A high radio frequency isolation optoelectronic conversion circuit based on a multi-layer ceramic substrate

Abstract

The present invention discloses a high radio frequency isolation optoelectronic conversion circuit based on a multi-layer ceramic substrate. The circuit includes a multi-layer ceramic substrate, a plurality of optoelectronic conversion chips, and a metal frame. The multi-layer ceramic substrate is provided with a plurality of channels and forms a surface layer plane A, a surface layer plane B, and an inner layer radio frequency line. The surface layer plane A and the surface layer plane B constitute a surface layer radio frequency line. The surface layer radio frequency line and the inner layer radio frequency line are arranged at intervals in the plurality of channels of the multi-layer ceramic substrate, and optoelectronic conversion chips are arranged. The metal frame is assembled on the ground attribute metal pattern of the surface layer plane A by an eutectic method to perform metal isolation on each optoelectronic conversion chip. The present invention designs a multi-channel optoelectronic conversion circuit that operates in the range of 2-18 GHz and has an isolation degree of more than 70 dBc by means of an eutectic metal frame structure on the surface layer plane A of the multi-layer ceramic substrate, non-adjacent radio frequency transmission lines on the surface layer plane B and the inner layer, and bridging a grounding shield gold wire above the transmission line on the surface layer plane B.

Description

Technical Field

[0001] The present invention relates to the fields of radio frequency technology and microwave photonics, and particularly to a high radio frequency isolation optoelectronic conversion circuit based on a multilayer ceramic substrate. Background Art

[0002] With the high-level and high-speed development of optical fiber communication technology and microwave technology, a cross-discipline that combines photon technology and microwave technology - microwave photonics has gradually formed. Microwave photon technology is a cross-discipline that transforms microwave signals into the optical domain and realizes processes such as signal generation, distribution, control, and processing through optical methods, thereby performing signal transmission and processing. Compared with traditional microwave and digital processing technologies, optical processing has a series of advantages such as broadband, high speed, parallelism, small size, and electromagnetic compatibility. Microwave photonics effectively solves the bottleneck problem of the development of radio frequency communication towards high frequencies and large capacities. The research scope of microwave photonics includes many civilian and military fields such as optoelectronic devices, radio frequency signal processing, and wireless communication systems. The optoelectronic hybrid integration technology is the future development trend of microwave photon technology. The hybrid integrated design of multi-professional bare chips such as photons, microwaves, and logic control is of great significance for improving product integration and reducing volume and power consumption.

[0003] In traditional digital optical communication, the optoelectronic conversion part is implemented by an array detector chip. The circuit design of the optoelectronic conversion part does not consider the problem of channel radio frequency isolation, and there will be relatively serious signal crosstalk between channels, resulting in an isolation problem. The radio frequency isolation of the optoelectronic conversion part in traditional digital optical communication is about 30 dBc, which cannot be used in microwave photon links, seriously affecting the performance of microwave photon links. In the design of traditional microwave links, metal isolation cavities are used between adjacent channels to achieve high radio frequency isolation. There are not only problems such as large volume and high weight (usually the channel spacing is about 5 mm), but also because a closed metal cavity structure needs to be used between different channels, it cannot be hybrid co-packaged and integrated with optical devices such as wavelength division multiplexers and optical mixers. Summary of the Invention

[0004] The main purpose of the present invention is to provide a high radio frequency isolation optoelectronic conversion circuit based on a multilayer ceramic substrate, aiming to solve the technical problem that the optoelectronic conversion part in current traditional digital optical communication is not applicable to microwave photon links. At the same time, it solves technical problems such as large volume, high weight, and inability to be hybrid co-packaged and integrated with optical devices such as wavelength division multiplexers and optical mixers when the traditional microwave uses a closed metal cavity isolation scheme.

[0005] To achieve the above object, the present invention provides a high radio frequency isolation optoelectronic conversion circuit based on a multilayer ceramic substrate, including a multilayer ceramic substrate, a plurality of optoelectronic conversion chips, and a metal frame; wherein:

[0006] The multi-layer ceramic substrate is provided with a plurality of channels. Metal patterns processed by thick film technology are provided on two adjacent planes and the inner layer of the multi-layer ceramic substrate, forming a surface layer plane A, a surface layer plane B, and an inner layer RF line. The surface layer plane A and the surface layer plane B constitute a surface layer RF line;

[0007] The surface layer RF line and the inner layer RF line are arranged at intervals in a plurality of channels of the multi-layer ceramic substrate. An optoelectronic conversion chip for connecting the inner layer RF line or the outer layer RF line is arranged in each channel;

[0008] The metal enclosure is of a comb-tooth structure and is assembled on the ground-attribute metal pattern of the surface layer plane A by an eutectic method to perform metal isolation on each optoelectronic conversion chip.

[0009] Optionally, the metal pattern on the surface layer plane B is a RF transmission line for non-adjacent channels, and ground-attribute copper foils are arranged on both sides of the RF transmission line.

