Band-pass filter and electronic equipment with same

Abstract

The invention discloses a band-pass filter and electronic equipment with the same, and relates to the technical field of microstrip filters. The band-pass filter comprises a dielectric substrate, a signal input end, a resonator array and a signal output end, the signal input end, the resonator array and the signal output end are sequentially arranged in the front area of the dielectric substrate, the signal input end and the signal output end are symmetrical about the center of the filter, and a grounding metal layer is arranged in the back area of the dielectric substrate; the signal input end comprises a signal input line and two first branch lines which form an included angle, and the lengths of the first branch lines are not equal; the resonator array comprises n + 1 resonators which are obliquely distributed, and n represents the order of the filter, is an integer and is greater than or equal to 1; the signal output end comprises a signal output line and two second branch lines which form an included angle, and the lengths of the second branch lines are not equal. By adopting the band-pass filter, the frequency selection characteristic is good, a plurality of transmission zeros can be provided at a low-end stop band and a high-end stop band, and the out-of-band rejection capability is effectively improved.

Description

Technical Field

[0001] The present application relates to the technical field of microstrip filters, and in particular to a bandpass filter and an electronic device having the same. Background Art

[0002] Microstrip filter is a device used to separate microwave signals of different frequencies. It can suppress unwanted signals so that they cannot pass through the filter and only allow the required signals to pass through. As the integration of RF microwave and millimeter wave circuits becomes higher and higher, the filter size is required to be smaller and smaller and have good out-of-band suppression capability.

[0003] At present, relevant technologies are used Figure 1 The hairpin microstrip bandpass filter shown in the figure has an asymmetric out-of-band frequency response with a concave low end and an upturned high end, which will result in poor out-of-band suppression of the high end of the passband. This has certain limitations for applications with high requirements for passband high-end suppression. Summary of the invention

[0004] In view of the above-mentioned defects or deficiencies in the related art, it is desired to provide a bandpass filter and an electronic device having the same, which can have multiple transmission zeros in the low-end stopband and the high-end stopband, effectively improve the out-of-band suppression capability, and make the overall performance of the filter more superior.

[0005] In a first aspect, the present application provides a bandpass filter, the bandpass filter comprising a dielectric substrate, and a signal input end, a resonator array and a signal output end are sequentially arranged in a front area of ​​the dielectric substrate, the signal input end and the signal output end are symmetrical about the filter center, and a grounding metal layer is arranged in a back area of ​​the dielectric substrate;

[0006] The signal input end includes a signal input line and two first branch lines at an angle to each other, and the lengths of the first branch lines are unequal; the resonator array includes n+1 obliquely distributed resonators, n represents the filter order, n is an integer and n≥1, wherein there is a gap between the resonator in the first position and the signal input end, there is a gap between the resonator in the last position and the signal output end, and there are gaps between adjacent resonators and the gap sizes are unequal; the signal output end includes a signal output line and two second branch lines at an angle to each other, and the lengths of the second branch lines are unequal.

[0007] Optionally, in some embodiments of the present application, the resonator includes a first bending portion, a second bending portion, a third bending portion, a fourth bending portion and a fifth bending portion which are vertical in sequence.

[0008] Optionally, in some embodiments of the present application, in the adjacent resonators, the first bending portion of the latter resonator is arranged opposite to the fifth bending portion of the former resonator;

[0009] Alternatively, the second bending portion of the latter resonator is arranged opposite to the fourth bending portion of the former resonator;

[0010] Alternatively, the third bending portion of the subsequent resonator is arranged opposite to the fifth bending portion of the previous resonator.

[0011] Optionally, the resonator in some embodiments of the present application is λ g / 2 resonator, where λ0 represents the wavelength corresponding to the center frequency of the filter passband in free space, ε re represents the effective dielectric constant of the dielectric substrate,

[0012]

[0013] ε r represents the relative dielectric constant of the dielectric substrate, h represents the thickness of the dielectric substrate, and w represents the line width of the microstrip line.

[0014] Optionally, in some embodiments of the present application, the line width of the microstrip line is 0.03 mm to 4 mm.

[0015] Optionally, in some embodiments of the present application, the angle between the first branch lines is 30° to 150°, and the angle between the second branch lines is 30° to 150°.

