CN113839639A

CN113839639A - Dual-frequency filter

Info

Publication number: CN113839639A
Application number: CN202111159963.2A
Authority: CN
Inventors: 李承泽; 王维; 肖攀
Original assignee: Dfine Technology Co Ltd
Current assignee: Dfine Technology Co Ltd
Priority date: 2021-09-30
Filing date: 2021-09-30
Publication date: 2021-12-24

Abstract

The invention discloses a double-frequency filter, which is an LC double-frequency filter, consists of an inductor and a capacitor and comprises: the input end of the first band-pass filter and the input end of the second band-pass filter are combined and connected in parallel and used for receiving an input signal; the output end of the first band-pass filter and the output end of the second band-pass filter are combined and connected in parallel, and the first band-pass filter and the second band-pass filter are used for outputting filtering signals processed by the double-frequency filter. The product of the invention only has an inductor and a capacitor without other devices, the whole filter belongs to a passive device, and the filter with centralized parameters has small volume, reliable process and easy production; in order to solve the problem of multiple frequency harmonics, the inductor and the capacitor in the inductor and the capacitor are respectively self-winding framework inductors and patch capacitors, the materials of magnetic cores are selected for the framework inductors, the harmonic waves after more octaves can be greatly suppressed, the size can be reduced, and the inductor and the capacitor are convenient to assemble and simple to debug.

Description

Dual-frequency filter

Technical Field

The invention relates to the technical field of filter design, in particular to a double-frequency filter.

Background

The filter is a filter circuit consisting of a capacitor, an inductor and a resistor. The filter can effectively filter the frequency point of the specific frequency in the power line or the frequencies except the frequency point to obtain a power signal of the specific frequency or eliminate the power signal of the specific frequency.

A novel planar integrated dual band filter is proposed in the utility model patent application with application number CN201920112164.1, which comprises three dielectric plates bonded together. The upper surface of the bottom dielectric plate is printed with a metal layer, the metal layer is provided with a rectangular gap, two ends of the metal layer are respectively connected with a transition gradual change line and a feed microstrip line, the lower surface of the metal layer is printed with a grounding metal layer, and two sides and the middle of the bottom dielectric plate are respectively provided with periodic metal through holes, so that the SIW filter is realized; a metal layer is printed on the upper surface of the top dielectric plate, a metal circular patch is printed on the lower surface of the top dielectric plate, and periodic metal through holes are punched in the dielectric plate to form an artificial magnetic conductor structure; the middle dielectric plate separates the top dielectric plate from the bottom dielectric plate. Among them are also mentioned: the microwave multi-passband filter is a vital component in a modern wireless communication system, and with the rapid development of a microwave integrated circuit and the increasing shortage of spectrum resources, the whole system is developed towards miniaturization and high performance, which puts higher requirements on the performance and the size of the filter in the wireless communication system. However, the early filter adopts a simple parallel connection or cascade connection mode, so that the size of the filter is greatly increased, and meanwhile, the transmission loss is large. The dual-band filter can inhibit space radiation and plane waves to form a novel planar integrated dual-band filter, and is favorable for realizing high performance and high cost performance of small-size circuit design. Meanwhile, the thickness of the dielectric plate can be adjusted to form a second filter passband. However, the frequency bandwidth of the filter is relatively narrow, and it is difficult to realize a multi-frequency ultra-wideband filter.

There are various filters on the market at present, but these conventional frequency filters need to have two filters to combine together to realize if there are two frequencies in the same frequency, and it is easy to appear that the multiple frequency harmonic of the first frequency will be in the in-band of another frequency filter, if adopt conventional method to make dual-frequency filter then difficult to realize, some conventional filters of existence mainly have following several characteristics:

1. some frequency filters on the market today are single frequency filters, and do not have the characteristics of two frequency filters within the same frequency.

2. The conventional filter has relatively narrow frequency bandwidth, and is difficult to realize a multi-frequency ultra-wideband filter.