[0010] Optionally, the optoelectronic conversion chip and the RF transmission line pads are arranged in the surface layer plane A, and the RF output end of the optoelectronic conversion chip is wire-bonded to the RF transmission line pads by gold wires.

[0011] Optionally, shielding gold wires are arranged across above the RF transmission line on the ground-attribute copper foils on both sides of the RF transmission line of the surface layer plane B.

[0012] Optionally, the multi-layer ceramic substrate is prepared by using LTCC or HTCC technology.

[0013] Optionally, the metal enclosure is prepared by using a conductive material.

[0014] The present invention provides a high-RF isolation optoelectronic conversion circuit based on a multi-layer ceramic substrate. The circuit includes a multi-layer ceramic substrate, a plurality of optoelectronic conversion chips, and a metal enclosure. The multi-layer ceramic substrate is provided with a plurality of channels and forms a surface layer plane A, a surface layer plane B, and an inner layer RF line. The surface layer plane A and the surface layer plane B constitute a surface layer RF line. The surface layer RF line and the inner layer RF line are arranged at intervals in a plurality of channels of the multi-layer ceramic substrate, and optoelectronic conversion chips are arranged. The metal enclosure is assembled on the ground-attribute metal pattern of the surface layer plane A by an eutectic method to perform metal isolation on each optoelectronic conversion chip. The present invention designs a multi-channel optoelectronic conversion circuit operating in the range of 2 - 18 GHz and having an RF isolation of more than 70 dBc by means of eutectic metal enclosure structure on the surface layer plane A of the multi-layer ceramic substrate, non-adjacent RF transmission lines on the surface layer plane B and the inner layer, and bridging ground shielding gold wires above the transmission lines on the surface layer plane B. Description of the Drawings

[0015] Figure 1It is a schematic structural diagram of a high radio frequency isolation optoelectronic conversion circuit based on a multi-layer ceramic substrate.

[0016] Figure 2 It is a disassembly schematic diagram of a high radio frequency isolation optoelectronic conversion circuit based on a multi-layer ceramic substrate.

[0017] Figure 3 It is a cross-sectional view of the inner layer radio frequency line of a high radio frequency isolation optoelectronic conversion circuit based on a multi-layer ceramic substrate.

[0018] Figure 4 It is a schematic diagram of the simulation result of the inter-channel isolation of a high radio frequency isolation optoelectronic conversion circuit based on a multi-layer ceramic substrate.

[0019] The realization, functional characteristics and advantages of the object of the present invention will be further described in conjunction with the embodiments with reference to the attached drawings. Specific Embodiments

[0020] It should be understood that the specific embodiments described herein are only used to explain the invention and are not used to limit the invention.

[0021] Next, the technical solutions in the embodiments of the invention will be clearly and completely described in conjunction with the drawings in the embodiments of the invention. Obviously, the described embodiments are only a part of the embodiments of the invention, rather than all the embodiments. Based on the embodiments of the invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the invention.

[0022] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the invention are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0023] In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the invention.

[0024] Currently, in the related technical field, there is a technical problem that the optoelectronic conversion part in traditional digital optical communication is not applicable to microwave photonic links.

[0025] To solve this problem, various embodiments of the high radio frequency isolation optoelectronic conversion circuit based on a multilayer ceramic substrate of the present invention are proposed. The high radio frequency isolation optoelectronic conversion circuit based on a multilayer ceramic substrate provided by the present invention designs a multi-channel optoelectronic conversion circuit operating in the range of 2 - 18 GHz with an isolation degree of more than 70 dBc by means of a eutectic metal frame structure on the surface plane A of the multilayer ceramic substrate, non-adjacent radio frequency transmission lines on the surface plane B and the inner layer, and bridging a grounded shielding gold wire above the transmission line on the surface plane B, thus solving the technical problem that the optoelectronic conversion part in current traditional digital optical communication is not applicable to microwave photon links.

[0026] Referring to Figure 1 , Figure 1 FIG. is a schematic structural diagram of a high radio frequency isolation optoelectronic conversion circuit based on a multilayer ceramic substrate proposed in this embodiment.

[0027] In this embodiment, a high radio frequency isolation optoelectronic conversion circuit based on a multilayer ceramic substrate mainly includes an optoelectronic conversion chip, a multilayer ceramic substrate, a shielding gold wire, and a metal frame, as Figure 1 shown.

[0028] The optoelectronic conversion chip is a bare chip made of indium phosphide material. The multilayer ceramic substrate adopts the method of LTCC multilayer ceramic circuit substrate, which is made of aluminum nitride material with a dielectric constant of 8.8, and the projection distance between adjacent channels is 2 mm.

