WO2018188292A1

WO2018188292A1 - Broadband band-pass filter having broadband out-of-band suppression function

Info

Publication number: WO2018188292A1
Application number: PCT/CN2017/106224
Authority: WO
Inventors: 曲美君; 邓力; 李书芳; 张贯京; 葛新科; 高伟明; 张红治
Original assignee: 深圳市景程信息科技有限公司
Priority date: 2017-04-15
Filing date: 2017-10-14
Publication date: 2018-10-18
Also published as: CN107196024A

Abstract

The present invention provides a broadband band-pass filter having a broadband out-of-band suppression function. The broadband band-pass filter is bilaterally symmetrical with respect to a central axis. One end of each first microstrip line is connected to one end of a second microstrip line to form a double-branch matching open-circuit load; the other end of each second microstrip line is vertically connected to a signal output end and a third microstrip line; each fourth microstrip line is provided above the third microstrip line in parallel to form a coupling structure; one end of each fourth microstrip line is connected to one end of a fifth microstrip line; both ends of the sixth microstrip line are separately connected to the other end of the fifth microstrip line. The broadband band-pass filter of the present invention can achieve a broadband out-of-band suppression function in a specific working band so that original microstrip lines have filtering performance, and can have a good out-of-band-signal suppression effect, have high selectivity for passband signals, introduce less noise, and prevent interference caused by a radio-frequency front end.

Description

Specification Name of Invention: Broadband Bandpass Filter with Broadband Out-of-Band Suppression Technical Field

[0001] The present invention relates to the field of microwave communication technologies, and in particular, to a wideband band pass filter having wideband out-of-band rejection.

Background technique

[0002] As a very important device in the RF front-end, the filter can filter out-of-band noise and improve the sensitivity of the circuit system. A microstrip filter is a device used to separate microwave signals of different frequencies. Its main function is to suppress unwanted signals so that they cannot pass through the filter and only pass the desired signal. In microwave circuit systems, the performance of the filter has a large impact on the performance of the circuit system. In general, the out-of-band rejection of the filter is an important indicator of impact, while the out-of-band rejection of existing filters is poor, which affects the performance of the entire communication system. Therefore, there is a need for a wideband bandpass filter with high bandwidth out-of-band rejection.

technical problem

SUMMARY OF THE INVENTION An object of the present invention is to provide a wideband band pass filter having wideband out-of-band rejection, which aims to solve the technical problem of poor band-band rejection performance of a band pass filter in the prior art.

Problem solution

Technical solution

[0004] In order to achieve the above object, the present invention provides a broadband band pass filter having broadband out-of-band rejection, comprising two first microstrip lines, two second microstrip lines, and two disposed on a surface of a dielectric board. a third microstrip line, two fourth microstrip lines, two fifth microstrip lines, a sixth microstrip line, and two signal transmission ends, the wideband band pass filter having wideband out-of-band rejection The central axis is bilaterally symmetric, and the central axis is a line connecting the midpoints of the upper and lower horizontal borders of the broadband band pass filter, wherein:

[0005] One end of each of the first microstrip lines is connected to one end of a second microstrip line and forms a double-branched matching circuit load, and the other end of each second microstrip line and a signal output end and A third microstrip line is vertically connected, and each of the fourth microstrip lines is disposed in parallel above a third microstrip line and forms a coupling structure, one end of each fourth microstrip line and a fifth One end of the microstrip line is connected, the sixth microstrip line The two ends are respectively connected to the other end of a fifth microstrip line.

[0006] Preferably, the two first microstrip lines and the two second microstrip lines are both parallel to the left and right vertical borders of the broadband band pass filter.

[0007] Preferably, the two third microstrip lines, two fourth microstrip lines, two fifth microstrip lines, one sixth microstrip line, and two signal transmission ends are connected to the broadband The upper and lower horizontal borders of the band pass filter are parallel.

[0008] Preferably, the wideband bandpass filter with wideband out-of-band rejection includes two double-branch-matching loop loads and two coupling structures.

