Radio frequency switch matrix and radio frequency switch circuit

Abstract

The invention discloses a radio frequency switch matrix and a radio frequency switch circuit. The radio frequency switch matrix comprises a top layer circuit board used for surface mounting of M radio frequency switch chips; the second connecting layer is used for placing N output channels corresponding to each radio frequency switch chip; the third connecting layer is used for placing N'output channels corresponding to each radio frequency switch chip and M 'input channels corresponding to the M radio frequency switch chips, and the type of each radio frequency switch chip is that one input channel corresponds to N + N' output channels; the bottom layer is provided with welding spot structures corresponding to the top layer circuit board, the second connecting layer and the third connecting layer, and a stacked structure in the vertical direction is formed among the top layer circuit board, the second connecting layer, the third connecting layer and the bottom layer through the welding spot structures. Multiple layers of two-dimensional microwave circuits are stacked in the vertical direction and are interconnected in the vertical direction and the horizontal direction, a high-integration-level three-dimensional microwave circuit system can be formed, space occupation is effectively reduced, and the integration degree is higher.

Description

Technical Field

[0001] The present invention belongs to the technical field of radio frequency switches, and particularly relates to a radio frequency switch matrix and a radio frequency switch circuit. Background Art

[0002] The radio frequency switch matrix is an important part of the large-scale quantum bit chip bus information automatic test equipment, and is also widely used in phased array radars. It is composed of different types of switches combined according to a certain topological structure. Its main function is to realize the interconnection between the multi-port device under test and the test instrument, and to realize the automatic control and switching of the radio frequency channels.

[0003] In the related art, coaxial switches are often used to build radio frequency switch matrices, and radio frequency switch chips or solid-state radio frequency switches are used to form radio frequency switch matrices. Specifically, the chips are surface-mounted on a microstrip circuit board to form a planar microwave circuit, but it still occupies a large space, which affects the integration improvement of the radio frequency switch matrix. Summary of the Invention

[0004] The purpose of the present invention is to propose a radio frequency switch matrix and a radio frequency switch circuit to solve the problems in the prior art.

[0005] To this end, the present invention provides a radio frequency switch matrix, which is characterized by comprising:

[0006] A top circuit board for surface-mounting M radio frequency switch chips;

[0007] A second connection layer for placing N output channels corresponding to each of the radio frequency switch chips;

[0008] A third connection layer for placing N' output channels corresponding to each of the radio frequency switch chips and M' input channels corresponding to the M radio frequency switch chips, where M = M', M ≥ 2, and the type of each radio frequency switch chip is 1 input channel corresponding to N + N' output channels;

[0009] A bottom layer provided with solder joint structures corresponding to the top circuit board, the second connection layer, and the third connection layer, and a vertical stacking structure is formed between the top circuit board, the second connection layer, the third connection layer, and the bottom layer through the solder joint structures.

[0010] As a further description of the above technical solution, it further includes a ground layer, and the ground layer is arranged between the second connection layer and the third connection layer.

[0011] As a further description of the above technical solution, the number of the N output channels on the second connection layer is equal to the number of the N' output channels on the third connection layer, and the output channels on the second connection layer and the output channels on the third connection layer are arranged in an interleaved manner.

[0012] As a further description of the above technical solution, five radio frequency switch chips are surface-mounted on the top circuit board, and the number of N output channels on the second connection layer is equal to the number of N' output channels on the third connection layer, and the output channels on the second connection layer and the output channels on the third connection layer are arranged in a staggered manner.

[0013] As a further description of the above technical solution, the stacked structure includes at least five input ports and at least twenty output ports, wherein at least ten output ports are distributed on the second connection layer, and at least ten output ports and five input ports are distributed on the third connection layer.

[0014] As a further description of the above technical solution, the size of the stacked structure is not greater than 50*50*2.5m 3 。

[0015] As a further description of the above technical solution, in the stacked structure, the signal transmission between adjacent upper and lower circuit boards is connected through a signal transmission line, and a vertical connection transition structure is provided between adjacent upper and lower circuit boards.

[0016] As a further description of the above technical solution, the vertical connection transition structure is respectively connected to the signal transmission lines on the upper and lower circuit boards. The vertical connection transition structure includes bonding wires, and the bonding wires pass through vias and are connected to the transition section on the lower circuit board, and the transition section is connected to the signal transmission line on the lower circuit board.

[0017] A radio frequency switch circuit includes the radio frequency switch matrix described in any one of the above.

[0018] A PCB board, the top surface of the PCB board is connected to the bottom layer of the radio frequency switch matrix, and the bottom surface of the PCB board is distributed with input ports and output ports corresponding to the radio frequency switch circuit.

