Topological structure and filter
By designing a topology that includes parallel lines and branches, the in-band notch characteristics of a broadband bandpass filter were realized, solving the problem of the inability to suppress in-band interference in existing technologies and improving the suppression effect and selectivity of the filter.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-19
- Publication Date
- 2026-03-27
AI Technical Summary
Most existing broadband bandpass filters do not have in-band notch characteristics, which cannot effectively suppress in-band interference and limit their application in modern wireless communication systems.
A topology is adopted, including a first parallel line, a second parallel line, a third parallel line, an input terminal, an output terminal, an open-circuit stub, and a short-circuit stub. Through the design of the parallel lines and the coupling of the stubs, the notch frequency can be independently adjusted to form an in-band notch to suppress interference.
It achieves effective suppression of in-band interference, improves the selectivity and anti-interference capability of the filter, and maintains the compactness and frequency control accuracy of the filter.
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Figure CN224053374U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The embodiment of the present application relates to the technical field of filter, and discloses a topology structure and a filter. BACKGROUND
[0002] As a core component of communication systems, the function of the band-pass filter is to allow signals of a specific frequency band to pass through and suppress out-of-band interference. However, with the rapid development of 5G / 6G, Internet of Things and other technologies, the communication frequency band is increasingly crowded, and the in-band interference problem is highlighted. Traditional band-pass filters often face the challenges of poor selectivity, limited tuning range, or difficulty in balancing miniaturization and high performance, especially in scenarios requiring in-band notch (in-band notch, i.e. setting a stop band within the passband to suppress a specific interference frequency band), the technical complexity is significantly improved.
[0003] During the implementation of the present application, the inventors found that most of the current wideband band-pass filters do not have the characteristics of in-band notch, and cannot effectively suppress in-band interference, which greatly limits their use in modern wireless communication systems. CONTENT OF THE UTILITY MODEL
[0004] The embodiment of the present application provides a topology structure and a filter, which can improve the current situation that most wideband band-pass filters do not have the characteristics of in-band notch and cannot effectively suppress in-band interference.
[0005] To solve the above technical problems, one technical scheme adopted by the present application is to provide a topology structure. The topology structure comprises a first parallel line, a second parallel line, a third parallel line, an input end, an output end, a first open-circuit stub, a second open-circuit stub, a first short-circuit stub and a second short-circuit stub. One end of the first parallel line is connected to the input end, the other end of the first parallel line is connected to one end of the second parallel line, the other end of the second parallel line is connected to one end of the third parallel line, and the other end of the third parallel line is connected to the output end. The first open-circuit stub is connected to one end of the first parallel line and the input end, and the second open-circuit stub is connected to one end of the third parallel line and the output end. One end of the first short-circuit stub is connected to one end of the first parallel line and the second parallel line, and the other end of the first short-circuit stub is grounded. One end of the second short-circuit stub is connected to one end of the third parallel line and the second parallel line, and the other end of the second short-circuit stub is grounded.
[0006] Optionally, the input end, the first parallel line, the second parallel line, the third parallel line, the output end, the first open-circuit stub and the second open-circuit stub are parallel. The input end, the first parallel line, the second parallel line, the third parallel line and the output end are collinear.
[0007] Optionally, the first open stub is located at a side of the input port close to the second parallel line. The second open stub is located at a side of the output port close to the second parallel line.
[0008] Optionally, the first short stub is perpendicular to the first parallel line, and the second short stub is perpendicular to the first parallel line.
[0009] Optionally, the first short stub and the first open stub are located at two sides of the first parallel line respectively. The second short stub and the second open stub are located at two sides of the third parallel line respectively. The first short stub and the second short stub are located at the same side of the second parallel line, and the first open stub and the second open stub are located at the same side of the second parallel line.
[0010] Optionally, the input port, the first parallel line, the first open stub and the first short stub, and the third parallel line, the second open stub, the second short stub and the output port, are symmetrical with respect to the second parallel line.
[0011] Optionally, the electrical length of the first parallel line, the electrical length of the second parallel line, the electrical length of the third parallel line, the electrical length of the first short stub and the electrical length of the second short stub are equal, and are equal to the corresponding quarter wavelength at the center frequency of the wideband bandpass filter.
