CN109244608A - Highly selective narrowband reflectionless filter based on duplexer principle - Google Patents
Highly selective narrowband reflectionless filter based on duplexer principle Download PDFInfo
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- CN109244608A CN109244608A CN201811024166.1A CN201811024166A CN109244608A CN 109244608 A CN109244608 A CN 109244608A CN 201811024166 A CN201811024166 A CN 201811024166A CN 109244608 A CN109244608 A CN 109244608A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
- H01P1/201—Filters for transverse electromagnetic waves
- H01P1/203—Strip line filters
- H01P1/20327—Electromagnetic interstage coupling
- H01P1/20354—Non-comb or non-interdigital filters
- H01P1/20381—Special shape resonators
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Abstract
The invention discloses a kind of highly selective narrowband reflectionless filter based on duplexer principle, including single-pass with bandpass filter, dual-pass band-pass filter, the input port of reflectionless filter, ground plane, medium substrate, plated-through hole, Chip-R, the output port of reflectionless filter and dual-pass band-pass filter output port；Design starting point is reflected into reduce filter radiofrequency signal, pass through the principle of duplexer, utilize single-pass band bandpass filter and dual-pass band-pass filter composition duplexer with sequential frequency band, 50 Ω build-out resistors are connected in the output port of dual-pass band-pass filter, realize reflectionless filter.The configuration of the present invention is simple, handling ease, and it is at low cost, it is light-weight, new technical solution is provided for the receive-transmit system Front-end Design of wireless communication, has expanded the application of microwave passive circuit.
Description
Technical field
The present invention relates to a kind of reflectionless filter, it is especially a kind of based on the highly selective narrowband of duplexer principle without anti-
Penetrate filter.
Background technique
Filter is essential microwave equipment in Wireless communication transceiver system.For traditional bandpass filter, it is
Realization frequency selectivity, energy bring a large amount of unwanted non-linear elements by different degrees of reflection, to radio-frequency front-end,
Make amplifier operation in nonlinear area, while increases the intermodulation product in conversion chains link.In order to reduce the reflection of radiofrequency signal,
It can use feedforward to eliminate, add the methods of passive annular device and isolator, but will be to sacrifice size and volume as cost.This
Over a little years, reflectionless filter is being increasingly becoming a kind of viable option.
Reflectionless filter is divided into band resistance and band logical reflectionless filter two major classes, wherein the number of areflexia bandstop filter
Amount accounts for the overwhelming majority, to areflexia bandstop filter, and can be divided into two kinds of forms of lamped element and microstrip line, does to this simple
Introduction: the areflexia bandstop filter of lamped element form is mainly constituted by acoustic resonator and lamped element are appropriately combined,
Reflective loads are made of N number of identical cascade sound wave lamped element resonator and N number of static impedance inverter, are reflected by increasing
The quantity of sound wave lamped element resonator, amplifies bandwidth of rejection with can be convenient in load；The areflexia band of microstrip line form hinders
Filter replaces lamped element resonance using the open stub of quarter-wave and half-wavelength using Kuroda rule
Device.To areflexia bandpass filter, implementation method is broadly divided into two major classes: a kind of method is the all-pass net configured by parallel cascade
Network realizes areflexia bandpass filter, but the transmission function for the all-pass filter for requiring two of them different keeps symmetry,
And in input terminal using wide-band coupler to improve bandwidth of rejection；Another method is to be based on lateral signal interference principle,
However, since the bandwidth of the limitation areflexia bandpass filter of characteristic impedance design equation is constrained in a smaller range.
It can be seen from the above, there is no highly selective narrowband although areflexia bandpass filter has good application prospect
The relevant report of reflectionless filter.
Summary of the invention
The purpose of the present invention is to provide a kind of highly selective narrowband reflectionless filter based on duplexer principle, can be
The reflection of radiofrequency signal is reduced in certain frequency band.
