CN221041498U - Tunable low-pass filter - Google Patents
Tunable low-pass filter Download PDFInfo
- Publication number
- CN221041498U CN221041498U CN202322760899.4U CN202322760899U CN221041498U CN 221041498 U CN221041498 U CN 221041498U CN 202322760899 U CN202322760899 U CN 202322760899U CN 221041498 U CN221041498 U CN 221041498U
- Authority
- CN
- China
- Prior art keywords
- quarter
- wavelength line
- line
- microstrip
- pass filter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 230000005284 excitation Effects 0.000 claims abstract description 18
- 239000000758 substrate Substances 0.000 claims abstract description 13
- 238000000034 method Methods 0.000 claims description 2
- 238000013461 design Methods 0.000 description 10
- 238000004088 simulation Methods 0.000 description 9
- 238000012545 processing Methods 0.000 description 7
- 230000005764 inhibitory process Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 3
- 238000003466 welding Methods 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical group [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
Landscapes
- Control Of Motors That Do Not Use Commutators (AREA)
Abstract
The utility model discloses a tunable low-pass filter, which comprises a dielectric substrate, a grounding layer and a microstrip line, wherein the grounding layer and the microstrip line are arranged on two sides of the dielectric substrate; the microstrip line comprises a first excitation port, a first quarter-wavelength line, a second quarter-wavelength line, a third quarter-wavelength line and a second excitation port which are sequentially connected; and the two sides of the junction of the first excitation port and the first quarter-wavelength line, the junction of the first quarter-wavelength line and the second quarter-wavelength line and the junction of the second quarter-wavelength line and the third quarter-wavelength line are symmetrical and are sequentially connected with a varactor diode and a sector microstrip stub line. Which can implement a tuning function.
Description
Technical Field
The utility model relates to the field of filters, in particular to a tunable low-pass filter.
Background
The filter has a frequency selective characteristic as a passive microwave device, and is widely used in various electronic devices such as a radar, an electronic countermeasure, communication, and frequency synthesis.
Existing low pass filters, such as the "microstrip line low pass filter" with application No. 20132002596. X, include microstrip transmission lines and capacitive microstrip lines, which, while improving the attenuation of the low pass filter, do not have a tuning function.
Disclosure of utility model
The utility model aims to overcome the defect that the prior art does not have a tuning function and provides a tunable low-pass filter which can realize the tuning function.
The aim of the utility model is achieved by the following technical scheme:
The utility model provides a tunable low-pass filter, which comprises a dielectric substrate, a grounding layer and a microstrip line, wherein the grounding layer and the microstrip line are arranged on two sides of the dielectric substrate; the microstrip line comprises a first excitation port, a first quarter-wavelength line, a second quarter-wavelength line, a third quarter-wavelength line and a second excitation port which are sequentially connected;
And the two sides of the junction of the first excitation port and the first quarter-wavelength line, the junction of the first quarter-wavelength line and the second quarter-wavelength line and the junction of the second quarter-wavelength line and the third quarter-wavelength line are symmetrical and are sequentially connected with a varactor diode and a sector microstrip stub line.
In one possible design, the central angle of the sector microstrip stub is 90 degrees.
In one possible design, the symmetry axis of the sector microstrip stub is arranged perpendicular to the first quarter wavelength line.
In one possible design, the diameter of the fan-shaped microstrip stub at the two sides of the connection of the first quarter-wavelength line and the second quarter-wavelength line is larger than the diameter of the fan-shaped microstrip stub at the two sides of the connection of the second quarter-wavelength line and the third quarter-wavelength line;
The diameters of the fan-shaped microstrip stubs at the two sides of the joint of the second quarter-wavelength line and the third quarter-wavelength line are larger than those of the fan-shaped microstrip stubs at the two sides of the joint of the first excitation port and the first quarter-wavelength line.
In one possible design, the length of the second quarter wavelength line is greater than the length of the third quarter wavelength line;
The length of the third quarter wavelength line is greater than the length of the first quarter wavelength line.
In one possible design, the dielectric substrate is Rogers RO4350 of Rogers, 0.254mm thick.
The utility model has the following advantages:
by adopting the design of the scheme, the tuning voltage externally added to the varactor is changed through the varactor resonant circuit, so that the self capacitance value of the varactor is changed, and the tuning function of the filter is realized.