Disclosure of Invention

The present invention is directed to overcome the deficiencies of the prior art and to provide a high frequency circuit testing platform to solve the above problems in the background art.

In order to achieve the above object, the present invention provides a dual-band filter, which is an LC dual-band filter, and comprises an inductor and a capacitor, and comprises: the input end of the first band-pass filter and the input end of the second band-pass filter are combined and connected in parallel and used for receiving an input signal; the output end of the first band-pass filter and the output end of the second band-pass filter are combined and connected in parallel, and the first band-pass filter and the second band-pass filter are used for outputting filtering signals processed by the double-frequency filter.

As a further improvement of the present technical solution, the first band-pass filter is formed by connecting a first low-pass filter and a first high-pass filter in series, wherein an output end of the first high-pass filter is connected to an input end of the first low-pass filter;

the second band-pass filter is formed by connecting a second low-pass filter and a second high-pass filter in series, wherein the output end of the second low-pass filter is connected with the input end of the second high-pass filter.

As a further improvement of the present technical solution, the first low-pass filter includes capacitors C1, C2, C3, C4, and C5, and inductors L1 and L2, wherein one end of the capacitor C1 is grounded, and the other end is connected to input ends of the inductor L1 and the capacitor C2; the inductor L1 and the capacitor C2 are connected in parallel to form a first parallel circuit, and the input end of the first parallel circuit receives an input signal; the L2 and the C4 are connected in parallel to form a second parallel circuit, and the input end of the second parallel circuit is connected with the output end of the first parallel circuit; one end of the C3 is connected between the first parallel circuit and the second parallel circuit, and the other end is grounded; one end of the C5 is grounded, and the other end is connected with the output end of the second parallel circuit.

As a further improvement of the present technical solution, the first high-pass filter includes capacitors C6, C7, C8, C9, C10 and inductors L3 and L4, wherein the capacitors C6, C8 and C10 are sequentially connected in series, and an input end of the capacitor C6 is connected to an output end of the first low-pass filter; the L3 is connected between C6 and C8 at one end, the other end is connected with one end of C7, and the other end of C7 is grounded; the L4 has one end connected between C8 and C10, the other end connected to one end of C9, and the other end of C9 connected to ground.

As a further improvement of the present technical solution, the second high-pass filter includes capacitors C11, C12, C13, C14, C15 and inductors L5 and L6, wherein the capacitors C11, C13 and C15 are sequentially connected in series, and an input end of the capacitor C11 receives an input signal; the L5 is connected between C11 and C13 at one end, the other end is connected with one end of C12, and the other end of C12 is grounded; the L6 has one end connected between C13 and C15, the other end connected to one end of C14, and the other end of C14 connected to ground.

As a further improvement of the present technical solution, the second low-pass filter includes capacitors C16, C17, C18, C19, C20 and inductors L7 and L8, wherein the capacitors L7 and C17 are connected in parallel to form a third parallel circuit, the capacitors L8 and C19 are connected in parallel to form a fourth parallel circuit, an input end of the third parallel circuit is connected to an output end of the second high-pass filter, and an output end of the third parallel circuit is connected to an input end of the fourth parallel circuit; one end of the C16 is connected with the input end of the third parallel circuit, and the other end is grounded; one end of the C18 is connected between the third parallel circuit and the fourth parallel circuit, and the other end is grounded; and one end of the C20 is connected with the output end of the fourth parallel circuit, and the other end of the C20 is grounded.

As a further improvement of the technical scheme, the inductor adopts a self-winding framework inductor.

As a further improvement of the technical scheme, the capacitor adopts a patch capacitor.

As a further improvement of the technical scheme, the self-winding framework inductor is made of a magnetic core material.