[0012] Optionally, the electrical length of the first open stub is equal to the electrical length of the second open stub, and is equal to the quarter wavelength corresponding to the notch center frequency.
[0013] Optionally, the odd mode characteristic impedance of the first parallel line is equal to the odd mode characteristic impedance of the third parallel line. The even mode characteristic impedance of the first parallel line is equal to the even mode characteristic impedance of the third parallel line. The characteristic impedance of the first open stub is equal to the characteristic impedance of the second open stub. The characteristic impedance of the first short stub is equal to the characteristic impedance of the second short stub.
[0014] To solve the above technical problems, another technical scheme adopted by the present application is to further provide a filter. The filter comprises the above-mentioned topological structure.
[0015] The embodiment of the present application has the beneficial effect that, different from the prior art, the embodiment of the present application provides a topology structure and a filter. The topology structure comprises a first parallel line, a second parallel line, a third parallel line, an input end, an output end, a first open-circuit stub, a second open-circuit stub, a first short-circuit stub and a second short-circuit stub. One end of the first parallel line is connected to the input end, the other end of the first parallel line is connected to one end of the second parallel line, the other end of the second parallel line is connected to one end of the third parallel line, and the other end of the third parallel line is connected to the output end. The first open-circuit stub is connected to one end of the first parallel line and the input end, and the second open-circuit stub is connected to one end of the third parallel line and the output end. One end of the first short-circuit stub is connected to one end of the first parallel line and the second parallel line, and the other end of the first short-circuit stub is grounded. One end of the second short-circuit stub is connected to one end of the third parallel line and the second parallel line, and the other end of the second short-circuit stub is grounded. Through the above structure, the first parallel line, the second parallel line and the third parallel line are arranged, the trap frequency is independently adjustable, and the stub structure generates a trap through a gap coupling, so that the filter has the characteristic of in-band trap, and effectively suppresses in-band interference. BRIEF DESCRIPTION OF DRAWINGS
[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced as follows. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of the drawings.
[0017] Figure 1 is a topology structure schematic diagram provided by one of the embodiments of the present application;
[0018] Figure 2 is a odd mode structure schematic diagram of the topology structure provided by one of the embodiments of the present application;
[0019] Figure 3 is an even mode structure schematic diagram of the topology structure provided by one of the embodiments of the present application;
[0020] Figure 4 is a layout layout of the filter provided by one of the embodiments of the present application;
[0021] Figure 5 is an S parameter simulation result diagram of the topology structure provided by one of the embodiments of the present application.
[0022] The reference signs are as follows:
[0023] Topology 100 Output 50 First parallel line 10 First open stub 60 Second parallel line 20 Second open stub 70 Third parallel line 30 First short stub 80 Input 40 Second short stub 90 DETAILED DESCRIPTION
[0024] For the purposes of promoting an understanding of the principles of the application, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the application. It will, nevertheless, be understood that no limitation of the scope of the application is intended by the use of such specific language. In addition, it should be understood that the use of the terms "including," "comprising," or "having" and variations thereof herein, is intended to be open-ended, and is not intended to exclude or to otherwise limit other moieties, additives, components, integers, steps, options, features, objects, or steps.
[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. The use of the terms "and / or" includes a combination of one or more of the associated listed items.
[0026] Referring to Figure 1 The present application provides a topology structure 100, which includes a first parallel line 10, a second parallel line 20, a third parallel line 30, an input end 40, an output end 50, a first open-circuit stub 60, a second open-circuit stub 70, a first short-circuit stub 80 and a second short-circuit stub 90. One end of the first parallel line 10 is connected to the input end 40, the other end of the first parallel line 10 is connected to one end of the second parallel line 20, the other end of the second parallel line 20 is connected to one end of the third parallel line 30, and the other end of the third parallel line 30 is connected to the output end 50. The first open-circuit stub 60 is connected to one end of the first parallel line 10 and the input end 40, and the second open-circuit stub 70 is connected to one end of the third parallel line 30 and the output end 50. One end of the first short-circuit stub 80 is connected to one end of the first parallel line 10 and the second parallel line 20, and the other end of the first short-circuit stub 80 is grounded. One end of the second short-circuit stub 90 is connected to one end of the third parallel line 30 and the second parallel line 20, and the other end of the second short-circuit stub 90 is grounded. Through the above structure, the first parallel line 10, the second parallel line 20 and the third parallel line 30 are set to realize the independent adjustable trap frequency, and the stub structure generates the trap through the slot coupling, so that the characteristics of the in-band trap are obtained, and the in-band interference is effectively suppressed.
