the passive components in the filter are eliminated in an equivalent manner, or the mutual inductance and parasitic capacitance generated by coupling are eliminated, which will be described in detail below.
  • the principle of elimination is explained by eliminating the inductance connected in series with the resonator.
  • the resonator 11 has an inductor 12 in series, and the two form a series body 13.
  • the piezoelectric acoustic resonator contains both mechanical and electrical effects, but it can be equivalent to a pure circuit element from an electrical point of view, as shown in Figure 2, which is the prior art
  • the equivalent circuit of an acoustic resonator includes two capacitors and one inductor.
  • Figure 3 shows the equivalent circuit of the resonator in Figure 3 after the inductance is connected in series.
  • the parameters of each element in its equivalent circuit can be changed, so that the performance of a single resonator after adjustment (the equivalent circuit is shown in Figure 2) is equivalent to that of the resonator before adjustment.
  • the performance of a series of inductors (the equivalent circuit is shown in Figure 3).
  • a resonator with an adjusted structure can be used to replace the original resonator and remove the inductance in series with the original resonator.
  • FIG. 4 is a circuit diagram of the filter after removing the series inductance according to the embodiment of the present invention.
  • the resonators shown by the dashed lines in FIG. 4 are equivalent to the series bodies in FIG. 1.
  • FIG. 5 is an impedance curve of the resonator before and after the series body and the adjustment structure according to the embodiment of the present invention.
  • the horizontal axis represents the frequency
  • the vertical axis represents the impedance.
  • Figure 6 is a partial enlarged view of Figure 5 at 2.43-2.46 GHz. As shown in Fig. 5, referring to the vicinity of the 2.4GHz frequency, the three curves from top to bottom correspond to the resonator and the above-mentioned series body after and before the adjustment of the structure, respectively.
  • the performance indicators of the resonator are close to the series body, that is, the two can be equivalent. Therefore, the series resonant frequency, parallel resonant frequency, and the impedance of each frequency point can be used as indicators to determine whether they are equivalent during adjustment. In addition, because the difference between the two is related to the electromechanical coupling coefficient, the electromechanical coupling coefficient can also be included in this indicator.
  • FIG. 6 the curve on the right corresponds to the resonator before the adjustment structure.
  • the upper and lower curves correspond to the resonator before and after the adjustment structure, respectively.
  • FIG. 7 because the resonator after adjustment The loss caused by the series inductance is avoided, so near the Fs frequency, the impedance of the resonator after adjusting the structure is smaller than the impedance of the series body, so that the loss of the device is lower, and the corresponding insertion loss performance is better.
  • FIG. 7 is the insertion loss curve of the series body and the resonator after adjusting the structure according to the embodiment of the present invention.
  • the horizontal axis represents the frequency
  • the vertical axis represents the loss.
  • the upper and lower curves at 2.45 GHz in Fig. 7 correspond to the resonator and series body after adjusting the structure, respectively. It can be seen from the figure that the resonator after adjusting the structure has better insertion loss performance than the series body.
  • FIG. 8 is a circuit diagram of a filter in which capacitors are connected in parallel with part of the resonators
  • FIG. 9 is a circuit diagram of a filter that eliminates the capacitors in FIG. 8.
  • the parallel body 81 and the parallel body 82 in FIG. 8 can be correspondingly equivalent to the two resonators shown by the dashed line in FIG. 9.
  • the equivalent effect can be seen in Figure 10 and Figure 11.
  • Fig. 10 is an impedance curve of the resonator before and after the parallel body and the adjustment structure of the embodiment of the present invention
  • Fig. 11 is an enlarged view of Fig. 10 at 2.49-2.51 GHz.
  • the curve from top to bottom corresponds to the resonator before and after the adjustment structure and the above-mentioned parallel body, respectively. Therefore, it can be seen that the performance of the resonator after adjusting the structure is close to that of the parallel body, that is, the two can be equivalent.