[0029] As Figure 2 and Figure 3 shown, metal patterns are processed by thick film technology in two adjacent planes and the inner layer of the multilayer ceramic substrate, which are the surface plane A, the surface plane B, and the inner layer radio frequency line respectively. The multilayer ceramic substrate contains two groups of radio frequency lines, namely the surface radio frequency lines formed by the metal patterns on the surface plane A and the surface plane B, and the inner layer radio frequency lines formed by the metal patterns of the surface plane A and the inner layer transmission line. The two groups of radio frequency lines appear at intervals. By adopting two different ways of surface radio frequency lines and inner layer radio frequency lines between adjacent channels, the distance between two channels in the same group is increased in space, and the radio frequency isolation degree between channels is improved. The metal patterns on the surface plane B are non-adjacent channel radio frequency transmission lines (such as the radio frequency transmission lines of channels 1, 3, 5, 7), and there are large-area property copper foils on both sides of the radio frequency transmission line. The inner layer transmission line is a strip line of another non-adjacent channel (such as the strip line of channels 2, 4, 6, 8).

[0030] The optoelectronic conversion chip is assembled on the surface plane A, and the radio frequency output end of the optoelectronic conversion chip is connected to the radio frequency line pad on the surface plane A by wire bonding with a gold wire.

[0031] The metal enclosure is of a comb-tooth structure, which provides metal isolation for different optoelectronic conversion chips; the metal enclosure is assembled on the ground property metal pattern of the surface plane A by means of eutectic bonding. The height of the metal enclosure is 0.5 mm, which can reduce the energy coupling between channels in free space.

[0032] In this embodiment, the multi-layer ceramic substrate is prepared by processes such as LTCC (Low Temperature Co-fired Ceramic) or HTCC (High Temperature Co-fired Ceramic).

[0033] In this embodiment, the metal enclosure is made of conductive materials such as kovar, aluminum, copper, etc.

[0034] There are large-area ground property copper foils on both sides of the RF transmission line on the surface plane B, and the shielding gold wires are on the ground copper foils on both sides of the transmission line on the surface plane B and span above the RF transmission line.

[0035] The simulation comparison results are as Figure 4 shown. Under the condition of maintaining a constant channel spacing, the dotted line is the RF isolation curve between adjacent channels of the optoelectronic conversion unit using a traditional single-layer substrate, and the solid line is the RF isolation curve between adjacent channels of the optoelectronic conversion unit using the LTCC multi-layer substrate in this embodiment. In the range of 2 - 18 GHz, the isolation degree of this embodiment is about 70 dBc.

[0036] The high RF isolation optoelectronic conversion circuit based on the multi-layer ceramic substrate implemented in this embodiment designs a multi-channel optoelectronic conversion circuit operating in the range of 2 - 18 GHz with an isolation degree of more than 70 dBc by means of eutectic metal enclosure structure on the surface plane A of the multi-layer ceramic substrate, on the surface plane B and non-adjacent inner-layer RF transmission lines, and by bridging grounding shielding gold wires above the transmission line on the surface plane B, thus solving the technical problem that the optoelectronic conversion part in current traditional digital optical communication is not applicable to microwave photonic links.

[0037] The above are only the preferred embodiments of the invention, and do not limit the patent scope of the invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the invention specification and drawings, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the invention.

Claims

1. A high radio frequency isolation optoelectronic conversion circuit based on a multilayer ceramic substrate, characterized in that It includes a multi-layer ceramic substrate, several optoelectronic conversion chips, and a metal enclosure; among which: The multi-layer ceramic substrate is provided with several channels. Metal patterns processed by thick film technology are provided on two adjacent planes and the inner layer of the multi-layer ceramic substrate to form a surface plane A, a surface plane B, and an inner layer RF line. The surface plane A and the surface plane B constitute a surface layer RF line; The surface layer RF line and the inner layer RF line are arranged at intervals in several channels of the multi-layer ceramic substrate, and an optoelectronic conversion chip for connecting the inner layer RF line or the outer layer RF line is arranged in each channel; The metal enclosure is of a comb-tooth structure and is assembled on the ground property metal pattern of the surface plane A by an eutectic method to perform metal isolation on each optoelectronic conversion chip.

2. The high radio frequency isolation optoelectronic conversion circuit based on a multilayer ceramic substrate according to claim 1, wherein The metal pattern on the surface plane B is a RF transmission line for non-adjacent channels, and ground property copper foils are provided on both sides of the RF transmission line.

3. The high radio frequency isolation optoelectronic conversion circuit based on a multi-layer ceramic substrate according to claim 2, characterized in that, The optoelectronic conversion chip and the RF transmission line pads are arranged in the surface plane A, and the RF output end of the optoelectronic conversion chip is wire-bonded to the RF transmission line pads by gold wires.

4. The high radio frequency isolation optoelectronic conversion circuit based on a multilayer ceramic substrate according to claim 2, wherein Shielding gold wires are arranged across above the RF transmission line on the ground property copper foils on both sides of the RF transmission line on the surface plane B.

5. The high radio frequency isolation optoelectronic conversion circuit based on a multi-layer ceramic substrate according to claim 1, characterized in that, The multi-layer ceramic substrate is prepared by using LTCC or HTCC technology.

6. The high radio frequency isolation optoelectronic conversion circuit based on a multilayer ceramic substrate according to claim 1, characterized in that The metal enclosure is prepared by using a conductive material.

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