The technical solution for realizing the aim of the invention is as follows: a kind of highly selective narrowband areflexia based on duplexer principle
Filter, including single-pass with bandpass filter, dual-pass band-pass filter, the input port of reflectionless filter, ground plane, Jie
Matter substrate, plated-through hole, Chip-R, the output port of reflectionless filter and dual-pass band-pass filter output end
Mouthful；
The upper surface printing single-pass of medium substrate is with bandpass filter, dual-pass band-pass filter, reflectionless filter
The output port of input port, the output port of reflectionless filter and dual-pass band-pass filter, the lower surface of medium substrate
Print one layer of metal copper sheet, the ground plane as microstrip line；The single-pass band bandpass filter is by closed stub, open circuit cutting back
Line, open circuit coupling line and the first microstrip transmission line composition, closed stub and open stub are connected to the phase of open circuit coupling line
Neighboring terminal mouth, carries out the transmission of energy, and two neighboring port passes through two the first microstrip transmission lines and reflectionless filter respectively
The output port connection of input port, reflectionless filter；The dual-pass band-pass filter uses T-type structure, and signal is double
Passband bandpass filter has two paths when transmitting, for the first paths, two open circuit coupling lines be connected to two it is second micro-
Center with transmission line, open stub are located at the center of two open circuit coupling lines；For the second paths, a short-circuit cutting back
Line is connected to the center of third microstrip transmission line, and the output port of dual-pass band-pass filter passes through Chip-R and medium substrate
On ground metallization through-hole be connected, the Chip-R is arranged in the upper surface of medium substrate, single-pass band bandpass filter and
Dual-pass band-pass filter is linked together by the input port of reflectionless filter.
It further, include ground metallization through-hole in single-pass band bandpass filter and dual-pass band-pass filter, and
Due to the difference of line width, included ground metallization through-hole number is different, and wherein the output port of dual-pass band-pass filter is logical
It crosses Chip-R to be connected with 9 ground metallization through-holes on medium substrate, 4 ground connection on closed stub and medium substrate
Plated-through hole is connected, and closed stub is connected with 2 ground metallization through-holes on medium substrate.
Further, the diameter of plated-through hole is 0.4mm-0.6mm, and the spacing of plated-through hole is 0.3mm-0.5mm,
Plated-through hole is 0.1mm-0.2mm away from back gauge.
Further, the first microstrip transmission line characteristic impedance is 65 Ω, and the second microstrip transmission line characteristic impedance is 153 Ω,
Third microstrip transmission line characteristic impedance is 50 Ω.
The dielectric constant of medium substrate is 2.2,2.23,2.55 or 2.65.
Medium substrate with a thickness of 0.5mm, 0.8mm, 1.0mm or 1.5mm.
The material of medium substrate is domestic polytetrafluoroethylene (PTFE), dielectric constant 2.65, with a thickness of 1.0mm
The present invention is compared with existing invention, remarkable advantage are as follows: (1) of the invention based on the highly selective of duplexer principle
Narrowband reflectionless filter design method simple and flexible；(2) it is of the invention based on the highly selective narrowband of duplexer principle without anti-
The bandwidth variation of wider range can be realized by penetrating filter；(3) it is of the invention based on the highly selective narrowband of duplexer principle without anti-
The number of transmission zero can be increased by penetrating filter.
The present invention is described in further detail below in conjunction with the accompanying drawings.
Detailed description of the invention
Fig. 1 is that the present invention is based on the working principle diagrams of the highly selective narrowband reflectionless filter of duplexer principle.
Fig. 2 is the top view of the highly selective narrowband reflectionless filter based on duplexer principle.
Fig. 3 is the bottom view of the highly selective narrowband reflectionless filter based on duplexer principle.
Fig. 4 is the emulation and test S parameter characteristic pair of the highly selective narrowband reflectionless filter based on duplexer principle
Than figure.
Fig. 5 is emulation and the test group delay frequency characteristic pair of the highly selective narrowband reflectionless filter based on duplexer principle
Than figure.
