Miniaturized stacked broadband circulator

Abstract

The application belongs to the technical field of microwave passive devices, and discloses a miniaturized super wideband stacked circulator, which comprises a center junction, a microstrip circuit, a first LTCC ceramic medium ring, a ferrite substrate, a first metal ground layer, a metal filling hole, a strip line circuit, a second LTCC ceramic medium ring and a second metal ground layer; the microstrip circuit and the center junction are located on the upper surface of the ferrite substrate and the first LTCC ceramic medium ring and are connected; the first metal ground layer is located on the upper surface of the second LTCC ceramic medium ring and is connected with the second metal ground layer located on the lower surface of the second LTCC ceramic medium ring through a metal through hole; the strip line circuit is located inside the second LTCC ceramic medium ring and is connected with the microstrip circuit, forming a three-dimensional stacked structure, and is connected with external ports to realize feeding. The application breaks through the limitation that the wide bandwidth and miniaturization of the circulator are incompatible, and realizes the excellent performance of miniaturization and super wideband.

Description

Technical Field

[0001] This invention belongs to the field of microwave passive device technology, and particularly relates to a miniaturized stacked broadband circulator. Background Technology

[0002] Currently, a circulator is a passive, non-reciprocal magnetic device capable of controlling the unidirectional circular transmission of electromagnetic waves. Circulators are widely used in radar, electronic countermeasures, telemetry and remote control, microwave measurement, and microwave communication. However, miniaturization and high bandwidth are often mutually exclusive in existing circulators; they generally have narrow bandwidth and large size, failing to meet the trends of low cost, miniaturization, high performance, and high integration.

[0003] The rapid development of LTCC (Low Temperature Co-fired Ceramic) technology can facilitate the development of novel microwave passive devices. LTCC technology is a multilayer wiring substrate technology that stacks unsintered cast ceramic materials together to create multilayer circuits containing printed interconnects, components, and circuits. This structure is then sintered into an integrated high-density microelectronic component made of multilayer ceramic materials. The high packaging density, good RF characteristics, and high reliability of LTCC technology help overcome the structural and design shortcomings of existing microstrip ferrite circulators, enabling the development of stacked microstrip ferrite circulators with three-dimensional structures.

[0004] Based on the above analysis, the problems and shortcomings of the existing technology are as follows:

[0005] Miniaturization and high bandwidth are usually mutually exclusive in existing circulators. They generally have narrow bandwidth and large size, which does not conform to the trend of low cost, miniaturization, high performance and high integration. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a method for implementing a miniaturized stacked broadband circulator.

[0007] This invention is implemented as follows: a miniaturized multilayer broadband circulator, the circulator structure comprising: a central junction, a microstrip circuit, a first LTCC ceramic dielectric ring, a ferrite substrate, a first metal ground layer, metal vias, a stripline circuit, a second LTCC ceramic dielectric ring, and a second metal ground layer; the microstrip circuit and the central junction are located on the upper surfaces of the ferrite substrate and the first LTCC ceramic dielectric ring and are connected thereto; the first metal ground layer is located on the upper surface of the second LTCC ceramic dielectric ring and is connected to the second metal ground layer located on the lower surface of the second LTCC ceramic dielectric ring through metal vias; the stripline circuit is located inside the second LTCC ceramic dielectric ring and is connected to the microstrip circuit, forming a three-dimensional multilayer structure, and is simultaneously connected to an external port for power feeding.

[0008] Furthermore, the metal vias include microstrip line connection metal vias and first and second ground layer connection metal vias.

[0009] Furthermore, three corresponding circular through holes are provided on the first metal grounding layer, the first LTCC ceramic dielectric ring, and the second LTCC ceramic dielectric ring. The three corresponding circular through holes can be connected to the metal vias via microstrip lines to realize the connection between the stripline circuit and the microstrip circuit.

[0010] Furthermore, the second LTCC ceramic dielectric ring is also provided with other circular through holes for setting the first and second grounding layer connection metal fill holes, which are used to connect the first metal grounding layer and the second metal grounding layer.