  • the right curve corresponds to the resonator before the adjustment structure
  • the upper and lower left curves respectively correspond to the resonator after the adjustment structure and the above-mentioned parallel body.
  • the insertion loss performance is improved due to the avoidance of the loss introduced by the parallel capacitor. This can be seen from FIG.
  • FIG. 13 is the out-of-band suppression curve of the parallel body and the resonator after adjusting the structure according to the embodiment of the present invention.
  • the lower and upper curves at 2.50 GHz correspond to the adjusted structure of the resonator and the above-mentioned parallel body, respectively.
  • the solid line shows better roll-off performance.
  • FIG. 14 is a schematic diagram of the mutual inductance between the inductors of the filter.
  • the inductances in the two parallel branches produce a mutual inductance M.
  • the two coupled inductors can be converted into circuits first to obtain an equivalent circuit without mutual inductance, as shown in FIG. 15, which is a solution of the coupled inductor in FIG. 14
  • the inductors 151, 152, and 153 jointly replace the two coupled inductors in FIG.
  • FIG. 16 is a circuit diagram of a filter, which shows the parasitic capacitance. According to the position of the parasitic capacitance, first transform it into an equivalent network, as shown in Figure 17, which is a schematic diagram of replacing the parasitic capacitance with an equivalent network in the filter.
  • the parasitic capacitance in Figure 16 is equivalent to two networks composed of resistors, capacitors, and inductances, network 1 and network 2, respectively. In this way, the combination body 171 and the combination body 172 can be divided in FIG.
  • the structure of the resonators (ie, the resonators 173 and 174) in the combination body can be adjusted in an equivalent manner so that the resonators 173 and 174 are equivalent to The combined body where it is located, thereby eliminating the resistance, capacitance, and inductance in the combined body.
  • the parasitic capacitance at the position in the figure is relatively obvious, so it is preferable to adjust the structure of the resonators 173 and 174 in the figure.
  • the above describes the method of adjusting the structure of the resonator to eliminate the passive components in the filter, or to eliminate the mutual inductance and parasitic capacitance caused by coupling.
  • you can specifically change the thickness of each layer of the resonator, including the upper electrode, the lower electrode, and the auxiliary structure of the two.
  • other layers can be included; or the resonator can be changed.
  • the structure and size of the boundary for example, adding additional patterns or structures around the upper and lower electrode layers to change the performance of the resonator.
  • the resonators are distributed on two wafers. At this time, the resonators whose structure needs to be changed can be placed on the same wafer, and other resonators can be placed on the other wafer, so that the pressure of these resonators can be adjusted.
  • the thickness of the electrical layer is distributed on two wafers.
  • the structure of the resonator is adjusted so that it is equivalent to a series body or a parallel body connected with a passive device, so that the passive device can be removed without impairing the performance of the filter. This way It can also eliminate the mutual inductance coupling and parasitic capacitance existing in the filter.

