Optimization Method for Surface Acoustic Wave Filter and Surface Acoustic Wave Filter

Abstract

The present invention provides an optimization method for a surface acoustic wave filter and a surface acoustic wave filter. The optimization method includes the following steps: taking the insertion loss of the surface acoustic wave filter as the first optimization target, optimizing the dual-mode surface acoustic wave filter to obtain a first optimization result; taking the out-of-band rejection of the surface acoustic wave filter as the second optimization target, optimizing the geometric parameters of the interdigital transducer to obtain a second optimization result; taking the voltage standing wave ratio and ripple of the surface acoustic wave filter as the third optimization target, optimizing the capacitance value of the capacitor and the inductance value of the inductor to obtain a third optimization result; taking the insertion loss index, out-of-band rejection index, voltage standing wave ratio index and ripple index of the surface acoustic wave filter as the fourth optimization target, optimizing the surface acoustic wave filter to obtain a fourth optimization result. The optimization method in the present invention can not only reduce the labor cost, but also reduce the probability of falling into a local optimal solution, improve the convergence speed of the optimization, and reduce the optimization time.

Description

Technical Field

[0001] The present invention relates to the technical field of filters, and in particular to an optimization method for a surface acoustic wave filter and a surface acoustic wave filter. Background Art

[0002] With the development of communication technologies, the communication era of 4G and 5G has arrived. The required communication frequency bands are getting higher and more diverse. Due to its excellent performance and low price, etc., the surface acoustic wave filter has now been applied to the radio frequency modules of more and more mobile devices, including the RX type surface acoustic wave filter for processing received signals.

[0003] The RX type surface acoustic wave filter mainly includes devices such as a dual-mode surface acoustic wave filter (DMS), interdigital transducers (IDT), capacitors, inductors, etc. It contains numerous geometric parameters, such as finger pitch, metallization rate, and aperture, etc. These parameters need to be adjusted according to the requirements of the frequency band to meet the requirements.

[0004] In the prior art, there are mainly the following two methods for optimizing the RX type surface acoustic wave filter:

[0005] 1. The designer determines an initial value according to experience, or extracts the parameters of the RX type surface acoustic wave filter in the database with a similar frequency band as the initial value, and then adjusts the geometric parameters of the RX type surface acoustic wave filter according to the simulation results. Its disadvantage is that it requires continuous manual parameter adjustment, with high labor costs, and cannot guarantee that the result is the optimal solution.

[0006] 2. All geometric parameters are used as optimization variables, and in the case of no initial value, an optimization method is used for the design of the RX type surface acoustic wave filter. Its disadvantages are that there are many optimization variables, it is easy to fall into a local optimal solution, and the optimization dimension is high, requiring a long optimization time.

[0007] It can be seen from this that the methods for optimizing the RX type surface acoustic wave filter in the prior art either have high labor costs and cannot guarantee that the result is the optimal solution, or have many optimization variables, are easy to fall into a local optimal solution, and have a long optimization time. Summary of the Invention

[0008] In view of the above deficiencies of the prior art, the present invention proposes an optimization method for a surface acoustic wave filter and a surface acoustic wave filter to solve the problems that the methods for optimizing the RX type surface acoustic wave filter in the prior art either have high labor costs and cannot guarantee that the result is the optimal solution, or have many optimization variables, are easy to fall into a local optimal solution, and have a long optimization time.

[0009] To solve the above technical problems, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides an optimization method for a surface acoustic wave filter, the surface acoustic wave filter including a dual-mode surface acoustic wave filter, interdigital transducers, capacitors, and inductors; the optimization method for the surface acoustic wave filter includes the following steps:

[0011] S1. Taking the geometric parameters of the dual-mode surface acoustic wave filter as optimization variables, and taking the insertion loss of the surface acoustic wave filter as the first optimization target, optimizing the dual-mode surface acoustic wave filter to obtain a first optimization result; wherein, the geometric parameters of the dual-mode surface acoustic wave filter include the number of finger electrodes, the finger electrode period length, the metallization rate, and the aperture of the dual-mode surface acoustic wave filter;

[0012] S2. Using the first optimization result as a fixed value to form a first circuit with the interdigital transducers, and taking the out-of-band rejection of the surface acoustic wave filter as the second optimization target, optimizing the geometric parameters of the interdigital transducers to obtain a second optimization result; wherein, the geometric parameters of the interdigital transducers include the finger electrode period length, the metallization rate, and the aperture of the interdigital transducers;

[0013] S3. Using the first optimization result and the second optimization result as fixed values to form a second circuit with the capacitors and the inductors, and taking the standing wave ratio and ripple of the surface acoustic wave filter as the third optimization target, optimizing the capacitance value of the capacitors and the inductance value of the inductors to obtain a third optimization result;

[0014] S4. Using the first optimization result, the second optimization result, and the third optimization result as initial values, and taking the insertion loss index, out-of-band rejection index, standing wave ratio index, and ripple index of the surface acoustic wave filter as the fourth optimization target, optimizing the surface acoustic wave filter to obtain a fourth optimization result.