[0009] Preferably, the two signal transmission ends are used for inputting and outputting signals, wherein one signal transmission end serves as a signal input end, and the other signal transmission end serves as a signal output end.

[0010] Preferably, the first microstrip line, the second microstrip line, the third microstrip line, the fourth microstrip line, the fifth microstrip line, the sixth microstrip line, and the signal transmission end are all strips Metal copper sheet with a structure.

[0011] Preferably, the length of the first microstrip line is L4=14.4 mm, the width is W4=2.95 mm, and the length of the second microstrip line is L3=15 mm, and the width is W3=0.97 mm, The length of the triple microstrip line is the same as the length of the fourth microstrip line and both C11=15.99 mm is C11=15.99 mm, and the width of the third microstrip line is the same as the width of the fourth microstrip line and both are Cwl=0.22 Mm, the distance between the third microstrip line and the fourth microstrip line is Csl=0.1m, the length of the fifth microstrip line is L1=15.2mm, and the width is Wl=0.73mm, the first The length of the six microstrip line is L2 = 15.3 mm and the width is W2 = 0.64 mm, and the length of the signal transmission end is L0 = 10 mm and the width is W0 = 1.66 mm.

[0012] Preferably, each first microstrip line has an impedance of 34 Ω, each second microstrip line has an impedance of 68 Ω, and each fifth microstrip line has an impedance of 78 Ω, each of the sixth microstrip lines The impedance is 83 Ω, the odd mode impedance of each coupling structure 22 is 60 Ω, the even mode impedance of each coupling structure 22 is 180 Ω, and the electrical length of each coupling structure 22 is 90 degrees.

[0013] Preferably, the dielectric plate is a PCB having a thickness of 0.762 mm and a relative dielectric constant of 3.66.

Advantageous effects of the invention

Beneficial effect

Compared with the prior art, the wideband bandpass filter with wideband out-of-band rejection according to the present invention can be formed in a specific operating frequency band by designing two double-branched matching circuit load and two coupling structures. Broadband out-of-band rejection, which makes the original microstrip line have filtering performance and can have good signal for out-of-band signals. The suppression effect has high selectivity to the passband signal and introduces less noise to avoid interference to the RF front end.

Brief description of the drawing

DRAWINGS

1 is a schematic structural view of a preferred embodiment of a broadband bandpass filter having broadband out-of-band rejection according to the present invention.

2 is a schematic illustration of the dimensions of various components of a preferred embodiment of a broadband bandpass filter having broadband out-of-band rejection in accordance with the present invention.

3 is a circuit schematic diagram of a preferred embodiment of a wideband bandpass filter with wideband out-of-band rejection of the present invention.

4 is a schematic diagram showing the results of S-parameters of a broadband band-pass filter with broadband out-of-band rejection of the present invention simulated by electromagnetic simulation software. [0018] FIG.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be further described in detail with reference to the specific embodiments, which are to be construed as the invention.

1 to 3, FIG. 1 is a schematic structural view of a preferred embodiment of a broadband bandpass filter having broadband out-of-band rejection according to the present invention; and FIG. 2 is a broadband bandpass filter having wideband out-of-band rejection of the present invention. BRIEF DESCRIPTION OF THE DIFFERENTS OF THE PARTS OF THE PREFERRED EMBODIMENT; Figure 3 is a circuit schematic of a preferred embodiment of a broadband bandpass filter having broadband out-of-band rejection in accordance with the present invention.

[0021] In this embodiment, the broadband bandpass filter 1 having broadband out-of-band rejection includes two first microstrip lines 101, two second microstrip lines 102, and two disposed on the surface of the dielectric board 1. The third microstrip line 103, the two fourth microstrip lines 104, the two fifth microstrip lines 105, one sixth microstrip line 106, and two signal transmission ends P.

