CN-121584182-B - Multistage multi-branch differential broadband power divider based on polyimide supporting bridge

CN121584182BCN 121584182 BCN121584182 BCN 121584182BCN-121584182-B

Abstract

The invention discloses a multi-stage multi-branch differential broadband power divider based on a polyimide supporting bridge, which comprises a differential signal input unit, a plurality of differential signal output units, a multi-stage multi-branch differential impedance conversion unit and a plurality of polyimide supporting bridge structures, wherein the differential signal input unit comprises input differential pairs, the differential signal output unit comprises multi-path output differential pairs which are symmetrically arranged about a central line, the multi-stage multi-branch differential impedance conversion units are respectively arranged between the input differential pairs and each path of output differential pairs, the differential impedance conversion sections realize stepped differential impedance conversion based on cascaded differential impedance conversion lines, thin film resistors are arranged at the connection positions of the adjacent two-stage differential impedance conversion sections and provide absorption and cancellation paths for signals reflected by output ports, and the polyimide supporting bridge structures realize dielectric isolation between microstrip lines. The invention has the advantages of small volume, strong anti-interference capability and large working bandwidth through the optimal design and the integration process.

Inventors

LI MENGMENG
Duan Haoxiang
LI SHUAISHUAI
Gu Jiangchuan
DING DAZHI

Assignees

南京理工大学

Dates

Publication Date: 20260505
Application Date: 20260129

Claims (10)

1. The utility model provides a multistage many knots differential broadband power divider based on polyimide supporting bridge, its characterized in that, this power divider includes differential signal input unit (1), a plurality of differential signal output unit (2), multistage many knots differential impedance transformation unit (3) and a plurality of polyimide supporting bridge structure (6), wherein: The differential signal input unit (1) comprises an input differential pair, three metal grounding pads (4) alternately arranged with the input differential pair and a metal grounding column (7) connected to the metal grounding pads (4), wherein the input differential pair is arranged along the horizontal direction; the differential signal output unit (2) comprises multiple paths of output differential pairs which are vertically symmetrically arranged about a horizontal central line, metal grounding pads (4) which are alternately arranged with each path of output differential pairs, and metal grounding columns (7) which are connected to the metal grounding pads (4); The multi-stage multi-node differential impedance conversion units (3) are respectively arranged between the input differential pair and each output differential pair to form one output channel of the power divider, and the number of the output differential pairs is equal to that of the output channels of the power divider; The multistage multi-branch differential impedance transformation unit (3) comprises one or more differential impedance transformation nodes and a thin film resistor (5) integrated on the microstrip line, wherein the differential impedance transformation nodes are based on cascaded differential impedance transformation lines to realize stepped differential impedance transformation, and the thin film resistor (5) is arranged at the joint of two adjacent differential impedance transformation nodes to provide absorption and cancellation paths for signals reflected from an output port; the polyimide supporting bridge structure (6) comprises a polyimide supporting bridge seat with a window and a microstrip line bridge body arranged on the bridge seat, wherein the polyimide supporting bridge seat is used for dielectric isolation of microstrip lines on the upper part and the lower part of the supporting bridge.
2. The multi-stage multi-leg differential broadband power divider based on a polyimide support bridge according to claim 1, further comprising a ceramic dielectric substrate (8) and a grounded metal layer (9) covering the bottom of the ceramic dielectric substrate (8), the dielectric constant of the ceramic dielectric substrate (8) being greater than 9; the differential signal input unit (1), the differential signal output unit (2), the multi-stage multi-section differential impedance transformation unit (3) and the polyimide support bridge structure (6) are all arranged at the top of the ceramic dielectric substrate (8), and the metal grounding column (7) penetrates through the space between the metal grounding pad (4) and the grounding metal layer (9).
3. The multi-stage multi-branch differential broadband power divider based on the polyimide supporting bridge according to claim 2, wherein multiple output channels of the power divider are arranged symmetrically up and down about a horizontal central line, each output channel is a differential signal channel, differential impedance transformation nodes corresponding to the output channels are also arranged symmetrically up and down about the horizontal central line, each stage of differential impedance transformation line in each differential impedance transformation node is in a shape of a Chinese character 'ji', and two microstrip lines forming the differential signal channels in each output channel are identical in length.
4. The multi-stage multi-node differential broadband power divider based on the polyimide supporting bridge according to claim 3, wherein the thin film resistor (5) is arranged at the joint of the differential impedance transformation nodes of each stage and is connected between two differential impedance transformation nodes which are vertically symmetrical with respect to the horizontal central line through microstrip lines, and two ends of the thin film resistor (5) are respectively connected with two differential impedance transformation lines separated by one input microstrip line for increasing isolation between output ports and optimizing impedance matching of the output ports.
5. The multi-stage multi-leg differential broadband power divider based on polyimide support bridge according to claim 2, wherein the input differential pair, the output differential pair, and each stage of differential impedance transformation line are differential microstrip transmission lines.
6. The multi-stage multi-node differential broadband power divider based on a polyimide supporting bridge according to claim 5, wherein the input differential pair and the output differential pair respectively comprise two differential microstrip transmission lines, the distance between the two differential microstrip transmission lines on one side of the port is wider than the distance between the two differential microstrip transmission lines on one side of the differential impedance transformation node, and the middle section is set to be a gradual change distance.
7. The multi-stage multi-node differential broadband power divider based on the polyimide supporting bridge according to claim 6, wherein for an input differential pair and an output differential pair, the metal grounding pads (4) positioned at two sides of the two differential microstrip transmission lines are rectangular, one side of a port of the metal grounding pad (4) positioned between the two differential microstrip transmission lines is rectangular, the other side opposite to the port is contracted into a rounded triangle, and a gap is reserved between the metal grounding pad (4) and the adjacent microstrip transmission line.
8. The multi-stage multi-section differential broadband power divider based on polyimide support bridge according to claim 6, characterized in that in each stage of differential impedance transformation section, the line width and the distance between two microstrip lines are related to the material and the thickness of the ceramic dielectric substrate (8) and the thickness of the microstrip line itself, specifically: By using The characteristic impedance of the single microstrip line is represented, and the calculation formula is as follows (1) Wherein, the Representing the characteristic impedance of the microstrip line in air; Representing the effective dielectric constant of the ceramic dielectric substrate (8), and the characteristic impedance of the microstrip line in air And the effective dielectric constant of the ceramic dielectric substrate (8) The calculation formula of (2) is as follows: (2) (3) Wherein, the The thickness of the ceramic dielectric substrate (8) is shown, Representing the line width of the microstrip line, The thickness of the microstrip line is indicated, The relative permittivity of the ceramic dielectric substrate (8); By characteristic impedance of a single microstrip line Calculating differential impedance of differential microstrip line The formula of (2) is: (4) Wherein, the Representing the pitch of the differential microstrip lines, The thickness of the ceramic dielectric substrate (8); By designing differential impedance values Determining the relative permittivity of the ceramic dielectric substrate (8) Thickness of microstrip line Thickness of ceramic dielectric substrate (8) And obtaining the constraint relation of the line widths and the distances of the two microstrip lines.
9. The multi-stage multi-node differential broadband power divider based on polyimide support bridge according to claim 6, wherein in the polyimide support bridge structure (6), bridge bases are covered on the connection parts of the thin film resistors (5) and the differential impedance transformation nodes, and the microstrip line bridge body is connected with the differential impedance transformation lines through windowing on the bridge bases.
10. The multi-stage multi-leg differential broadband power divider based on polyimide support bridge according to claim 6, wherein the materials of the input differential pair, the output differential pair, each stage differential impedance transformation line and the thin film resistor (5) are all metals.

