Optimization method of surface acoustic wave filter and surface acoustic wave filter

Abstract

The invention provides an optimization method of a surface acoustic wave filter and the surface acoustic wave filter, and the optimization method comprises the following steps: taking the insertion loss of the surface acoustic wave filter as a first optimization target, optimizing a dual-mode surface acoustic wave filter, and obtaining a first optimization result; by taking out-of-band rejection of the surface acoustic wave filter as a second optimization target, optimizing the geometric parameters of the interdigital transducer to obtain a second optimization result; optimizing the capacitance value of the capacitor and the inductance value of the inductor by taking the standing-wave ratio and the ripple of the surface acoustic wave filter as a third optimization target to obtain a third optimization result; and optimizing the surface acoustic wave filter by taking the insertion loss index, the out-of-band rejection index, the standing-wave ratio index and the ripple index of the surface acoustic wave filter as fourth optimization targets to obtain a fourth optimization result. According to the optimization method, the labor cost can be reduced, the probability of falling into a local optimal solution can be reduced, the convergence speed of optimization is improved, and the optimization time is shortened.

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 technology, we have entered the era of 4G and 5G communication, and the communication frequency bands required are getting higher and higher, and the types are increasing. Due to its excellent performance and low price, surface acoustic wave filters have been applied to the RF modules of more and more mobile devices, including RX type surface acoustic wave filters for processing received signals.

[0003] RX type surface acoustic wave filters mainly include dual-mode surface acoustic wave filters (DMS), interdigital transducers (IDTs), capacitors, inductors and other devices, and contain many geometric parameters, such as insertion period, metallization rate and aperture, etc. These parameters need to be adjusted according to the requirements of the frequency band so that they can meet the requirements.

[0004] There are two main methods for optimizing RX type surface acoustic wave filters in the prior art: 1. The designer determines an initial value based on experience, or extracts the parameters of the RX-type surface acoustic wave filter in a similar frequency band from the database as the initial value, and then adjusts the geometric parameters of the RX-type surface acoustic wave filter according to the simulation results. The disadvantage is that the parameters need to be adjusted manually, the labor cost is high, and the result cannot be guaranteed to be the optimal solution.

[0005] 2. All geometric parameters are taken as optimization variables, and without an initial value, the optimization method is used to design the RX type surface acoustic wave filter. The disadvantages are that there are many optimization variables, it is easy to fall into the local optimal solution, and the optimization dimension is high, which takes a long time to optimize.

[0006] It can be seen that the methods for optimizing RX type surface acoustic wave filters in the prior art either have high labor costs and cannot guarantee that the results are the optimal solutions, or have many optimization variables and are prone to falling into local optimal solutions and take a long time to optimize. Summary of the invention

[0007] In view of the above shortcomings of the prior art, the present invention proposes a surface acoustic wave filter optimization method and a surface acoustic wave filter to solve the problems that the methods for optimizing RX type surface acoustic wave filters in the prior art either have high labor costs and cannot guarantee that the results are the optimal solutions, or have many optimization variables, are prone to falling into local optimal solutions, and take a long time to optimize.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a method for optimizing a surface acoustic wave filter, wherein the surface acoustic wave filter comprises a dual-mode surface acoustic wave filter, an interdigital transducer, a capacitor, and an inductor; the method for optimizing the surface acoustic wave filter comprises the following steps: S1, taking the geometric parameters of the dual-mode surface acoustic wave filter as optimization variables and 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 insertion fingers, the insertion finger period length, the metallization rate and the aperture of the dual-mode surface acoustic wave filter; S2, taking the first optimization result as a fixed value and the IDT to form a first circuit, and taking the out-of-band suppression of the surface acoustic wave filter as a second optimization target, optimizing the geometric parameters of the IDT to obtain a second optimization result; wherein the geometric parameters of the IDT include the interdigital period length, metallization rate and aperture of the IDT; S3, 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 standing wave ratio and ripple of the surface acoustic wave filter as the third preferred target, optimizing the capacitance value of the capacitor and the inductance value of the inductor to obtain a third optimization result; S4. 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 suppression index, standing wave ratio index and ripple index of the surface acoustic wave filter as the fourth preferred target, the surface acoustic wave filter is optimized to obtain a fourth optimization result.