[0011] Furthermore, the ferrite substrate is cylindrical in shape and uses a low-temperature sintered microwave ferrite material with a high dielectric constant. Its relative dielectric constant is 22-28, its saturation magnetization 4πMs is 1750-1950Gs, and its sintering temperature is 880-900℃.

[0012] Furthermore, the microstrip circuit and the stripline circuit each have three branches that are 120° apart and surround the central junction.

[0013] Furthermore, the first LTCC ceramic dielectric ring and the second LTCC ceramic dielectric ring are made of low-temperature sintered dielectric ceramic material with a dielectric constant of 5 to 20.

[0014] Furthermore, the materials used for the center junction, microstrip circuit, stripline circuit, metal via, first metal grounding layer, and second metal grounding layer are metals with high electrical conductivity, typically silver.

[0015] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows:

[0016] First, this invention employs a compact circuit design. Addressing the issue of excessive space occupied by multi-stage matching circuits in traditional ultra-wideband circulator designs, which often results in the matching section of the circulator being larger than the ferrite portion, this invention utilizes a three-dimensional stacked structure to connect microstrip transmission lines and stripline transmission lines, achieving three-dimensional multi-stage impedance matching and effectively reducing the size of the matching circuit. Simultaneously, addressing the problem of excessively large central ferrite volume in traditional ultra-wideband circulator designs, this invention employs microwave ferrite materials with high dielectric constant and high saturation magnetization, achieving a wider operating bandwidth with a smaller ferrite volume. This invention overcomes the current limitation of incompatibility between high bandwidth and miniaturization in circulator design, achieving excellent performance in both miniaturization and ultra-wideband capability.

[0017] Secondly, the technical solution of this invention combines the advantages of high bandwidth and miniaturization. Compared with traditional circulator designs, the technical solution of this invention greatly improves the bandwidth by using broadband impedance matching and high saturation magnetization ferrites to expand the bandwidth, achieving a larger relative bandwidth and effectively meeting the ultra-wideband requirements in circulator applications. At the same time, compared with the large size problem caused by the planar design of traditional broadband impedance matching, this solution adopts an LTCC three-dimensional stacked structure design to effectively reduce the circulator volume, and introduces high dielectric constant gyromagnetic materials to further reduce the size of the ferrite substrate. Ultimately, it achieves an effective combination of high bandwidth and small size in the circulator, improving the integration of the ultra-wideband circulator and facilitating its adaptation to various applications.

[0018] Third, does the technical solution of this invention solve a technical problem that people have long desired to solve but have never been able to successfully solve?

[0019] This invention introduces an LTCC stacked structure into the design of ultra-wideband circulators, effectively combining it with YIG microwave ferrites, which have high dielectric constant and high saturation magnetization. This solves the problem of narrow bandwidth and poor practicality of LTCC circulators in previous designs, effectively expanding the bandwidth. It also addresses the issue of excessively large impedance matching structures in ultra-wideband circulators, which severely impact circulator size. By achieving three-dimensional impedance matching across multiple circulator sections, the size of ultra-wideband circulators is effectively reduced, improving their integration. The miniaturized broadband stacked circulator developed in this project shows great promise for applications in military / civilian phased array T / R module systems and broadband multi-channel communication systems.

[0020] Does the technical solution of this invention overcome technical bias? The technical solution of this invention overcomes the problem of excessively large size in previous broadband circulator designs. It combines LTCC technology with ultra-wideband circulator design and utilizes novel high dielectric constant microwave ferrite materials, thus effectively balancing the comprehensive technical requirements of miniaturization and wide bandwidth.

[0021] Fourth, the miniaturized ultrawideband stacked circulator provided by this invention involves multiple professional fields, such as microwave engineering, electronic engineering, and materials science, and has several significant technological advancements:

[0022] Three-dimensional stacked structure: By utilizing a three-dimensional stacked structure, not only is space saved, but the overall circuit performance and integration can also be improved.