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  • Acoustics & Sound (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)

Abstract

一种调整滤波器电路的方法和滤波器、多工器、通讯设备。在该方法中，调整谐振器的结构从而使其等效于连接有无源器件的串联体或并联体，可以去除该无源器件而不削弱滤波器性能，还可以消除滤波器中存在的互感耦合与寄生电容。

Description

调整滤波器电路的方法和滤波器、多工器、通讯设备 技术领域
本发明涉及滤波器技术领域，特别地涉及一种调整滤波器电路的方法和滤波器、多工器、通讯设备。
背景技术
近年来的通信设备小型化和高性能趋势的加快，给射频前端提出了更高的挑战。在射频通信前端中，一方面要通过减小芯片尺和封装基板的尺寸来实现小型化，另一方面要通过减少损耗来源以及更好的谐振器配合设计来实现更好的性能。在现有的滤波器结构中，用于匹配的无源器件的无源器件较多，同时用于改善特定性能比如滚降插损等也需要额外引入更多的电感、电容、耦合等多种结构。
图1是根据现有技术的一种滤波器拓扑结构的示意图。如图1所示，滤波器的输入输出端(如图中黑点所示，二者可互换)之间依次串联有一个电感和5个压电声波谐振器(称作串联谐振器)以及另一个电感，如图中横向的支路所示；该滤波器还具有4条并联支路，如图中4条纵向的支路所示，每条并联支路包含1个谐振器(称作并联谐振器)和1个电感。在实际的滤波器中，具体结构不限于图1所示的结构，但至少需包含2个串联谐振器和1个并联谐振器。
无源器件一般是在芯片版图或者封装基板上实现，额外的无源损耗以及不可消除的不利耦合会恶化损耗，带外抑制以及隔离度等性能，同时，为了实现特定的无源器件以及避免不利耦合，引入的多个无源器件会增大芯片版图以及封装结构的尺寸，这限制了器件的小型化。
发明内容
有鉴于此，本发明提出以等效的方式消除滤波器结构中的无源器件，提供了一种调整滤波器电路的方法和滤波器、多工器、通讯设备，有助于射频通信前端的小型化。
为实现上述目的，根据本发明的一个方面，提供了一种调整滤波器电路的方法。
本发明的调整滤波器电路的方法中，所述滤波器包含多个压电声波谐振器，该方法包括以下的一项或多项：对于滤波器中的1个谐振器与1个电感组成的串联体，对该谐振器调整结构，使调整后的该谐振器的指定性能指标按指定误差范围接近所述串联体的指定性能指标，然后去除所述电感；对于滤波器中的1个谐振器与1个电容组成的并联体，对该谐振器调整结构，使调整后的该谐振器的指定性能指标按指定误差范围接近所述并联体的指定性能指标，然后去除所述电容；对于滤波器中的存在互感耦合的2个电感，先将该2个电感等效改变为第一电感、第二电感、以及第三电感，其中第三电感的第一端接地，第二端连接至第一电感和第二电感的第一端，第一电感和第二电感的第二端分别连接第一谐振器和第二谐振器从而分别构成第一串联体和第二串联体，然后对该第一谐振器和第二谐振器调整结构，使调整后的所述第一谐振器和第二谐振器的指定性能指标按指定误差范围接近所述第一串联体和所述第二串联体的指定性能指标，再去除第一电感和第二电感；对于滤波器中的第三谐振器和第四谐振器之间的寄生电容，对该第三谐振器和第四谐振器调整结构，使调整后的所述第三谐振器和第四谐振器的指定性能指标按指定误差范围接近第三组合体和第四组合体的指定性能指标，并且使第三谐振器直接连接滤波器的输入端或输出端，第四谐振器直接接地，其中，第三谐振器为串联谐振器并且在调整之前连接有第三电感，第四谐振器为并联谐振器并且在调整之前连接有第四电感，第三组合体包含第三电感和第三网络以及调整之前的第三谐振器，第四组合体包含第四电感和第四网络以及调整之前的第四谐振器，第三网络和第四网络用于等效所述寄生电容，第三网络一端位于第三谐振器和第三电感的连接点，另一端接 地，第四网络一端位于第四谐振器和第四电感的连接点，另一端接地。