[0009] Preferably, the first optimization objective satisfies the following conditions: object1=IL spec -IL min ; Among them, object1 is the first optimization target, IL spec is the insertion loss index of the surface acoustic wave filter, IL min It is the maximum insertion loss within the passband of the SAW filter.

[0010] Preferably, the second optimization objective satisfies the following conditions: object2=Rejection max -Rejection spec ; Among them, object2 is the second optimization goal, Rejection max is the maximum out-of-band suppression of the SAW filter, Rejection spec It is the out-of-band suppression index of the surface acoustic wave filter.

[0011] Preferably, the third optimization objective satisfies the following conditions: ; Wherein, object3 is the third optimization target, a is a real number between 0 and 100, and VSWR max is the maximum standing wave ratio of the surface acoustic wave filter, VSWR spec is the standing wave ratio index of the surface acoustic wave filter, b is a real number between 0 and 100, Ripple max Ripple is the maximum ripple of the surface acoustic wave filter. spec It is the ripple index of surface acoustic wave filter.

[0012] Preferably, the fourth preferred target meets the following conditions: ; Among them, object4 is the fourth preferred target, c is a real number between 0 and 100, d is a real number between 0 and 100, e is a real number between 0 and 100, and f is a real number between 0 and 100.

[0013] Preferably, a genetic algorithm is used to optimize the dual-mode surface acoustic wave filter; a genetic algorithm is used to optimize the geometric parameters of the interdigital transducer; and a genetic algorithm is used to optimize the capacitance value of the capacitor and the inductance value of the inductor.

[0014] In a second aspect, the present invention provides a surface acoustic wave filter, the insertion loss index, out-of-band suppression index, standing wave ratio index and ripple index of the surface acoustic wave filter are obtained by the surface acoustic wave filter optimization method as described above.

[0015] 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 sequence. The entire optimization process does not require too much manual adjustment of parameters, thereby reducing labor costs. In addition, the dual-mode surface acoustic wave filter, the interdigital transducer, the capacitor, and the inductor are first optimized separately. When optimizing separately, the optimization variables are reduced, the optimization convergence speed is faster, the optimization time is reduced, and the probability of falling into a local optimal solution is lower. Finally, when the surface acoustic wave filter is optimized as a whole, the results of the first three separate optimizations are used as initial values, which can ensure the optimization results while accelerating the optimization convergence speed, thereby further reducing the optimization time. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be described in detail below in conjunction with the accompanying drawings. The above and other aspects of the present invention will become clearer and easier to understand through the detailed description made in conjunction with the following drawings. In the accompanying drawings: Figure 1 A circuit structure diagram of a surface acoustic wave filter provided by an embodiment of the present invention; Figure 2 A flow chart of the steps of a method for optimizing a surface acoustic wave filter provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of the present application; the terms used in the specification of the application herein are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "including" and "having" and any variations thereof in the specification and claims of the present application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of the present application or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0018] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Embodiment 1 The embodiment of the present invention provides a method for optimizing a surface acoustic wave filter, such as 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 .

[0021] The surface acoustic wave filter 100 is an RX type surface acoustic wave filter, the dual-mode surface acoustic wave filter 1, the capacitor 3 and the inductor 4 are each one, and the number of the interdigital transducers 2 is four. Of course, according to actual needs, the number of the dual-mode surface acoustic wave filter 1, the interdigital transducer 2, the capacitor 3 and the inductor 4 can also be adaptively modified.

[0022] The performance indicators of the surface acoustic wave filter 100 mainly include insertion loss (IL), out-of-band rejection (Rejection), standing wave ratio (VSWR) and ripple (Ripple).

[0023] like Figure 2 As shown, the optimization method of the surface acoustic wave filter comprises the following steps: S11, taking the geometric parameters of the dual-mode surface acoustic wave filter as optimization variables and the insertion loss of the surface acoustic wave filter as the first optimization target, optimizing the dual-mode surface acoustic wave filter using a genetic algorithm to obtain a first optimization result.