Compared with the prior art, the invention has the beneficial effects that:

1. the two paths of signals are combined into one path of signal to filter out stray signals, and the filter only needs one antenna port to input or output in this way, so that the cost is greatly reduced, and the overall performance of the product is improved;

2. the inside of the product is only provided with an inductor and a capacitor without other devices, the whole filter belongs to a passive device, and the filter with centralized parameters has small volume, reliable process and easy production;

3. the structure is realized by adopting a LC high-low pass mixing form, and has the characteristics of small volume, capability of enabling harmonic suppression of multiple frequency to be farther and wider bandwidth;

4. in order to solve the problem of multiple frequency harmonics, the inductor and the capacitor in the inductor are respectively a self-winding framework inductor and a surface mounted capacitor, the framework inductor is made of a magnetic core material, so that the harmonic waves after more octaves can be greatly suppressed, the size can be reduced, the assembly is convenient, and the debugging is simple;

5. compared with the traditional filter, the double-frequency filter has the advantages that the size is greatly reduced, more space is saved on the whole machine, the weight is greatly reduced, the cost is greatly reduced, other electrical performance indexes can be guaranteed to be unchanged, and the frequency range can be designed according to actual requirements.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a schematic diagram of a dual-band filter of the present invention;

fig. 2 is a filter curve in embodiment 1 of the present invention.

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the equipment or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.

In order to solve the above problems, a dual-band filter is proposed, which can solve the following problems:

1. the characteristic of having two filters in the same frequency is achieved.

2. A multi-frequency-multiplication ultra-wideband filter is realized, so that the harmonic of the first filter is out of band of the second filter.

The following examples are set forth for the convenience of the reader.

Example 1

As shown in fig. 2, in this embodiment, a dual-band filter is proposed, where the dual-band filter is an LC dual-band filter, and is composed of an inductor and a capacitor, and includes: the input end of the first band-pass filter and the input end of the second band-pass filter are combined and connected in parallel and used for receiving an input signal; the output end of the first band-pass filter and the output end of the second band-pass filter are combined and connected in parallel, and the first band-pass filter and the second band-pass filter are used for outputting filtering signals processed by the double-frequency filter.

In this embodiment, the first band-pass filter is formed by connecting a first low-pass filter and a first high-pass filter in series, wherein the output end of the first high-pass filter is connected with the input end of the first low-pass filter;

In this embodiment, the first low-pass filter includes capacitors C1, C2, C3, C4, and C5, and inductors L1 and L2, wherein one end of the capacitor C1 is grounded, and the other end of the capacitor C1 is connected to the input ends of the inductor L1 and the capacitor C2; the inductor L1 and the capacitor C2 are connected in parallel to form a first parallel circuit, and the input end of the first parallel circuit receives an input signal; the L2 and the C4 are connected in parallel to form a second parallel circuit, and the input end of the second parallel circuit is connected with the output end of the first parallel circuit; one end of the C3 is connected between the first parallel circuit and the second parallel circuit, and the other end is grounded; one end of the C5 is grounded, and the other end is connected with the output end of the second parallel circuit.

In this embodiment, the first high-pass filter includes capacitors C6, C7, C8, C9, C10, and inductors L3 and L4, wherein the capacitors C6, C8, and C10 are sequentially connected in series, and the input terminal of the C6 is connected to the output terminal of the first low-pass filter; the L3 is connected between C6 and C8 at one end, the other end is connected with one end of C7, and the other end of C7 is grounded; the L4 has one end connected between C8 and C10, the other end connected to one end of C9, and the other end of C9 connected to ground.

In this embodiment, the second high-pass filter includes capacitors C11, C12, C13, C14, C15, and inductors L5 and L6, where the capacitors C11, C13, and C15 are sequentially connected in series, and the input end of the capacitor C11 receives an input signal; the L5 is connected between C11 and C13 at one end, the other end is connected with one end of C12, and the other end of C12 is grounded; the L6 has one end connected between C13 and C15, the other end connected to one end of C14, and the other end of C14 connected to ground.