Specific embodiment
Highly selective narrowband reflectionless filter working principle based on duplexer principle of the invention is as shown in Figure 1, packet
Containing single-pass with bandpass filter 1, dual-pass band-pass filter 2, the input port 3 of reflectionless filter, ground plane 4, medium base
Plate 5, plated-through hole 6, Chip-R 7, the output port 8 of reflectionless filter and the output port of dual-pass band-pass filter
9.The continuous single-pass of frequency band is connected with bandpass filter and dual-pass band-pass filter by the input port 3 of reflectionless filter
Together, when single-pass band bandpass filter works, dual-pass band-pass filter is in stopband；Dual-pass band-pass filter work
When, single-pass band bandpass filter is in stopband, constitutes duplexer.Connect 50 Ω's in the output port of dual-pass band-pass filter
Ground patch resistance, then being inhaled from the energy that input port is transferred to dual-pass band-pass filter by the ground patch resistance of 50 Ω
It receives without being reflected, therefore becomes reflectionless filter.Highly selective areflexia narrow band filter is designed, is needed
The highly selective narrow band filter of corresponding single band.Compared to other single-passes band bandpass filter, open/short double resonator
The bandpass filter of composition is selective good, the simple advantage of structure, therefore this single-pass band bandpass filtering is selected in the present invention
Device can be closed stub, open stub and the open circuit in open/short double resonator in order to reduce circuit area
Coupling line carries out folding appropriate.Using the dual-pass band-pass filter of T-type structure, pass band width can be by open circuit coupling line
The coefficient of coup is adjusted, convenient to constitute duplexer with single-pass band bandpass filter.
In conjunction with Fig. 2 and Fig. 3, the highly selective narrowband reflectionless filter of the invention based on duplexer principle, including list
Passband bandpass filter 1, dual-pass band-pass filter 2, the input port 3 of reflectionless filter, ground plane 4, medium substrate 5,
Plated-through hole 6, Chip-R 7, the output port 8 of reflectionless filter and dual-pass band-pass filter output port 9.
Upper surface printing single-pass the band bandpass filter 1, dual-pass band-pass filter 2, reflectionless filter of medium substrate 5
Input port 3, the output port 8 of reflectionless filter and the output port 9 of dual-pass band-pass filter, under medium substrate
One layer of metal copper sheet is printed on surface, and as the ground plane 4 of microstrip line, the single-pass band bandpass filter 1 is by closed stub 1-
1, the first microstrip transmission line 1-4 that open stub 1-2, open circuit coupling line 1-3 and characteristic impedance are 65 Ω is formed, short-circuit cutting back
Line 1-1 and open stub 1-2 is connected to the adjacent port of open circuit coupling line 1-3, carries out the transmission of energy, two neighboring port
The the first microstrip transmission line 1-4 and the input port 3 of reflectionless filter, areflexia for being respectively 65 Ω by two characteristic impedances
The output port 8 of filter connects；The dual-pass band-pass filter 2 uses T-type structure, and signal is in dual-pass band-pass filter
There are two paths when 2 transmission, for the first paths, it is 153 Ω's that two open circuit coupling line 2-1, which are connected to two characteristic impedances,
The center of second microstrip transmission line 2-4, open stub 2-2 is located at the center of two open circuit coupling line 2-1, for Article 2 road
Diameter, a closed stub 2-3 are connected to the center for the third microstrip transmission line 2-5 that characteristic impedance is 50 Ω, dual-passband band logical
The output port 9 of filter is connected by Chip-R 7 with the ground metallization through-hole 6 on medium substrate 5, the Chip-R
7 are also disposed at the upper surface of medium substrate 5, and single-pass band bandpass filter 1 and dual-pass band-pass filter 2 are filtered by areflexia
The input port 3 of device links together.
It include ground metallization through-hole in single-pass band bandpass filter and dual-pass band-pass filter, and due to line width
Difference, included ground metallization through-hole number is different, and the diameter of plated-through hole is 0.4mm-0.6mm, plated-through hole
Spacing is 0.3mm-0.5mm, and plated-through hole is 0.1mm-0.2mm away from back gauge.