[0027] In some embodiments, referring to Figure 1, the input end 40, the first parallel line 10, the second parallel line 20, the third parallel line 30, the output end 50, the first open-circuit stub 60 and the second open-circuit stub 70 are parallel. The input end 40, the first parallel line 10, the second parallel line 20, the third parallel line 30 and the output end 50 are collinear. By arranging the input end 40, the first parallel line 10, the second parallel line 20, the third parallel line 30, the output end 50, the first open-circuit stub 60 and the second open-circuit stub 70 in parallel, the coupling uniformity of the topology structure 100 is enhanced, a wide band-pass characteristic is formed through adjacent strong electromagnetic coupling, which is beneficial to band-pass flattening and reduction of in-band ripple. And the three-parallel-line parallel design can realize independent adjustment of the notch frequency.
[0028] In some embodiments, referring to Figure 1 , the first open-circuit stub 60 is located on the side of the input end 40 close to the second parallel line 20. The second open-circuit stub 70 is located on the side of the output end 50 close to the second parallel line 20. By arranging the first open-circuit stub 60 parallel to the first parallel line 10, a wide stopband or notch is generated through direct coupling of the edge electric field. By arranging the second open-circuit stub 70 parallel to the third parallel line 30, a wide stopband or notch is generated through direct coupling of the edge electric field. Arranging towards the second parallel line 20 can improve the coupling efficiency, improve the compactness of the topology structure 100, and also improve the frequency control accuracy, so that the anti-interference and stability of the topology structure 100 are enhanced.
[0029] In some embodiments, referring to Figure 1 , the first short-circuit stub 80 is perpendicular to the first parallel line 10, and the second short-circuit stub 90 is perpendicular to the first parallel line 10. Through the above structure, the magnetic coupling and the electric coupling cooperate to form a transmission zero point and form a notch or enhance the stopband suppression. And the first short-circuit stub 80 and the second short-circuit stub 90 form a double-notch structure, which reduces the passband ripple and out-of-band spurious response. As described above, the first short-circuit stub 80 is grounded, and the second short-circuit stub 90 is grounded, forming a local electromagnetic shield to reduce the risk of crosstalk of adjacent circuits (such as radio frequency front-end amplifiers).
[0030] In some embodiments, referring to Figure 1 , the first short-circuit stub 80 and the first open-circuit stub 60 are respectively located on the two sides of the first parallel line 10. The second short-circuit stub 90 and the second open-circuit stub 70 are respectively located on the two sides of the third parallel line 30. The first short-circuit stub 80 and the second short-circuit stub 90 are located on the same side of the second parallel line 20, and the first open-circuit stub 60 and the second open-circuit stub 70 are located on the same side of the second parallel line 20. Thus, the layout of the topology structure 100 is optimized, the compactness of the topology structure 100 is improved, and the symmetry of the overall structure is further improved.
[0031] In some embodiments, the input terminal 40, the first parallel line 10, the first open stub 60 and the first short stub 80, and the third parallel line 30, the second open stub 70, the second short stub 90 and the output terminal 50, are symmetrical to the second parallel line 20. Thus, the coupling path is optimized, the selectivity and anti-interference ability are enhanced, the parameter optimization and multi-field simulation process are simplified, the processing errors and environmental disturbances are offset, the consistency is improved, and the reliability is improved under complex working conditions such as temperature and mechanical stress.
[0032] In some embodiments, referring to Figure 1 , the electrical length of the first parallel line 10, the electrical length of the second parallel line 20, the electrical length of the third parallel line 30, the electrical length of the first short stub 80 and the electrical length of the second short stub 90 are equal, and are equal to the corresponding quarter wavelength at the center frequency of the wideband bandpass filter.