[0023] Composite material applications: The use of ferrite substrates and LTCC (low-temperature co-fired ceramic) dielectric rings enhances device performance, providing wider bandwidth and higher Q factor.

[0024] External port power supply: Connect to an external port to provide power supply, facilitating the integration of complex systems.

[0025] Metal via connection: The microstrip line is connected to the metal via and the first and second ground layers are connected to the metal via, which further improves the structural stability and electrical performance of the circuit.

[0026] Circular through-hole design: By setting three corresponding circular through-holes on the first metal grounding layer, the first LTCC ceramic dielectric ring, and the second LTCC ceramic dielectric ring, a more efficient and reliable connection method is provided.

[0027] Flexible connection method: The three corresponding circular through holes can be connected to the metal vias via microstrip lines to realize the connection between stripline circuits and microstrip circuits, which increases the flexibility of the design.

[0028] Overall, this design is highly innovative and has great application potential, finding wide application in communications, radar, and other fields requiring high-performance microwave devices. It integrates various advanced materials and structural designs to achieve miniaturization and high performance, significantly improving the practicality and reliability of ultra-wideband circulators. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the appearance of the miniaturized ultrawideband stacked circulator provided in an embodiment of the present invention.

[0030] Figure 2 This is an exploded structural diagram of the miniaturized ultrawideband stacked circulator provided in an embodiment of the present invention.

[0031] Figure 3 This is a plan view of the miniaturized ultrawideband stacked circulator provided in an embodiment of the present invention.

[0032] Figure 4 This is a schematic diagram of the center junction and microstrip circuit structure of the miniaturized ultrawideband stacked circulator provided in an embodiment of the present invention.

[0033] Figure 5 This is a schematic diagram of the stripline circuit structure of the miniaturized ultrawideband stacked circulator provided in an embodiment of the present invention.

[0034] Figure 6 This is an S-parameter curve of the miniaturized ultrawideband stacked circulator provided in an embodiment of the present invention.

[0035] Figure 7 This describes the relationship between the standing wave ratio (VSWR) and frequency of the miniaturized ultrawideband stacked circulator provided in this embodiment of the invention.

[0036] In the figure: 1. Central junction; 2. Microstrip circuit; 3. First LTCC ceramic dielectric ring; 4. Ferrite substrate; 5. First metal ground layer; 6. Microstrip circuit stripline connection metal via; 7. Stripline circuit; 8. First and second ground layer connection metal via; 9. Second LTCC ceramic dielectric ring; 10. Second metal ground layer. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0038] like Figure 1 As shown, the miniaturized ultrawideband stacked circulator is circular in shape.

[0039] like Figure 2 As shown, the miniaturized ultra-wideband stacked circulator includes: a central junction 1, a microstrip circuit 2, a first LTCC ceramic dielectric ring 3, a ferrite substrate 4, a first metal ground layer 5, metal vias, a stripline circuit 7, a second LTCC ceramic dielectric ring 9, and a second metal ground layer 10. The microstrip circuit 2 and the central junction 1 are located on the upper surfaces of the ferrite substrate 4 and the first LTCC ceramic dielectric ring 3 and are connected. The first metal ground layer 5 is located on the upper surface of the second LTCC ceramic dielectric ring 9 and is connected to the second metal ground layer 10 located on the lower surface of the second LTCC ceramic dielectric ring 9 through metal vias. The stripline circuit 7 is located inside the second LTCC ceramic dielectric ring 9 and is connected to the microstrip circuit 2 to form a three-dimensional stacked structure, while being connected to an external port for power feeding.

[0040] The metal vias include microstrip line connection metal vias 6 and first and second ground layer connection metal vias 8.

[0041] Three corresponding circular through holes are provided on the first metal grounding layer 5, the first LTCC ceramic dielectric ring 3, and the second LTCC ceramic dielectric ring 9. The three corresponding circular through holes can be connected to the metal filling holes 6 through the microstrip line to realize the connection between the stripline circuit 7 and the microstrip circuit 2.