可选地，所述调整结构的步骤包括如下一项或几项：改变谐振器中如下一者或多者的厚度：压电层，上电极及其附属结构，下电极及其附属结构，衬底，以及选择的其他层；改变谐振器中如下一者或多者的结构：压电层，上电极及其附属结构，下电极及其附属结构，衬底，以及选择的其他层；改变谐振器边界或者内部的结构；在被调整结构的谐振器位于所述滤波器的第一晶圆、该滤波器的其他谐振器位于所述滤波器的第二晶圆的情况下，改变第一晶圆的谐振器的压电层的厚度。
可选地，所述指定性能指标包括串联谐振频率和并联谐振频率以及机电耦合系数。
可选地，所述指定误差范围是：串联谐振频率和并联谐振频率误差为±5M，优选地为±2M，并且机电耦合系数误差为±0.5％，优选地为±0.2％。
可选地，所述指定性能指标还包括阻抗。
可选地，所述指定误差范围还包括：阻抗误差为±50％，优选地为±20％。
可选地，所述第三网络和所述第四网络结构相同，均包含第一电容、第二电容、第一电感、第一电阻，其中后三者并联且第一端与第一电容连接，第二端接地。
可选地，所述滤波器包含5个串联谐振器和4个并联谐振器，各个并联谐振器的第一端位于相邻串联谐振器的连接点，第二端经由电感接地；所述第三谐振器直接与所述滤波器的输入端连接，所述第四 谐振器的第一端与第三谐振器之间具有2个串联谐振器；或者，所述第三谐振器经由电感与所述滤波器的输出端连接，所述第四谐振器的第一端与第三谐振器之间具有2个串联谐振器。
根据本发明的第二方面，提供了一种滤波器，包含多个压电声波谐振器，所述滤波器的电路是根据本发明的方法调整电路之后得到。
可选地，所述滤波器在调整电路之后无源器件完全或者部分被消除。
根据本发明的第三方面，提供了一种多工器，包含多个本发明的滤波器。
根据本发明的第四方面，提供了一种通讯设备，包含本发明的滤波器。
本发明的有益效果主要有：
1、减小了无源器件的损耗，有效改善插损。无源器件有有限的Q值，因此任何无源器件的引入都会引入额外的损耗，因此减少了无源器件的使用会有效减低损耗，改善插损。
2、减少基板走线的不利耦合，改善带外抑制和插损。无源器件的实现方式一般是在版图和基板上实现，在较小的封装尺寸上，各个无源器件之间的耦合不可避免，多余的耦合会恶化隔离度、带外抑制甚至匹配特性。减少了无源器件就有效避免了耦合。
3、减少了版图和基板设计的复杂度。由于减少了无源器件，因此减少了在设计中对版图和基板所需的隔离和改善措施，有助于缩短设计周期。
附图说明
为了说明而非限制的目的，现在将根据本发明的优选实施例、特 别是参考附图来描述本发明，其中：
图1是根据现有技术的一种滤波器拓扑结构的示意图；
图2是现有技术中的声波谐振器的等效电路；
图3的谐振器串联电感之后的等效电路；
图4是根据本发明实施方式的去除串联电感之后的滤波器的电路图；
图5是根据本发明实施方式的串联体和调整结构前后的谐振器的阻抗曲线；
图6是图5在2.43-2.46GHz的局部放大图；
图7是本发明实施方式的串联体和调整结构后的谐振器的插损曲线；
图8是一种滤波器的电路图，其中部分谐振器上并联有电容；
图9是消除图8中的电容的滤波器的电路图；
图10是本发明实施方式的并联体和调整结构前后的谐振器的阻抗曲线；
图11是图10在2.49-2.51GHz的放大图；
图12是本发明实施方式的并联体和调整结构后的谐振器的插损曲线；
图13是本发明实施方式的并联体和调整结构后的谐振器的带外抑制曲线；
图14是滤波器的电感之间产生互感的示意图，其中两个并联支路中的电感产生了互感M；
图15是将图14中的耦合电感进行解耦后的电路；