[0016] Optionally, in some embodiments of the present application, at least one concave structure is provided on both the first branch line and the second branch line.

[0017] Optionally, in some embodiments of the present application, the signal input end and the signal output end are both 50Ω microstrip lines.

[0018] Optionally, the dielectric substrate in some embodiments of the present application includes any one of a ceramic substrate, a quartz substrate, a beryllium oxide substrate, an aluminum nitride substrate and a microcrystalline glass substrate.

[0019] In a second aspect, the present application provides an electronic device, comprising the bandpass filter described in any one of the first aspects.

[0020] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0021] The embodiment of the present application provides a bandpass filter and an electronic device having the same. A signal input terminal, a resonator array and a signal output terminal are sequentially arranged in a front area of ​​a dielectric substrate. The signal input terminal and the signal output terminal are symmetrical about the center of the filter, and the signal input terminal includes a signal input line and two first branch lines at an angle to each other, and the lengths of the first branch lines are unequal. The resonator array includes n+1 obliquely distributed resonators, n represents the filter order, n is an integer and n≥1, wherein there is a gap between the resonator at the first position and the signal input terminal, there is a gap between the resonator at the last position and the signal output terminal, there are gaps between adjacent resonators and the gap sizes are unequal, and the signal output terminal includes a signal output line and two second branch lines at an angle to each other, and the lengths of the second branch lines are unequal. Therefore, the dielectric substrate space can be fully and reasonably utilized, the size of the filter device can be reduced, and a very small coupling coefficient can be achieved under the premise that the line seam width is feasible. Test results show that the bandpass filter has good frequency selection characteristics, has multiple transmission zeros in the low-end stop band and the high-end stop band, and effectively improves the out-of-band suppression capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A schematic diagram of the structure of a hairpin microstrip bandpass filter in a related art provided in an embodiment of the present application;

[0024] Figure 2 A schematic diagram of the structure of a bandpass filter provided in an embodiment of the present application;

[0025] Figure 3 A method provided in the embodiment of the present application Figure 2 A top view of the bandpass filter shown;

[0026] Figure 4 A top view of another bandpass filter provided in an embodiment of the present application;

[0027] Figure 5 A schematic diagram of the structure of a resonator provided in an embodiment of the present application;

[0028] Figure 6 A schematic diagram of the arrangement of adjacent resonators provided in an embodiment of the present application;

[0029] Figure 7 A schematic diagram of another arrangement of adjacent resonators provided in an embodiment of the present application;

[0030] Figure 8 A schematic diagram of another arrangement of adjacent resonators provided in an embodiment of the present application;

[0031] Fig. 9 A schematic diagram of a coupling coefficient and a gap curve response between resonators provided in an embodiment of the present application;

[0032] Fig.10 A schematic diagram of a curve showing the relationship between delay and frequency provided in an embodiment of the present application;

[0033] Fig.11 A schematic diagram comparing the S-parameter responses of a 7th-order hairpin microstrip bandpass filter in a related technology of the same frequency band provided in an embodiment of the present application and the 7th-order bandpass filter in this embodiment;

[0034] Fig.12 A structural block diagram of an electronic device provided in an embodiment of the present application.

[0035] Reference numerals:

[0036] 1-bandpass filter, 11-dielectric substrate, 12-signal input terminal, 121-signal input line, 122-first branch line, 13-resonator array, 131-resonator, 1311-first bending portion, 1312-second bending portion, 1313-third bending portion, 1314-fourth bending portion, 1315-fifth bending portion, 14-signal output terminal, 141-signal output line, 142-second branch line, 2-electronic device. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0038] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0039] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. Figures 2 to 12 The bandpass filter and the electronic device having the same provided by the embodiments of the present application are described in detail.

[0040] Please refer to Figure 2, which is a schematic diagram of the structure of a bandpass filter provided in an embodiment of the present application, the bandpass filter 1 comprises a dielectric substrate 11, and a signal input terminal 12, a resonator array 13 and a signal output terminal 14 are sequentially arranged in the front area of ​​the dielectric substrate 11, the signal input terminal 12 and the signal output terminal 14 are symmetrical about the center of the filter, and a grounding metal layer (not shown in the figure) is arranged in the back area of ​​the dielectric substrate 11. Figure 3 As shown, the signal input terminal 12 includes a signal input line 121 and two first branch lines 122 at an angle to each other, and the lengths of the first branch lines 122 are unequal; the resonator array 13 includes n+1 obliquely distributed resonators 131, n represents the filter order, n is an integer and n≥1, wherein there is a gap between the resonator 131 located in the first position and the signal input terminal 12, a gap exists between the resonator 131 located in the last position and the signal output terminal 14, and gaps exist between adjacent resonators 131 and the sizes of the gaps are unequal; the signal output terminal 14 includes a signal output line 141 and two second branch lines 142 at an angle to each other, and the lengths of the second branch lines 142 are unequal.