[0042] like Figure 3 As shown, the second LTCC ceramic dielectric ring 9 is also provided with other circular through holes for setting the first and second grounding layer connection metal filling holes 8, which are used to connect the first metal grounding layer 5 and the second metal grounding layer 10.

[0043] The ferrite substrate 4 is cylindrical; the ferrite substrate 4 is used to apply a bias magnetic field perpendicular to the circulator. The ferrite substrate 4 is made of a low-temperature sintered microwave ferrite material with a high dielectric constant, a relative dielectric constant of 22 to 28, a saturation magnetization of 4πMs of 1750 to 1950 Gs, and a sintering temperature of 880 to 900℃.

[0044] like Figure 4 and Figure 5 As shown, the microstrip circuit 2 and the stripline circuit 7 each have three branches that are 120° apart, connected by metal vias, and surround the central junction 1.

[0045] The first LTCC ceramic dielectric ring 3 and the second LTCC ceramic dielectric ring 9 are made of low-temperature sintered dielectric ceramic material with a dielectric constant of 5 to 20.

[0046] Among them, the materials of the central junction 1, microstrip circuit 2, stripline circuit 7, metal via, first metal grounding layer 5 and second metal grounding layer 10 are metals with high electrical conductivity such as gold, silver or silver-palladium alloy.

[0047] Example 1:

[0048] Miniaturized ultrawideband stacked circulator made of metallic silver.

[0049] A miniaturized ultrawideband stacked circulator comprises, from bottom to top, a central junction 1, a microstrip circuit 2, a first LTCC ceramic dielectric ring 3, a ferrite substrate 4, a first metal ground layer 5, a microstrip line connecting metal vias 6, a stripline circuit 7, a first and second ground layer connecting metal vias 8, a second LTCC ceramic dielectric ring 9, and a second metal ground layer 10.

[0050] Ferrite substrate 4: Ferrite substrate 4 is a YIG ferrite substrate with a relative permittivity of 24, a saturation magnetization of 155.2 kA / m (1950 G), a radius of 2.3 mm, and a thickness of 0.82 mm.

[0051] The lower surface of the ferrite substrate 4 and the second LTCC ceramic dielectric ring 9 is printed with a second metal ground layer 10 using silver paste, with a thickness of 10 μm. The upper surface of the ferrite layer is printed with a central junction 1 using silver paste.

[0052] Microstrip circuit 2: The three microstrip branches of microstrip circuit 2 are the same size, and are divided into three sections around the central junction 1. The thickness is consistent with that of the metal central junction 1, which is 10μm. The three microstrip branches intersect and connect with the central junction 1, and form a 120° angle with each other with their center as the point of symmetry.

[0053] First LTCC ceramic dielectric ring 3: The first LTCC ceramic dielectric ring 3 is fitted outside the ferrite substrate 4 and is made of LTCC ceramic films with a relative permittivity of 10 and a loss tangent of 0.005, with a thickness of 0.2 mm. Three circular through holes are drilled at appropriate positions on this ceramic dielectric layer, and silver paste is used to fill the holes to create the upper half of the microstrip line connecting the metal filling hole 6, with a radius of 0.1 mm and a height of 0.2 mm.

[0054] First metal grounding layer 5: Located below the first LTCC ceramic dielectric ring 3, with a thickness of 10μm, three through holes are drilled at appropriate positions to realize the connection between stripline circuit 7 and microstrip circuit 2 through microstrip line connection metal filling hole 6;