图16是一种滤波器的电路图，其中示出了寄生耦合电容；
图17是在滤波器中采用等效网络替换寄生耦合电容的示意图。
具体实施方式
本发明实施方式中，采用等效的方式消除滤波器中的无源器件，或者消除耦合产生的互感以及寄生电容，以下具体加以说明。
1、消除的原理以及消除电感
先结合消除与谐振器串联的电感来说明消除的原理。从图1可以看出，若干谐振器与电感串联，例如谐振器11串联有电感12，二者组成串联体13。压电声波谐振器作为微型机电元件，其同时包含机械效应和电效应，但可以从电学的角度将其等效为一个纯电路元件，即如图2所示，图2是现有技术中的声波谐振器的等效电路，其包含两个电容和一个电感。在串联一个电感之后如图3所示，图3的谐振器串联电感之后的等效电路。通过调整谐振器的结构，可以改变其等效电路中的各元件的参数，从而使调整后的单个谐振器(等效电路如图2所示)的性能，等效于调整之前该谐振器与一个电感的串联体(等效电路如图3所示)的性能。也就是说，可以用一个调整过结构的谐振器，代替原有的谐振器并且去除与该原有谐振器串联的电感。这样，将图1中的各串联体进行上述等效处理之后，得到图4中的滤波器电路，图4是根据本发明实施方式的去除串联电感之后的滤波器的电路图。图4中的虚线所示的谐振器等效于图1中的各串联体。
以下结合阻抗曲线图来具体说明调整过结构的谐振器与上述串联体的等效情况。图5是根据本发明实施方式的串联体和调整结构前后的谐振器的阻抗曲线，横轴表示频率，纵轴表示阻抗。图6是图5在2.43-2.46GHz的局部放大图。如图5所示，参见2.4GHz频率附近，从上至下3条曲线分别对应于调整结构之后和之前的谐振器以及上述串联体。因此可以看出，调整结构之后的谐振器，谐振器各项性能指标与串联体接近，即二者可以等效。因此在调整时可以以串联谐振频率、并联谐振频率以及各频点的阻抗值为指标来确定是否等效。另外因为二者的差值与机电耦合系数相关，所以还可将机电耦合系数纳入该指标。
在图6中，右边曲线对应于调整结构之前的谐振器，在2.44GHz附近，上方和下方曲线分别对应于调整结构之前和之后的谐振器，从图6可以看出，因为调整之后的谐振器避免了串联电感带来的损耗，所以在Fs频率附近，调整结构之后的谐振器的阻抗比串联体的阻抗更 小，这样器件的损耗更低，对应的插入损耗的性能更佳，这可以从图7中看出，图7是本发明实施方式的串联体和调整结构后的谐振器的插损曲线，横轴表示频率，纵轴表示损耗。图7中2.45GHz处上方和下方的曲线分别对应于调整结构后的谐振器和串联体。从图中可以看出，调整结构之后的谐振器比之于串联体，有更好的插损性能。
2、消除电容
为了减小谐振器的机电耦合系数，可在谐振器上并联电容。对于谐振器和电容构成的并联体，可以用一个机电耦合系数较小的谐振器来等效。图8是一种滤波器的电路图，其中部分谐振器上并联有电容，图9是消除图8中的电容的滤波器的电路图。如图8和图9所示，图8中的并联体81和并联体82，可以对应地等效为图9中的虚线所示的两个谐振器。等效的效果可从图10和图11中看出。图10是本发明实施方式的并联体和调整结构前后的谐振器的阻抗曲线，图11是图10在2.49-2.51GHz的放大图。
如图10所示，在2.53GHz附近，曲线从上至下分别对应于调整结构之前和之后的谐振器以及上述并联体。因此可以看出，调整结构之后的谐振器，性能与并联体接近，即二者可以等效。在图11中，右边曲线对应于调整结构之前的谐振器，左边上方和下方曲线分别对应于调整结构之后的谐振器和上述并联体。从图11可看出，因避免了并联电容引入的损耗，所以改善了插损性能，这从图12可以看出，图12是本发明实施方式的并联体和调整结构后的谐振器的插损曲线。图12中，2.45GHz处上方和下方的曲线分别对应于调整结构后的谐振器和并联体。可以看出实线显示出更好的插损性能。