Drawings
FIG. 1 is a schematic diagram of a tunable low-pass filter of the present utility model employing an identification scheme;
FIG. 2 is a schematic diagram of a tunable low-pass filter according to another embodiment of the present utility model;
FIG. 3 is a diagram showing simulation results of an embodiment;
Fig. 4 is a diagram of an LC model corresponding to the tunable low-pass filter of the present utility model.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model, and it is apparent that the described embodiments are some embodiments of the present utility model, but not all embodiments. The components of the embodiments of the present utility model generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the utility model, as presented in the figures, is not intended to limit the scope of the utility model, as claimed, but is merely representative of selected embodiments of the utility model. All other embodiments, based on the embodiments of the utility model, which are apparent to those of ordinary skill in the art without inventive faculty, are intended to be within the scope of the utility model.
In addition, the embodiments of the present utility model and the features of the embodiments may be combined with each other without collision.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.
In the description of the present utility model, it should be noted that, directions or positional relationships indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., are directions or positional relationships based on those shown in the drawings, or are directions or positional relationships conventionally put in use of the inventive product, or are directions or positional relationships conventionally understood by those skilled in the art, are merely for convenience of describing the present utility model and for simplifying the description, and are not to indicate or imply that the apparatus or element to be referred to must have a specific direction, be constructed and operated in a specific direction, and thus should not be construed as limiting the present utility model. Furthermore, the terms "first," "second," and the like, are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.
In the description of the present utility model, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.
As shown in fig. 1, the utility model provides a tunable low-pass filter, which comprises a dielectric substrate 1, a ground layer and a microstrip line, wherein the ground layer and the microstrip line are arranged on two sides of the dielectric substrate; the microstrip line comprises a first excitation port 2, a first quarter-wavelength line 3, a second quarter-wavelength line 4, a third quarter-wavelength line 5 and a second excitation port 6; the first excitation port 2, the first quarter wavelength line 3, the second quarter wavelength line 4, the third quarter wavelength line 5 and the second excitation port 6 are sequentially connected and arranged on a straight line, and the whole filter is arranged with the straight line as axisymmetry.
The connection part of the first excitation port and the first quarter wavelength line, the connection part of the first quarter wavelength line and the second quarter wavelength line, and the connection part of the second quarter wavelength line and the third quarter wavelength line are symmetrically arranged on two sides and are sequentially connected with a varactor diode and a sector microstrip stub line. The varactor diode and the sector microstrip stub are arranged on two sides of the quarter wavelength line and are symmetrically arranged, namely the whole tunable low-pass filter comprises 6 varactor diodes and 6 sector microstrip stubs.
With the above structure, the corresponding LC model is shown in fig. 4. The symmetrical varactor resonant circuits are designed, and the tuning voltage externally applied to the varactor is changed, so that the self capacitance value of the varactor is changed, and the tuning function of the filter is realized.
According to the filter structure, the resonance matching branches can be finely adjusted, so that the simulated inductance and capacitance impedance are improved, the purposes of adjusting the stop band transmission zero position, the rectangular coefficient and the out-of-band suppression degree are achieved, redesign and processing are not needed, and engineering period and cost are greatly saved. And the capacity-variable diode type can be replaced, so that the characteristics of the capacity resonant circuit can be changed, the tunable bandwidth range and the tunable center frequency can be adjusted, various frequency-selecting application scenes can be adapted, and the customized function required by the system can be realized.
In order to further improve the filter performance, the central angle of the fan-shaped microstrip stub is 90 degrees, and the symmetry axis of the fan-shaped microstrip stub is perpendicular to the first quarter-wavelength line.
Based on the structure principle of the tunable low-pass filter, in order to embody the technical effect of the tunable low-pass filter conveniently, a low-pass filter with 2.5GHz tuning to 3.2GHz is selected for simulation design.
The filter index requirements are as follows:
1: operating frequency: DC-2.5 GHz is tuned to DC-3.2 GHz;
2: standing waves of input and output: less than or equal to 1.5;
3: insertion loss: less than or equal to 3dB;
4: out-of-band rejection ratio: more than or equal to 30dBc@5GHz tuned is more than or equal to 30dBc@6.4GHz
5: Tuning voltage: 0V-10V;
The following is a simulation of the structural requirements described in the above-described implementation of the electrically tuned low pass filter.
Performing preliminary modeling simulation by using simulation software Genesye, and selecting a substrate material of Rogers RO4350 of Rogers according to the working frequency and the processing difficulty requirement; the dielectric constant is 3.48, the thickness of the plate is 0.254mm, the length is 40mm, and the width is 30mm. The upper layer of the substrate is an equivalent inductance capacitance resonator, the substrate is simulated ground, and the upper and lower outermost layers are theoretical air cavities. The RO4350 circuit board technology can process small-size circuits with the precision of 0.2mm, can ensure the precision error within 0.05mm, ensures the accurate realization of the circuits to the greatest extent, and has excellent consistency.