[0033] In some embodiments, referring to Figure 1 , the electrical length of the first open stub 60 and the electrical length of the second open stub 70 are equal, and are equal to the corresponding quarter wavelength at the notch center frequency.
[0034] In some embodiments, referring to Figure 1 , the odd-mode characteristic impedance of the first parallel line 10 and the odd-mode characteristic impedance of the third parallel line 30 are equal, denoted as Z o1 . The even-mode characteristic impedance of the first parallel line 10 and the even-mode characteristic impedance of the third parallel line 30 are equal, denoted as Z e1 . The odd-mode characteristic impedance of the second parallel line 20 is denoted as Z o2 ; the even-mode characteristic impedance of the second parallel line 20 is denoted as Z e2 . The characteristic impedance of the first open stub 60 and the characteristic impedance of the second open stub 70 are equal, denoted as Z1. The characteristic impedance of the first short stub 80 and the characteristic impedance of the second short stub 90 are equal, denoted as Z2.
[0035] It should be further pointed out that since the topology structure 100 can be equivalent to a symmetrical structure, its transmission poles can be calculated in the odd-even mode. In order to simplify the calculation process, it is first assumed that the electrical length of the first open stub 60 and the electrical length of the second open stub 70 are both equal to the corresponding quarter wavelength at the center frequency of the wideband bandpass filter. At this time, Figure 2 is the odd-mode form of the topology structure 100, wherein the electrical length of the odd-mode transmission line is the electrical length of the second parallel line 20; the characteristic impedance of the odd-mode transmission line is the odd-mode characteristic impedance of the second parallel line 20. When Y ino = 0, it can be obtained that the topology structure 100 has four odd-mode transmission poles. When f0 is the center frequency of the bandpass filter, the frequencies corresponding to the four odd-mode transmission poles are respectively:
[0036]
[0037] Thus, Δ1= 2Z2(Z e1 -Z o1 ) 2
[0038] Δ2= 4Z2Z o2 (Z e1 +Z o1 +2)+8Z2Z o1 Z e1 +
[0039] Z o2 (Z e1 -Z o1 ) 2 +4Z1Z2(Z e1 +Z o1 )
[0040] Δ3= 4Z o1 Z e1 Z o2 +Z1Z o2
[0041] Figure 3 is an even-mode version of the topology 100, where the electrical length of the even-mode transmission line is the electrical length of the second parallel line 20; and the characteristic impedance of the even-mode transmission line is the even-mode characteristic impedance of the second parallel line 20.
[0042] When Y ine = 0, it can be derived that the topology 100 has four even-mode transmission poles. When f0is the center frequency of the bandpass filter, the frequencies corresponding to the four even-mode transmission poles are:
[0043]
[0044]
[0045] Thus, Δ1= 2Z2(Z e1 -Z o1 ) 2
[0046] Δ2= 4Z2Z e2 (Z e1 +Z o1 +2)+8Z2Z o1 Z e1 +
[0047] Z e2 (Z e1 -Z o1 ) 2 +4Z1Z2(Z e1 +Zo1 )
[0048] Δ3 = 4Z o1 Z e1 Z e2 + Z1Z e2
[0049] For the topology 100, its transmission zeros can be calculated by the following method: multiply the ABCD matrices of the cascaded resonators that constitute the topology 100 in turn to obtain the ABCD matrix corresponding to the topology 100; convert the ABCD matrix of the topology 100 into the corresponding S matrix. When |S21| = 0, it can be obtained that the topology 100 has three transmission zeros, and the frequencies corresponding to the three transmission zeros are respectively:
[0050] f z1 = 0
[0051] f z2 = f0
[0052] f z3 = 2f0
[0053] From the above analysis, when the electrical length of the first open-circuit stub 60 and the electrical length of the second open-circuit stub 70 are both the quarter wavelength corresponding to the center frequency of the wideband bandpass filter, the topology 100 has four odd-mode transmission poles, four even-mode transmission poles, and three transmission zeros. Regardless of how the values of the parameters Z o1 , Z e1 , Z o2 , Z e2 , Z1 and Z2 are changed, the relative positions of the transmission zeros and poles, i.e., f z1 < f ep1 < f op1 < f op2 < f ep2 < f z2 < f ep3 < f op3 < f op4 < f z3 , will not change. In addition, appropriately changing the electrical length of the first open-circuit stub 60 and the electrical length of the second open-circuit stub 70 will not change the performance of the filter, but only change the position of the notch. Therefore, based on the topology 100, a wideband bandpass filter with a notch characteristic can be designed, and there are eight transmission poles in the passband to ensure the flatness in the passband, there are two transmission zeros in the stopband to ensure high selectivity and high isolation, and there is one transmission zero in the passband to form the required notch.
[0054] This invention uses a simulation example to illustrate the characteristics of this topology 100. This filter example is designed on a circuit board with a dielectric constant of 3.38, a dielectric loss of 0.0022, and a thickness of 0.813 mm. Its layout is shown below. Figure 2 As shown. The entire layout measures only 39.8mm x 13.6mm, and the specific dimensions of the filter are: l P1 =10.2mm,s P1 =0.1mm,w P1 =0.2mm,l P2 =10.2mm,s P2 =0.1mm,w P2 =0.1mm, l1=9.8mm, l2=10.6mm, w1=0.3mm, w2=2.8mm, s1=0.15mm.
[0055] Among them, l P1 This indicates the physical length of the first parallel line 10 or the physical length of the third parallel line 30;
[0056] s P1 This indicates the spacing between the first and second transmission lines that make up the first parallel line 10, or the spacing between the fifth and sixth transmission lines that make up the third parallel line 30.
[0057] w P1 This indicates the physical width of the first transmission line, the second transmission line, the fifth transmission line, or the sixth transmission line.
[0058] l P2 This indicates the physical length of the second parallel line 20;
[0059] s P2 This indicates the spacing between the third and fourth transmission lines that make up the second parallel line 20;
[0060] w P2 Indicates the physical width of the third transmission line or the physical width of the fourth transmission line;
[0061] l1 represents the physical length of the first open branch 60 or the physical length of the second open branch 70;
[0062] l2 represents the physical length of the first short-circuit stub 80 or the physical length of the second short-circuit stub 90;
[0063] w1 represents the physical width of the first open branch 60 or the width of the second open branch 70;
[0064] w2 represents the physical width of the first short-circuit stub 80 or the physical width of the second short-circuit stub 90;
[0065] s1 represents the distance between the first open stub 60 and the first parallel line 10, or the distance between the second open stub 70 and the third parallel line 30.
[0066] The S parameter simulation result of the filter is shown in the following table. Figure 3 The passband range with the reflection coefficient better than -10dB is 2.24GHz to 6.96GHz, the center frequency is 4.6GHz, the absolute bandwidth is 4.72GHz, and the relative bandwidth is 102.6%. In addition, there are six transmission poles in the passband, which are respectively located at 2.28, 2.6, 3.24, 4.74, 6.08, and 6.88GHz, and the six transmission poles ensure the flatness of the passband; there is also a transmission zero in the passband, which is located at 4.9GHz to form the required notch, and the isolation at the center frequency of the notch is 28.2dB, which shows good isolation. There are two transmission zeros in the stopband, which are respectively located at 0 and 8.88GHz, and the two transmission zeros ensure the high selectivity and high isolation of the stopband of the filter.
[0067] The present application aims to provide a topology structure 100, which comprises a first parallel line 10, a second parallel line 20, a third parallel line 30, an input end 40, an output end 50, a first open stub 60, a second open stub 70, a first short-circuit stub 80, and a second short-circuit stub 90. One end of the first parallel line 10 is connected to the input end 40, the other end of the first parallel line 10 is connected to one end of the second parallel line 20, the other end of the second parallel line 20 is connected to one end of the third parallel line 30, and the other end of the third parallel line 30 is connected to the output end 50. The first open stub 60 is connected to the end of the first parallel line 10 connected to the input end 40, and the second open stub 70 is connected to the end of the third parallel line 30 connected to the output end 50. One end of the first short-circuit stub 80 is connected to the end of the first parallel line 10 connected to the second parallel line 20, and the other end of the first short-circuit stub 80 is grounded. One end of the second short-circuit stub 90 is connected to the end of the third parallel line 30 connected to the second parallel line 20, and the other end of the second short-circuit stub 90 is grounded. Through the above structure, the first parallel line 10, the second parallel line 20, and the third parallel line 30 are arranged to realize the independent adjustment of the notch frequency, and the notch is generated by the gap coupling of the stub structure, so that the filter has the characteristic of in-band notch, and effectively suppresses the in-band interference.