另外采用调整结构之后的谐振器还有助于改善滚降性能。可参考图13，图13是本发明实施方式的并联体和调整结构后的谐振器的带外抑制曲线。其中2.50GHz处下方和上方的曲线分别对应于调整结构后的谐振器和上述并联体。从图13中可以看出，实线显示出更好的滚降 性能。
3、消除互感
在滤波器电路中，有可能因电感的互感效应而在两个电感之间产生互感，即两个电感耦合，如图14所示，图14是滤波器的电感之间产生互感的示意图，其中两个并联支路中的电感产生了互感M。对于这种情况，在本发明实施方式中，可先将耦合的两个电感作电路变换以得到无互感的等效电路，如图15所示，图15是将图14中的耦合电感进行解耦后的电路，其中电感151、152、153共同替代图14中的耦合的两个电感，且电感151、152、153之间无互感。从图15中可以看出，解耦的处理得到了两个新的串联体，各包含一个谐振器和一个电感，可以采用上述第1节中介绍的方式来消除该串联体中的电感。这样只剩下电感153，即较之于原始的电路消除了1个电感。
需要说明的是，因器件的布置，互感可能产生在任意两个电感之间。因此上述仅为举例，在实现中不限于消除相邻并联支路的电感之间的互感。
4、消除寄生电容
在滤波器电路中，还广泛存在着寄生电容，如以电路形式表示，可参考图16，图16是一种滤波器的电路图，其中示出了寄生电容。根据该寄生电容的位置，先将其变换为等效网络，如图17所示，图17是在滤波器中采用等效网络替换寄生电容的示意图。在图17中，将图16中的寄生电容等效为2个由电阻、电容、电感组成的网络，分别是网络1和网络2。这样，在图17中可以划分出组合体171和组合体172，采用等效的方式，调整组合体中的谐振器(即谐振器173、174)的结构，使谐振器173、174等效于其所在的组合体，从而消除组合体中的电阻、电容、电感。对于图16所示的滤波器来说，图中位置的寄生电容相对明显，所以优选地是调整图中谐振器173、174的结构。
以上对于通过调整谐振器的结构来消除滤波器中的无源器件，或者消除耦合产生的互感以及寄生电容的方法做出了说明。在调整谐振器的结构时，具体可以改变谐振器各层的厚度，包括上电极、下电极以及二者的附属结构，对于有特殊功能的谐振器还会包含其他的层；或者可改变谐振器边界的结构和尺寸，例如在上下电极层的周围加入额外的图形或结构来改变谐振器的性能。在有些滤波器中，谐振器分布在两个晶圆上，此时可以将需要改变结构的谐振器置于同一晶圆，其他谐振器置于另一晶圆，从而可以调节这些谐振器的压电层的厚度。
根据本发明实施方式的技术方案，调整谐振器的结构从而使其等效于连接有无源器件的串联体或并联体，这样可以去除该无源器件而不削弱滤波器性能，利用这种方式还可以消除滤波器中存在的互感耦合与寄生电容。
上述具体实施方式，并不构成对本发明保护范围的限制。本领域技术人员应该明白的是，取决于设计要求和其他因素，可以发生各种各样的修改、组合、子组合和替代。任何在本发明的精神和原则之内所作的修改、等同替换和改进等，均应包含在本发明保护范围之内。

Claims (14)

  1. 一种调整滤波器电路的方法，所述滤波器包含多个压电声波谐振器，其特征在于，该方法包括以下的一项或多项：
    对于滤波器中的1个谐振器与1个电感组成的串联体，对该谐振器调整结构，使调整后的该谐振器的指定性能指标按指定误差范围接近所述串联体的指定性能指标，然后去除所述电感；
    对于滤波器中的1个谐振器与1个电容组成的并联体，对该谐振器调整结构，使调整后的该谐振器的指定性能指标按指定误差范围接近所述并联体的指定性能指标，然后去除所述电容；