The varactors comprise C2, C3, C6, C7, C10, C11; referring to fig. 1 and 2, C2 and C3 are respectively connected to two sides of the connection part of the first excitation port and the first quarter wavelength line through welding points; c6 and C7 are respectively connected with two sides of the connection part of the first quarter wavelength line and the second quarter wavelength line through welding points; c10 and C11 are respectively connected with two sides of the connection part of the second quarter wavelength line and the third quarter wavelength line through welding points.
The sector microstrip stub comprises C1, C4, C5, C8, C9 and C12; referring to fig. 1 and 2, C1 and C4 are respectively connected to two sides of C2 and C3, and have a radius of 1.6mm and a central angle of 90 degrees; c5 and C8 are respectively connected with two sides of C6 and C7, the radius is 1.2.3mm, and the central angle is 90 degrees; c9 and C12 are respectively connected with two sides of C10 and C11, the radius is 12.1mm, and the central angle is 90 degrees. The diameter of the fan-shaped microstrip stub lines at the two sides of the joint of the first quarter wavelength line and the second quarter wavelength line is larger than that of the fan-shaped microstrip stub lines at the two sides of the joint of the second quarter wavelength line and the third quarter wavelength line; the diameters of the fan-shaped microstrip stubs at the two sides of the joint of the second quarter-wavelength line and the third quarter-wavelength line are larger than those of the fan-shaped microstrip stubs at the two sides of the joint of the first excitation port and the first quarter-wavelength line.
The first quarter wavelength line 3, the second quarter wavelength line 4 and the third quarter wavelength line 5 are all quarter wavelength high-low impedance lines loaded by inductance, and the length of the second quarter wavelength line is longer than that of the third quarter wavelength line; the length of the third quarter wavelength line is greater than the length of the first quarter wavelength line. Wherein the length of the first quarter wavelength line 3 is 7.5mm and the width is 0.15mm; the second quarter wavelength line 4 has a length of 8.3mm and a width of 0.15mm; the third quarter wavelength line 5 has a length of 4.1mm and a width of 0.15mm.
The ground layer is a copper layer, and has a length of 23.5mm and a width of 8mm.
The result data obtained after simulation optimization of the above design is shown in fig. 3.
As can be seen from fig. 3, when the tuning voltage vt=0v, the filter is a narrow-band low-pass filter, the passband range is DC-2.5 GHz, the in-band S11 is worst to be-18.6 dB, the standing wave of input and output is less than or equal to 1.3dB through conversion, and the actual processing can meet the requirement less than or equal to 1.5; the maximum loss of the S21 parameter obtained through simulation is 2.5GHz, the simulation loss is 0.27dB, and the final loss of the physical processing can be less than or equal to 3dB; for the inhibition point of 5GHz, the inhibition is more than or equal to 35dBc, and the out-of-band inhibition is more than or equal to 30dBc.
When the tuning voltage VT=10V, the filter is a broadband low-pass filter, the passband range DC-3.2 GHz, the worst in-band S11 is-16 dB, the input/output standing wave is less than or equal to 1.4dB through conversion, and the actual processing can meet the requirement less than or equal to 1.5; the maximum loss of the S21 parameter obtained through simulation is 3.2GHz, the simulation loss is 0.38dB, and the final loss of the physical processing can be less than or equal to 3dB; for the inhibition point of 6.4GHz, the inhibition is more than or equal to 32dBc, and the out-of-band inhibition is more than or equal to 30dBc.
In summary, the tunable low-pass filter is designed successfully.
The design concept can be used for fine adjustment of the resonance matching branches so as to improve the simulated inductance and capacitance impedance, thereby achieving the purpose of adjusting the stop band transmission zero position, the rectangular coefficient and the out-of-band suppression degree without redesigning and processing, and greatly saving engineering period and cost.
The design concept can change the model of the varactor diode, further change the characteristics of the capacitance resonant circuit, adjust the tunable bandwidth range and the tunable center frequency, adapt to various frequency-selecting application scenes and realize the customized function required by the system.
The filter designed by the utility model has compact structure, small volume, good performance index, adjustability in later period and extremely high engineering practicability, and can be suitable for most microstrip filter indexes by adjusting the order or the capacitance-inductance loading capacity.
Although the present utility model has been described with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described, or equivalents may be substituted for elements thereof, and any modifications, equivalents, improvements and changes may be made without departing from the spirit and principles of the present utility model.