In this embodiment, the second low-pass filter includes capacitors C16, C17, C18, C19, C20 and inductors L7 and L8, where L7 and C17 are connected in parallel to form a third parallel circuit, L8 and C19 are connected in parallel to form a fourth parallel circuit, an input end of the third parallel circuit is connected to an output end of the second high-pass filter, and an output end of the third parallel circuit is connected to an input end of the fourth parallel circuit; one end of the C16 is connected with the input end of the third parallel circuit, and the other end is grounded; one end of the C18 is connected between the third parallel circuit and the fourth parallel circuit, and the other end is grounded; and one end of the C20 is connected with the output end of the fourth parallel circuit, and the other end of the C20 is grounded.

In this embodiment, the inductor is a self-wound bobbin inductor.

In this embodiment, the capacitor is a patch capacitor.

In this embodiment, the self-wound bobbin inductor is made of a magnetic core material.

Specifically, the structure is realized by adopting a LC high-low pass mixing mode, and has the characteristics of small volume, capability of enabling harmonic suppression of multiple frequency to be farther and wide bandwidth. The method in this way is mainly based on the principle diagram (as shown in fig. 1).

1. In order to realize the two filters, the LC low-pass filter and the LC high-pass filter are connected in series and then matched, and then the two filters are connected in parallel.

2. In order to solve the problem of multiple frequency harmonics, the inductor and the capacitor in the inductor are respectively self-winding framework inductors and patch capacitors, the framework inductors are made of magnetic core materials, so that the harmonic waves after more octaves can be greatly suppressed, the size can be reduced by adopting the mode, and the assembly and the debugging are also convenient.

The dual-frequency filter comprises capacitors to ground C1, C3, C5, C16, C18 and C20; series capacitances C7, C9, C12, C14; parallel capacitors C2, C4, C17, C19; coupling capacitances C6, C8, C10, C11, C13 and C15. The upper half is a first filter and the lower half is a second filter. The principle is as follows: the capacitors C1, C2, C3, C4 and C5 and the inductors L1 and L2 form a low-pass filter, the capacitors C6, C7, C8, C9 and C10 and the inductors L3 and L4 form a high-pass filter, and then the two types of filters are connected in series to form a band-pass filter. The capacitors C11, C12, C13, C14 and C15 and the inductors L5 and L6 form a high-pass filter; the capacitors C16, C17, C18, C19 and C20 and the inductors L7 and L8 form a low-pass filter, and then the two types of filters are connected in series to form two band-pass filters. And finally, combining the input and the output of the two band-pass filters in parallel to form a double-frequency filter.

Specifically, the main components of the double-frequency filter are composed of an inductor part and a capacitor part, and the inductor part and the capacitor part are mainly formed by L1 and C2; l2, C4; l3, C7; l4, C9; l5, C12; l6, C14; l7, C17; l8 and C19 form an out-of-band rejection upper resonance point, and the size of the out-of-band rejection can be adjusted. The independent capacitors C1, C3, C5, C16, C18 and C20 are cut-off frequencies of the low-pass section, and C6, C8, C10, C11, C13 and C15 are cut-off frequencies of the low-pass section. The mode enables the whole filter to have a high Q value, greatly improves the performance of the whole multi-double frequency filter, and breaks through the situation that the conventional pass filter can only realize double-frequency filters in one filter.

The dual-frequency filter is applied to national defense, microwave communication, aviation, aerospace or other radio frequency systems. The main effect is to synthesize two paths of signals into one path to filter out stray signals, and the filter only needs one antenna port for input or output, so that the cost is greatly reduced. The overall performance of the product is improved. According to a schematic diagram, the inside of the product only has an inductor and a capacitor without other devices, the whole filter belongs to a passive device, and the filter with the centralized parameters has the advantages of small volume, reliable process and easy production.