Description

Multistage multi-branch differential broadband power divider based on polyimide supporting bridge Technical Field The invention relates to the technical field of microwave circuits, in particular to a multistage multi-branch differential broadband power divider based on a polyimide support bridge. Background With the rapid development of wireless communication technology, the space electromagnetic environment is increasingly complex, and the signal interference problem between devices is becoming serious. The differential radio frequency circuit adopts a symmetrical balance design mode, so that common mode noise can be effectively restrained, and the anti-interference capability and communication stability of the system are improved. In this system, the differential power divider acts as a key passive device, and its performance directly affects the performance of the entire differential system. The differential power divider usually adopts a differential port design, and two paths of output signals have equal amplitude and opposite phases. When external electromagnetic interference is coupled to two signal lines at the same time, the interference is presented as a common mode signal, and the useful signal is a differential mode signal, and by carrying out differential processing on two paths of disturbed signals, the common mode noise can be effectively counteracted, and the original signal waveform is restored, so that the electromagnetic compatibility of the system is obviously improved. In recent years, several designs for differential power splitters have been proposed. For example, document 1（H. Zhu, P. -Y. Qin and Y. J. 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 rejection, which achieves a low cross polarization level in a linearly polarized antenna array by achieving high-level, broadband common mode rejection. Literature 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 filter power divider based on a three-mode resonator, which achieves common mode rejection of 28.5 dB and port isolation higher than 17.6 dB in the passband. These works demonstrate the potential of differential power splitters in terms of improving system performance. In terms of process implementation, the dielectric bridge process is an important technology in manufacturing microelectronic and microwave integrated circuits, and is particularly suitable for interconnection scenes requiring jumper wires. The process realizes circuit connection by constructing a bridge structure on an insulating dielectric layer, and relates to dielectric material coating, curing and patterning, wherein common dielectric materials comprise polyimide, benzocyclobutene and other polymer films. The material has the characteristics of high mechanical strength, good heat resistance, excellent insulating property, low dielectric constant, small loss and the like, can effectively support a bridge deck structure, avoids the problem that the traditional air bridge is easy to break due to overlong suspension, and simultaneously provides better design freedom degree and electrical stability. For example, polyimide support bridge is composed of bridge deck and bridge pier, and is made up by using photoetching, metal evaporation, stripping and etching processes, and polyimide is used as support material, its high strength can ensure that the bridge deck is not easy to break, and its bridge deck height can be kept constant in micrometer level, and its good heat resistance and good insulating property can ensure electric signal integrity of circuit on the bridge, and its low dielectric constant and low dielectric loss are suitable for high-frequency circuit application. Despite the above advances, the current differential power divider design and process still suffers from the following significant drawbacks: (1) The process integration level is low, the structural reliability is limited, and most reported differential power dividers adopt the traditional PCB process and rely on an air bridge to realize dielectric isolation. The dielectric constant of the conventional PCB dielectric substrate is low, so that the size of the device is large, and the air bridge is easy to break when the bridge body is long, so that the risk of electric short circuit exists, and the long-term reliability of the circuit is affected. At present, research on combining a differential power divider with a semiconductor process (particularly a dielectric bridge process with high mechanical stre