N-order multi-frequency band-pass filter circuit with good non-reflection characteristic

Abstract

The invention provides a multi-frequency band-pass filter circuit with a good non-reflection characteristic. The multi-frequency band-pass filter circuit comprises an input port, an output port, a multi-frequency band-pass filter circuit and a multi-frequency non-reflection circuit, the multi-frequency band-pass filter circuit is arranged between the input port and the output port; a load of the input port; the multi-frequency band-pass filter circuit comprises a plurality of single-frequency band-pass filter circuits; the single-frequency band-pass filter circuit comprises a capacitor and an inductor; when one level of circuit is added, a capacitor and an inductor are connected in parallel and then are connected in series with an upper level of inductor to form a multi-frequency band-pass filter circuit. The multi-frequency non-reflection circuit comprises a plurality of single-frequency non-reflection circuits. The single-frequency non-reflection circuit comprises a capacitor, an inductor and a resistor; when one level of circuit is added, the inductor and the capacitor are connected in series and then are connected with the previous level of capacitor in parallel to form a multi-frequency non-reflection circuit. According to the invention, the device value relation between the multi-frequency non-reflection circuit and the multi-frequency band-pass filter circuit is determined, so that the performance requirement can be met without complicated parameter debugging.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of filter circuits, in particular, especially relates to a kind of n order multi-band pass filter circuit with good non-reflection characteristic n . BACKGROUND

[0002] Return loss is a main performance index of LC filter, and the signal of the stopband of the traditional filter will return to the signal source, which will cause interference to the signal source and affect the performance of the circuit. However, the non-reflection band-pass filter can increase the non-reflection circuit while maintaining the characteristics of the traditional band-pass filter, so as to increase the return loss and realize the non-reflection function without affecting the performance of the traditional band-pass filter, thereby avoiding interference. Therefore, it is of great significance to study the non-reflection filter for signal transmission. However, the existing non-reflection band-pass filter circuit is mostly single-frequency and double-frequency circuit, and the research on multi-frequency circuit is insufficient.

[0003] The concept of non-reflection was first proposed by American scientists Matthew A. Morgan and others in the early 21st century. As the performance requirements of filters in the field of communication are becoming higher and higher, more and more scholars from various countries have begun to study non-reflection filters. Under the development trend of multi-band and multi-standard in communication systems, in order to simplify the system architecture and improve the system performance, the research on multi-passband zero-reflection filter becomes inevitable. However, the existing band-pass filter circuits with non-reflection characteristics are mostly single-frequency or double-frequency band-pass filter circuits. SUMMARY

[0004] In view of the above technical problems of the lack of application of non-reflection band-pass filter circuit in multi-band scene, the present application provides an n order multi-band pass filter circuit with good non-reflection characteristic. The circuit proposed in the present application not only can realize single-frequency and double-frequency non-reflection characteristics, but also can realize multi-frequency non-reflection characteristics, thereby improving the performance of the circuit.

[0005] The technical means adopted by the present application is as follows: A multi-band pass filter circuit with good non-reflection characteristic, comprising: an input port, an output port, a multi-band pass filter circuit and a multi-frequency non-reflection circuit; The multi-band pass filter circuit is arranged between the input port and the output port; and the load of the input port is . The multi-band pass filter circuit comprises a plurality of single-frequency band-pass filter circuits; each single-frequency band-pass filter circuit comprises a capacitor C and an inductor L; and each time one level of circuit is added, the capacitor C and the inductor L are connected in parallel, and then connected in series with the inductor L of the previous level to form a multi-band pass filter circuit. The multi-frequency non-reflection circuit comprises a plurality of single-frequency non-reflection circuits; the single-frequency non-reflection circuit comprises a capacitor C, an inductor L and a resistor R; and each time a circuit is added, the inductor L and the capacitor C are connected in series and then connected in parallel with the capacitor C of the previous stage to form a multi-frequency non-reflection circuit.

[0006] Further, the voltage relationship and the current relationship between the input port and the output port are described by an ABCD matrix.