[0015] Preferably, the first optimization target satisfies the following conditions:

[0016] object1 = IL spec -IL min ;

[0017] wherein, object1 is the first optimization target, IL spec is the insertion loss index of the surface acoustic wave filter, and IL min is the maximum insertion loss within the passband frequency band of the surface acoustic wave filter.

[0018] Preferably, the second optimization target satisfies the following conditions:

[0019] object2 = Rejection max -Rejection spec ;

[0020] Among them, object2 is the second optimization objective, Rejection max is the maximum out-of-band rejection of the surface acoustic wave filter, Rejection spec is the out-of-band rejection index of the surface acoustic wave filter.

[0021] Preferably, the third optimization objective satisfies the following conditions:

[0022] ;

[0023] Among them, object3 is the third optimization objective, a is a real number from 0 to 100, VSWR max is the maximum voltage standing wave ratio of the surface acoustic wave filter, VSWR spec is the voltage standing wave ratio index of the surface acoustic wave filter, b is a real number from 0 to 100, Ripple max is the maximum ripple of the surface acoustic wave filter, Ripple spec is the ripple index of the surface acoustic wave filter.

[0024] Preferably, the fourth optimization objective satisfies the following conditions:

[0025] ;

[0026] Among them, object4 is the fourth optimization objective, c is a real number from 0 to 100, d is a real number from 0 to 100, e is a real number from 0 to 100, and f is a real number from 0 to 100.

[0027] Preferably, the genetic algorithm is used to optimize the dual-mode surface acoustic wave filter; the genetic algorithm is used to optimize the geometric parameters of the interdigital transducer; the genetic algorithm is used to optimize the capacitance value of the capacitor and the inductance value of the inductor.

[0028] In a second aspect, the present invention provides a surface acoustic wave filter, and the insertion loss index, out-of-band rejection index, voltage standing wave ratio index, and ripple index of the surface acoustic wave filter are obtained by the optimization method of the surface acoustic wave filter as described above.

[0029] Compared with the prior art, the optimization method of the surface acoustic wave filter in the present invention optimizes the dual-mode surface acoustic wave filter, optimizes the geometric parameters of the interdigital transducer, optimizes the capacitance value of the capacitor and the inductance value of the inductor, and finally optimizes the surface acoustic wave filter. In the whole optimization process, there is no need for excessive manual parameter adjustment, which reduces the labor cost. In addition, the dual-mode surface acoustic wave filter, interdigital transducer, capacitor and inductor are optimized separately first. When optimizing separately, the number of optimization variables is reduced, the convergence speed of optimization is faster, the optimization time is reduced, and the probability of falling into the local optimal solution is lower. When the surface acoustic wave filter is optimized as a whole finally, the results of the first three separate optimizations are used as the initial values, which can ensure the optimization results and accelerate the convergence speed of optimization, thereby further reducing the optimization time. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be described in detail below with reference to the accompanying drawings. Through the detailed description in combination with the following drawings, the above or other aspects of the present invention will become clearer and easier to understand. In the drawings:

[0031] Figure 1 is the circuit structure diagram of the surface acoustic wave filter provided by the embodiment of the present invention;

[0032] Figure 2 is the step flow chart of the optimization method of the surface acoustic wave filter provided by the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used in the description of the present application in the specification are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the specification and claims of this application or the above drawings are used to distinguish different objects and not to describe a specific order.

[0034] Reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of this application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] Embodiment 1

[0037] An embodiment of the present invention provides an optimization method for a surface acoustic wave filter. As Figure 1 shown, the surface acoustic wave filter 100 includes a dual-mode surface acoustic wave filter 1, interdigital transducers 2, capacitors 3, and inductors 4.

[0038] Among them, the surface acoustic wave filter 100 is an RX-type surface acoustic wave filter. There is one each of the dual-mode surface acoustic wave filter 1, the capacitor 3, and the inductor 4, and there are four interdigital transducers 2. Of course, according to actual needs, the quantities of the dual-mode surface acoustic wave filter 1, the interdigital transducers 2, the capacitor 3, and the inductor 4 can also be adaptively modified.

[0039] The performance indicators of the surface acoustic wave filter 100 mainly include insertion loss (IL), out-of-band rejection, voltage standing wave ratio (VSWR), and ripple, etc.

[0040] As Figure 2 shown, the optimization method for the surface acoustic wave filter includes the following steps:

[0041] S11: Take the geometric parameters of the dual-mode surface acoustic wave filter as the optimization variables, and take the insertion loss of the surface acoustic wave filter as the first optimization goal. Use the genetic algorithm to optimize the dual-mode surface acoustic wave filter to obtain the first optimization result.