    对于滤波器中的存在互感耦合的2个电感，先将该2个电感等效改变为第一电感、第二电感、以及第三电感，其中第三电感的第一端接地，第二端连接至第一电感和第二电感的第一端，第一电感和第二电感的第二端分别连接第一谐振器和第二谐振器从而分别构成第一串联体和第二串联体，然后对该第一谐振器和第二谐振器调整结构，使调整后的所述第一谐振器和第二谐振器的指定性能指标按指定误差范围接近所述第一串联体和所述第二串联体的指定性能指标，再去除第一电感和第二电感；
    对于滤波器中的第三谐振器和第四谐振器之间的寄生电容，对该第三谐振器和第四谐振器调整结构，使调整后的所述第三谐振器和第四谐振器的指定性能指标按指定误差范围接近第三组合体和第四组合体的指定性能指标，并且使第三谐振器直接连接滤波器的输入端或输出端，第四谐振器直接接地，其中，第三谐振器为串联谐振器并且在调整之前连接有第三电感，第四谐振器为并联谐振器并且在调整之前连接有第四电感，第三组合体包含第三电感和第三网络以及调整之前的第三谐振器，第四组合体包含第四电感和第四网络以及调整之前的第四谐振器，第三网络和第四网络用于等效所述寄生电容，第三网络一端位于第三谐振器和第三电感的连接点，另一端接地，第四网络一端位于第四谐振器和第四电感的连接点，另一端接地。
  2. 根据权利要求1所述的方法，其特征在于，所述调整结构的步骤包括如下一项或几项：
    改变谐振器中如下一者或多者的厚度：压电层，上电极及其附属结构，下电极及其附属结构，衬底，以及选择的其他层；
    改变谐振器中如下一者或多者的结构：压电层，上电极及其附属结构，下电极及其附属结构，衬底，以及选择的其他层；
    改变谐振器边界或者内部的结构；
    在被调整结构的谐振器位于所述滤波器的第一晶圆、该滤波器的其他谐振器位于所述滤波器的第二晶圆的情况下，改变第一晶圆的谐振器的压电层的厚度。
  3. 根据权利要求1或2所述的方法，其特征在于，所述指定性能指标包括串联谐振频率和并联谐振频率以及机电耦合系数。
  4. 根据权利要求3所述的方法，其特征在于，所述指定误差范围是：串联谐振频率和并联谐振频率误差为±5M并且机电耦合系数误差为±0.5％。
  5. 根据权利要求4所述的方法，其特征在于，所述指定误差范围是：串联谐振频率和并联谐振频率误差为±2M并且机电耦合系数误差为±0.2％。
  6. 根据权利要求4所述的方法，其特征在于，所述指定性能指标还包括阻抗。
  7. 根据权利要求5所述的方法，其特征在于，所述指定误差范围还包括：阻抗误差为±50％。
  8. 根据权利要求7所述的方法，其特征在于，所述指定误差范围还包括：阻抗误差为±20％。
  9. 根据权利要求1所述的方法，其特征在于，所述第三网络和所述第四网络结构相同，均包含第一电容、第二电容、第一电感、第一电阻，其中后三者并联且第一端与第一电容连接，第二端接地。
  10. 根据权利要求1、2或9所述的方法，其特征在于，所述滤波器包含5个串联谐振器和4个并联谐振器，各个并联谐振器的第一端位于相邻串联谐振器的连接点，第二端经由电感接地；
    所述第三谐振器直接与所述滤波器的输入端连接，所述第四谐振器的第一端与第三谐振器之间具有2个串联谐振器；或者，所述第三谐振器经由电感与所述滤波器的输出端连接，所述第四谐振器的第一端与第三谐振器之间具有2个串联谐振器。
  11. 一种滤波器，包含多个压电声波谐振器，其特征在于，所述滤波器的电路是根据权利要求1至10中任一项的方法调整电路之后得到。
  12. 根据权利要求11所述的滤波器，其特征在于，所述滤波器在调整电路之后无源器件完全或者部分被消除。
  13. 一种多工器，其特征在于，包含多个权利要求11或12所述的滤波器。
  14. 一种通讯设备，其特征在于，包含权利要求11或12所述的滤波器。
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