[0019] As a further description of the above technical solution, a plurality of solder joint structures are distributed on the top surface of the PCB board, and five input ports and twenty output ports are distributed on the bottom surface of the PCB board.

[0020] Beneficial effects:

[0021] 1. The present invention provides a radio frequency switch matrix, which stacks multi-layer two-dimensional microwave circuits in the vertical direction and interconnects them in the vertical and horizontal directions, so as to form a three-dimensional microwave circuit system with high integration, effectively reducing space occupation and having a higher degree of integration.

[0022] 2. The present invention provides an optimization of the vertical connection transition structure of a radio frequency switch matrix, which significantly improves the parameters of the S-curve of the optimized radio frequency switch, effectively reduces the insertion loss and voltage standing wave ratio, and improves the overall performance at the same time.

[0023] 3. The present invention provides a radio frequency switch matrix for measuring the bus information of a 20-bit chip, with only one pair of input and output interfaces. When accessing a vector network analyzer, there is no need to frequently replace connectors, the wiring is more flexible, and channel switching can be achieved by switching the switch, effectively improving the efficiency.

[0024] 4. The present invention provides a radio frequency switch matrix that can be connected to XY control lines or Z control lines. Only five signal input terminals and twenty signal output terminals are required to access the 20-bit XY control lines or Z control lines, enabling the performance measurement of a single bit, reducing the number of control signal generators or the steps of connector plugging and unplugging, and improving the efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0026] Figure 1 It is a top layer schematic diagram of a radio frequency switch matrix provided by the present invention.

[0027] Figure 2 It is a schematic diagram of the second connection layer of a radio frequency switch matrix provided by the present invention.

[0028] Figure 3 It is a schematic diagram of the ground layer of a radio frequency switch matrix provided by the present invention.

[0029] Figure 4 It is a schematic diagram of the third connection layer of a radio frequency switch matrix provided by the present invention.

[0030] Figure 5 It is a schematic diagram of the bottom layer structure of a radio frequency switch matrix provided by the present invention.

[0031] Figure 6 It is a schematic diagram of the top layer of the PCB board in a radio frequency switch circuit provided by the present invention.

[0032] Figure 7 It is a schematic diagram of the bottom layer of the PCB board in a radio frequency switch circuit provided by the present invention.

[0033] Figure 8Schematic diagram before optimization of the vertical connection transition structure of a radio frequency switch matrix provided by the present invention.

[0034] Figure 9 S-parameter curve diagram before optimization of the vertical connection transition structure of a radio frequency switch matrix provided by the present invention.

[0035] Figure 10 Schematic diagram after optimization of the vertical connection transition structure of a radio frequency switch matrix provided by the present invention.

[0036] Figure 11 S-parameter curve diagram after optimization of the vertical connection transition structure of a radio frequency switch matrix provided by the present invention.

[0037] In the figure: 100, top circuit board; 110, radio frequency switch chip; 200, second connection layer; 300, ground layer; 400, third connection layer; 500, bottom layer; 600, PCB board; 610, top surface; 620, bottom surface; 700, input channel; 800, output channel; 900, input port; 1000, output port; 1100, vertical connection transition structure; 1110, microstrip line; 1120, bonding wire; 1130, transition section; 1140, via hole. Detailed implementation mode

[0038] The content of the present invention can be more easily understood by referring to the following detailed description of the preferred implementation methods of the present invention and the included embodiments. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. When there is a conflict, the definition in this specification shall prevail.

[0039] The present invention provides a radio frequency switch matrix, which solves the problem in the prior art that due to the limitation of its own structure or the two-dimensional planar microwave circuit composed of multiple radio frequency switches, the structural size is large, resulting in a large occupied space and being unfavorable for the promotion of miniaturization. The technical concept of the present invention is to stack the two-dimensional microwave circuit in the vertical direction by using LTCC technology, and form a highly integrated three-dimensional microwave circuit through vertical and horizontal interconnections, which is more miniaturized and has a higher integration degree. At the same time, the present invention utilizes an integrated five-way 1-4 radio frequency switch, and two pairs of them can be used to measure the bus information of a 20-bit chip. The input ports of the four buses are connected to the four branches of a 1-4 radio frequency switch, and the output ports of the four buses are connected to the four branches of another 1-4 radio frequency switch, so that there is only one pair of interfaces for input and output. When accessing a vector network analyzer, there is no need to frequently replace the connectors, and the channel switching can be realized by switching the switch, effectively improving the efficiency.

[0040] Meanwhile, the RF switch matrix in this case can be connected to the XY control line or the Z control line. Only five signal input terminals and twenty signal output terminals need to be connected to the 20-bit XY control line or Z control line to achieve the performance measurement of a single bit, reduce the number of control signal generators or the steps of connector plugging and unplugging, and improve the efficiency.