[0007] Further, the relationship between the ABCD matrix and the impedance and the return loss is:

[0008]

[0009] When =0, the multi-frequency band-pass filter circuit achieves the non-reflection characteristic, i.e.

[0010] The (1) is substituted into the (3) to obtain the relationship (4),

[0011] When the impedance of the multi-frequency band-pass filter circuit and the impedance of the multi-frequency non-reflection circuit satisfy the (4), the circuit can achieve good non-reflection characteristics.

[0012] Further, the relationship between the values of the devices in the multi-frequency non-reflection circuit and the values of the devices in the multi-frequency band-pass filter circuit is:

[0013] wherein, C represents the capacitor of the multi-frequency non-reflection circuit, L represents the inductor of the multi-frequency non-reflection circuit, C represents the capacitor of the multi-frequency band-pass filter circuit, L represents the inductor of the multi-frequency band-pass filter circuit, Z0 represents the characteristic impedance, and n represents the number of stages of the circuit.

[0014] Further, the impedance and the impedance of the multi-frequency non-reflection circuit are one-to-one corresponding.

[0015] Compared with the prior art, the present application has the following advantages: 1. The n-order multi-band pass filter circuit with non-reflection characteristics provided by the application realizes the non-reflection characteristics in the multi-band by the collaborative design of the multi-band pass filter circuit and the multi-frequency non-reflection circuit. The multi-band pass filter circuit realizes the multi-band pass function by cascading expansion, and the multi-frequency non-reflection circuit matches the impedance by the corresponding cascading structure. The combination of the two increases the return loss significantly and avoids the interference of the stopband signal to the signal source.

[0016] 2. The application simplifies the circuit design process by determining the device value relationship of the multi-frequency non-reflection circuit and the multi-band pass filter circuit, ensures the stable realization of the non-reflection characteristics, and meets the performance requirements without complex parameter debugging.

[0017] 3. The application breaks through the limitation of the existing non-reflection band pass filter circuit which is limited to single frequency or double frequency, and realizes the n-order multi-frequency non-reflection function flexibly through the modular cascading expansion structure, adapts to the development needs of multi-band and multi-standard of communication systems, and improves the universality and expansibility of the circuit.

[0018] In summary, the technical scheme of the application effectively solves the problems of the existing non-reflection band pass filter circuit in the multi-band scene, such as the interference of stopband signal to the signal source, and the complex circuit design and poor expansibility. The application realizes the multi-band non-reflection characteristics through the multi-frequency circuit structure innovation, device parameter matching design and modular expansion capability, simplifies the system architecture and improves the performance. Therefore, the technical scheme of the application solves the problems of the existing non-reflection band pass filter circuit, such as the inability to meet the multi-band application requirements, the interference of stopband signal to the signal source, and the insufficient design flexibility and universality.

[0019] Based on the above reasons, the application can be widely popularized in the fields of wireless communication, radar system, satellite communication, multi-band electronic equipment and the like. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical scheme in the embodiments of the application or the prior art, the drawings needed to be used in the embodiment or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0021] Figure 1 A multi-frequency (4-6 frequency) band pass filter circuit structure with good non-reflection characteristics.

[0022] Figure 2 A three-frequency band pass filter circuit structure with good non-reflection characteristics.

[0023] Figure 3 The diagram shows the S11 theory, simulation, and test results of a three-bandpass filter circuit with good non-reflection characteristics according to the present invention.

[0024] Figure 4 The diagram shows the theoretical, simulation, and test results of the S21 method for a three-bandpass filter circuit with good non-reflective characteristics according to the present invention. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0026] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0027] like Figures 1-4 As shown, the present invention provides a multi-bandpass filter circuit with good anti-reflection characteristics, comprising: Input ports, output ports, multi-frequency bandpass filter circuits, and multi-frequency anti-reflection circuits; The multi-bandpass filter circuit is disposed between the input port and the output port; the load of the input port is ; The multi-bandpass filter circuit includes: multiple single-bandpass filter circuits; each single-bandpass filter circuit includes: a capacitor C and an inductor L; for each additional stage of the circuit, the capacitor C and the inductor L are connected in parallel and then connected in series with the inductor L of the previous stage to form a multi-bandpass filter circuit. The multi-frequency anti-reflection circuit includes: multiple single-frequency anti-reflection circuits; each single-frequency anti-reflection circuit includes: a capacitor C, an inductor L, and a resistor R; for each additional stage of the circuit, the inductor L and the capacitor C are connected in series and then connected in parallel with the capacitor C of the previous stage to form a multi-frequency anti-reflection circuit.