The dielectric constant of medium substrate is 2.2,2.23,2.55 or 2.65.Medium substrate with a thickness of 0.5mm, 0.8mm,
1.0mm or 1.5mm.
Preferably, the material of medium substrate is domestic polytetrafluoroethylene (PTFE), dielectric constant 2.65, with a thickness of 1.0mm.
Specifically, the present invention is single layer PCB construction, 5 upper and lower surface of medium substrate is metal copper sheet, and wherein upper surface is
Microstrip line construction, lower surface is for metal.Single-pass band bandpass filter 1 and dual-pass band-pass filter 2 are filtered by areflexia
The input port 3 of device is connected, and single-pass has 2 plated-through holes, dual-passband band with the closed stub 1-1 in bandpass filter 1
Closed stub 2-3 in bandpass filter 2 has 4 plated-through holes, and Chip-R 7, which is grounded connected plated-through hole, 9
A, 15 plated-through holes 6 are to connect copper sheet up and down altogether.Patch is loaded in the output port 9 of dual-pass band-pass filter
Resistance 7, the other end ground connection of Chip-R 7.
The permittivity ε of the medium substrate 5rIt is 2.65, with a thickness of 1mm.The optional range of dielectric constant is 2.2-2.65,
The optional range of thickness is 0.5mm-1.5mm.
The highly selective narrowband reflectionless filter based on duplexer principle retain up and down 10mm away from side spacing,
Input/output terminal is 50 Ω microstrip lines.
Refinement explanation is carried out to the present invention below with reference to embodiment.
Embodiment
Complete circuit board size is 92.62mm × 60.02mm；The line width of 50 Ω microstrip line of input/output terminal is
2.72mm, to weld sub-miniature A connector, the wire length of 50 Ω microstrip lines is 10mm.In order to avoid single-pass band bandpass filter and double as far as possible
Coupling between passband bandpass filter, the spacing above and below them are 4.09mm.The bending of microstrip line will lead to microstrip line not
Continuity is handled, corner cut is isosceles right triangle, triangle to reduce the shunt capacitance effect at turning using corner cut
Right-angle side side length is consistent with microstrip line line width where corner cut.Single-pass in bandpass filter microstrip line and coupling line all not into
Row corner cut, wherein the line width of open stub is 1.78mm, and lateral micro-strip line length is 16.58mm, longitudinal microstrip line after bending
Length is 6.34mm, and the line width of closed stub is also 1.78mm, a length of 44.1mm of bus, and the line width for coupling line of opening a way is
0.44mm, gap 0.35mm, a length of 32.4mm of bus.Line width is the micro- of 2.72mm and 3.53mm in dual-pass band-pass filter
Band transmission line has all carried out corner cut processing in corner, and the line width for coupling line of opening a way in dual-pass band-pass filter is 0.67mm,
Gap is 0.21mm, and in the range of can processing in processing technology, the wire length for coupling line of opening a way is 25.75mm, in order to realize
Areflexia characteristic loads Chip-R in the output port of dual-pass band-pass filter, encapsulates model 0402, resistance value is
49.9Ω.The radius of 15 plated-through holes is 0.3mm, is highly 1mm.
The filter bandwidht of the example meets design requirement, and plate bending may cause of part frequency point in test process
With not being fine.As shown in figure 4, the centre frequency of passband slightly moves one to high frequency compared with simulation result in test result
A bit, within the acceptable range.Although the passband group delay in addition tested as shown in figure 5, equally in frequency some deviate,
It is that test is very close with simulation result.
Below to the present invention is based on the preparation process of the highly selective narrowband reflectionless filter of duplexer principle to carry out in detail
Thin description.
(1) firstly, determining the centre frequency of reflectionless filter and the parameter of medium substrate, mainly dielectric constant and thickness
Degree.Based on the considerations of the size and total weight of pcb board material, thickness is usually chosen between 0.5mm-1.6mm.
(2) its centre frequency and bandwidth are determined by the index of areflexia bandpass filter.
