Balanced filter cross with high frequency selectivity

Abstract

The application discloses a balanced filter crosser with high frequency selectivity, comprising a balanced differential first input port A, a balanced differential first output port B, a balanced differential second input port C, a balanced differential second output port D, four half-wavelength inverted connection lines, eight eighth-wavelength microstrip transmission lines and four quarter-wavelength filter resonance lines. The balanced filter crosser is a planar structure, can be realized on a single PCB board, has a simple structure and is conducive to processing integration. In addition, the filter crosser can not only effectively suppress common-mode noise and improve the electromagnetic compatibility characteristics of a communication system, but also can realize high frequency selectivity of a differential-mode signal while ensuring high isolation cross transmission of two differential signals, thereby improving the overall performance of the microwave crosser and having a wide application prospect.

Description

Technical Field

[0001] This invention relates to a balanced crossover, and more specifically to a balanced filter crossover with high frequency selectivity. Background Technology

[0002] Balanced circuits play a crucial role in modern wireless communication systems. Compared to unbalanced single-port input / output circuits, balanced circuits can effectively suppress ambient noise and noise generated by internal active components, thus exhibiting superior electromagnetic compatibility characteristics. Various radio frequency microwave devices, such as filters, mixers, and power amplifiers, are widely designed with balanced topologies. With the rapid development of integrated circuits, the demand for balanced devices will become even more urgent, offering broad application prospects.

[0003] In recent years, filter crossovers have received considerable attention in many communication systems. Filter crossovers not only enable two signals to be transmitted crossovers while maintaining high isolation, but also achieve frequency selectivity, thus they are widely used in Butler matrices of modern array antenna beamforming technology.

[0004] However, most existing filter crossovers are based on transmission lines such as jumpers, slotted lines, or substrate-integrated waveguides, and typically achieve frequency selectivity by cascading filter structures at the input and output ports. These methods are often too large and complex, and suffer from problems such as low filter selectivity. Research on balanced filter crossovers with electromagnetic compatibility (EMC) characteristics is even scarcer. Therefore, researching balanced filter crossovers based on planar microstrip structures that achieve high isolation, high common-mode rejection, and high frequency selectivity is of great significance. In view of this, it is indeed necessary to propose a balanced filter crossover with high frequency selectivity. Summary of the Invention

[0005] Based on this, in order to address the shortcomings of existing technologies, a balanced filter crossover with high frequency selectivity is proposed.

[0006] Based on the above objectives, the technical solution of the present invention includes: a balanced differential first input port A, a balanced differential first output port B, a balanced differential second input port C, a balanced differential second output port D, four half-wavelength anti-connection wires, eight half-wavelength microstrip transmission lines, and four quarter-wavelength filter resonant lines.

[0007] The balanced differential first input port A includes a first input port A+ and a first input port A-.

[0008] The balanced differential first output port B includes a first output port B+ and a first output port B-.

[0009] The balanced differential second input port C includes a second input port C+ and a second input port C-.

[0010] The balanced differential second output port D includes a second output port D+ and a second output port D-.

[0011] The four half-wavelength reverse connection wires include a first reverse connection wire, a second reverse connection wire, a third reverse connection wire, and a fourth reverse connection wire; wherein one end of the first reverse connection wire is connected to the first input port A+ and the other end is connected to the first input port A-; one end of the second reverse connection wire is connected to the first output port B+ and the other end is connected to the first output port B-; one end of the third reverse connection wire is connected to the second input port C+ and the other end is connected to the second input port C-; one end of the fourth reverse connection wire is connected to the second output port D+ and the other end is connected to the second output port D-.

[0012] The eight-segment 1 / 8 wavelength microstrip transmission lines include a first microstrip transmission line, a second microstrip transmission line, a third microstrip transmission line, a fourth microstrip transmission line, a fifth microstrip transmission line, a sixth microstrip transmission line, a seventh microstrip transmission line, and an eighth microstrip transmission line. One end of the first microstrip transmission line is connected to the connection between the first input port A+ and the first reverse connection wire, and the other end is connected to the connection between the first filter resonant line and the third filter resonant line. One end of the second microstrip transmission line is connected to the connection between the first input port A- and the first reverse connection wire, and the other end is connected to the connection between the first filter resonant line and the fourth filter resonant line. One end of the third microstrip transmission line is connected to the connection between the first output port B+ and the second reverse connection wire, and the other end is connected to the connection between the second filter resonant line and the third filter resonant line. One end of the fourth microstrip transmission line is connected to the first output port B+. One end of the fifth microstrip transmission line is connected to the second input port C+ and the third reverse connection, and the other end is connected to the first filter resonant line and the third filter resonant line. One end of the sixth microstrip transmission line is connected to the second input port C- and the third reverse connection, and the other end is connected to the second filter resonant line and the third filter resonant line. One end of the seventh microstrip transmission line is connected to the second output port D+ and the fourth reverse connection, and the other end is connected to the first filter resonant line and the fourth filter resonant line. One end of the eighth microstrip transmission line is connected to the second output port D- and the fourth reverse connection, and the other end is connected to the second filter resonant line and the fourth filter resonant line.

[0013] The four quarter-wavelength filter resonant lines include a first filter resonant line, a second filter resonant line, a third filter resonant line, and a fourth filter resonant line. One end of the first filter resonant line is connected to the junction of the first and fifth microstrip transmission lines, and the other end is connected to the junction of the second and seventh microstrip transmission lines. One end of the second filter resonant line is connected to the junction of the third and sixth microstrip transmission lines, and the other end is connected to the junction of the fourth and eighth microstrip transmission lines. One end of the third filter resonant line is connected to the junction of the first and fifth microstrip transmission lines, and the other end is connected to the junction of the third and sixth microstrip transmission lines. One end of the fourth filter resonant line is connected to the junction of the second and seventh microstrip transmission lines, and the other end is connected to the junction of the fourth and eighth microstrip transmission lines.

[0014] Furthermore, the common-mode signal suppression characteristics of the cross-connector can be adjusted by adjusting the first, second, third, and fourth reverse connection connections.

[0015] Furthermore, the in-band matching characteristics of the crossover are adjusted by modifying the first microstrip transmission line, the second microstrip transmission line, the third microstrip transmission line, the fourth microstrip transmission line, the fifth microstrip transmission line, the sixth microstrip transmission line, the seventh microstrip transmission line, and the eighth microstrip transmission line.

[0016] Furthermore, the selective filtering characteristics of the crossover are adjusted by modifying the first, second, third, and fourth filter resonant lines.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] To address current research shortcomings in planar design, improved filter selectivity, and balanced extension of microwave crossovers, this invention provides a balanced filter crossover with high frequency selectivity. This balanced filter crossover has a planar structure, can be implemented on a single PCB board, and its simple structure facilitates fabrication and integration. Furthermore, this filter crossover effectively suppresses common-mode noise, improving the electromagnetic compatibility of communication systems. It also achieves high frequency selectivity for differential signals while ensuring high isolation during crossover transmission of two differential signals, thereby enhancing the overall performance of the microwave crossover and demonstrating broad application prospects. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of a balanced filter crossover with high frequency selectivity according to the present invention;

[0021] Figure 2 This is a hybrid S-parameter amplitude curve of a balanced filter crossover with high frequency selectivity under differential signal excitation according to the present invention.

[0022] Figure 3 This is a hybrid S-parameter amplitude curve of a balanced filter crossover with high frequency selectivity under common-mode signal excitation according to the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0024] The present invention provides a balanced filter crossover with high frequency selectivity, comprising: a balanced differential first input port A, a balanced differential first output port B, a balanced differential second input port C, a balanced differential second output port D, four half-wavelength anti-connection wires, eight one-eighth-wavelength microstrip transmission lines, and four quarter-wavelength filter resonant lines.

[0025] The balanced differential first input port A includes a first input port A+1 and a first input port A-2;

[0026] The balanced differential first output port B includes a first output port B+3 and a first output port B-4;

[0027] The balanced differential second input port C includes a second input port C+5 and a second input port C-6;

[0028] The balanced differential second output port D includes a second output port D+7 and a second output port D-8;

[0029] The four half-wavelength reverse connection wires include a first reverse connection wire 9, a second reverse connection wire 10, a third reverse connection wire 11, and a fourth reverse connection wire 12; wherein one end of the first reverse connection wire 9 is connected to the first input port A+1 and the other end is connected to the first input port A-2; one end of the second reverse connection wire 10 is connected to the first output port B+3 and the other end is connected to the first output port B-4; one end of the third reverse connection wire 11 is connected to the second input port C+5 and the other end is connected to the second input port C-6; one end of the fourth reverse connection wire 12 is connected to the second output port D+7 and the other end is connected to the second output port D-8;

[0030] The eight-segment 1 / 8 wavelength microstrip transmission lines include a first microstrip transmission line 13, a second microstrip transmission line 14, a third microstrip transmission line 15, a fourth microstrip transmission line 16, a fifth microstrip transmission line 17, a sixth microstrip transmission line 18, a seventh microstrip transmission line 19, and an eighth microstrip transmission line 20. One end of the first microstrip transmission line 13 is connected to the connection between the first input port A+1 and the first reverse connection wire 9, and the other end is connected to the connection between the first filter resonant line 21 and the third filter resonant line 23. One end of the second microstrip transmission line 14 is connected to the connection between the first input port A-2 and the first reverse connection wire 9, and the other end is connected to the connection between the first filter resonant line 21 and the fourth filter resonant line 24. One end of the third microstrip transmission line 15 is connected to the connection between the first output port B+3 and the second reverse connection wire 10, and the other end is connected to the connection between the second filter resonant line 22 and the third filter resonant line 23. One end of the fourth microstrip transmission line 16 is connected to the first output port B+3. One end of the fifth microstrip transmission line 17 is connected to the second input port C+5 and the third reverse connection line 11, and the other end is connected to the first filter resonant line 21 and the third filter resonant line 23; one end of the sixth microstrip transmission line 18 is connected to the second input port C-6 and the third reverse connection line 11, and the other end is connected to the second filter resonant line 22 and the third filter resonant line 23; one end of the seventh microstrip transmission line 19 is connected to the second output port D+7 and the fourth reverse connection line 12, and the other end is connected to the first filter resonant line 21 and the fourth filter resonant line 24; one end of the eighth microstrip transmission line 20 is connected to the second output port D-8 and the fourth reverse connection line 12, and the other end is connected to the second filter resonant line 22 and the fourth filter resonant line 24.

[0031] The four quarter-wavelength filter resonant lines include a first filter resonant line 21, a second filter resonant line 22, a third filter resonant line 23, and a fourth filter resonant line 24. One end of the first filter resonant line 21 is connected to the junction of the first microstrip transmission line 13 and the fifth microstrip transmission line 17, and the other end is connected to the junction of the second microstrip transmission line 14 and the seventh microstrip transmission line 19. One end of the second filter resonant line 22 is connected to the junction of the third microstrip transmission line 15 and the sixth microstrip transmission line 18, and the other end is connected to the junction of the fourth microstrip transmission line 16 and the eighth microstrip transmission line 20. One end of the third filter resonant line 23 is connected to the junction of the first microstrip transmission line 13 and the fifth microstrip transmission line 17, and the other end is connected to the junction of the third microstrip transmission line 15 and the sixth microstrip transmission line 18. One end of the fourth filter resonant line 24 is connected to the junction of the second microstrip transmission line 14 and the seventh microstrip transmission line 19, and the other end is connected to the junction of the fourth microstrip transmission line 16 and the eighth microstrip transmission line 20.

[0032] The common-mode signal suppression characteristics of the cross-connector can be adjusted by adjusting the first anti-connection wire 9, the second anti-connection wire 10, the third anti-connection wire 11, and the fourth anti-connection wire 12.

[0033] The in-band matching characteristics of the crossover are adjusted by modifying the first microstrip transmission line 13, the second microstrip transmission line 14, the third microstrip transmission line 15, the fourth microstrip transmission line 16, the fifth microstrip transmission line 17, the sixth microstrip transmission line 18, the seventh microstrip transmission line 19, and the eighth microstrip transmission line 20.

[0034] The selective filtering characteristics of the crossover are adjusted by adjusting the first filter resonant line 21, the second filter resonant line 22, the third filter resonant line 23, and the fourth filter resonant line 24.

[0035] To further illustrate the high frequency selectivity balanced filter crossover provided by the present invention, specific examples of implementation based on the technical solution of the present invention are described in detail below. However, the scope of protection of the present invention is not limited to the following embodiments, and the methods used in the following embodiments are conventional methods unless otherwise specified.

[0036] Specific example: This example illustrates a balanced filter crossover with high frequency selectivity. For example... Figure 2 As shown, the reflection coefficient |S| of the first input port A at a center frequency of 2.45 GHz under differential mode signal excitation, according to the frequency-selective balanced filter crossover described in this invention, is... ddAA |S is -18.2dB, the transmission loss of the differential signal from the first input port A to the first output port B. ddBA | is -1.74dB; transmission isolation of differential signal from first input port A to second input port C | SddCA |Transmission isolation from the first input port A to the second output port D|S ddDA The voltage is the same, and the difference is less than -25dB in the frequency range of 0.5 to 4.5 GHz, exhibiting wideband differential mode isolation characteristics. For example... Figure 3 As shown, the frequency-selective balanced filter crossover described in this invention exhibits common-mode transmission suppression (CMTS) of the common-mode signal from the first input port A to the first output port B under common-mode signal excitation. ccBA The common-mode transmission isolation is less than -30dB in the frequency range of 1.5–4.2GHz, from the first input port A to the second input port C. ccCA |Isolation from common-mode transmission from the first input port A to the second output port D|S ccDA The common-mode noise levels are the same, and the common-mode noise level is less than -30dB in the 1.5–4.2 GHz frequency range, exhibiting wideband common-mode rejection characteristics. This indicates that the frequency-selective balanced filter crossover described in this invention not only suppresses common-mode noise but also enables high-frequency-selective crossover transmission of two differential signals while maintaining high isolation.

[0037] In summary, the frequency-selective balanced filter crossover described in this invention not only effectively suppresses common-mode noise and possesses superior electromagnetic compatibility characteristics, but also achieves highly selective and highly isolated crossover transmission of two differential signals. Furthermore, the frequency-selective balanced filter crossover of this invention has a planar structure that can be implemented on a single PCB board, resulting in a simple structure that facilitates fabrication and integration. Therefore, it is highly suitable for application in various balanced microwave systems and Butler matrices in array antenna beamforming technology to improve overall performance.

[0038] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A balanced filter cross-over with high frequency selectivity, characterized in that, include: Balanced differential first input port A, balanced differential first output port B, balanced differential second input port C, balanced differential second output port D, four half-wavelength reverse interconnection lines, eight half-wavelength microstrip transmission lines, and four quarter-wavelength filter resonant lines. The balanced differential first input port A includes a first input port A+(1) and a first input port A-(2); The balanced differential first output port B includes a first output port B+(3) and a first output port B-(4); The balanced differential second input port C includes a second input port C+(5) and a second input port C-(6); The balanced differential second output port D includes a second output port D+(7) and a second output port D-(8); The four half-wavelength reverse connection wires include a first reverse connection wire (9), a second reverse connection wire (10), a third reverse connection wire (11), and a fourth reverse connection wire (12); wherein one end of the first reverse connection wire (9) is connected to the first input port A+ (1) and the other end is connected to the first input port A- (2); one end of the second reverse connection wire (10) is connected to the first output port B+ (3) and the other end is connected to the first output port B- (4); one end of the third reverse connection wire (11) is connected to the second input port C+ (5) and the other end is connected to the second input port C- (6); one end of the fourth reverse connection wire (12) is connected to the second output port D+ (7) and the other end is connected to the second output port D- (8); The eight-segment one-eighth wavelength microstrip transmission lines include a first microstrip transmission line (13), a second microstrip transmission line (14), a third microstrip transmission line (15), a fourth microstrip transmission line (16), a fifth microstrip transmission line (17), a sixth microstrip transmission line (18), a seventh microstrip transmission line (19), and an eighth microstrip transmission line (20); wherein one end of the first microstrip transmission line (13) is connected to the connection between the first input port A+ (1) and the first reverse connection wire (9), and the other end is connected to the first filter resonant line (21) and the third filter resonant line (20). 3) The connection point of the second microstrip transmission line (14); one end of the second microstrip transmission line (14) is connected to the connection point of the first input port A- (2) and the first reverse connection line (9), and the other end is connected to the connection point of the first filter resonant line (21) and the fourth filter resonant line (24); one end of the third microstrip transmission line (15) is connected to the connection point of the first output port B+ (3) and the second reverse connection line (10), and the other end is connected to the connection point of the second filter resonant line (22) and the third filter resonant line (23); one end of the fourth microstrip transmission line (16) is connected to the first output port B+ (3) and the second reverse connection line (10). One end of port B-(4) is connected to the second reverse connection wire (10), and the other end is connected to the connection between the second filter resonant line (22) and the fourth filter resonant line (24); one end of the fifth microstrip transmission line (17) is connected to the connection between the second input port C+(5) and the third reverse connection wire (11), and the other end is connected to the connection between the first filter resonant line (21) and the third filter resonant line (23); one end of the sixth microstrip transmission line (18) is connected to the connection between the second input port C-(6) and the third reverse connection wire (11), and the other end is connected to the connection between the second input port C-(6) and the third reverse connection wire (11). At the connection point of the second filter resonant line (22) and the third filter resonant line (23); one end of the seventh microstrip transmission line (19) is connected to the connection point of the second output port D+ (7) and the fourth reverse connection line (12), and the other end is connected to the connection point of the first filter resonant line (21) and the fourth filter resonant line (24); one end of the eighth microstrip transmission line (20) is connected to the connection point of the second output port D- (8) and the fourth reverse connection line (12), and the other end is connected to the connection point of the second filter resonant line (22) and the fourth filter resonant line (24); The four quarter-wavelength filter resonant lines include a first filter resonant line (21), a second filter resonant line (22), a third filter resonant line (23), and a fourth filter resonant line (24); wherein one end of the first filter resonant line (21) is connected to the connection between the first microstrip transmission line (13) and the fifth microstrip transmission line (17), and the other end is connected to the connection between the second microstrip transmission line (14) and the seventh microstrip transmission line (19); one end of the second filter resonant line (22) is connected to the connection between the third microstrip transmission line (15) and the sixth microstrip transmission line (18). One end of the third filter resonant line (23) is connected to the connection between the first microstrip transmission line (13) and the fifth microstrip transmission line (17), and the other end is connected to the connection between the third microstrip transmission line (15) and the sixth microstrip transmission line (18); one end of the fourth filter resonant line (24) is connected to the connection between the second microstrip transmission line (14) and the seventh microstrip transmission line (19), and the other end is connected to the connection between the fourth microstrip transmission line (16) and the eighth microstrip transmission line (20).

2. A high frequency selective balanced filter crossover according to claim 1, characterised in that: The common-mode signal suppression characteristics of the cross-connector can be adjusted by adjusting the first reverse connection (9), the second reverse connection (10), the third reverse connection (11), and the fourth reverse connection (12).

3. A high frequency selective balanced filter crossover according to claim 1, wherein: The in-band matching characteristics of the crossover are adjusted by adjusting the first microstrip transmission line (13), the second microstrip transmission line (14), the third microstrip transmission line (15), the fourth microstrip transmission line (16), the fifth microstrip transmission line (17), the sixth microstrip transmission line (18), the seventh microstrip transmission line (19), and the eighth microstrip transmission line (20).

4. A high frequency selective balanced filter crossover according to claim 1, wherein: The selective filtering characteristics of the crossover are adjusted by adjusting the first filter resonant line (21), the second filter resonant line (22), the third filter resonant line (23), and the fourth filter resonant line (24).

Images