[0024] The geometric parameters of the dual-mode surface acoustic wave filter include the number of fingers, the length of the finger period, the metallization rate and the aperture, etc. When optimizing the dual-mode surface acoustic wave filter, a global genetic algorithm is used.

[0025] The smaller the first optimization target is, the better the performance of the surface acoustic wave filter is.

[0026] The first optimization objective satisfies the following conditions: object1=IL spec -IL min ; object1 is the first optimization target, IL spec is the insertion loss index of the surface acoustic wave filter, IL min is the maximum insertion loss in the passband frequency band of the surface acoustic wave filter, which is equivalent to the difference between the maximum insertion loss in the passband frequency band of the surface acoustic wave filter and the insertion loss index of the surface acoustic wave filter.

[0027] S12, taking the first optimization result as a fixed value and the IDT to form a first circuit, taking the out-of-band suppression of the surface acoustic wave filter as a second optimization target, and using a genetic algorithm to optimize the geometric parameters of the IDT to obtain a second optimization result.

[0028] The geometric parameters of the IDT include the interdigital period length, metallization rate and aperture of the IDT.

[0029] The second optimization objective satisfies the following conditions: object2=Rejection max -Rejection spec ; object2 is the second optimization goal, Rejection max is the maximum out-of-band suppression of the SAW filter, Rejection spec It is the out-of-band suppression index of the surface acoustic wave filter.

[0030] S13. Use the first optimization result and the second optimization result as constants to form a second circuit with the capacitor and the inductor, and use the standing wave ratio and ripple of the surface acoustic wave filter as the third preferred target, and use a genetic algorithm to optimize the capacitance value of the capacitor and the inductance value of the inductor to obtain a third optimization result.

[0031] Wherein, the third optimization objective satisfies the following conditions: ; object3 is the third optimization target, a is a real number between 0 and 100, VSWR max is the maximum standing wave ratio of the surface acoustic wave filter, VSWR spec is the standing wave ratio index of the surface acoustic wave filter, b is a real number between 0 and 100, Ripple max Ripple is the maximum ripple of the surface acoustic wave filter. 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.

[0032] S14, 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 suppression index, standing wave ratio index and ripple index of the surface acoustic wave filter as the fourth preferred target, optimizing the surface acoustic wave filter to obtain a fourth optimization result.

[0033] The insertion loss index, out-of-band suppression index, standing wave ratio index and ripple index of the surface acoustic wave filter respectively represent the insertion loss, out-of-band suppression, standing wave ratio and ripple required by the surface acoustic wave filter. The surface acoustic wave filter can be optimized by using a genetic algorithm or other algorithms.

[0034] The smaller the fourth optimization target is, the better the performance of the surface acoustic wave filter is.

[0035] The fourth preferred target meets the following conditions: ; Wherein, object4 is the fourth preferred object, c is a real number between 0 and 100, d is a real number between 0 and 100, e is a real number between 0 and 100, and f is a real number between 0 and 100. The values ​​of c, d, e and f are obtained according to the designer's experience.

[0036] The above optimization of the dual-mode surface acoustic wave filter, the optimization of the geometric parameters of the interdigital transducer, and the optimization of the capacitance value of the capacitor and the inductance value of the inductor may also be performed using other algorithms.

[0037] Compared with the prior art, the optimization method of the surface acoustic wave filter in the present embodiment 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 sequence. The entire optimization process does not require too much manual adjustment of parameters, thereby reducing labor costs. In addition, the dual-mode surface acoustic wave filter, the interdigital transducer, the capacitor, and the inductor are optimized separately first. When optimizing separately, the optimization variables are reduced, the optimization convergence speed is faster, the optimization time is reduced, and the probability of falling into a local optimal solution is lower. Finally, when the surface acoustic wave filter is optimized as a whole, the results of the first three separate optimizations are used as initial values, which can ensure the optimization results while accelerating the optimization convergence speed, thereby further reducing the optimization time.

