Ultra-wideband differential and common mode isolation high selectivity filter single-ended to differential type power divider

Abstract

The present invention provides a high-selectivity filtering single-ended to differential power divider with ultra-wideband differential common-mode isolation, comprising: a metal grounding layer, a dielectric plate layer and a metal circuit layer are sequentially arranged from bottom to top. The metal circuit layer is composed of a four-wire coupling line, two isolation resistors, a short-circuit branch, two sections of open-circuit branches, two sections of filter coupling lines and a balanced transmission line between two sections of differential output ports. With the single-ended input port as the symmetry point, the entire metal circuit layer is vertically symmetrical. The five-port power divider provided by the present invention realizes equal power distribution from a single end to two differential output ports. At the same time, the power divider has a simple circuit structure, a high-selectivity filtering function, a flexible filtering bandwidth adjustable design function, a deep isolation performance of differential mode / common mode within an ultra-wideband, a suppression performance, and a high suppression performance of signal conversion between differential mode / common mode within an ultra-wideband.

Description

Technical Field

[0001] The invention relates to the technical field of microwave transmission, and in particular to a high-selectivity filtering single-end to differential power divider with ultra-wideband differential common mode isolation. Background Art

[0002] In the field of microwave and / or radio frequency, differential circuit is a very common functional circuit. The input and output of this circuit are both the input and output of two signals, and the effective input and output signals of the circuit are the difference between the two input and output signals. When there is interference in the external environment, and the same interference signal is loaded on the two input and output ports at the same time, the difference between the two will eliminate the influence of the interference on the effective input and output signals of the circuit, thereby realizing the function of resisting common-mode noise (Common-Mode Noises, CM Noises) interference and transmitting differential-mode signals (Differential-Mode Signals, DM Signals).

[0003] In addition, the power divider (PD) is a crucial device in the microwave and / or radio frequency field, and its application scenarios are very wide, including: mixers, power amplifiers, multi-channel communication networks, phased array radars, etc. In the prior art, the Wilson power divider (Wilkinson PD) is one of the most commonly used power divider structures. The Wilson power divider is a typical binary power divider, which consists of power distribution branches at both ends and isolation resistors. According to the type of input and output ports, the power divider can also be divided into the following four types: single-ended to single-ended (SETSE) structure, differential to single-ended (Balanced-to-Single-Ended, BTSE) structure, differential to differential (Balanced-to-Balanced, BTB) structure and single-ended to differential (Single-Ended-to-Balanced, SETB) structure. Compared with the single-ended port structure, the circuit using differential (balanced) ports is more complex in design, but it can effectively reduce common-mode noise and electromagnetic radiation interference, and improve the circuit's anti-interference ability and transmission efficiency.

[0004] So far, in the existing technology, the research on differential-to-single-ended BTSE structure and differential-to-differential BTB structure power dividers has been relatively mature, and can simultaneously have outstanding filtering performance and ultra-wideband differential mode / common mode isolation and suppression performance. However, for single-ended-to-differential structure power dividers, there is still much room for improvement in the research on their filtering performance and ultra-wideband differential mode / common mode isolation and suppression performance. Summary of the invention

[0005] In view of this, an embodiment of the present invention provides a high-selectivity filtering single-ended to differential power divider with ultra-wideband differential common mode isolation to eliminate or improve one or more defects existing in the prior art, and solve the problems in the prior art that the filtering performance of the power divider with a single-port to differential port structure, the isolation performance of ultra-wideband differential mode / common mode, and the suppression performance are all poor.

[0006] The present invention provides an ultra-wideband differential common mode isolation high selectivity filtering single-ended to differential type power divider, which is characterized by comprising:

[0007] Metal ground plane;

[0008] A dielectric layer, arranged above the metal grounding layer;

[0009] A metal circuit layer is arranged above the dielectric board layer; the metal circuit layer is provided with a single-ended input port, a four-wire coupling line, a short-circuit branch, and a first branch and a second branch symmetrical in the longitudinal direction in sequence; the four-wire coupling line includes a first coupling transmission line, a second coupling transmission line, a third coupling transmission line and a fourth coupling transmission line connected in sequence from top to bottom; one end of the second coupling transmission line and the third coupling transmission line on the same side are respectively connected to the single-ended input port, and the other end is respectively connected to the short-circuit branch; a first isolation resistor is provided between one end of the first coupling transmission line and the fourth coupling transmission line on the same side, and a second isolation resistor is provided between the other ends; the first branch is provided with a first open-circuit branch, a first filter coupling line and a first differential output port in sequence in the horizontal direction; the first filter coupling line includes a first filter transmission line and a second filter transmission line connected in sequence from top to bottom; one end of the first filter transmission line is connected to the first an open-circuit branch, and the other end is connected to the first differential output port; one end of the second filtering transmission line is connected to the first coupled transmission line of the four-wire coupled line, and the other end is open; a first balanced transmission line is arranged between the first differential output ports; the second branch is provided with a second open-circuit branch, a second filtering coupled line and a second differential output port in sequence in the horizontal direction; the second filtering coupled line includes a third filtering transmission line and a fourth filtering transmission line connected in sequence from top to bottom; one end of the third filtering transmission line is connected to the fourth coupled transmission line of the four-wire coupled line, and the other end is open; one end of the fourth filtering transmission line is connected to the second open-circuit branch, and the other end is connected to the second differential output port; a second balanced transmission line is arranged between the second differential output ports; the metal circuit layer is a symmetrical structure with the horizontal line where the single-ended input port, the four-wire coupled line and the short-circuit branch as the axis, and the first branch and the second branch are longitudinally symmetrical.