[0041] For example, in the embodiment of the present application, the dielectric substrate 11 may be a ceramic substrate, and the relative dielectric constant ε of the ceramic substrate is r =9.8, thickness h=0.254 mm. In addition, the dielectric substrate 11 can also be any one of a quartz substrate, a beryllium oxide substrate, an aluminum nitride substrate and a microcrystalline glass substrate.

[0042] For example, in the embodiment of the present application, the signal input end 12 and the signal output end 14 are both 50Ω microstrip lines, the angle between the first branch lines 122 is 30° to 150°, and the angle between the second branch lines 142 is 30° to 150°, that is, the first branch line 122 and the second branch line 142 can be both straight lines, or they can be as follows: Figure 4 As shown, at least one concave structure is disposed on each of the first branch line 122 and the second branch line 142 .

[0043] Another example Figure 5 As shown, the resonator 131 in the embodiment of the present application includes but is not limited to a first bending portion 1311, a second bending portion 1312, a third bending portion 1313, a fourth bending portion 1314 and a fifth bending portion 1315 which are vertical in sequence. In adjacent resonators 131, as Figure 3 or Figure 6 As shown, the first bending portion 1311 of the latter resonator 131 is arranged opposite to the fifth bending portion 1315 of the former resonator 131, or as shown in Figure 7 As shown, the second bending portion 1312 of the latter resonator 131 is arranged opposite to the fourth bending portion 1314 of the former resonator 131, or as shown in FIG. Figure 8As shown, the third bending portion 1313 of the next resonator 131 is arranged opposite to the fifth bending portion 1315 of the previous resonator 131. Further, the resonator 131 may be λ g / 2 resonator, where λ0 represents the wavelength corresponding to the center frequency of the filter passband in free space, ε re represents the effective dielectric constant of the dielectric substrate 11,

[0044]

[0045] In formula (1), ε r represents the relative dielectric constant of the dielectric substrate 11, h represents the thickness of the dielectric substrate 11, w represents the line width of the microstrip line, which may be 0.03 mm to 4 mm, and the length of the resonator 131 is determined by the center frequency of the filter passband.

[0046] The design process of the bandpass filter 1 in the embodiment of the present application is described in detail below. ① Determine the low-pass prototype: According to the filter bandwidth, in-band ripple and attenuation and other indicators, select the Chebyshev low-pass prototype, determine the filter order n and the conductance parameters g1, g2, g3, . . . , g n , the filter order n can be obtained by formula (2), that is,

[0047]

[0048] In formula (2) L As Indicates the maximum stopband attenuation; L Ar Indicates the maximum value of passband attenuation; f0 represents the filter passband center frequency, and f1 represents the passband attenuation frequency; f s Represents the stopband attenuation frequency. After determining the filter order n, the conductivity parameters of each order g1, g2, g3, ···, g n .

[0049] ② Determine the coupling coefficient K and external Q value: According to the conductivity parameters of each order g1, g2, g3, ···, g n , the coupling coefficient K and external Q value can be obtained, that is,

[0050]

[0051] In formula (3), FBW represents bandwidth.

[0052] ③Determine the delay t value, that is

[0053]

[0054] In formula (4), L represents the resonator length, Z0 represents the characteristic impedance of the microstrip tap line, which can be 50Ω, and Z r It represents the characteristic impedance of the resonator without coupling, Q e Represents the external quality factor of the filter terminal.