[0022] The broadband bandpass filter 1 having broadband out-of-band rejection is bilaterally symmetric about a central axis, which is a line connecting the midpoints of the upper and lower horizontal borders of the broadband bandpass filter 1 (ie, a line a-b) in FIG. 1, the two first microstrip lines 101 and the two second microstrip lines 102 are both parallel to the left and right vertical borders of the broadband bandpass filter 1, Two third microstrip lines 103, two fourth microstrip lines 104, two fifth microstrip lines 105, one sixth microstrip line 106, and two signal transmission ends P are both bandpass filtered The upper and lower horizontal borders of the device 1 are parallel. It should be noted that the broadband bandpass filter 1 having the central axis in the broadband out-of-band rejection is not a component of metal, but is produced or designed. The user can conveniently connect the components on the broadband bandpass filter 1 (for example, two first microstrip lines 101, two second microstrip lines 102, two third microstrip lines 103, two fourth The microstrip line 104, the two fifth microstrip lines 105, one sixth microstrip line 106, and the two signal transmission ends P) are bilaterally symmetrical about the central axis. When the wideband bandpass filter 1 is activated, the central axis does not participate in any operation such as signal filtering. In the present embodiment, the central axis is for the convenience of describing the left-right symmetric structure of the broadband band pass filter 1.

[0023] One end of each of the first microstrip lines 101 is connected to one end of a second microstrip line 102 and forms a double-branched matching circuit load 20, and the other end of each second microstrip line 102 and one The signal output terminal P and a third microstrip line 103 are vertically connected, and each of the fourth microstrip lines 104 is disposed in parallel above a third microstrip line 103 and forms a coupling structure, and each fourth microstrip One end of the line 104 is connected to one end of a fifth microstrip line 105, and both ends of the sixth microstrip line 106 are respectively connected to the other end of a fifth microstrip line 105.

[0024] The dielectric plate 1 is a PCB board, and the specific plate type is Roger RO4350B, wherein the relative dielectric constant is 3.66, and the plate thickness is 0.762 mm.

[0025] In this embodiment, the first microstrip line 101, the second microstrip line 102, the third microstrip line 103, the fourth microstrip line 104, the fifth microstrip line 105, and the sixth microstrip line 106 And the signal transmission end P is a metal copper piece of a strip structure. The wideband bandpass filter with wideband out-of-band rejection according to the present invention can achieve wideband bandpass filtering with wideband out-of-band rejection according to the present invention by changing the length and width of the microstrip line relative to the existing bandpass filter. Device 1 achieves a good match in the operating band.

[0026] In this embodiment, the operating band of the broadband bandpass filter 1 is in the range of 1.88 GHz to 4.12 GHz. The first microstrip line 101 disposed on the surface of the dielectric board 1 and the second embodiment are described by way of specific embodiments. The length and width of the microstrip line 102, the third microstrip line 103, the fourth microstrip line 104, the fifth microstrip line 105, the sixth microstrip line 106, and the signal transmission end P.

[0027] Specifically, as shown in FIG. 2:

[0028] The length of the first microstrip line 101 is L4 = 14.4 mm, and the width of the first microstrip line 101 is W4 = 2.95 mm.

[0029] The length of the second microstrip line 102 is L3 = 15 mm, and the width of the second microstrip line 102 is W3 = 0.97 mm.

[0030] The length of the third microstrip line 103 is the same as the length of the fourth microstrip line 104, both C11=15.99 mm is C11=15.99 mm, the width of the third microstrip line 103 and the fourth microstrip line 104 are The width is the same, both are Cwl=0.22 mm, and the distance between the third microstrip line 103 and the fourth microstrip line 104 is Csl=0.1 m. [0031] The length of the fifth microstrip line 105 is L1 = 15.2 mm, and the width of the fifth microstrip line 105 is Wl = 0.73 mm.

[0032] The length of the sixth microstrip line 106 is L2 = 15.3 mm, and the width of the sixth microstrip line 106 is W2 = 0.64 mm.

[0033] The length of the signal transmission end P is L0=10 mm, and the width of the signal transmission end P is W0=1.66 mm.