[0068] Based on the same inventive concept, the present application also provides a filter comprising the above-mentioned topology structure 100. Since the topology structure 100 has the same effect as the structure mentioned above, it will not be described here. Therefore, the filter provided by the present application can also improve the current status that most wideband bandpass filters do not have the characteristic of in-band notch and cannot effectively suppress the in-band interference.
[0069] It should be noted that the preferred embodiments of the present application are described in the specification and its attached drawings, but the present application can be implemented in many different forms and is not limited to the embodiments described in the specification, and these embodiments are not intended to be additional limitations on the content of the present application, and the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive. Furthermore, each of the above technical features continues to combine to form various embodiments not listed above, which are considered to be within the scope of the present application specification; further, for those skilled in the art, the above description can be improved or changed, and all these improvements and changes shall fall within the scope of protection of the claims of the present application.
Claims
1. A topology applied to a filter, characterized in that, The topology comprises: a first parallel line, a second parallel line, a third parallel line, an input terminal and an output terminal, one end of the first parallel line is connected to the input terminal, the other end of the first parallel line is connected to one end of the second parallel line, the other end of the second parallel line is connected to one end of the third parallel line, the other end of the third parallel line is connected to the output terminal; a first open stub connected to one end of the first parallel line and the input terminal, and a second open stub connected to one end of the third parallel line and the output terminal; and a first short stub having one end connected to one end of the first parallel line and the second parallel line and the other end grounded, and a second short stub having one end connected to one end of the third parallel line and the second parallel line and the other end grounded. The input terminal, the first parallel line, the second parallel line, the third parallel line, the output terminal, the first open stub and the second open stub are parallel.
2. The topology of claim 1, wherein, The input terminal, the first parallel line, the second parallel line, the third parallel line and the output terminal are collinear.
3. The topology according to claim 1, wherein: the first open stub is located on the side of the input terminal close to the second parallel line; the second open stub is located on the side of the output terminal close to the second parallel line. The first short stub is perpendicular to the first parallel line, and the second short stub is perpendicular to the first parallel line.
4. The topology of claim 1, wherein, 5. The topology according to claim 1, wherein: the first short stub and the first open stub are respectively located on the two sides of the first parallel line; the second short stub and the second open stub are respectively located on the two sides of the third parallel line; wherein the first short stub and the second short stub are located on the same side of the second parallel line, and the first open stub and the second open stub are located on the same side of the second parallel line. The input terminal, the first parallel line, the first open stub and the first short stub, and the third parallel line, the second open stub, the second short stub and the output terminal are symmetrical relative to the second parallel line.
6. The topology of claim 1, wherein, The electrical length of the first parallel line, the electrical length of the second parallel line, the electrical length of the third parallel line, the electrical length of the first short stub and the electrical length of the second short stub are equal, and all equal to the corresponding quarter wavelength at the center frequency of the wideband bandpass filter.
7. The topology of any of claims 1-6, wherein, The electrical length of the first open stub is equal to the electrical length of the second open stub, which is the quarter wavelength corresponding to the notch center frequency.
8. The topology of any of claims 1-6, wherein, The odd mode characteristic impedance of the first parallel line and the odd mode characteristic impedance of the third parallel line are equal; 9. The topology of any of claims 1-6, wherein, The even mode characteristic impedance of the first parallel line and the even mode characteristic impedance of the third parallel line are equal; The characteristic impedance of the first open stub and the characteristic impedance of the second open stub are equal; The characteristic impedance of the first short-circuit stub and the characteristic impedance of the second short-circuit stub are equal.
10. A filter, characterized by, comprising a topology as claimed in any of claims 1-9.