[0055] The second LTCC ceramic dielectric ring 9: The second LTCC ceramic dielectric ring 9 and the first LTCC ceramic dielectric ring 3 are formed by stacking the same ceramic diaphragm and are fitted over the ferrite substrate 4, with a thickness of 0.61 mm. Twenty-one circular through-holes (i.e., the metal-filled holes 8 connecting the first and second ground layers) and three blind holes (i.e., the lower half of the metal-filled holes 6 connecting the microstrip lines) are fabricated at appropriate locations within this ceramic dielectric layer, and silver paste is used to fill the holes to create the metal-filled holes 6 connecting the microstrip lines and the metal-filled holes 8 connecting the first and second ground layers. At appropriate locations inside this ceramic dielectric layer, a stripline circuit 7 is fabricated using silver paste. Its three stripline branches have the same size, are 120° apart, and have a thickness of 10 μm. The stripline circuit 7 and the microstrip circuit 2 are connected through the metal-filled holes 6 connecting the microstrip lines, allowing them to be connected to three external microwave ports for power supply. Silver paste is brushed onto the lower surface of this layer to create a second metal ground layer 10 with a thickness of 10 μm.

[0056] The dimensions and material performance parameters of the above-mentioned parts were initially calculated using the admittance slope method. Then, a device model was built using the 3D electromagnetic simulation software HFSS, and simulation experiments were conducted. After parameter optimization, the final values ​​were obtained. The optimized parameters, including reflection S11, isolation S21, insertion loss S31, and standing wave ratio (VSWR), are related to the operating frequency as follows: Figure 6 and Figure 7 As shown.

[0057] In summary, because the circulator of this invention uses low-temperature sintered microwave ferrite with high dielectric constant and adopts a multi-section impedance matching method combining stripline and microstrip lines, it achieves device miniaturization and improves the operating bandwidth of the circulator. Its size is only 7mm×7mm×0.83mm, and its isolation exceeds -11dB, return loss is less than -11dB, and insertion loss is greater than -1.5dB in the frequency range of 3.5GHz to 11GHz, which well balances the requirements of miniaturization and ultra-wideband.

[0058] This invention provides a method for manufacturing a miniaturized ultrawideband stacked circulator:

[0059] The circulator of this invention uses YIG low-temperature ferrite material with a relative permittivity of 24 and a saturation magnetization of 155.2 kA / m (1950 G) as its ferrite substrate, and low-temperature co-fired ceramic material with a relative permittivity of 10 as its matching ceramic dielectric. This circulator employs LTCC technology. The ferrite substrate 4 and the first and second LTCC ceramic dielectric rings (3 and 9) are respectively formed by casting and sintering of laminated films. The LTCC processing flow mainly includes: dicing, pretreatment, punching, drilling, filling, printing of conductive strips, inspection, layer alignment, lamination, co-firing, post-firing, electrical testing, segmentation, and final inspection. Finally, the LTCC ceramic dielectric rings (3 and 9) are assembled with the ferrite substrate 4, and a center junction 1 and a microstrip circuit 2 are printed on the upper surface of the assembled unit, and a second metal ground layer 10 is printed on the lower surface to complete the assembly.

[0060] This invention, as an ultra-wideband small-volume circulator, can be applied to fields such as active phased array radar T / R components and broadband multi-channel communication.

[0061] In active phased array radars, the transceiver unit (T / R) is a core component with a crucial role. Each element of an active phased array radar antenna array is connected to a sub-T / R unit, and each sub-T / R unit requires a circulator as a transceiver switch. With the development of phased array radars, broadband and high data rates are the future directions; therefore, the T / R units and their crucial component, the circulator, must meet these requirements. Furthermore, depending on the array configuration, a typical active phased array radar array requires hundreds or even thousands of T / R units, thus the size of the T / R units directly impacts the overall radar size. The ultra-wideband circulator in this embodiment combines ultra-wideband and miniaturization, effectively meeting the development requirements of active phased array radars. This ultra-wideband circulator has a wide bandwidth, meeting the signal processing needs of the phased array radar within its operating frequency band; its miniaturization advantage allows for higher integration of the T / R units in the active phased array radar, improving radar mobility and adaptability. Therefore, this ultra-wideband circulator, when applied to T / R modules, is highly effective in achieving multi-functionality and miniaturization of novel active phased array radars.