[0034] It should be noted that the thickness of the metal copper plate disposed on the PCB board is generally um, so the present invention does not apply to the first microstrip line 101, the second microstrip line 102, and the third microstrip line 103, The thickness of the metal copper piece of the length and width of the fourth microstrip line 104, the fifth microstrip line 105, the sixth microstrip line 106, and the signal transmission end P is limited, and does not affect the broadband having broadband out-of-band rejection according to the present invention. Band pass filter characteristics. In addition, two signal transmission terminals P are used for signal input and output, wherein one signal transmission terminal P serves as a signal input terminal, and the other signal transmission terminal P serves as a signal output terminal. Further, the signal input end may be the signal transmission end P on the left side in FIG. 1 or the signal transmission end P on the right side; the signal output end may be the signal transmission end P on the left side in FIG. 1 or the signal transmission on the right side. End P. For example, if the signal transmission terminal P on the left side of FIG. 1 serves as a signal input terminal, the signal transmission terminal P on the right side of FIG. 1 serves as a signal output terminal, and the signal enters from the signal transmission terminal P on the left side, and is output from the signal transmission terminal P on the right side. . If the signal transmission terminal P on the left side of Fig. 1 is used as the signal output terminal, the signal transmission terminal P on the right side of Fig. 1 serves as a signal input terminal, and the signal enters from the signal transmission terminal P on the right side, and is output from the signal transmission terminal P on the left side.

[0035] Further, as shown in FIG. 3, a first microstrip line 101 and a second microstrip line 102 form a double-branched matching circuit load 20, a third microstrip line 103 and a The fourth microstrip line 104 forms a coupling structure 22. As can be seen from Fig. 3, the wideband bandpass filter 1 having wideband out-of-band rejection includes two double-branch-matching ramp loads 20 and two coupling structures 22.

[0036] In this embodiment, the impedance of each of the first microstrip lines 101 is 34 ohms (Ω), and the impedance of each of the second microstrip lines 102 is 68 ohms (Ω), each of the fifth microstrips. The impedance of line 105 is 78 ohms (Ω), the impedance of each sixth microstrip line 106 is 83 ohms (Ω), and the odd mode impedance of each coupling structure 22 is 60 ohms (Ω), for each coupling structure 22 The even mode impedance is 180 ohms (Ω) and the electrical length of each coupling structure 22 is 90 degrees.

[0037] The wideband bandpass filter with wideband out-of-band rejection according to the present invention can be designed to form broadband out-of-band rejection in a specific operating frequency band by designing two double-branched matching circuit load 20 and two coupling structures 22. The characteristics make the original microstrip line have filtering performance, can have a good suppression effect on the out-of-band signal, have high selectivity to the passband signal, introduce less noise, and avoid interference to the RF front end. Referring to FIG. 4, FIG. 4 is a schematic diagram of S-parameter results of a broadband bandpass filter with broadband out-of-band rejection according to the present invention simulated by electromagnetic simulation software.

As can be seen from FIG. 4, the wideband bandpass filter 1 with wideband out-of-band rejection has a relative bandwidth of 74.67% between 1.88 GHz and 4.12 GHz in the operating band. Similarly, IS11I is less than -10dB outside the operating band and below 1.64GHz, and IS12I is less than -10dB between 4.36GHz and 7.64GHz in the operating band. As can be seen from Figure 4, the broadband band The pass filter 1 has a broadband out-of-band rejection characteristic. It can be seen that the wideband bandpass filter with wideband out-of-band rejection of the present invention can have a good suppression effect on the out-of-band signal, has high selectivity to the passband signal, introduces less noise, and avoids interference to the RF front end.

The above are only the preferred embodiments of the present invention, and are not intended to limit the scope of the invention, and the equivalent structure or equivalent process transformations made by the description of the present invention and the contents of the drawings may be directly or indirectly applied to other related The technical field is equally included in the scope of patent protection of the present invention.