Claims (6)
1. A tunable low-pass filter comprises a dielectric substrate, a grounding layer and a microstrip line, wherein the grounding layer and the microstrip line are arranged on two sides of the dielectric substrate; the method is characterized in that: the microstrip line comprises a first excitation port, a first quarter-wavelength line, a second quarter-wavelength line, a third quarter-wavelength line and a second excitation port which are sequentially connected;
And the two sides of the junction of the first excitation port and the first quarter-wavelength line, the junction of the first quarter-wavelength line and the second quarter-wavelength line and the junction of the second quarter-wavelength line and the third quarter-wavelength line are symmetrical and are sequentially connected with a varactor diode and a sector microstrip stub line.
2. A tunable low-pass filter according to claim 1, characterized in that: the central angle of the sector microstrip stub is 90 degrees.
3. A tunable low-pass filter according to claim 1, characterized in that: the symmetry axis of the sector microstrip stub is arranged perpendicular to the first quarter wavelength line.
4. A tunable low-pass filter according to claim 1, characterized in that: the diameters of the fan-shaped microstrip stubs at the two sides of the joint of the first quarter wavelength line and the second quarter wavelength line are larger than those of the fan-shaped microstrip stubs at the two sides of the joint of the second quarter wavelength line and the third quarter wavelength line; the diameters of the fan-shaped microstrip stubs at the two sides of the joint of the second quarter-wavelength line and the third quarter-wavelength line are larger than those of the fan-shaped microstrip stubs at the two sides of the joint of the first excitation port and the first quarter-wavelength line.
5. A tunable low-pass filter according to claim 1, characterized in that: the length of the second quarter wavelength line is greater than the length of the third quarter wavelength line;
The length of the third quarter wavelength line is greater than the length of the first quarter wavelength line.
6. A tunable low-pass filter according to claim 1, characterized in that: the dielectric substrate is Rogers RO4350 of Rogers, and the thickness is 0.254mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322760899.4U CN221041498U (en) | 2023-10-13 | 2023-10-13 | Tunable low-pass filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322760899.4U CN221041498U (en) | 2023-10-13 | 2023-10-13 | Tunable low-pass filter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN221041498U true CN221041498U (en) | 2024-05-28 |
Family
ID=91174256
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202322760899.4U Active CN221041498U (en) | 2023-10-13 | 2023-10-13 | Tunable low-pass filter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN221041498U (en) |
-
2023
- 2023-10-13 CN CN202322760899.4U patent/CN221041498U/en active Active
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US9515362B2 (en) | Tunable bandpass filter | |
| CN108566175B (en) | Adjustable negative group delay circuit | |
| CN110085959B (en) | Miniaturized harmonic suppression equal power divider based on H-shaped defected ground artificial transmission line | |
| CN112002979B (en) | Filtering power divider and communication system | |
| CN102055049A (en) | 360-degree radio-frequency simulated electrical modulation phase shifter of lumped element | |
| CN113193316A (en) | Non-reflection band-pass filter based on double-sided parallel strip lines | |
| US6091312A (en) | Semi-lumped bandstop filter | |
| CN111934069A (en) | Coplanar waveguide dual-frequency band-pass filter based on spiral defected ground | |
| CN221041498U (en) | Tunable low-pass filter | |
| KR100441993B1 (en) | High Frequency Lowpass Filter | |
| US6064281A (en) | Semi-lumped bandpass filter | |
| CN109786905B (en) | Strip line low pass filter | |
| CN114256573B (en) | Microstrip low-pass filter and design method thereof | |
| CN217114739U (en) | Miniaturized ultra wide band pass filter | |
| CN113285188B (en) | Coplanar waveguide band-pass filter with reconfigurable pass band | |
| CN112993501B (en) | Microstrip miniaturized wide stop band filtering power divider loaded with resonator slow wave transmission line | |
| CN116130910A (en) | Electromagnetic band gap filtering power divider | |
| CN110071351B (en) | Adjustable frequency band-pass filter based on cross coupling line | |
| JP4501729B2 (en) | High frequency filter | |
| Bhat et al. | Electronically tunable dual band microwave filter | |
| CN116315535A (en) | Suspension stripline filter | |
| CN111262546B (en) | LTCC filter with adjustable center frequency and fixed absolute bandwidth and simulation method | |
| CN110444839A (en) | Wide stop bands low-pass filter based on T-type minor matters in parallel | |
| KR20210025947A (en) | Wide band filter of PCB structure for minimizing the phase balance of the signal | |
| Prajapati et al. | Microstrip Passive Low Pass Filter (MPLPF) for Maximally Flat Response |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |