Multistage multi-limb differential broadband power divider based on polyimide support bridges

Abstract

This invention discloses a multi-stage, multi-segment differential broadband power divider based on a polyimide support bridge. The power divider includes a differential signal input unit, multiple differential signal output units, a multi-stage, multi-segment differential impedance transformation unit, and multiple polyimide support bridge structures. The differential signal input unit includes input differential pairs, and the differential signal output unit includes multiple output differential pairs symmetrically arranged about a center line. Multi-stage, multi-segment differential impedance transformation units are respectively arranged between the input differential pairs and each output differential pair. The differential impedance transformation sections are based on cascaded differential impedance transformation lines to achieve stepped differential impedance transformation. Thin-film resistors are placed at the connection points of adjacent differential impedance transformation sections to provide absorption and cancellation paths for signals reflected from the output ports. The polyimide support bridge structure achieves dielectric isolation between microstrip lines. This invention, through optimized design and integration processes, possesses advantages such as small size, strong anti-interference capability, and large operating bandwidth.

Description

Technical Field

[0001] This invention relates to the field of microwave circuit technology, and in particular to a multi-stage, multi-segment differential broadband power divider based on a polyimide support bridge. Background Technology

[0002] With the rapid development of wireless communication technology, the electromagnetic environment in space is becoming increasingly complex, and signal interference between devices is becoming more and more severe. Differential radio frequency circuits, employing a symmetrical balanced design, can effectively suppress common-mode noise and improve the system's anti-interference capability and communication stability. In this system, the differential power divider, as a key passive component, directly affects the performance of the entire differential system. Differential power dividers typically use a differential port design, with two output signals having equal amplitude and opposite phase. When external electromagnetic interference is coupled to both signal lines simultaneously, the interference presents as a common-mode signal, while the useful signal is a differential-mode signal. By differentially processing the two disturbed signals, common-mode noise can be effectively canceled, the original signal waveform can be restored, and thus the electromagnetic compatibility of the system can be significantly improved.

[0003] In recent years, several designs for differential power dividers have been proposed. For example, reference 1 (H. Zhu, P.-Y. Qin and YJ Guo, "Single-Ended-to-Balanced Power Divider With Extended Common-Mode Suppression and Its Application to Differential 2*4 Butler Matrices," in IEEE Transactions on Microwave Theory and Techniques, vol. 68, no. 4, pp. 1510-1519, April 2020.) proposes a single-ended to differential power divider with common-mode suppression. By achieving high-level, wide-bandwidth common-mode suppression, a low cross-polarization level is obtained in a linearly polarized antenna array. Reference 2 (W.-S. Liu et al., "Miniaturized Single-Ended-to-Balanced Filtering Power Divider With High Selectivity Based on Tri-Mode Resonator," in IEEE Transactions on Circuits and Systems II: Express Briefs, vol. 70, no.11, pp. 4048-4052, Nov. 2023.) proposes a single-ended to differential filtering power divider based on a tri-mode resonator, achieving 28.5 dB common-mode rejection and port isolation higher than 17.6 dB within the passband. These works demonstrate the potential of differential power dividers to improve system performance.

[0004] In terms of process implementation, dielectric bridging is an important technology in microelectronics and microwave integrated circuit manufacturing, especially suitable for interconnection scenarios requiring bridging wires. This process achieves circuit connections by constructing a bridge structure on an insulating dielectric layer, involving dielectric material coating, curing, and patterning. Commonly used dielectric materials include polymer films such as polyimide and benzocyclobutene. These materials possess characteristics such as high mechanical strength, good heat resistance, excellent insulation performance, low dielectric constant, and low loss, effectively supporting the bridge structure and avoiding the problem of traditional air bridges being prone to breakage due to excessive suspension, while providing better design freedom and electrical stability. For example, a polyimide-supported bridge consists of a bridge deck and piers, fabricated through photolithography, metal evaporation, stripping, and etching processes. Polyimide, as the supporting material, ensures the bridge deck is not easily broken due to its high strength, and the bridge height remains constant at the micrometer level. Its good heat resistance and excellent insulation performance ensure the electrical signal integrity of the circuits on the bridge; its low dielectric constant and low dielectric loss are suitable for high-frequency circuit applications.

[0005] Despite the progress made above, the current design and manufacturing process of differential power dividers still have the following significant shortcomings:

[0006] (1) Low process integration and limited structural reliability: Most reported differential power dividers use traditional PCB processes and rely on air bridges for dielectric isolation. Due to the low dielectric constant of conventional PCB substrates, the device size is relatively large; and air bridges are prone to breakage when the bridge body is long, posing a risk of electrical short circuit and affecting the long-term reliability of the circuit. At present, research on combining differential power dividers with semiconductor processes (especially dielectric bridge processes with high mechanical strength and good insulation properties) is relatively lacking, which limits the application of this device in high integration and high stability scenarios.

[0007] (2) Limited operating bandwidth and difficulty in impedance implementation: Existing designs mostly focus on narrowband power divider characteristics, with little discussion on broadband performance. The fundamental reason is that to achieve broadband impedance matching, a multi-section impedance transformation structure is often required, in which the transmission linewidth corresponding to high differential impedance is extremely thin, which is difficult to achieve in traditional PCB processes due to limitations in processing precision. Although semiconductor processes have been able to achieve even thinner linewidths, research combining multi-section broadband differential power dividers with advanced semiconductor processes is still relatively rare.

[0008] Therefore, there is an urgent need to develop a differential power divider structure that can integrate high-reliability dielectric bridge technology and achieve broadband and high-performance characteristics, so as to meet the urgent needs of modern wireless communication systems for miniaturization, high stability, wide bandwidth and strong anti-interference capabilities. Summary of the Invention

[0009] The purpose of this invention is to provide a multi-stage, multi-segment differential broadband power divider based on a polyimide support bridge that is small in size, has strong anti-interference ability, and a large operating bandwidth.

[0010] The technical solution for achieving the objective of this invention is: a multi-stage, multi-span differential broadband power divider based on polyimide support bridges. This power divider includes a differential signal input unit, multiple differential signal output units, a multi-stage, multi-span differential impedance transformation unit, and multiple polyimide support bridge structures, wherein:

[0011] The differential signal input unit includes an input differential pair, three metal grounding pads arranged alternately with the input differential pair, and a metal grounding post connected to the metal grounding pad; the input differential pair is arranged in a horizontal direction.

[0012] The differential signal output unit includes multiple output differential pairs symmetrically arranged about the horizontal center line, metal grounding pads arranged alternately with each output differential pair, and metal grounding posts connected to the metal grounding pads.

[0013] Between each input differential pair and each output differential pair, a multi-stage, multi-segment differential impedance transformation unit is set to form one output channel of the power divider. The number of output differential pairs is equal to the number of output channels of the power divider.

[0014] The multi-stage, multi-segment differential impedance transformation unit includes one or more differential impedance transformation sections and thin-film resistors integrated on the microstrip line; the differential impedance transformation section realizes stepped differential impedance transformation based on cascaded differential impedance transformation lines; the thin-film resistor is placed at the connection between two adjacent differential impedance transformation sections to provide a path for absorption and cancellation of signals reflected from the output port.

[0015] The polyimide support bridge structure includes a polyimide support bridge base with windows and a microstrip line bridge body disposed on the bridge base. The polyimide support bridge base is used to dielectrically isolate the microstrip lines above and below the support bridge.

[0016] Furthermore, the differential broadband power divider also includes a ceramic dielectric substrate and a ground metal layer covering the bottom of the ceramic dielectric substrate, wherein the dielectric constant of the ceramic dielectric substrate is greater than 9.

[0017] The differential signal input unit, differential signal output unit, multi-stage multi-segment differential impedance transformation unit, and polyimide support bridge structure are all disposed on the top of the ceramic dielectric substrate, and the metal grounding post passes through the metal grounding pad and the grounding metal layer.

[0018] Furthermore, the multiple output channels of the power divider are symmetrically arranged about the horizontal center line, and each output channel is a differential signal path; the differential impedance transformation sections corresponding to each output channel are also symmetrically arranged about the horizontal center line, and each differential impedance transformation line in each differential impedance transformation section has a Z-shaped structure, and the two microstrip lines constituting the differential signal path in each output channel are of the same length.

[0019] Furthermore, the thin-film resistor is placed at the junction of the differential impedance transformation sections and is connected between two differential impedance transformation sections that are symmetrical about the horizontal center line via microstrip lines. The two ends of the thin-film resistor are respectively connected to two differential impedance transformation lines branched off from the input microstrip line, which is used to increase the isolation between the output ports and optimize the impedance matching of the output ports.

[0020] Furthermore, the input differential pair, output differential pair, and differential impedance transformation lines at each stage are all differential microstrip transmission lines.

[0021] Furthermore, the input differential pair and the output differential pair each include two differential microstrip transmission lines. The spacing between the two differential microstrip transmission lines on the port side is wider than the spacing on the differential impedance transformation section side, and the middle section is set to a gradually changing spacing.

[0022] Furthermore, for the input differential pair and the output differential pair, the metal grounding pads located on both sides of the two differential microstrip transmission lines are rectangular, and the metal grounding pad located in the middle of the two differential microstrip transmission lines has a rectangular side on one side of the port, and the other side opposite the port shrinks towards the middle into a rounded triangle; a gap is left between the metal grounding pad and the adjacent microstrip transmission line.

[0023] Furthermore, in each stage of the differential impedance transformation, the linewidth and spacing of the two microstrip lines are related to the material and thickness of the ceramic dielectric substrate and the thickness of the microstrip lines themselves, specifically:

[0024] use The characteristic impedance of a single microstrip line is expressed by the following formula:

[0025]

[0026] in, This represents the characteristic impedance of a microstrip line in air. The effective dielectric constant of a ceramic dielectric substrate; the characteristic impedance of a microstrip line in air. and the effective dielectric constant of ceramic dielectric substrate The calculation formula is as follows:

[0027]

[0028]

[0029] in, Indicates the thickness of the ceramic dielectric substrate. Indicates the linewidth of the microstrip line. Indicates the thickness of the microstrip line. Indicates the relative permittivity of the ceramic dielectric substrate;

[0030] Characteristic impedance of a single microstrip line Calculate the differential impedance of the differential microstrip line The formula is:

[0031]

[0032] in, Indicates the spacing of the differential microstrip lines. Indicates the thickness of the ceramic dielectric substrate;

[0033] By designing the differential impedance value Determine the relative permittivity of the ceramic dielectric substrate. thickness of microstrip lines Thickness of ceramic dielectric substrate Then, the constraint relationship between the linewidth and spacing of the two microstrip lines is obtained.

[0034] Furthermore, in the polyimide support bridge structure, the bridge base covers the connection between the thin film resistor and each differential impedance transformation section, and the microstrip bridge body and the differential impedance transformation line are connected by opening a window on the bridge base.

[0035] Furthermore, the input differential pairs, output differential pairs, differential impedance transformation lines at each stage, and thin-film resistors are all made of metal.

[0036] Compared with the prior art, the present invention has the following significant advantages: (1) It adopts a ceramic dielectric substrate with high dielectric constant, which can effectively realize the miniaturization of the overall size; (2) By combining with the polyimide support bridge process, the dielectric isolation and stability of the differential power divider are improved; (3) It adopts an expandable tree structure design, which can realize multiple outputs such as one to two, one to four, and one to eight; (4) It takes into account both differential design and multi-section impedance transformation design, and has the advantages of strong anti-interference ability and wide operating bandwidth. Attached Figure Description

[0037] Figure 1 This is a full view of a three-section, two-equal-division differential power divider with in-phase output based on a polyimide-supported bridge, according to an embodiment of the present invention.

[0038] Figure 2 This is a top view of a three-section, two-equal-division differential power divider with in-phase output based on a polyimide support bridge, according to an embodiment of the present invention.

[0039] Figure 3 This is a top view of a three-section, two-equal-division differential power divider with inverted output based on a polyimide-supported bridge, according to an embodiment of the present invention.

[0040] Figure 4 This is a schematic diagram of the polyimide support bridge structure in a three-section, two-equal-division differential power divider based on a polyimide support bridge, according to an embodiment of the present invention.

[0041] Figure 5 This is a comparison diagram of the dielectric isolation performance of the polyimide-supported bridge and the traditional air bridge in the three-section two-equal-division differential power divider based on the polyimide-supported bridge in an embodiment of the present invention.

[0042] Figure 6 The differential mode S-parameter diagram is shown for a three-section, two-equal-division differential power divider with in-phase output based on a polyimide support bridge, according to an embodiment of the present invention.

[0043] Figure 7 The differential mode S-parameter diagram is shown for a three-section, two-equal-division differential power divider with inverted output based on a polyimide-supported bridge, according to an embodiment of the present invention.

[0044] Figure 8 This is a diagram showing the differential-mode and common-mode conversion S-parameters of a three-section, two-equal-division differential power divider with in-phase and reverse outputs based on a polyimide-supported bridge, according to an embodiment of the present invention.