[0038] Embodiment 2 This embodiment provides a surface acoustic wave filter 100 , the insertion loss index, out-of-band suppression index, standing wave ratio index and ripple index of the surface acoustic wave filter are obtained by the surface acoustic wave filter optimization method in the first embodiment.

[0039] 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 .

[0040] 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.

[0041] 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. A method for optimizing a surface acoustic wave filter, wherein the surface acoustic wave filter comprises a dual-mode surface acoustic wave filter, an interdigital transducer, a capacitor and an inductor; characterized in that: The optimization method of the surface acoustic wave filter comprises the following steps: Taking the geometric parameters of the dual-mode surface acoustic wave filter as optimization variables and the insertion loss of the surface acoustic wave filter as the first optimization target, the dual-mode surface acoustic wave filter is optimized to obtain a first optimization result; wherein the geometric parameters of the dual-mode surface acoustic wave filter include the number of insertion fingers, the insertion finger period length, the metallization rate and the aperture of the dual-mode surface acoustic wave filter; The first optimization result is used as a fixed value to form a first circuit with the IDT, and the out-of-band suppression of the surface acoustic wave filter is used as a second optimization target to optimize the geometric parameters of the IDT to obtain a second optimization result; wherein the geometric parameters of the IDT include the interdigital period length, metallization rate and aperture of the IDT; The first optimization result and the second optimization result are used as fixed values ​​to form a second circuit with the capacitor and the inductor, and the standing wave ratio and ripple of the surface acoustic wave filter are used as third optimization targets to optimize the capacitance value of the capacitor and the inductance value of the inductor to obtain a third optimization result; The first optimization result, the second optimization result and the third optimization result are used as initial values, and the insertion loss index, out-of-band suppression index, standing wave ratio index and ripple index of the surface acoustic wave filter are used as the fourth preferred target to optimize the surface acoustic wave filter and obtain the fourth optimization result.

2. The method for optimizing a surface acoustic wave filter according to claim 1, wherein: The first optimization objective satisfies the following conditions: object1=IL spec -HE min ; Among them, object1 is the first optimization target, IL spec is the insertion loss index of the surface acoustic wave filter, IL min It is the maximum insertion loss within the passband of the SAW filter.

3. The method for optimizing a surface acoustic wave filter according to claim 2, wherein: The second optimization objective satisfies the following conditions: object2=Rejection max -Rejection spec ; Among them, object2 is the second optimization goal, Rejection max is the maximum out-of-band suppression of the SAW filter, Rejection spec It is the out-of-band suppression index of the surface acoustic wave filter.

4. The method for optimizing a surface acoustic wave filter according to claim 3, wherein: The third optimization objective satisfies the following conditions: ； Wherein, object3 is the third optimization target, a is a real number between 0 and 100, and VSWR max is the maximum standing wave ratio of the surface acoustic wave filter, VSWR spec is the standing wave ratio index of the surface acoustic wave filter, b is a real number between 0 and 100, Ripple max Ripple is the maximum ripple of the surface acoustic wave filter. spec It is the ripple index of surface acoustic wave filter.

5. The method for optimizing a surface acoustic wave filter according to claim 4, wherein: The fourth preferred target meets the following conditions: ； Among them, object4 is the fourth preferred target, c is a real number between 0 and 100, d is a real number between 0 and 100, e is a real number between 0 and 100, and f is a real number between 0 and 100.

6. The method for optimizing a surface acoustic wave filter according to claim 1, wherein: The dual-mode surface acoustic wave filter is optimized by a genetic algorithm; the geometric parameters of the interdigital transducer are optimized by a genetic algorithm; the capacitance value of the capacitor and the inductance value of the inductor are optimized by a genetic algorithm.

7. A surface acoustic wave filter, characterized in that: The insertion loss index, out-of-band suppression index, standing wave ratio index and ripple index of the surface acoustic wave filter are obtained by the surface acoustic wave filter optimization method according to any one of claims 1 to 6.

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