[0055] ④ Use simulation software to optimize parameters: set the initial filter order n = 7 and select the Chebyshev prototype, that is,

[0056] Table 1 Component values ​​of Chebyshev prototype (g0=1, ω c =1, ripple is 0.01dB)

[0057] n <![CDATA[g1]]> <![CDATA[g2]]> <![CDATA[g3]]> <![CDATA[g4]]> <![CDATA[g5]]> <![CDATA[g6]]> <![CDATA[g7]]> <![CDATA[g8]]> 7 0.7969 1.3924 1.7481 1.6331 1.7481 1.3924 0.7969 1.000

[0058] To simplify the calculation process, the initial length of a single resonator 131 is calculated according to the center frequency of the filter passband, the line width of the resonator 131 is set to 0.15 mm, and the simulation software is used to simulate and determine the final size of the single resonator 131. Simulate the resonant frequencies f1 and f2 of two adjacent resonators, scan the gap between the two resonators, and use the formula Determine the coupling coefficient and calculate the coupling coefficient K according to formula (3): i,i+1 , determine the gap size between adjacent resonators one by one (the coupling coefficient K value and the gap curve response diagram between resonators are shown in Fig. 9 As shown). Through the external Q e Calculate the delay t value, simulate the gap between the signal input terminal 12 and the first resonator 131 in the resonator array 13, change the gap size and the length of the first resonator 131 in the resonator array 13 to meet the delay t value, and finally determine the gap size and the length of the first resonator 131 in the resonator array 13 (such as Fig.10 The optimized data are recorded in Table 2.

[0059] Table 2 Final parameter values ​​of the bandpass filter in this embodiment

[0060] Resonator Section Number 0～1 1～2 2～3 3～4 4～5 5～6 6～7 Resonator length / mm 4.291 4.391 4.391 4.391 4.391 4.391 4.291 Gap between resonators / mm - 0.143 0.168 0.175 0.175 0.168 0.143 Resonator line width / mm 0.150 0.150 0.150 0.150 0.150 0.150 0.150 Gap between signal input terminal and resonator / mm 0.048 - - - - - -

[0061] Based on the above method, a bandpass filter 1 with an operating frequency of 16.7GHz to 16.9GHz is designed. The center frequency is 16.8GHz, the relative bandwidth is 1.19%, it has narrowband characteristics, and the passband insertion loss is less than 5.5dB, the return loss is better than -17dB, and the low-end stopband transmission zero points of the bandpass filter 1 are located at 5.38GHz and 14.36GHz, respectively, and the high-end stopband transmission zero points are located at 17.96GHz and 18.84GHz, respectively. The out-of-band suppression level is greatly improved. In the low-frequency stopband of DC to 15.31GHz, the suppression level is better than -60dB, and in the high-frequency stopband of 17.88GHz to 31.40GHz, the suppression level is better than -60dB, and the out-of-band suppression at the low end and high end of the passband is relatively symmetrical. In addition, the size of the bandpass filter 1 is 9.5mm*2.5mm, which has the characteristics of miniaturization, and does not use the short-circuit through-hole method, which is convenient for simplifying the processing and manufacturing process, reducing costs, and has good application value in engineering. For the convenience of comparing performance, please refer to Fig.11 , which is a schematic diagram comparing the S parameter responses of a 7th-order hairpin microstrip bandpass filter in a related technology of the same frequency band provided in an embodiment of the present application and the 7th-order bandpass filter in this embodiment. It can be seen from the figure that the 7th-order bandpass filter in this embodiment generates transmission zeros at the high ends of the passband 17.96 GHz and 18.84 GHz, which greatly improves the out-of-band suppression effect at the high end of the passband compared to the hairpin microstrip bandpass filter in the related technology with the same order of 7 and the same passband frequency. As for the out-of-band suppression at the low end of the passband, its suppression can reach -80 dB below the frequency of 14.7 GHz, and it has good out-of-band suppression capability. As for the parasitic passband, the parasitic passband appears at 32 GHz (the parasitic passband of the hairpin microstrip bandpass filter in the related technology appears at 26.6 GHz), which effectively broadens the frequency range of high-frequency out-of-band suppression.

[0062] As another aspect, an embodiment of the present application provides an electronic device. Fig.12 , which is a structural block diagram of an electronic device provided in an embodiment of the present application, the electronic device 2 includes Figures 2 to 11 This corresponds to the bandpass filter 1 of the embodiment.

[0063] It should be noted that, for the description of the same contents in this embodiment as those in other embodiments, reference can be made to the description in other embodiments and will not be repeated here.