[0042] Among them, the geometric parameters of the dual-mode surface acoustic wave filter include the number of finger pairs, the finger period length, the metallization rate, and the aperture of the dual-mode surface acoustic wave filter, etc. When optimizing the dual-mode surface acoustic wave filter, use the global genetic algorithm.

[0043] The smaller the first optimization goal, the better the performance of the surface acoustic wave filter.

[0044] The first optimization goal satisfies the following conditions:

[0045] object1 = IL spec -IL min ;

[0046] object1 is the first optimization goal, IL specFor the insertion loss index of the surface acoustic wave filter, IL min It is the maximum insertion loss within the passband frequency range of the surface acoustic wave filter. Equivalent to the first optimization objective being the difference between the maximum insertion loss within the passband frequency range of the surface acoustic wave filter and the insertion loss index of the surface acoustic wave filter.

[0047] S12. Take the first optimization result as a fixed value and form a first circuit with the interdigital transducer, and use the out-of-band rejection of the surface acoustic wave filter as the second optimization objective. Use the genetic algorithm to optimize the geometric parameters of the interdigital transducer to obtain the second optimization result.

[0048] Among them, the geometric parameters of the interdigital transducer include the finger period length, metallization rate, and aperture of the interdigital transducer.

[0049] The second optimization objective satisfies the following conditions:

[0050] object2 = Rejection max -Rejection spec ;

[0051] object2 is the second optimization objective, Rejection max is the maximum out-of-band rejection of the surface acoustic wave filter, Rejection spec is the out-of-band rejection index of the surface acoustic wave filter.

[0052] S13. Take the first optimization result and the second optimization result as fixed values and form a second circuit with the capacitor and the inductor, and use the voltage standing wave ratio and ripple of the surface acoustic wave filter as the third optimization objective. Use the genetic algorithm to optimize the capacitance value of the capacitor and the inductance value of the inductor to obtain the third optimization result.

[0053] Among them, the third optimization objective satisfies the following conditions:

[0054] ;

[0055] object3 is the third optimization objective, a is a real number from 0 to 100, VSWR max is the maximum voltage standing wave ratio of the surface acoustic wave filter, VSWR spec is the voltage standing wave ratio index of the surface acoustic wave filter, b is a real number from 0 to 100, Ripple max is the maximum ripple of the surface acoustic wave filter, Ripple spec is the ripple index of the surface acoustic wave filter. The values of a and b are obtained according to the designer's experience.

[0056] S14. Use the first optimization result, the second optimization result, and the third optimization result as the initial values, and use the insertion loss index, out-of-band rejection index, voltage standing wave ratio index, and ripple index of the surface acoustic wave filter as the fourth optimization target to optimize the surface acoustic wave filter to obtain a fourth optimization result.

[0057] Among them, the insertion loss index, out-of-band rejection index, voltage standing wave ratio index, and ripple index of the surface acoustic wave filter respectively represent the insertion, out-of-band rejection, voltage standing wave ratio, and ripple required by the surface acoustic wave filter. Genetic algorithm or other algorithms can be used to optimize the surface acoustic wave filter.

[0058] The smaller the fourth optimization target, the better the performance of the surface acoustic wave filter.

[0059] The fourth optimization target satisfies the following conditions:

[0060] ;

[0061] Among them, object4 is the fourth optimization target, c is a real number from 0 to 100, d is a real number from 0 to 100, e is a real number from 0 to 100, and f is a real number from 0 to 100. The values of c, d, e, and f are obtained according to the designer's experience.

[0062] The above optimizations of the dual-mode surface acoustic wave filter, the geometric parameters of the interdigital transducer, and the capacitance value of the capacitor and the inductance value of the inductor can also be carried out using other algorithms.

[0063] Compared with the prior art, the optimization method of the surface acoustic wave filter in this embodiment optimizes the dual-mode surface acoustic wave filter, the geometric parameters of the interdigital transducer, the capacitance value of the capacitor and the inductance value of the inductor, and finally optimizes the surface acoustic wave filter. The entire optimization process does not require excessive manual parameter adjustment, reducing labor costs. In addition, by optimizing the dual-mode surface acoustic wave filter, interdigital transducer, capacitor, and inductor separately first, the number of optimization variables is reduced during individual optimization, the convergence speed of optimization is faster, the optimization time is reduced, and the probability of falling into a local optimal solution is lower. When finally optimizing the surface acoustic wave filter as a whole, using the results of the previous three individual optimizations as the initial values can ensure the optimization results while accelerating the convergence speed of optimization, thereby further reducing the optimization time.