[0010] In some embodiments of the present invention, ignoring the loose coupling between the second coupled transmission line and the third coupled sensing line in the four-wire coupled line, the structure of the four-wire coupled line is equivalent to a parallel structure consisting of a first common coupled line and a second common coupled line; the first common coupled line is composed of the first coupled transmission line and the second coupled transmission line; the second common coupled line is composed of the third coupled transmission line and the fourth coupled transmission line.

[0011] In some embodiments of the present invention, the odd-mode circuit corresponding to the metal circuit layer is provided with the first ordinary coupling line and the first branch in sequence along the horizontal direction; one end of the first coupling transmission line in the first ordinary coupling line is grounded through the first isolation resistor, and the other end is connected in parallel with the second isolation resistor and the second filtering transmission line, and the second isolation resistor is grounded; both ends of the second coupling transmission line in the first ordinary coupling line are grounded; the odd-mode circuit is obtained by adding an odd-mode excitation signal to the metal circuit layer.

[0012] In some embodiments of the present invention, in the odd-mode circuit, the resistance value of the first isolation resistor becomes half of that in the metal circuit layer; and the resistance value of the second isolation resistor becomes half of that in the metal circuit layer.

[0013] In some embodiments of the present invention, the even-mode circuit corresponding to the metal circuit layer is provided with the first common coupling line and the first branch in sequence along the horizontal direction; one end of the first coupling transmission line in the first common coupling line is open, and the other end is connected to the second filtering transmission line; one end of the second coupling transmission line in the first common coupling line is connected to the single-ended input port, and the other end is grounded through the short-circuit branch; the even-mode circuit is obtained by adding an even-mode excitation signal to the metal circuit layer.

[0014] In some embodiments of the present invention, in the even-mode circuit, the impedance of the single-ended input port and the short-circuit branch are both twice that in the metal circuit layer.

[0015] In some embodiments of the present invention, the first open-circuit branch and the second open-circuit branch are both composed of a first characteristic transmission line and a second characteristic transmission line; one end of the second characteristic transmission line is connected to the first characteristic transmission line, and the other end is open-circuited.

[0016] In some embodiments of the present invention, the electrical lengths of the four-wire coupled line, the short-circuit branch, the first filter coupled line and the second filter coupled line are all 90°; the electrical lengths of the first balanced transmission line and the second balanced transmission line are all 180°.

[0017] In some embodiments of the present invention, the impedances of the single-ended input port, the first differential output port, and the second differential output port are the same.

[0018] In some embodiments of the present invention, the dielectric constant of the dielectric layer is 3.66, and the loss constant is 0.0037.

[0019] The beneficial effects of the present invention are at least:

[0020] The present invention provides a high-selectivity filtering single-end to differential power divider with ultra-wideband differential common mode isolation. The power divider is provided with a metal grounding layer, a dielectric board layer and a metal circuit layer in sequence from bottom to top. The metal circuit layer is a single-sided design circuit, and utilizes a four-wire coupling line, two isolation resistors, a short-circuit branch, two sections of open-circuit branches, two sections of filtering coupling lines and a balanced transmission line between two sections of differential output ports to achieve equal power distribution from a single end to two differential output ports. The circuit structure is simple and easy to implement. At the same time, the power divider has a high-selectivity filtering function, deep isolation performance of differential mode / common mode within an ultra-wideband, suppression performance, and high suppression performance of signal conversion between differential mode / common mode within an ultra-wideband.

[0021] Furthermore, the metal circuit layer is a longitudinally symmetrical structure with the single-ended input port as the symmetry point. In order to simplify the circuit theoretical analysis, the four-wire coupled line is equivalent to two sections of ordinary coupled line parallel structure, and odd-even mode analysis is performed to design the power divider parameters; the simulation results of the four-wire coupled line structure are compared with the equivalent two sections of ordinary coupled line parallel structure, and the two simulation results are highly consistent, which confirms the feasibility of the simplified analysis method.

[0022] Furthermore, by adjusting the impedance values ​​of the first characteristic transmission line and the second characteristic transmission line in the first open branch and the second open branch, the filter bandwidth range can be adjusted. When designing the power divider provided by the present invention, the impedance values ​​of the first characteristic transmission line and the second characteristic transmission line can be set according to specific needs and / or specific application scenarios, and the filter bandwidth can be adjusted flexibly.

[0023] Additional advantages, purposes, and features of the present invention will be described in part in the following description, and will become apparent to those skilled in the art after studying the following, or may be learned from the practice of the present invention. The purposes and other advantages of the present invention may be achieved and obtained by the structures specifically indicated in the specification and the accompanying drawings.

[0024] Those skilled in the art will appreciate that the objectives and advantages that can be achieved with the present invention are not limited to the above specific description, and the above and other objectives that can be achieved by the present invention will be more clearly understood from the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described herein are used to provide a further understanding of the present invention, constitute a part of the present application, and do not constitute a limitation of the present invention. In the drawings:

[0026] Figure 1 (a) is a schematic diagram of a high selectivity filtering single-ended to differential power divider port network for ultra-wideband differential common mode isolation in one embodiment of the present invention.

[0027] Figure 1 (b) is a schematic diagram of an equivalent circuit system of a high selectivity filtering single-ended to differential power divider with ultra-wideband differential common mode isolation in one embodiment of the present invention.

[0028] Figure 2 The circuit schematic diagram of a high selectivity filtering single-ended to differential power divider with ultra-wideband differential common mode isolation in one embodiment of the present invention.

[0029] Figure 3 The diagram is a schematic diagram of an odd-mode circuit of a high-selectivity filtering single-ended to differential power divider with ultra-wideband differential common-mode isolation under odd-mode excitation in one embodiment of the present invention.

[0030] Figure 4 It is an even-mode circuit principle diagram of a circuit of a high-selectivity filtering single-ended to differential power divider with ultra-wideband differential common-mode isolation under even-mode excitation in one embodiment of the present invention.

[0031] Figure 5 (a) and (b) are ideal simulation result diagrams of an ultra-wideband differential common mode isolated high selectivity filtering single-ended to differential power divider equivalent to a parallel structure of two sections of ordinary coupled lines in one embodiment of the present invention.

[0032] Figure 6 (a), (b) and (c) are comparison diagrams of ideal simulation results of a four-wire coupled line structure of a high selectivity filtered single-ended to differential power divider with ultra-wideband differential common mode isolation in one embodiment of the present invention and an equivalent structure of two sections of ordinary coupled lines in parallel.

[0033] Figure 7 It is a simulation result diagram of three filter bandwidth designs of a high selectivity filtering single-ended to differential power divider with ultra-wideband differential common mode isolation in one embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0035] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the solutions according to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0036] It should be emphasized that the term “include / comprises” when used herein refers to the presence of features, elements, steps or components, but does not exclude the presence or addition of one or more other features, elements, steps or components.

[0037] It should also be noted that, unless otherwise specified, the term “connection” herein may refer not only to a direct connection but also to an indirect connection involving an intermediate.

[0038] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals represent the same or similar components, or the same or similar steps.

[0039] In order to solve the problems in the prior art of poor filtering performance, ultra-wideband differential mode / common mode isolation performance and suppression performance of a power divider with a single-port to differential port structure, the present invention provides a high-selectivity filtering single-ended to differential power divider with ultra-wideband differential and common mode isolation. Figure 1 (a) shows a port network diagram of a high-selectivity filtered single-ended to differential power divider based on ultra-wideband differential common-mode isolation of the present invention, including an input port, two output ports and a filtered single-ended to differential power divider using a four-wire coupling line provided by the present invention. Among them, the input port is P1 single-ended input port 1, and the output ports are respectively the first differential output port, i.e., differential (balanced) output port A and the second differential output port, i.e., differential (balanced) output port B, wherein the differential (balanced) output port A is composed of P2 (+) port and P3 (-) port, and the differential (balanced) output port B is composed of P4 (+) port and P5 (-) port.

[0040] Ultra-wideband differential and common mode isolated high selectivity filtered single-ended to differential type power dividers include:

[0041] Metal ground plane.

[0042] The dielectric layer is arranged above the metal ground layer.

[0043] The metal circuit layer is arranged above the dielectric layer. Figure 2As shown, the metal circuit layer is provided with a single-ended input port, a four-wire coupling line, a short-circuit branch, and a first branch and a second branch that are symmetrical in the longitudinal direction in sequence in the horizontal direction. The four-wire coupling line includes a first coupling transmission line, a second coupling transmission line, a third coupling transmission line and a fourth coupling transmission line that are connected in sequence from top to bottom. One end of the second coupling transmission line and the third coupling transmission line on the same side is respectively connected to the single-ended input port, and the other end is respectively connected to the short-circuit branch; a first isolation resistor is provided between one end of the first coupling transmission line and the fourth coupling transmission line on the same side, and a second isolation resistor is provided between the other ends. The first branch is provided with a first open-circuit branch, a first filter coupling line and a first differential output port in sequence in the horizontal direction. The first filter coupling line includes a first filter transmission line and a second filter transmission line that are connected in sequence from top to bottom. One end of the first filter transmission line is connected to the first open-circuit branch, and the other end is connected to the first differential output port. One end of the second filter transmission line is connected to the first coupling transmission line of the four-wire coupling line, and the other end is open. A first balanced transmission line is provided between the first differential output ports. The second branch is provided with a second open-circuit branch, a second filter coupling line and a second differential output port in sequence along the horizontal direction. The second filter coupling line includes a third filter transmission line and a fourth filter transmission line connected in sequence from top to bottom; one end of the third filter transmission line is connected to the fourth coupling transmission line of the four-wire coupling line, and the other end is open; one end of the fourth filter transmission line is connected to the second open-circuit branch, and the other end is connected to the second differential output port. A second balanced transmission line is provided between the second differential output ports.

[0044] The metal circuit layer is a symmetrical structure with the single-ended input port, the four-wire coupling line and the horizontal line where the short-circuit branch is located as the axis, and the first branch and the second branch are longitudinally symmetrical.

[0045] In some embodiments, the dielectric plate layer uses RogersRO4350B dielectric plate, which has a thickness of 0.762 mm and a dielectric constant of ε r =3.66, and the loss constant is tanδ=0.0037.

[0046] In some embodiments, the thickness of the metal ground layer and the metal circuit layer is 0.035 mm.

[0047] In the metal circuit layer, such as Figure 2 As shown in FIG. 1 , a circuit schematic diagram of a high selectivity filtering single-ended to differential power divider with ultra-wideband differential common mode isolation is shown. The first open-circuit branch and the second open-circuit branch are both composed of a first characteristic transmission line and a second characteristic transmission line. Figure 1 As shown in (b), the circuit of the power divider of the present invention can achieve the performance of a complex network formed by a Wilson power divider, two bandpass filters and two baluns connected in series.

[0048] In some embodiments, the electrical lengths of the four-wire coupled line, the short-circuit branch, the first characteristic transmission line, the second characteristic transmission line, the first filter coupled line, and the second filter coupled line are all set to θ=90°, and the electrical lengths of the first balanced transmission line and the second balanced transmission line are all set to 2θ=180°. The impedances of the single-ended input port P1, the first differential output ports P2 and P3, and the second differential output ports P4 and P5 are all set to Z0, the impedance of the short-circuit branch is set to Z3, the impedance of the first characteristic transmission line is set to Z4, the impedance of the second characteristic transmission line is set to Z5, and the impedances of the first balanced transmission line and the second balanced transmission line are all set to Z6. The resistance value of the first isolation resistor is set to R1, and the resistance value of the second isolation resistor is set to R2.

[0049] Among them, the first isolation resistor and the second isolation resistor are both arranged between the first coupled transmission line and the fourth coupled transmission line of the four-wire coupled line. At the same time, the first coupled transmission line and the fourth coupled transmission line are respectively connected to the first branch and the second branch, that is, two differential output ports. Therefore, the first isolation resistor and the second isolation resistor are arranged to ensure that the two output signals do not interfere with each other.

[0050] like Figure 2 As shown, the circuit of the present invention is a symmetrical structure with the single-ended input port, the four-wire coupling line and the horizontal line where the short-circuited branch is located as the axis, and the first branch and the second branch are longitudinally symmetrical. Therefore, the odd-even mode impedance analysis method can be used for theoretical analysis to calculate and obtain the relationship between the impedance parameters in the circuit to realize the power divider design.

[0051] In some embodiments, considering that the four-wire coupled line structure adopted by the power divider of the present invention is difficult to be theoretically analyzed according to the odd-even mode analysis method, the loose coupling between the second coupled transmission line and the third coupled sensing line in the four-wire coupled line structure is ignored. Therefore, the four-wire coupled line structure can be equivalent to a parallel structure of two sections of ordinary coupled lines, wherein the two sections of ordinary coupled lines are the first ordinary coupled line and the second ordinary coupled line mentioned above.

[0052] In some embodiments, the gaps between the transmission lines in the four-wire coupled line are equal, denoted as s.

[0053] The equivalent circuit is analyzed theoretically using odd-even mode impedance analysis.

[0054] First, add an odd-mode excitation signal to the metal circuit layer and analyze the corresponding odd-mode circuit. Figure 3As shown, the odd-mode circuit is obtained by cutting the circuit in the horizontal direction of the original metal circuit layer with the single-ended input port P1 as the symmetrical point, and all are grounded at the cutting point. Specifically, the odd-mode circuit is provided with a first common coupling line and a first branch in sequence along the horizontal direction. Among them, one end of the first coupling transmission line in the first common coupling line is grounded through the first isolation resistor, and the other end is connected in parallel with the second isolation resistor and the second filter transmission line, and the second isolation resistor is grounded; both ends of the second coupling transmission line in the first common coupling line are grounded.

[0055] At this time, the single-ended input port P1 is grounded, and the resistance values ​​of the first isolation resistor and the second isolation resistor are both reduced to half of the resistance value in the original metal circuit layer, that is, the resistance value of the first isolation resistor becomes The resistance of the second isolation resistor becomes

[0056] In some embodiments, the even-mode impedances of the first common coupled line and the second common coupled line are both set to Z e1 , the odd-mode impedance of the first ordinary coupled line and the second ordinary coupled line are both set to Z o1 ; The even-mode impedance of the first filter coupling line and the second filter coupling line are both set to Z e2 The odd-mode impedance of the first filter coupling line and the second filter coupling line are both set to Z o2 .

[0057] After the preset theoretical derivation and impedance calculation, when the single-ended input port P1 and the first differential output ports P2 and P3 all meet the port impedance matching conditions, the impedance parameter relationship satisfied by the odd-mode circuit is obtained, as shown in formula (1):

[0058]

[0059] In formula (1), R1 represents the resistance value of the first isolation resistor; R2 represents the resistance value of the second isolation resistor; Z e1 represents the even-mode impedance of the first common coupled line; Z o1 represents the odd-mode impedance of the first common coupled line; Z e2 represents the even-mode impedance of the first filter coupling line; Z o2 represents the odd-mode impedance of the first filter coupling line; Z0 represents the impedance of the single-ended input port P1.

[0060] Then, add an even-mode excitation signal to the metal circuit layer and analyze the corresponding even-mode circuit. Figure 4As shown, the even-mode circuit is obtained by dividing and cutting the circuit with port P1 as the symmetrical point in the horizontal direction of the original metal circuit layer. At all cutting points, the circuit impedance becomes twice that of the original metal circuit layer and is placed in an open circuit. Specifically, the even-mode circuit is provided with a first common coupling line and a first branch in sequence along the horizontal direction. Among them, one end of the first coupling transmission line in the first common coupling line is open-circuited, and the other end is connected to the second filtering transmission line; one end of the second coupling transmission line in the first common coupling line is connected to the single-ended input port, and the other end is grounded through a short-circuit branch.

[0061] At this time, the impedance of the single-ended input port P1 becomes twice that of the original metal circuit layer, that is, 2Z0; the impedance of the short-circuited branch also becomes twice that of the original metal circuit layer, that is, 2Z3.

[0062] After the preset theoretical derivation and impedance calculation, when the single-ended input port P1 and the first differential output ports P2 and P3 all meet the port impedance matching conditions, the impedance parameter relationship satisfied by the odd-mode circuit is obtained, as shown in formula (2):

[0063]

[0064] In formula (2), Z e1 represents the even-mode impedance of the first common coupled line; Z o1 represents the odd-mode impedance of the first common coupled line; Z e2 represents the even-mode impedance of the first filter coupling line; Z o2 represents the odd-mode impedance of the first filtering coupled line.

[0065] In some embodiments, the even-mode characteristic impedance and the isolation resistance value in the metal circuit layer are set according to the impedance parameter relationship obtained by formula (1) and formula (2). Specifically, the even-mode impedance Z of the first common coupling line and the second common coupling line is e1 =117Ω, the odd-mode impedance Z of the first common coupled line and the second common coupled line o1 =46Ω; the even-mode impedance Z of the first filter coupling line and the second filter coupling line e2 =92Ω, the odd-mode impedance Z of the first filter coupling line and the second filter coupling line o2 =56.5Ω; the resistance value of the first isolation resistor R1 =240Ω, and the resistance value of the second isolation resistor R2 =39Ω. The center frequency point of the metal circuit layer is set to f0 =3.5GHz.

[0066] According to the impedance parameter relationship obtained from formula (1) and formula (2), there is no restriction on the impedance values ​​of the short-circuited branch, the first open-circuited branch, the second open-circuited branch, the first balanced transmission line and the second balanced transmission line.

[0067] In some embodiments, the impedance Z3 of the short-circuited branch is 54Ω; the impedance Z4 of the first characteristic transmission line in the first open-circuited branch and the second open-circuited branch is 58Ω, and the impedance Z5 of the second characteristic transmission line is 44Ω; the impedance Z6 of the first balanced transmission line and the second balanced transmission line is 20Ω.

[0068] Based on the impedance values ​​set above, the circuit that converts the four-wire coupled line into two ordinary coupled lines in parallel is simulated. The ideal simulation result is shown in the figure below. Figure 5 As shown, the horizontal axis represents frequency in GHz, and the vertical axis represents S parameters in decibels (dB). For example, the horizontal axis ranges from 0 to 8 GHz, that is, the range of full-band ultra-wideband is 0 to 8 GHz, and corresponds to 0 to 200%; the vertical axis ranges from -70 to 0 dB.

[0069] exist Figure 5 The S parameters include: Input return loss of the single-ended input port |S ss11 |, Single-ended input port to first differential output port signal distribution |S dsA1 |, Single-ended input port to second differential output port signal distribution |S dsB1 |, the first differential output port output signal isolation |S ddAA |, differential mode suppression between the first differential output port and the second differential output port |S ddBA |, common-mode noise transmission suppression between the single-ended input port and the first differential output port |S csA1 |, common-mode noise transmission suppression between the single-ended input port and the second differential output port |S csB1 |、Conversion suppression of differential mode and common mode signal mode inside the first differential output port|S cdAA |, conversion suppression of differential mode and common mode signal modes between the first differential output port and the second differential output port |S cdBA |, Common-mode noise suppression inside the first differential output port |S ccAA |, common mode noise suppression between the first differential output port and the second differential output port |S ccBA |.

[0070] like Figure 5 As shown in (a), at the center frequency f0 = 3.5 GHz, the signal distribution from the single-ended input port to the first differential output port |S dsA1 |, Single-ended input port to second differential output port signal distribution |S dsB1 | are all 3.01dB, achieving equal power distribution of the signal at the output port. Among them, |S dsB1 | and |S dsB1 |The curves coincide.

[0071] like Figure 5As shown in (a), the signal distribution from the single-ended input port to the first differential output port |S dsA1 |, Single-ended input port to second differential output port signal distribution |S dsB1 | At 6dB, the bandwidth is about 20%, achieving a highly selective filtering function.

[0072] like Figure 5 As shown in (a) and (b), at 21.58dB, the conversion suppression of the internal differential mode and common mode signal mode of the first differential output port |S cdAA The bandwidth of | is about 102.3%; the conversion suppression of the differential mode and common mode signal mode between the first differential output port and the second differential output port |S cdBA |Exceeds 40dB in the full-band ultra-bandwidth range (200%); Differential mode suppression between the first differential output port and the second differential output port |S ddBA |In the full-band ultra-wideband range (200%), it exceeds 18.91dB and has broadband deep suppression performance for differential mode / common mode conversion.

[0073] like Figure 5 As shown in (b), the conversion suppression of the differential mode and common mode signal modes between the first differential output port and the second differential output port |S cdBA |, common-mode noise transmission suppression between the single-ended input port and the first differential output port |S csA1 |, common-mode noise transmission suppression between the single-ended input port and the second differential output port |S csB1 |In the full-band ultra-wideband range (200%), it exceeds 29.56dB, with ultra-wideband common-mode transmission deep suppression. Among them, |S csA1 | and |S csB1 |The curves coincide.

[0074] like Figure 5 As shown in (b), the common-mode noise inside the first differential output port is suppressed by |S ccAA |It is fully reflected within the full-band ultra-wideband range (200%), completely eliminating the transmission impact of noise.

[0075] In the ideal simulation results, the signal distribution from the single-ended input port to the first differential output port |S dsA1 | and single-ended input port to second differential output port signal distribution |S dsB1 The transmission zero value of | will have a direct impact on the filtering performance and bandwidth. dsA1 | and |S dsB1 | Except for the transmission zero frequencies at 0GHz and 2f0, they are denoted as f z2 and f z3 , the calculation formula is shown in formula (3):

[0076]

[0077] In formula (3), f z2 and f z3 Indicates |S dsA1 | and |S dsB1 |excluding the transmission zero frequency at 0 GHz and 2f0; f0 represents the center frequency; Z4 represents the impedance of the first characteristic transmission line; Z5 represents the impedance of the second characteristic transmission line.

[0078] In the above analysis, the loose coupling between the second coupled transmission line and the third coupled sensing line in the four-wire coupled line is ignored, and the four-wire coupled line is equivalent to a parallel structure of two ordinary coupled lines, and the equivalent circuit is subjected to odd-even mode analysis, and the performance analysis is performed on the ideal simulation diagram. In order to return the power divider provided by the present invention to the four-wire coupled line structure, the influence of loose coupling is reconsidered, such as Figure 6 As shown in the figure, the four-wire coupled line structure and the equivalent ordinary coupled line parallel structure are simulated at the same time. Figure 6 It can be intuitively found that the S parameter performances of the two structures are highly consistent, which confirms the feasibility of the simplified analysis method of equivalently connecting the four-wire coupled line to two ordinary coupled lines in parallel in the power divider circuit provided by the present invention.

[0079] In some embodiments, the filtering bandwidth may be adjusted by adjusting the impedance Z4 of the first characteristic transmission line and the impedance Z5 of the second characteristic transmission line.

[0080] Specifically, Figure 7 As shown in the figure, when the impedance Z4 of the first characteristic transmission line increases and the impedance Z5 of the second characteristic transmission line decreases, the transmission zero point f z2 and f z3 The transmission zero point f is shifted in and out of the frequency band, that is, the filtering bandwidth of the power divider of the present invention becomes wider; when the impedance Z4 of the first characteristic transmission line decreases and the impedance Z5 of the second characteristic transmission line increases, the transmission zero point f z2 and f z3 The frequency band moves inward, that is, the filtering bandwidth of the power divider of the present invention becomes narrower.

[0081] In some embodiments, the impedance Z4 of the first characteristic transmission line and the impedance Z5 of the second characteristic transmission line are designed.

[0082] In Design I, the impedance of the first characteristic transmission line is Z4 = 58Ω, and the impedance of the second characteristic transmission line is Z5 = 44Ω. At this time, the filtering bandwidth of the power divider is at a medium level. According to formula (3), f z2 =1.6GHz and f z3 =5.4GHz. Input return loss of single-ended input port |S ss11|Bandwidth at 15dB is 11.2%; signal distribution from single-ended input port to first differential output port |S dsA1 | and single-ended input port to second differential output port signal distribution |S dsB1 |Bandwidth at 6dB is 21.7%; Output signal isolation at the first differential output port |S ddAA |Bandwidth at 15dB is 12.6%; Conversion suppression of differential mode and common mode signal modes within the first differential output port |S cdAA |The bandwidth at 15dB is 120.6%.

[0083] In design II, the impedance of the first characteristic transmission line is Z4 = 52Ω, and the impedance of the second characteristic transmission line is Z5 = 90Ω. At this time, the filtering bandwidth of the power divider becomes narrower. According to formula (3), f z2 =2.05GHz and f z3 =4.95GHz. Input return loss of single-ended input port |S ss11 |Bandwidth is 6% at 15dB; signal distribution from single-ended input port to first differential output port |S dsA1 | and single-ended input port to second differential output port signal distribution |S dsB1 |Bandwidth at 6dB is 15.7%; Output signal isolation at the first differential output port |S ddAA | Bandwidth is 6% at 15dB; Conversion suppression of differential mode and common mode signal modes within the first differential output port |S cdAA |The bandwidth at 15dB is 108.7%.

[0084] In design III, the impedance of the first characteristic transmission line is Z4 = 97.5Ω, and the impedance of the second characteristic transmission line is Z5 = 42.5Ω. At this time, the filtering bandwidth of the power divider becomes wider. According to formula (3), f z2 =1.3GHz and f z3 =5.7GHz. Input return loss of single-ended input port |S ss11 |Bandwidth at 15dB is 18.1%; signal distribution from single-ended input port to first differential output port |S dsA1 | and single-ended input port to second differential output port signal distribution |S dsB1 |Bandwidth at 6dB is 32.5%; Output signal isolation at the first differential output port |S ddAA |Bandwidth at 15dB is 22.9%; Conversion suppression of differential mode and common mode signal modes within the first differential output port |S cdAA |The bandwidth at 15dB is 129.7%.

[0085] Therefore, when designing the power divider provided by the present invention, the impedance values ​​of the first characteristic transmission line and the second characteristic transmission line can be set according to specific needs and / or specific application scenarios to obtain a filtering bandwidth range that meets specific needs and / or functions, and has a flexible filtering bandwidth adjustable design function.

[0086] Based on the above analysis and design, the ultra-wideband differential common mode isolated high selectivity filtering single-ended to differential power divider provided by the present invention is obtained. The power divider can be widely used in antenna feeder arrays, highly selective microwave / RF systems and multi-channel communication networks to reduce differential mode noise and electromagnetic radiation interference, so that the system has higher signal transmission efficiency.

[0087] In summary, the present invention provides a high-selectivity filtering single-ended to differential power divider with ultra-wideband differential common-mode isolation, and the power divider is provided with a metal grounding layer, a dielectric board layer and a metal circuit layer in sequence from bottom to top. The metal circuit layer is a single-sided design circuit, which utilizes a four-wire coupling line, two isolation resistors, a short-circuit branch, two sections of open-circuit branches, two sections of filtering coupling lines and a balanced transmission line between two sections of differential output ports to achieve equal power distribution from a single end to two differential output ports, and the circuit structure is simple and easy to implement. At the same time, the power divider has a high-selectivity filtering function, deep isolation performance of differential mode / common mode within an ultra-wideband, suppression performance, and high suppression performance of signal conversion between differential mode / common mode within an ultra-wideband.

[0088] Furthermore, the metal circuit layer is a longitudinally symmetrical structure with the single-ended input port as the symmetry point. In order to simplify the circuit theoretical analysis, the four-wire coupled line is equivalent to two sections of ordinary coupled line parallel structure, and odd-even mode analysis is performed to design the power divider parameters; the simulation results of the four-wire coupled line structure are compared with the equivalent two sections of ordinary coupled line parallel structure, and the two simulation results are highly consistent, which confirms the feasibility of the simplified analysis method.

[0089] Furthermore, by adjusting the impedance values ​​of the first characteristic transmission line and the second characteristic transmission line in the first open branch and the second open branch, the filter bandwidth range can be adjusted. When designing the power divider provided by the present invention, the impedance values ​​of the first characteristic transmission line and the second characteristic transmission line can be set according to specific needs and / or specific application scenarios, and the filter bandwidth can be adjusted flexibly.

[0090] It should be understood by those skilled in the art that the exemplary components, systems and methods described in conjunction with the embodiments disclosed herein can be implemented in hardware, software or a combination of the two. Whether it is performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention. When implemented in hardware, it can be, for example, an electronic circuit, an application specific integrated circuit (ASIC), appropriate firmware, a plug-in, a function card, etc. When implemented in software, the elements of the present invention are programs or code segments used to perform the required tasks. The program or code segment can be stored in a machine-readable medium, or transmitted on a transmission medium or a communication link via a data signal carried in a carrier.

[0091] It should be clear that the present invention is not limited to the specific configuration and processing described above and shown in the figures. For the sake of simplicity, a detailed description of the known method is omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications and additions, or change the order between the steps after understanding the spirit of the present invention.

[0092] In the present invention, features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, and / or combined with features of other embodiments or replace features of other embodiments.

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the embodiments of the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high selectivity filtering single-ended to differential power divider with ultra-wideband differential common mode isolation, characterized in that: include: Metal ground plane; A dielectric layer, arranged above the metal grounding layer; A metal circuit layer is arranged above the dielectric plate layer; The metal circuit layer is provided with a single-ended input port, a four-wire coupling line, a short-circuit branch, and a first branch and a second branch symmetrical in the longitudinal direction in sequence; the four-wire coupling line includes a first coupling transmission line, a second coupling transmission line, a third coupling transmission line and a fourth coupling transmission line connected in sequence from top to bottom; one end of the second coupling transmission line and the third coupling transmission line on the same side is respectively connected to the single-ended input port, and the other end is respectively connected to the short-circuit branch; a first isolation resistor is provided between one end of the first coupling transmission line and the fourth coupling transmission line on the same side, and a second isolation resistor is provided between the other ends; the first branch is provided with a first open-circuit branch, a first filter coupling line and a first differential output port in sequence in the horizontal direction; the first filter coupling line includes a first filter transmission line and a second filter transmission line connected in sequence from top to bottom; one end of the first filter transmission line is connected to the first open-circuit branch, and the other end is connected to connected to the first differential output port; one end of the second filtering transmission line is connected to the first coupling transmission line of the four-wire coupling line, and the other end is open; a first balanced transmission line is arranged between the first differential output ports; the second branch is provided with a second open-circuit branch, a second filtering coupling line and a second differential output port in sequence along the horizontal direction; the second filtering coupling line includes a third filtering transmission line and a fourth filtering transmission line connected in sequence from top to bottom; one end of the third filtering transmission line is connected to the fourth coupling transmission line of the four-wire coupling line, and the other end is open; one end of the fourth filtering transmission line is connected to the second open-circuit branch, and the other end is connected to the second differential output port; a second balanced transmission line is arranged between the second differential output ports; the metal circuit layer is a symmetrical structure with the horizontal line where the single-ended input port, the four-wire coupling line and the short-circuit branch as the axis, and the first branch and the second branch are longitudinally symmetrical.

2. The ultra-wideband differential common mode isolation high selectivity filtering single-ended to differential power divider according to claim 1, characterized in that: When the loose coupling between the second coupled transmission line and the third coupled sensing line in the four-wire coupled line is ignored, the structure of the four-wire coupled line is equivalent to a parallel structure consisting of a first common coupled line and a second common coupled line; the first common coupled line is composed of the first coupled transmission line and the second coupled transmission line; and the second common coupled line is composed of the third coupled transmission line and the fourth coupled transmission line.

3. The ultra-wideband differential common mode isolation high selectivity filtering single-ended to differential power divider according to claim 2, characterized in that: The odd-mode circuit corresponding to the metal circuit layer is provided with the first common coupling line and the first branch in sequence along the horizontal direction; one end of the first coupling transmission line in the first common coupling line is grounded through the first isolation resistor, and the other end is connected in parallel with the second isolation resistor and the second filtering transmission line, and the second isolation resistor is grounded; both ends of the second coupling transmission line in the first common coupling line are grounded; the odd-mode circuit is obtained by adding an odd-mode excitation signal to the metal circuit layer.

4. The ultra-wideband differential common mode isolation high selectivity filtering single-ended to differential power divider according to claim 3, characterized in that: In the odd-mode circuit, the resistance value of the first isolation resistor becomes half of that in the metal circuit layer; and the resistance value of the second isolation resistor becomes half of that in the metal circuit layer.

5. The ultra-wideband differential common mode isolation high selectivity filtering single-ended to differential power divider according to claim 2, characterized in that: The even-mode circuit corresponding to the metal circuit layer is provided with the first common coupling line and the first branch in sequence along the horizontal direction; one end of the first coupling transmission line in the first common coupling line is open, and the other end is connected to the second filtering transmission line; one end of the second coupling transmission line in the first common coupling line is connected to the single-ended input port, and the other end is grounded through the short-circuit branch; the even-mode circuit is obtained by adding an even-mode excitation signal to the metal circuit layer.

6. The ultra-wideband differential common mode isolation high selectivity filtering single-ended to differential power divider according to claim 5, characterized in that: In the even-mode circuit, the impedance of the single-ended input port and the short-circuit branch both become twice that in the metal circuit layer.

7. The ultra-wideband differential common mode isolation high selectivity filtering single-ended to differential power divider according to claim 1, characterized in that: The first open-circuit branch and the second open-circuit branch are both composed of a first characteristic transmission line and a second characteristic transmission line; one end of the second characteristic transmission line is connected to the first characteristic transmission line, and the other end is open-circuited.

8. The ultra-wideband differential common mode isolation high selectivity filtering single-ended to differential power divider according to claim 1, characterized in that: The electrical lengths of the four-wire coupling line, the short-circuit branch, the first filter coupling line and the second filter coupling line are all 90°; the electrical lengths of the first balanced transmission line and the second balanced transmission line are both 180°.

9. The ultra-wideband differential common mode isolation high selectivity filtering single-ended to differential power divider according to claim 1, characterized in that: The impedances of the single-ended input port, the first differential output port, and the second differential output port are the same.

10. The ultra-wideband differential common mode isolation high selectivity filtering single-ended to differential power divider according to claim 1, characterized in that: The dielectric constant of the dielectric layer is 3.66, and the loss constant is 0.0037.

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