[0041] As Figures 1-5 shown, a kind of RF switch matrix includes:

[0042] At least three layers of circuit boards are included, where the top circuit board 100 is used for surface mounting M RF switch chips 110 and the power supply lines of the RF switch chips 110.

[0043] Optionally, the RF switch chip 110 is a 1-4 RF switch chip 110. Each 1-4 RF switch has 1 input port 900 and 4 output ports 1000. Refer to Figure 1 , the black lines represent signal transmission lines. Among them, four black squares are output ports 1000, and one independent black square is the input port 900. By distributing the input signal to each RF switch chip 110 and guiding the output signal of the switch to the corresponding output port 1000 for distribution.

[0044] The second connection layer 200 is used to place N output channels 800 of each RF switch chip 110;

[0045] The third connection layer 400 is used to place N' output channels 800 and M' input channels 700 of each RF switch chip 110, where M = M', M ≥ 2, and the type of each RF switch chip is 1 input channel corresponding to N + N' output channels.

[0046] Optionally, a bottom layer 500 is provided below the third connection layer 400, that is, at the bottom of the entire multi-layer stacked integrated circuit board. A number of solder joint structures are arrayed on the surface of the bottom layer 500. Each layer of signal transmission line is connected to the solder joint structures arrayed on the bottom layer 500 through vertical vias 1140. And a number of solder joint structures are also provided on the top surface 610 of the PCB board 600. The multi-layer stacked integrated circuit board is accurately attached to the PCB board 600 through surface mounting technology, so as to realize the processing and manufacturing of the entire miniaturized RF switch matrix.

[0047] The solder joint structures provided on the bottom layer 500 correspond to the solder joint structures on the top circuit board 100, the second connection layer 200, and the third connection layer 400. Through the solder joint structures, a stacked structure in the vertical direction is formed among the top circuit board, the second connection layer 200, the third connection layer 400, and the bottom layer 500.

[0048] The stacked structure is a multi-layer stacked integrated circuit board, which can be fabricated by LTCC technology. Specifically, LTCC stands for Low Temperature Co-fired Ceramic. It involves making a precisely thick and dense green ceramic tape from low-temperature sintered ceramic powder as the circuit board substrate material. Then, processes such as laser drilling, micro-hole grouting, and precise conductor paste printing are used to create the required circuit patterns on the green ceramic tape. LTCC can embed multiple passive components into it and, through sintering at 900°C, fabricate a passive integrated component with a three-dimensional circuit network. It can also mount devices on its surface to form passive or active integrated functional modules.

[0049] Optionally, a ground layer 300 is provided between the second connection layer 200 and the third connection layer 400. Refer to Figure 3 , and multiple vias 1140 are formed on the surface of the ground layer 300. The ground layer 300 is a conductive layer with a specific potential (usually zero potential). It mainly serves as a reference potential, providing a stable benchmark for the signals within the chip.

[0050] Optionally, in some embodiments, the number of N output channels on the second connection layer is equal to the number of N' output channels on the third connection layer, and the output channels on the second connection layer and the output channels on the third connection layer are arranged in an interleaved manner. Refer to Figure 2 And Figure 4 , where there are ten output channels 800 provided, that is, N' = N = 10.

[0051] Optionally, in some embodiments, M = 5, that is, five radio frequency switch chips are provided. In some other achievable embodiments, the radio frequency switch chip 110 can be set to six or more, but the area of the corresponding top circuit board 100 needs to be increased to a certain extent. The number of N output channels on the second connection layer is equal to the number of N' output channels on the third connection layer, and the output channels on the second connection layer and the output channels on the third connection layer are arranged in an interleaved manner. Refer to Figure 2 And Figure 4 , N = N' = 10, M' = 5.

[0052] Optionally, the size of the multi-layer stacked integrated circuit board is not greater than 50*50*2.5m 3 , in some embodiments, the multi-layer stacked integrated circuit board is 50*50*2.5m 3 , and the size of the PCB board 600 is 50*50*0.7mm3. The combined size after connection is approximately 50*50*3.2m 3 , which is more miniaturized and has a higher degree of integration compared to the existing size of 482*482*44mm 3 .