Industrial applicability

Compared with the prior art, the wideband band pass filter with wideband out-of-band rejection of the present invention can be formed in a specific operating frequency band by designing two double-branch joint matching circuit loads and two coupling structures. The broadband out-of-band rejection feature makes the original microstrip line have filtering performance, which can have a good suppression effect on the out-of-band signal, high selectivity to the passband signal, introduce less noise, and avoid interference to the RF front end.

Claims

Claim

A broadband bandpass filter with broadband out-of-band rejection, comprising: two first microstrip lines, two second microstrip lines, two third microstrip lines, two on the surface of the dielectric plate a fourth microstrip line, two fifth microstrip lines, a sixth microstrip line, and two signal transmission ends, wherein the broadband band pass filter having broadband out-of-band rejection is bilaterally symmetric about a central axis, The central axis is a line connecting the midpoints of the upper and lower horizontal borders of the broadband bandpass filter, wherein: one end of each of the first microstrip lines is connected to one end of a second microstrip line and forms a double branch Matching the crotch load, the other end of each second microstrip line is vertically connected to a signal output end and a third microstrip line, and each fourth microstrip line is parallelly disposed on a third microstrip line An upper position and a coupling structure, one end of each fourth microstrip line is connected to one end of a fifth microstrip line, and the two ends of the sixth microstrip line are respectively connected with a fifth microstrip line Connected at one end.

The broadband bandpass filter with broadband out-of-band rejection according to claim 1, wherein the two first microstrip lines and the two second microstrip lines are both connected to the broadband bandpass filter The two vertical borders are parallel.

The broadband bandpass filter with broadband out-of-band rejection according to claim 1, wherein the two third microstrip lines, the two fourth microstrip lines, and the two fifth microstrip lines, one The sixth sixth microstrip line and the two signal transmission ends are both parallel to the upper and lower horizontal borders of the broadband band pass filter.

The broadband bandpass filter with wideband out-of-band rejection according to claim 1, wherein said wideband bandpass filter with wideband out-of-band rejection comprises two double-branch-matching ramp loads and two coupling structures .

The broadband bandpass filter with broadband out-of-band rejection according to claim 1, wherein the two signal transmission ends are used for signal input and output, wherein one signal transmission end serves as a signal input end, and the other The signal transmission end serves as a signal output terminal.

The broadband bandpass filter with broadband out-of-band rejection according to claim 1, wherein the first microstrip line, the second microstrip line, the third microstrip line, the fourth microstrip line, and the first The five microstrip lines, the sixth microstrip line and the signal transmission end are metal copper sheets of a strip structure. [Claim 7] The wideband bandpass filter with wideband out-of-band rejection according to claim 6, wherein the length of the first microstrip line is L4=14.4 mm and the width is W4=2.95 mm. The length of the second microstrip line is L3=15 mm and the width is W3=0.97 mm, and the length of the third microstrip line is the same as the length of the fourth microstrip line and both C11=15.99 mm is C11=15.99 mm, The width of the third microstrip line is the same as the width of the fourth microstrip line and both are Cwl=0.22 mm, and the distance between the third microstrip line and the fourth microstrip line is Csl=0.1 m. The length of the fifth microstrip line is L1=15.2mm, the width is Wl=0.73mm, the length of the sixth microstrip line is L2=15.3mm, the width is W2=0.64mm, and the length of the signal transmission end is L0= 10mm, width W0=1.66mm.

[Claim 8] The wideband band pass filter having broadband out-of-band rejection according to claim 6, wherein each first microstrip line has an impedance of 34 Ω, and each second microstrip line has an impedance of 68Ω, the impedance of each fifth microstrip line is 78Ω, the impedance of each sixth microstrip line is 83Ω, the odd mode impedance of each coupling structure 22 is 60Ω, and the even mode impedance of each coupling structure 22 is 180Ω. Each coupling structure 22 has an electrical length of 90 degrees.

[Claim 9] A wideband bandpass filter having wideband out-of-band rejection according to any one of claims 1-8

The dielectric plate is a PCB having a thickness of 0.762 mm and a relative dielectric constant of 3.6 6 .