[0028] In the present application, as preferred, the voltage relationship and the current relationship between the input port and the output port are described by ABCD matrix. The relationship between ABCD matrix and impedance and return loss is:

[0029]

[0030] When =0, the multi-band pass filter circuit realizes the non-reflection characteristic, i.e.:

[0031] Substituting (1) into (3), the relationship (4) is obtained,

[0032] When the multi-band pass filter circuit impedance and the impedance of the multi-frequency non-reflection circuit satisfy (4), the circuit can realize good non-reflection characteristics.

[0033] In the present application, as preferred, the relationship between the values of the devices in the multi-frequency non-reflection circuit and the values of the devices in the multi-band pass filter circuit is:

[0034] Wherein, represents the capacitance of the multi-frequency non-reflection circuit, represents the inductance of the multi-frequency non-reflection circuit, represents the capacitance of the multi-band pass filter circuit, represents the inductance of the multi-band pass filter circuit, represents the characteristic impedance, represents the circuit of each stage.

[0035] In the present application, the impedance and the impedance of the multi-frequency non-reflection circuit are one-to-one corresponding.

[0036] Taking a three-frequency non-reflection band pass filter circuit as an example, and are respectively:

[0037] Introducing the relationship into equations (6) and (7): ; then the equation can be simplified to obtain (8) and (9):

[0038]

[0039] Similarly, the impedance Z1 of the multi-band pass filter circuit and the impedance Z2 of the multi-band pass filter circuit are given as follows:

[0040]

[0041] Similarly, for simplifying the equation, the relationship is introduced as follows: Then (12) and (13) are obtained:

[0042]

[0043] Embodiment 1 As shown in Figure 1 a multi-band pass filter circuit with good non-reflection characteristics is shown, which includes the 4-6 frequency band.

[0044] As shown in Figure 2 a three-band pass filter circuit with good non-reflection characteristics is shown, which includes: an input and an output with a load of Z0, a three-band pass filter circuit composed of LC is connected in series between the input and output ports, and a corresponding three-band non-reflection circuit composed of RLC is connected in parallel. Among them, the capacitor C3 and the inductor L3 are connected in parallel, and the whole is connected in series with the inductor L2, and then connected in parallel with the capacitor C2, and then connected in series with the capacitor C1 and the inductor L1, forming a three-band pass filter circuit; the capacitor C6 and the inductor L6 are connected in series, and the whole is connected in parallel with the capacitor C5, and then connected in series with the inductor L5, and then connected in parallel with the capacitor C4 and the inductor L4, and finally connected in series with a resistor R to form a three-band non-reflection circuit.

[0045] The relationship between the ABCD matrix and the impedance and return loss is: ; ; If the non-reflection characteristic is to be realized, i.e. S11=0, then: ; When Z1 and Z2 satisfy , the circuit has good non-reflection characteristics.

[0046] In the present application, the relationship between the values of the devices in the non-reflection circuit and the values of the devices in the multi-band pass filter circuit is given:

[0047] Regarding the impedance Z1 of the multi-band pass filter circuit and the impedance Z2 of the corresponding multi-band non-reflection circuit in the circuit, taking a three-band non-reflection band pass filter circuit as an example, Z1 and Z2 are respectively: ; ; The introduction relationship is: ; then:

[0048]

[0049] The simulation results of the circuit return loss are shown in Figure 3 , and the simulation results of the circuit insertion loss are shown in Figure 4 . As shown in Figure 3 , Figure 4 , the circuit has a full-band non-reflection characteristic. The frequency of the circuit is 57.6 MHz, 155.4 MHz, and 225.0 MHz, respectively, and the corresponding return loss is 20.8 dB, 16.7 dB, and 12.1 dB, respectively, and the corresponding insertion loss is 3.18 dB, 1.44 dB, and 3.46 dB, respectively. The function of multi-frequency non-reflection band-pass filtering can be realized. The expected target is achieved, and it can be verified that the theoretical method is effective.