[0062] Furthermore, with the rapid development of modern information technology, such as the Internet, the Internet of Things, and artificial intelligence, the amount of data generated is growing exponentially, requiring higher bandwidth to transmit and process this data. This demand is driving signal transmission technology towards broadband and high-speed applications. The ultra-wideband circulator in this embodiment has advantages such as wide bandwidth, low loss, and high integration, enabling it to meet the signal processing needs of broadband communication, achieve multi-channel signal processing, and adapt to the signal processing requirements of different application scenarios, such as multi-channel wireless communication and satellite communication.

[0063] This invention presents a miniaturized ultra-wideband circulator, measuring only 7mm × 7mm × 0.83mm, achieving an operating bandwidth of 3.5GHz to 11GHz. Simulation experiments were conducted on this miniaturized ultra-wideband circulator. A model was established using the 3D electromagnetic simulation software HFSS, and corresponding results were obtained. The relationships between its reflection S11, isolation S21, insertion loss S31, and standing wave ratio (VSWR) and the operating frequency are as follows: Figure 6 and Figure 7 As shown

[0064] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A miniaturized ultrawideband stacked circulator, characterized in that, The miniaturized ultra-wideband stacked circulator includes: a center junction, a microstrip circuit, a first LTCC ceramic dielectric ring, a ferrite substrate, a first metal ground layer, metal vias, a stripline circuit, a second LTCC ceramic dielectric ring, and a second metal ground layer. The microstrip circuit and the center junction are located on the upper surfaces of the ferrite substrate and the first LTCC ceramic dielectric ring and are connected. The first metal ground layer is located on the upper surface of the second LTCC ceramic dielectric ring and is connected to the second metal ground layer located on the lower surface of the second LTCC ceramic dielectric ring through metal vias. The stripline circuit is located inside the second LTCC ceramic dielectric ring and is connected to the microstrip circuit to form a three-dimensional stacked structure, while also being connected to an external port for power feeding.

2. The miniaturized ultrawideband stacked circulator as described in claim 1, characterized in that, Metal vias include microstrip line connection metal vias and first and second ground layer connection metal vias.

3. The miniaturized ultrawideband stacked circulator as described in claim 2, characterized in that, Three corresponding circular vias are provided on the first metal grounding layer, the first LTCC ceramic dielectric ring, and the second LTCC ceramic dielectric ring. The three corresponding circular vias are connected to the metal vias through microstrip lines to realize the connection between the stripline circuit and the microstrip circuit.

4. The miniaturized ultrawideband stacked circulator as described in claim 1, characterized in that, The central knot is directly connected to an external port via a stripline circuit.

5. The miniaturized ultrawideband stacked circulator as described in claim 3, characterized in that, The second LTCC ceramic dielectric ring is also provided with other circular through holes for setting the first and second grounding layer connection metal fill holes, which are used to connect the first metal grounding layer and the second metal grounding layer.

6. The miniaturized ultrawideband stacked circulator as described in claim 1, characterized in that, The ferrite substrate is cylindrical in shape and uses a low-temperature sintered microwave ferrite material with a high dielectric constant. Its relative dielectric constant is 22~28, 4πMs is 1750~1950 Gs, and the sintering temperature is 880~900℃.

7. The miniaturized ultrawideband stacked circulator as described in claim 1, characterized in that, The microstrip circuit and the stripline circuit each have three branches that are 120° apart and surround the central junction.

8. The miniaturized ultrawideband stacked circulator as described in claim 1, characterized in that, The first LTCC ceramic dielectric ring and the second LTCC ceramic dielectric ring are made of low-temperature sintered dielectric ceramic material with a dielectric constant of 5~20.

9. The miniaturized ultrawideband stacked circulator as described in claim 1, characterized in that, The materials used for the center junction, microstrip circuit, stripline circuit, metal via, first metal grounding layer, and second metal grounding layer are metals with high electrical conductivity.

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