(3) single-pass band bandpass filter and dual-pass band-pass filter are placed on suitably apart from upper, when between the two away from
Reduce, unnecessary coupling can be generated, need constantly to debug in simulation process.
(4) it needs to keep suitable distance according to two filters in step (3), need input port to binary channels band
The length of the microstrip transmission line bending of bandpass filter is selected as suitable value.
(5) two-channel band pass filter output port is at a distance from ground metallization through-hole to areflexia bandpass filter
Influence is also very big, needs to consider the size of actual processing bak stay resistance additionally to facilitate welding.
(6) duplexer can be first designed in design process, according to the parameter of duplexer again dual-pass band-pass filter
Output port connects the ground patch resistance of 50 Ω, is then finely adjusted again to the circuit parameter having determined, to obtain best nothing
Reflection filter effect.
From the foregoing, it will be observed that the present invention is to reduce filter to the reflection of radiofrequency signal to make Wireless communication transceiver system more
Add and stablize and design, is based on duplexer principle, connects the ground patch resistance of 50 Ω in the output port of dual-pass band-pass filter,
Make the energy for being transmitted to dual-pass band-pass filter be grounded Chip-R absorption no longer to reflect, will not be generated in certain frequency band
Reflection signal causes adverse effect to other devices in Wireless communication transceiver system.Areflexia bandpass filter is in centre frequency
Insertion Loss at 2GHz is 1.43dB, and the relative bandwidth of passband is that 8.5%, S11 is low in 1.33GHz-2.81GHz frequency range
In -10dB, there is good areflexia filtering characteristic.
Claims (8)
1. a kind of highly selective narrowband reflectionless filter based on duplexer principle, which is characterized in that including single-pass band band logical
Filter (1), dual-pass band-pass filter (2), the input port (3) of reflectionless filter, ground plane (4), medium substrate
(5), plated-through hole (6), Chip-R (7), the output port (8) of reflectionless filter and dual-pass band-pass filter is defeated
Exit port (9)；
Upper surface printing single-pass band bandpass filter (1) of medium substrate (5), dual-pass band-pass filter (2), areflexia filtering
The output port (9) of the input port (3) of device, the output port (8) of reflectionless filter and dual-pass band-pass filter, medium
Print one layer of metal copper sheet, the ground plane (4) as microstrip line in the lower surface of substrate；Single-pass band bandpass filter (1) by
Closed stub (1-1), open stub (1-2), open circuit coupling line (1-3) and the first microstrip transmission line (1-4) composition, short circuit
Stub (1-1) and open stub (1-2) are connected to the adjacent port of open circuit coupling line (1-3), carry out the transmission of energy, phase
Adjacent two ports pass through the input port (3) of two the first microstrip transmission lines (1-4) and reflectionless filter, areflexia filter respectively
The output port (8) of wave device connects；The dual-pass band-pass filter (2) uses T-type structure, and signal is in dual-passband bandpass filtering
Device (2) has two paths when transmitting, and for the first paths, two open circuit coupling lines (2-1) are connected to two the second micro-strips and pass
The center of defeated line (2-4), open stub (2-2) are located at the center of two open circuits coupling line (2-1)；For the second paths,
One closed stub (2-3) is connected to the center of third microstrip transmission line (2-5), the output port of dual-pass band-pass filter
(9) it is connected by Chip-R (7) with the ground metallization through-hole (6) on medium substrate (5), Chip-R (7) setting
In the upper surface of medium substrate (5), single-pass band bandpass filter (1) and dual-pass band-pass filter (2) are filtered by areflexia
The input port (3) of device links together.
2. the highly selective narrowband reflectionless filter according to claim 1 based on duplexer principle, which is characterized in that
It include ground metallization through-hole in single-pass band bandpass filter (1) and dual-pass band-pass filter (2), and not due to line width
Together, included ground metallization through-hole number is different, and wherein the output port (9) of dual-pass band-pass filter passes through Chip-R
(7) it is connected with 9 ground metallization through-holes on medium substrate (5), 4 on closed stub (2-3) and medium substrate (5)
Ground metallization through-hole is connected, and closed stub (1-1) is connected with 2 ground metallization through-holes on medium substrate (5).