[0064] Embodiment 2

[0065] This embodiment provides a surface acoustic wave filter 100, and the insertion loss index, out-of-band rejection index, voltage standing wave ratio index, and ripple index of the surface acoustic wave filter are obtained by the optimization method of the surface acoustic wave filter in Embodiment 1 above.

[0066] like Figure 1 As shown, the surface acoustic wave filter 100 includes a dual-mode surface acoustic wave filter 1 , an interdigital transducer 2 , a capacitor 3 and an inductor 4 .

[0067] Since the insertion loss index, out-of-band suppression index, standing wave ratio index and ripple index of the surface acoustic wave filter 100 in this embodiment are obtained through the optimization method of the surface acoustic wave filter in the above-mentioned embodiment 1, it can also achieve the technical effect achieved by the optimization method of the surface acoustic wave filter in the above-mentioned embodiment 1, and will not be elaborated here.

[0068] It should be noted that the various embodiments described above with reference to the accompanying drawings are only used to illustrate the present invention rather than to limit the scope of the present invention. Those skilled in the art should understand that any modification or equivalent substitution of the present invention without departing from the spirit and scope of the present invention should be included within the scope of the present invention. In addition, unless otherwise indicated by the context, words appearing in the singular include the plural form, and vice versa. In addition, unless otherwise specified, all or part of any embodiment may be used in combination with all or part of any other embodiment.

Claims

1. An optimization method for a surface acoustic wave filter, the surface acoustic wave filter comprising a dual-mode surface acoustic wave filter, interdigital transducers, capacitors, and inductors; characterized in that, The optimization method of the surface acoustic wave filter includes the following steps: Taking the geometric parameters of the dual-mode surface acoustic wave filter as optimization variables, and taking the insertion loss of the surface acoustic wave filter as the first optimization target, optimizing the dual-mode surface acoustic wave filter to obtain a first optimization result; wherein, the geometric parameters of the dual-mode surface acoustic wave filter include the number of finger pairs, the finger period length, the metallization rate, and the aperture of the dual-mode surface acoustic wave filter; Taking the first optimization result as a fixed value and forming a first circuit with the interdigital transducer, and taking the out-of-band rejection of the surface acoustic wave filter as the second optimization target, optimizing the geometric parameters of the interdigital transducer to obtain a second optimization result; wherein, the geometric parameters of the interdigital transducer include the finger period length, the metallization rate, and the aperture of the interdigital transducer; Taking the first optimization result and the second optimization result as fixed values and forming a second circuit with the capacitor and the inductor, and taking the voltage standing wave ratio and ripple of the surface acoustic wave filter as the third optimization target, optimizing the capacitance value of the capacitor and the inductance value of the inductor to obtain a third optimization result; Taking the first optimization result, the second optimization result, and the third optimization result as initial values, and taking the insertion loss index, out-of-band rejection index, voltage standing wave ratio index, and ripple index of the surface acoustic wave filter as the fourth optimization target, optimizing the surface acoustic wave filter to obtain a fourth optimization result; The first optimization target satisfies the following conditions: object1=IL spec -IL max ; Among them, object1 is the first optimization target, and IL spec is the insertion loss index of the surface acoustic wave filter, and IL max is the maximum insertion loss within the passband frequency band of the surface acoustic wave filter; The second optimization target satisfies the following conditions: object2=Rejection max -Rejection spec ; Among them, object2 is the second optimization target, Rejection max is the maximum out-of-band rejection of the surface acoustic wave filter, Rejection spec is the out-of-band rejection index of the surface acoustic wave filter; The third optimization target satisfies the following conditions: ； Among them, object3 is the third optimization goal, a is a real number from 0 to 100, and VSWR max is the maximum voltage standing wave ratio of the surface acoustic wave filter, and VSWR spec is the voltage standing wave ratio index of the surface acoustic wave filter, b is a real number from 0 to 100, and Ripple max is the maximum ripple of the surface acoustic wave filter, and Ripple spec is the ripple index of the surface acoustic wave filter; The fourth optimization target satisfies the following conditions: ； Wherein, object4 is the fourth optimization target, c is a real number from 0 to 100, d is a real number from 0 to 100, e is a real number from 0 to 100, and f is a real number from 0 to 100; The genetic algorithm is used to optimize the dual-mode surface acoustic wave filter; the genetic algorithm is used to optimize the geometric parameters of the interdigital transducer; the genetic algorithm is used to optimize the capacitance value of the capacitor and the inductance value of the inductor; the genetic algorithm is used to optimize the surface acoustic wave filter.

2. A surface acoustic wave filter, characterized in that, The insertion loss index, out-of-band rejection index, voltage standing wave ratio index, and ripple index of the surface acoustic wave filter are obtained by the optimization method of the surface acoustic wave filter as described in claim 1.

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