[0064] The bandpass filter and the electronic device having the same provided by the embodiment of the present application are provided by sequentially arranging a signal input terminal, a resonator array and a signal output terminal in the front area of ​​a dielectric substrate, the signal input terminal and the signal output terminal are symmetrical about the center of the filter, and the signal input terminal includes a signal input line and two first branch lines at an angle to each other, the lengths of each first branch line are unequal, the resonator array includes n+1 obliquely distributed resonators, n represents the filter order, n is an integer and n≥1, wherein there is a gap between the resonator at the first position and the signal input terminal, there is a gap between the resonator at the last position and the signal output terminal, there are gaps between adjacent resonators and the gap sizes are unequal, and the signal output terminal includes a signal output line and two second branch lines at an angle to each other, the lengths of each second branch line are unequal, thereby being able to fully and reasonably utilize the dielectric substrate space, reduce the size of the filter device, and achieve a very small coupling coefficient under the premise that the line seam width is feasible, and the test results show that the bandpass filter has good frequency selection characteristics, has multiple transmission zeros in the low-end stop band and the high-end stop band, and effectively improves the out-of-band suppression capability.

[0065] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0066] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A bandpass filter, characterized in that: The bandpass filter (1) comprises a dielectric substrate (11), and a signal input end (12), a resonator array (13) and a signal output end (14) are sequentially arranged in a front area of ​​the dielectric substrate (11), the signal input end (12) and the signal output end (14) are symmetrical about the center of the filter, and a grounding metal layer is arranged in a back area of ​​the dielectric substrate (11); The signal input end (12) comprises a signal input line (121) and two first branch lines (122) at an angle to each other, and the lengths of the first branch lines (122) are unequal; the resonator array (13) comprises n+1 obliquely distributed resonators (131), n ​​represents the filter order, n is an integer and n≥1, wherein a gap exists between the first resonator (131) and the signal input end (12), a gap exists between the last resonator (131) and the signal output end (14), and gaps exist between adjacent resonators (131) and the sizes of the gaps are unequal; the signal output end (14) comprises a signal output line (141) and two second branch lines (142) at an angle to each other, and the lengths of the second branch lines (142) are unequal.

2. The bandpass filter according to claim 1, characterized in that The resonator (131) comprises a first bending portion (1311), a second bending portion (1312), a third bending portion (1313), a fourth bending portion (1314) and a fifth bending portion (1315) which are vertical in sequence.

3. The bandpass filter according to claim 2, characterized in that In the adjacent resonators (131), the first bending portion (1311) of the latter resonator (131) is arranged opposite to the fifth bending portion (1315) of the former resonator (131); Alternatively, the second bending portion (1312) of the latter resonator (131) is arranged opposite to the fourth bending portion (1314) of the former resonator (131); Alternatively, the third bending portion (1313) of the subsequent resonator (131) is arranged opposite to the fifth bending portion (1315) of the previous resonator (131).

4. The bandpass filter according to any one of claims 1 to 3, characterized in that: The resonator (131) is λ g / 2 resonator, where λ0 represents the wavelength corresponding to the center frequency of the filter passband in free space, ε re represents the effective dielectric constant of the dielectric substrate, ε r represents the relative dielectric constant of the dielectric substrate, h represents the thickness of the dielectric substrate, and w represents the line width of the microstrip line.

5. The bandpass filter according to claim 4, characterized in that: The line width of the microstrip line is 0.03 mm to 4 mm.

6. The bandpass filter according to any one of claims 1 to 3, characterized in that: The included angles between the first branch lines (122) are 30° to 150°, and the included angles between the second branch lines (142) are 30° to 150°.

7. The bandpass filter according to claim 6, characterized in that At least one concave structure is provided on each of the first branch line (122) and the second branch line (142).

8. The bandpass filter according to claim 6, characterized in that: The signal input end (12) and the signal output end (14) are both 50Ω microstrip lines.

9. The bandpass filter according to any one of claims 1 to 3, characterized in that: The dielectric substrate (11) comprises any one of a ceramic substrate, a quartz substrate, a beryllium oxide substrate, an aluminum nitride substrate and a microcrystalline glass substrate.

10. An electronic device, characterized in that: The electronic device (2) comprises the bandpass filter (1) according to any one of claims 1 to 9.

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