3. the highly selective narrowband reflectionless filter according to claim 2 based on duplexer principle, which is characterized in that
The diameter of plated-through hole (6) is 0.4mm-0.6mm, and the spacing of plated-through hole (6) is 0.3mm-0.5mm, plated-through hole
It (6) is 0.1mm-0.2mm away from back gauge.
4. the highly selective narrowband reflectionless filter according to claim 1 based on duplexer principle, which is characterized in that
(1-4) characteristic impedance of first microstrip transmission line is 65 Ω.
5. the highly selective narrowband reflectionless filter according to claim 1 based on duplexer principle, which is characterized in that
(2-4) characteristic impedance of second microstrip transmission line is 153 Ω.
6. the highly selective narrowband reflectionless filter according to claim 1 based on duplexer principle, which is characterized in that
(2-5) characteristic impedance of third microstrip transmission line is 50 Ω.
7. the highly selective narrowband reflectionless filter according to claim 1,2 or 3 based on duplexer principle, feature
It is, the dielectric constant of medium substrate (5) is 2.2,2.23,2.55 or 2.65.
8. the highly selective narrowband reflectionless filter according to claim 7 based on duplexer principle, which is characterized in that
Medium substrate (5) with a thickness of 0.5mm, 0.8mm, 1.0mm or 1.5mm.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201811024166.1A CN109244608B (en) | 2018-09-04 | 2018-09-04 | High-selectivity narrow-band reflection-free filter based on duplexer principle |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811024166.1A CN109244608B (en) | 2018-09-04 | 2018-09-04 | High-selectivity narrow-band reflection-free filter based on duplexer principle |
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| CN109244608B CN109244608B (en) | 2020-02-14 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114499455A (en) * | 2022-01-17 | 2022-05-13 | 西南交通大学 | All-pass adjustable delay filter circuit |
| CN114628873A (en) * | 2022-03-09 | 2022-06-14 | 南通大学 | Absorption type microstrip line band elimination filter structure |
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| US20100205233A1 (en) * | 2009-02-09 | 2010-08-12 | Matthew Alexander Morgan | Reflectionless filters |
| CN102664296A (en) * | 2012-04-27 | 2012-09-12 | 西安电子科技大学 | Low-insertion-loss and constant-absolute-bandwidth electrically-tunable band-pass filter |
| CN103928732A (en) * | 2014-05-07 | 2014-07-16 | 电子科技大学 | Micro-strip line absorption band-pass filter |
| CN105529515A (en) * | 2016-01-28 | 2016-04-27 | 华南理工大学 | Adjustable bandpass-bandstop filter based on loading on open circuit branch |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100205233A1 (en) * | 2009-02-09 | 2010-08-12 | Matthew Alexander Morgan | Reflectionless filters |
| CN102664296A (en) * | 2012-04-27 | 2012-09-12 | 西安电子科技大学 | Low-insertion-loss and constant-absolute-bandwidth electrically-tunable band-pass filter |
| CN103928732A (en) * | 2014-05-07 | 2014-07-16 | 电子科技大学 | Micro-strip line absorption band-pass filter |
| CN105529515A (en) * | 2016-01-28 | 2016-04-27 | 华南理工大学 | Adjustable bandpass-bandstop filter based on loading on open circuit branch |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114499455A (en) * | 2022-01-17 | 2022-05-13 | 西南交通大学 | All-pass adjustable delay filter circuit |
| CN114499455B (en) * | 2022-01-17 | 2023-04-28 | 西南交通大学 | Full-general adjustable delay filter circuit |
| CN114628873A (en) * | 2022-03-09 | 2022-06-14 | 南通大学 | Absorption type microstrip line band elimination filter structure |
| CN114628873B (en) * | 2022-03-09 | 2023-08-18 | 南通大学 | Absorption type microstrip line band elimination filter structure |
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| CN109244608B (en) | 2020-02-14 |
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