[0045] Figure 9 The phase difference of the output port signal of a three-section two-equal-division differential power divider based on a polyimide-supported bridge with in-phase and reverse outputs is shown in an embodiment of the present invention. Detailed Implementation

[0046] It is readily understood that, based on the technical solution of this invention, those skilled in the art can conceive of various embodiments of this invention without altering its essential spirit. Therefore, the following specific embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of this invention or as limitations or restrictions on its technical solution.

[0047] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0048] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0049] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0050] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0051] This invention provides a multi-stage, multi-span differential broadband power divider based on polyimide support bridges. The power divider includes a differential signal input unit 1, multiple differential signal output units 2, a multi-stage, multi-span differential impedance transformation unit 3, and multiple polyimide support bridge structures 6, wherein:

[0052] The differential signal input unit 1 includes an input differential pair, three metal grounding pads 4 arranged alternately with the input differential pair, and a metal grounding post 7 connected to the metal grounding pads 4; the input differential pair is arranged in a horizontal direction.

[0053] The differential signal output unit 2 includes multiple output differential pairs symmetrically arranged about the horizontal center line, metal grounding pads 4 arranged alternately with each output differential pair, and metal grounding posts 7 connected to the metal grounding pads 4.

[0054] Between each input differential pair and each output differential pair, a multi-stage, multi-segment differential impedance transformation unit 3 is set to form one output channel of the power divider. The number of output differential pairs is equal to the number of output channels of the power divider.

[0055] The multi-stage, multi-segment differential impedance transformation unit 3 includes one or more differential impedance transformation sections and a thin-film resistor 5 integrated on the microstrip line; the differential impedance transformation section realizes stepped differential impedance transformation based on cascaded differential impedance transformation lines; the thin-film resistor 5 is set at the connection of two adjacent differential impedance transformation sections to provide a path for absorption and cancellation of signals reflected from the output port.

[0056] The polyimide support bridge structure 6 includes a polyimide support bridge base with windows and a microstrip line bridge body disposed on the bridge base. The polyimide support bridge base is used to dielectrically isolate the microstrip lines above and below the support bridge.

[0057] As a specific example, the differential broadband power divider further includes a ceramic dielectric substrate 8 and a ground metal layer 9 covering the bottom of the ceramic dielectric substrate 8, wherein the dielectric constant of the ceramic dielectric substrate 8 is greater than 9.

[0058] The differential signal input unit 1, differential signal output unit 2, multi-stage multi-segment differential impedance transformation unit 3, and polyimide support bridge structure 6 are all disposed on the top of the ceramic dielectric substrate 8, and the metal grounding post 7 passes through the metal grounding pad 4 and the grounding metal layer 9.

[0059] As a specific example, the power divider has multiple output channels arranged symmetrically about the horizontal center line, and each output channel is a differential signal path; the differential impedance transformation sections corresponding to each output channel are also arranged symmetrically about the horizontal center line, and each differential impedance transformation line in each differential impedance transformation section has a Z-shaped structure, and the two microstrip lines constituting the differential signal path in each output channel are of the same length.

[0060] As a specific example, the thin-film resistor 5 is set at the junction of the differential impedance transformation sections and is connected between two differential impedance transformation sections that are symmetrical about the horizontal center line via microstrip lines. The two ends of the thin-film resistor 5 are respectively connected to two differential impedance transformation lines branched off from the input microstrip line, which is used to increase the isolation between the output ports and optimize the impedance matching of the output ports.

[0061] As a specific example, the input differential pair, output differential pair, and differential impedance transformation lines at each stage are all differential microstrip transmission lines.

[0062] As a specific example, the input differential pair and the output differential pair each include two differential microstrip transmission lines. The spacing between the two differential microstrip transmission lines on the port side is wider than the spacing on the differential impedance transformation section side, and the middle section is set to a gradually changing spacing.

[0063] As a specific example, for the input differential pair and the output differential pair, the metal grounding pads 4 located on both sides of the two differential microstrip transmission lines are rectangular, and the metal grounding pad 4 located in the middle of the two differential microstrip transmission lines has a rectangular side on one side of its port, and the other side opposite the port shrinks towards the middle into a rounded triangle; a gap is left between the metal grounding pad 4 and the adjacent microstrip transmission lines.

[0064] As a specific example, in each stage of differential impedance transformation, the linewidth and spacing of the two microstrip lines are related to the material and thickness of the ceramic dielectric substrate 8 and the thickness of the microstrip lines themselves, specifically:

[0065] use The characteristic impedance of a single microstrip line is expressed by the following formula:

[0066] (1)

[0067] in, This represents the characteristic impedance of a microstrip line in air after the dielectric is removed. The effective dielectric constant of the ceramic dielectric substrate 8 is determined by the relative magnitudes of the electric field's extent in air and the dielectric, as well as the shape and size of the boundary between the dielectric and the conductor. The characteristic impedance of the microstrip line in air... and the effective dielectric constant of the ceramic dielectric substrate 8 The calculation formula is as follows:

[0068] (2)

[0069] (3)

[0070] in, This indicates the thickness of the ceramic dielectric substrate 8. Indicates the linewidth of the microstrip line. Indicates the thickness of the microstrip line. This represents the relative permittivity of the ceramic dielectric substrate 8;

[0071] Characteristic impedance of a single microstrip line Calculate the differential impedance of the differential microstrip line The formula is:

[0072] (4)

[0073] in, Indicates the spacing of the differential microstrip lines. Indicates the thickness of the ceramic dielectric substrate 8;

[0074] By designing the differential impedance value Determine the relative permittivity of the ceramic dielectric substrate 8. thickness of microstrip lines Thickness of ceramic dielectric substrate 8 Then, the constraint relationship between the linewidth and spacing of the two microstrip lines is obtained.

[0075] As a specific example, in the polyimide support bridge structure 6, the bridge base covers the connection between the thin film resistor 5 and each differential impedance transformation section, and the microstrip bridge body and the differential impedance transformation line are connected by opening windows on the bridge base.

[0076] As a specific example, the input differential pair, output differential pair, differential impedance transformation lines at each stage, and thin-film resistor 5 are all made of metal.

[0077] This invention utilizes a cascaded multi-stage impedance transformation mechanism, combined with controlled linewidth and spacing parameters of the impedance transformation lines, to form a stepped impedance transformation mechanism. This increases the circuit's resonant points and extends the return loss bandwidth and isolation bandwidth to a wide frequency band. Different connection methods for the input units enable in-phase and out-of-phase outputs of the power divider. A tree structure provides scalable power distribution capabilities. Polyimide support bridges achieve dielectric isolation between microstrip lines. Through optimized design and integration processes, this invention offers advantages such as small size, strong anti-interference capability, and a large operating bandwidth.

[0078] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0079] Example

[0080] This embodiment provides a three-section, two-equal-division differential power divider based on a polyimide-supported bridge, including in-phase output and out-of-phase output designs. A full view of the in-phase output differential power divider is shown below. Figure 1 As shown, the top views of the non-inverting and inverting output differential power dividers are respectively as follows: Figure 2 , Figure 3 As shown, the two designs are identical except for the input circuit connection method. When the exact same differential signal enters the power divider from the input port, the two designs can respectively provide output signals with the same phase and opposite phase between the two output ports. Establish a Cartesian coordinate system as described below, where the x-axis and y-axis are parallel to the two sides of the dielectric substrate, and the direction of the power divider from the ground metal layer to the microstrip structure layer points in the positive z-axis direction.

[0081] The entire power divider comprises, from top to bottom, a microstrip structure layer, a ceramic dielectric substrate 8, and a ground metal layer 9. Both the microstrip line and the ground metal layer 9 are made of gold, and the microstrip line height is 4 μm. The ceramic dielectric substrate 8 is made of alumina, with a relative permittivity of 9.8, a dielectric loss tangent of 0.0002, a substrate thickness of 0.254 mm, and a size of 6.1 mm. The thickness of the differential microstrip line is 4 mm, and different materials and thicknesses will affect the width and spacing of the differential microstrip line. The ground metal layer 9 is 6 μm thick and has the same size as the ceramic dielectric substrate 8.

[0082] The microstrip structure layer includes a differential signal input unit 1, a differential signal output unit 2, a multi-stage multi-segment differential impedance transformation unit 3, a metal grounding pad 4, a thin film resistor 5, and a polyimide support bridge structure 6. The multi-stage multi-segment differential impedance transformation unit 3 includes a first differential impedance transformation section 3-1, a second differential impedance transformation section 3-2, and a third differential impedance transformation section 3-3.

[0083] The differential signal input unit 1 and differential signal output unit 2 are specifically implemented as input and output differential pairs, both using differential microstrip lines. The linewidth and spacing are related to the material and thickness of the dielectric substrate and the thickness of the microstrip line itself. The differential impedance of both the input and output differential microstrip lines is 100 ohms, and the linewidth is 82 μm. The input front end 1-1 of the input differential microstrip line has a line spacing of 0.42 mm and a line length of 0.28 mm, while the input rear end 1-3 has a line spacing of 11 μm and a line length of 0.269 mm. The input middle section 1-2 has a gradually changing line spacing. The length in the direction is 0.209mm; the line spacing of the output front end 2-1 of the output differential microstrip line is 0.42mm, and the line length is 0.28mm; the line spacing of the output rear end 2-3 is 0.11mm, and the line length is 1.359mm; the output middle section 2-2 has a gradually changing line spacing. The length in the direction is 0.209mm.

[0084] The metal grounding pads 4 are made of gold. Each input or output port has three metal grounding pads 4, two of which are located on either side of the differential microstrip line and have a size of 0.38 mm. 0.36mm; another metal grounding pad 4 is located in the middle of the differential microstrip line, with a length of 0.462mm and a width of 0.36mm, gradually narrowing towards the center at the rear end of the pad to form a rounded triangle. The center via of each pad is connected to a cylindrical metal grounding post 7, with a base diameter of 0.1mm, a distance of 80μm from the edge of the hole to the edge of the pad, and a height of 0.258mm, connecting exactly from the microstrip structure layer to the grounding metal layer.

[0085] The differential impedances of the first differential impedance transformation section 3-1, the second differential impedance transformation section 3-2, and the third differential impedance transformation section 3-3 are 174 ohms, 141.4 ohms, and 115 ohms, respectively. The line length L is one-quarter wavelength in each section. The linewidth and spacing are calculated based on the differential impedance and are related to the material and thickness of the dielectric substrate and the thickness of the microstrip line itself. Specifically: the first differential impedance transformation section 3-1 has a linewidth of 22 μm and a spacing of 0.27 mm; the second differential impedance transformation section 3-2 has a linewidth of 53 μm and a spacing of 0.26 mm; and the third differential impedance transformation section 3-3 has a linewidth of 96 μm and a spacing of 0.23 mm. A transition structure is provided between the sections, resulting in gradually changing linewidths and spacings. The isolation resistor is a thin-film resistor 5 with a sheet resistance of 100 ohms and a width of 50 μm. The aspect ratios of the three thin-film resistors 5 are 1, 2.125, and 4, respectively. The thin-film resistors 5 are placed between each impedance transformation stage and connected to the differential impedance transformation line through microstrip lines. They provide a path for absorption and cancellation of signals reflected from the output port, which can significantly increase the isolation between output ports and improve the impedance matching of the output ports.

[0086] The microstrip lines used to connect the isolation resistors intersect with the impedance transformation section. To avoid microstrip line crossing, a polyimide support bridge structure 6 is used to isolate the two intersecting microstrip lines. Polyimide support bridges are divided into open and windowed types. An open type involves laying a dielectric bridge surface on the lower microstrip line, with the upper microstrip line laid on the dielectric bridge surface. A windowed type involves completely covering an area with dielectric, and creating windows at the bridging locations to fabricate the bridging lines. Due to its small size and small spacing between microstrip lines, this invention chooses a windowed bridging method. The polyimide dielectric bridge structure 6 is shown below. Figure 4 As shown, the specific process is as follows: the supporting bridge area is fully covered with dielectric material; a microstrip line in the y-direction connecting the isolation resistor is used as the lower layer microstrip line; and intersecting impedance transformation sections are used as the upper layer microstrip lines laid on the bridge deck. Windows are opened at the bridge pier locations, with a window size of 0.14mm. 0.11mm, the upper microstrip line extends to both sides of the bridge surface to connect with the original microstrip line, allowing electrical signals to pass through. Figure 4 The bridge structure shown has input and output ports added to its two microstrip lines respectively. When only one microstrip line is used as the input, the signal amplitude at the output of the other line is observed. The lower the received signal amplitude, the better the dielectric isolation performance of the bridge structure for the two microstrip lines. Figure 5 The comparison of dielectric isolation performance between a polyimide-supported bridge with a bridge height of 8μm and a traditional air bridge is shown. It can be seen that in the 3-15GHz frequency band discussed in the power divider, the dielectric isolation performance of the polyimide-supported bridge is more than 6dB stronger than that of the traditional air bridge, fully demonstrating the superior dielectric isolation performance of the polyimide-supported bridge.

[0087] Regarding the performance of the designed power divider, Figure 6 Simulation results of a three-section, two-equal-division differential power divider with in-phase output are presented, with a center frequency of 8 GHz, an input port of 1, and output ports of 2 and 3. Differential-mode return loss is also discussed. It outperforms the standard by 15dB in the 3.64-12.29GHz wideband, achieving a relative bandwidth of 108.13%; insertion loss The insertion loss remains below 1dB in the frequency band below 12.65GHz, with the lowest insertion loss at 5.25GHz, at only 0.3dB; the differential mode return loss at the output port... The differential isolation of the two output ports is better than 15dB in the frequency band below 12.06GHz, with a relative bandwidth of 110.25%.

[0088] Figure 7Simulation results of a three-section, two-equal-division differential power divider with inverted output are presented. Its center frequency is 9 GHz, with input port 1 and output ports 2 and 3. Differential-mode return loss is also discussed. It outperforms the standard by 15dB in the 3.79-13.41GHz wideband, achieving a relative bandwidth of 106.89%; insertion loss The differential mode return loss at the output port remains below 2dB in frequency bands below 13.0GHz. It is better than 20dB in the frequency band below 13.44GHz and better than 15dB in the frequency band below 14.56GHz; the differential mode isolation of the two output ports is better than 20dB in the wide frequency band of 4.25-14.86GHz, with a relative bandwidth of 117.89%.

[0089] Figure 8 Simulation results of the differential-mode to common-mode conversion of two power dividers are presented. The smaller the value, the stronger the common-mode rejection capability of the differential power divider. It can be seen that, due to the disruption of symmetry, the amplitude of the differential-mode signal to common-mode signal conversion of the inverting power divider is higher than that of the non-inverting power divider. Both power dividers perform well in suppressing the conversion of common-mode signals to differential-mode signals.

[0090] Figure 9 This demonstrates the phase difference between the output signals of two output ports. In an ideal design, the phase difference between the two output ports of a non-inverting output is 0 degrees, and the phase difference between the two output ports of an inverting output is 180 degrees. Figure 9 As shown, the phase difference between the output signals of the two output ports of the differential power divider with in-phase output is 0 except for a jump at 12.6GHz, which is a superior performance. The phase difference between the output signals of the two output ports of the differential power divider with in-phase output fluctuates slightly between 179 and 181 degrees, but does not affect its in-phase output function.

[0091] In summary, this invention can significantly reduce the size of the power divider, improve the dielectric isolation and stability of the differential power divider, and has the advantages of strong anti-interference ability and wide operating bandwidth.

[0092] 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 changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

[0093] It should be understood that, in order to simplify the present invention and help those skilled in the art understand its various aspects, in the above description of exemplary embodiments of the present invention, various features of the present invention are sometimes described in a single embodiment or with reference to a single figure. However, the present invention should not be construed as including all features in the exemplary embodiments as essential technical features.

Claims

1. A multi-stage, multi-span differential broadband power divider based on a polyimide-supported bridge, characterized in that, The power divider includes a differential signal input unit (1), multiple differential signal output units (2), a multi-stage multi-segment differential impedance transformation unit (3), and multiple polyimide support bridge structures (6), wherein: The differential signal input unit (1) includes an input differential pair, three metal grounding pads (4) arranged alternately with the input differential pair, and a metal grounding post (7) connected to the metal grounding pads (4); the input differential pair is arranged in a horizontal direction. The differential signal output unit (2) includes multiple output differential pairs symmetrically arranged about the horizontal center line, metal grounding pads (4) arranged alternately with each output differential pair, and metal grounding posts (7) connected to the metal grounding pads (4). Between each input differential pair and each output differential pair, a multi-stage, multi-segment differential impedance transformation unit (3) is set to form one output channel of the power divider. The number of output differential pairs is equal to the number of output channels of the power divider. The multi-stage, multi-segment differential impedance transformation unit (3) includes one or more differential impedance transformation sections and a thin-film resistor (5) integrated on the microstrip line; the differential impedance transformation section realizes stepped differential impedance transformation based on cascaded differential impedance transformation lines; the thin-film resistor (5) is set at the connection of adjacent two-stage differential impedance transformation sections to provide a path for absorption and cancellation of signals reflected from the output port; The polyimide support bridge structure (6) includes a polyimide support bridge base with windows and a microstrip bridge body disposed on the bridge base. The polyimide support bridge base is used to dielectrically isolate the microstrip lines above and below the support bridge.

2. The multi-stage, multi-span differential broadband power divider based on a polyimide-supported bridge according to claim 1, characterized in that, The differential broadband power divider further includes a ceramic dielectric substrate (8) and a ground metal layer (9) covering the bottom of the ceramic dielectric substrate (8), wherein the dielectric constant of the ceramic dielectric substrate (8) is greater than 9. The differential signal input unit (1), differential signal output unit (2), multi-stage multi-segment differential impedance transformation unit (3) and polyimide support bridge structure (6) are all disposed on the top of the ceramic dielectric substrate (8), and the metal grounding post (7) passes through the metal grounding pad (4) and the grounding metal layer (9).

3. The multi-stage, multi-span differential broadband power divider based on a polyimide-supported bridge according to claim 2, characterized in that, The power divider has multiple output channels arranged symmetrically about the horizontal center line, and each output channel is a differential signal path. The differential impedance transformation sections corresponding to each output channel are also arranged symmetrically about the horizontal center line, and each differential impedance transformation line in each differential impedance transformation section has a Z-shaped structure. The two microstrip lines that constitute the differential signal path in each output channel are of the same length.

4. The multi-stage, multi-span differential broadband power divider based on a polyimide-supported bridge according to claim 3, characterized in that, The thin film resistor (5) is set at the junction of the differential impedance transformation sections and is connected between two differential impedance transformation sections that are symmetrical about the horizontal center line via microstrip lines. The two ends of the thin film resistor (5) are respectively connected to two differential impedance transformation lines branched off from the input microstrip line, which are used to increase the isolation between the output ports and optimize the impedance matching of the output ports.

5. The multi-stage, multi-span differential broadband power divider based on a polyimide-supported bridge according to claim 2, characterized in that, The input differential pairs, output differential pairs, and differential impedance transformation lines at each stage are all differential microstrip transmission lines.

6. The multi-stage, multi-span differential broadband power divider based on a polyimide-supported bridge according to claim 5, characterized in that, The input differential pair and the output differential pair each include two differential microstrip transmission lines. The spacing between the two differential microstrip transmission lines on the port side is wider than the spacing on the differential impedance transformation section side, and the middle section is set to a gradually changing spacing.

7. The multi-stage, multi-span differential broadband power divider based on a polyimide-supported bridge according to claim 6, characterized in that, For input differential pairs and output differential pairs, the metal grounding pads (4) located on both sides of the two differential microstrip transmission lines are rectangular, and the metal grounding pad (4) located in the middle of the two differential microstrip transmission lines has a rectangular side on one side of the port and a rounded triangle on the other side opposite to the port; a gap is left between the metal grounding pad (4) and the adjacent microstrip transmission lines.

8. The multi-stage, multi-span differential broadband power divider based on a polyimide-supported bridge according to claim 6, characterized in that, In each stage of differential impedance transformation, the linewidth and spacing of the two microstrip lines are related to the material and thickness of the ceramic dielectric substrate (8) and the thickness of the microstrip lines themselves, specifically: use The characteristic impedance of a single microstrip line is expressed by the following formula: (1) in, This represents the characteristic impedance of a microstrip line in air. The effective dielectric constant of the ceramic dielectric substrate (8); the characteristic impedance of the microstrip line in air. and the effective dielectric constant of the ceramic dielectric substrate (8) The calculation formula is as follows: (2) (3) in, Indicates the thickness of the ceramic dielectric substrate (8), Indicates the linewidth of the microstrip line. Indicates the thickness of the microstrip line. The relative permittivity of the ceramic dielectric substrate (8) is indicated; Characteristic impedance of a single microstrip line Calculate the differential impedance of the differential microstrip line The formula is: (4) in, Indicates the spacing of the differential microstrip lines. Indicates the thickness of the ceramic dielectric substrate (8); By designing the differential impedance value The relative permittivity of the ceramic dielectric substrate (8) was determined. thickness of microstrip lines Thickness of ceramic dielectric substrate (8) Then, the constraint relationship between the linewidth and spacing of the two microstrip lines is obtained.

9. The multi-stage, multi-span differential broadband power divider based on a polyimide-supported bridge according to claim 6, characterized in that, In the polyimide support bridge structure (6), the bridge base covers the connection between the thin film resistor (5) and each differential impedance transformation section, and the microstrip bridge body and the differential impedance transformation line are connected by opening a window on the bridge base.

10. The multi-stage, multi-span differential broadband power divider based on a polyimide-supported bridge according to claim 6, characterized in that, The input differential pair, output differential pair, differential impedance transformation lines at each stage, and thin film resistor (5) are all made of metal.

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