As shown in fig. 2, the dual-band filter has been proved to be reliable in process and simple in assembly and debugging through a plurality of tests. The volume of the product can be greatly reduced by the design of the method, more space is made on the whole machine, and the weight and the cost are greatly reduced. The other electrical performance indexes are unchanged even if the volume is reduced, and the indexes are stable and reliable in the using process. The frequency range of the frequency can be designed according to actual requirements, and the frequency range is recommended to be realized in a double-frequency filter in the future.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and the preferred embodiments of the present invention are described in the above embodiments and the description, and are not intended to limit the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. The dual-frenquency filter, the dual-frenquency filter is LC dual-frenquency filter, comprises inductance and electric capacity, its characterized in that includes: the input end of the first band-pass filter and the input end of the second band-pass filter are combined and connected in parallel and used for receiving an input signal; the output end of the first band-pass filter and the output end of the second band-pass filter are combined and connected in parallel, and the first band-pass filter and the second band-pass filter are used for outputting filtering signals processed by the double-frequency filter.

2. The dual-band filter according to claim 1, wherein the first band-pass filter is composed of a first low-pass filter and a first high-pass filter connected in series, wherein the first high-pass filter output is connected to the first low-pass filter input;

3. The dual-band filter of claim 2, wherein the first low-pass filter comprises capacitors C1, C2, C3, C4, C5 and inductors L1 and L2, wherein one end of the capacitor C1 is grounded, and the other end is connected to the input ends of the inductor L1 and the capacitor C2; the inductor L1 and the capacitor C2 are connected in parallel to form a first parallel circuit, and the input end of the first parallel circuit receives an input signal; the L2 and the C4 are connected in parallel to form a second parallel circuit, and the input end of the second parallel circuit is connected with the output end of the first parallel circuit; one end of the C3 is connected between the first parallel circuit and the second parallel circuit, and the other end is grounded; one end of the C5 is grounded, and the other end is connected with the output end of the second parallel circuit.

4. The dual-band filter of claim 2, wherein the first high-pass filter comprises capacitors C6, C7, C8, C9, C10 and inductors L3 and L4, wherein the capacitors C6, C8 and C10 are connected in series in sequence, and the C6 input end is connected to the first low-pass filter output end; the L3 is connected between C6 and C8 at one end, the other end is connected with one end of C7, and the other end of C7 is grounded; the L4 has one end connected between C8 and C10, the other end connected to one end of C9, and the other end of C9 connected to ground.

5. The dual-band filter of claim 2, wherein the second high-pass filter comprises capacitors C11, C12, C13, C14, C15 and inductors L5 and L6, wherein the capacitors C11, C13 and C15 are connected in series in sequence, and the input end of the C11 receives an input signal; the L5 is connected between C11 and C13 at one end, the other end is connected with one end of C12, and the other end of C12 is grounded; the L6 has one end connected between C13 and C15, the other end connected to one end of C14, and the other end of C14 connected to ground.

6. The dual-band filter of claim 2, wherein the second low-pass filter comprises capacitors C16, C17, C18, C19, C20 and inductors L7, L8, wherein the capacitors L7 and C17 are connected in parallel to form a third parallel circuit, the capacitors L8 and C19 are connected in parallel to form a fourth parallel circuit, the third parallel circuit input is connected to the second high-pass filter output, and the third parallel circuit output is connected to the fourth parallel circuit input; one end of the C16 is connected with the input end of the third parallel circuit, and the other end is grounded; one end of the C18 is connected between the third parallel circuit and the fourth parallel circuit, and the other end is grounded; and one end of the C20 is connected with the output end of the fourth parallel circuit, and the other end of the C20 is grounded.

7. The dual-band filter of claim 1, wherein the inductor is a self-wound bobbin inductor.

8. The dual-band filter of claim 1, wherein the capacitor is a patch capacitor.

9. The dual-band filter of claim 7, wherein the self-wound skeletal inductor is formed from a magnetic core material.