[0050] The above-mentioned embodiment numbers of the application are only for description, and do not represent the advantages and disadvantages of the embodiments.

[0051] In the above-mentioned embodiments of the application, the description of each embodiment has its own emphasis, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.

[0052] In several embodiments provided in the present application, it should be understood that the disclosed technical contents can be implemented by other ways. Among them, the above-mentioned device embodiments are only schematic, for example, the division of the units can be a logical function division, and actual implementation can have another division way, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point, the coupling or direct coupling or communication connection between the displayed or discussed each other can be through some interface, indirect coupling or communication connection between units or modules, which can be electrical or other forms.

[0053] The units described as separate components can or can not be physically separated, and the components displayed as units can or can not be physical units, that is, they can be located in one place, or they can be distributed on a plurality of units. According to actual needs, part or all of the units can be selected to achieve the purpose of the embodiment scheme.

[0054] In addition, each function unit in each embodiment of the present application can be integrated in one processing unit, or each unit can be physically present separately, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software function unit.

[0055] When the integrated unit is realized in the form of a software function unit and sold or used as an independent product, it can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application or the entire or part of the technical solutions that essentially contribute to the prior art can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes a U disk, a read-only memory (ROM), a random access memory (RAM), a mobile hard disk, a magnetic disk or an optical disk, and various media that can store program codes.

[0056] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of each embodiment of the present application.

Claims

1. A multi-bandpass filter circuit with good anti-reflection characteristics, characterized in that, include: Input ports, output ports, multi-frequency bandpass filter circuits, and multi-frequency anti-reflection circuits; The multi-bandpass filter circuit is disposed between the input port and the output port; The load of the input port is ; The multi-bandpass filter circuit includes: multiple single-bandpass filter circuits; each single-bandpass filter circuit includes: a capacitor C and an inductor L; for each additional stage of the circuit, the capacitor C and the inductor L are connected in parallel and then connected in series with the inductor L of the previous stage to form a multi-bandpass filter circuit. The multi-frequency anti-reflection circuit includes: multiple single-frequency anti-reflection circuits; each single-frequency anti-reflection circuit includes: a capacitor C, an inductor L, and a resistor R; for each additional stage of the circuit, the inductor L and the capacitor C are connected in series and then connected in parallel with the capacitor C of the previous stage to form a multi-frequency anti-reflection circuit.

2. The multi-bandpass filter circuit with good anti-reflection characteristics according to claim 1, characterized in that, The voltage and current relationships between the input and output ports are described using an ABCD matrix.

3. A multi-bandpass filter circuit with good non-reflective characteristics according to claim 2, characterized in that, The relationship between the ABCD matrix and impedance and return loss is as follows: when When = 0, the multi-bandpass filter circuit achieves reflection-free characteristics, that is: Substituting (1) into (3), we obtain relation (4). When the impedance of the multi-bandpass filter circuit Impedance of multi-frequency non-reflective circuits When condition (4) is satisfied, the circuit can achieve good non-reflective characteristics.

4. A multi-bandpass filter circuit with good anti-reflection characteristics according to claim 1, characterized in that, The relationship between the values ​​of each stage of the multi-frequency reflection-free circuit and the values ​​of the components in the multi-frequency bandpass filter circuit is as follows: in, Indicates a capacitor in a multi-frequency non-reflective circuit. Indicates the inductance of a multi-frequency non-reflective circuit. This refers to the capacitor in a multi-bandpass filter circuit. Indicates the inductance of a multi-bandpass filter circuit. Indicates characteristic impedance, This indicates each stage of the circuit.

5. A multi-bandpass filter circuit with good non-reflective characteristics according to claim 1, characterized in that, The impedance Impedance of multi-frequency non-reflective circuits One-to-one correspondence.

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