[0053] Optionally, refer to Figure 8 and Figure 10 , in a multi-layer stacked integrated circuit board, the signal transmission between adjacent upper and lower circuit boards is connected through a signal transmission line, i.e., a microstrip line 1110. A vertical connection transition structure 1100 is provided between the adjacent upper and lower circuit boards. The vertical connection transition structure 1100 is respectively connected to the signal transmission lines on the upper and lower circuit boards. The vertical connection transition structure 1100 includes a bonding wire 1120. The bonding wire 1120 passes through a via 1140 and is connected to a transition section 1130 on the lower circuit board. The transition section 1130 is connected to the signal transmission line on the lower circuit board. In some embodiments, the width of the signal transmission line is 0.2 mm, the width of the transition section 1130 is 0.08 mm, and the length of the transition section 1130 is 0.6 mm. By optimizing the vertical connection transition structure 1100, the insertion loss and voltage standing wave ratio can be effectively reduced. Reducing the insertion loss enables more signal power to be transmitted from the input port 900 to the output port 1000, which helps improve the performance of the entire radio frequency switch matrix. Reducing the voltage standing wave ratio can also effectively improve the power transmission efficiency and increase the intensity of signal input and output.

[0054] For reference Figure 9 and Figure 11 , where Figure 9 is the S curve before the optimization of the vertical connection transition structure 1100, and where Figure 10 is the S curve after the optimization of the vertical connection transition structure 1100. The red curve is the forward transmission coefficient curve, and the purple curve is the input reflection coefficient curve. The abscissa represents the frequency, and the ordinate represents the magnitude of the S parameter, i.e., the decibel value.

[0055] The value of the input reflection coefficient before optimization is relatively high in the low-frequency band, indicating that there is a large reflection of the input signal. The input reflection coefficient after optimization remains at a low level throughout the frequency band, indicating that through optimization, the matching performance of the circuit at the input port 900 has been significantly improved, reducing signal reflection and increasing power transmission efficiency. The forward transmission coefficient before optimization has a rapid upward trend in the low-frequency band (about 0 - 50 Hz), which may lead to unstable gain at low frequencies. The forward transmission coefficient after optimization has a relatively gentle upward trend in the low-frequency band, indicating that the gain at low frequencies is more stable, which helps reduce signal distortion.

[0056] Such as Figures 1-7As shown, a radio frequency switch circuit includes the above-mentioned stacked structure, i.e., a multi-layer stacked integrated circuit board and a PCB board 600. The PCB board 600 is connected to the multi-layer stacked integrated circuit board through the BGA packaging technology. The BGA packaging technology is a high-density surface mounting packaging technology, and its packaging pins are an array of solder balls or solder joint structures. By placing the solder balls between the chip and the circuit board substrate and heating to melt the metal solder balls to form conductive bumps, not only can the mechanical connection of the chip system be achieved, but also it has a data transmission function. The BGA packaging technology has the characteristics of small integrated area, high interconnection density, and excellent high-frequency transmission performance;

[0057] By integrally connecting the multi-layer stacked integrated circuit board and the PCB board 600, the integration degree of the entire radio frequency switch matrix can be higher and the volume can be greatly reduced. For example, it can be reduced from the original 482*482*44mm 3 to 50*50*3.2mm 3 , so that the space that could originally only integrate one radio frequency switch can distribute five radio frequency switches.

[0058] Optionally, for the description of the PCB board 600, refer to Figures 6-7 , because the material of the low-temperature co-fired ceramic is relatively hard, by connecting the PCB board 600 and welding the external joints on the PCB board 600. In some embodiments, the joints are ssmp joints, i.e., ultra-small push-on radio frequency coaxial connectors. It can meet the requirements of quantum bits being sensitive to the environment and the signal transmission requiring high precision and high stability. The PCB board 600 includes a top layer 610 and a bottom layer 620. The multi-layer stacked integrated circuit board is connected to the PCB board 600 through the BGA packaging technology, and the input port 900 and the output port 1000 of the multi-layer stacked integrated circuit board are placed on the other side of the PCB board 600, i.e., the bottom layer 620, and led out through the ssmp joints.

[0059] Optionally, the model line of the PCB is routed from the middle layer and the signals are connected in the way of coplanar waveguide to meet the high isolation requirement of the radio frequency switch matrix. The coplanar waveguide refers to a structure composed of a dielectric substrate, two large conductor ground planes on the same side of the dielectric substrate, and a conductor strip between them. It is named coplanar waveguide because the ground plane and the conductor strip are on the same side of the dielectric substrate.

[0060] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A radio frequency switch matrix, characterized in that: include: The top circuit board is used for surface mounting M RF switch chips; The second connection layer is used to place N output channels corresponding to each of the radio frequency switch chips; The third connection layer is used to place N' output channels corresponding to each of the RF switch chips and M' input channels corresponding to the M RF switch chips, wherein M=M', M≥2, and the type of each of the RF switch chips is 1 input channel corresponding to N+N' output channels; The bottom layer is provided with a solder joint structure corresponding to the top circuit board, the second connection layer, and the third connection layer, and the solder joint structure forms a stacked structure in a vertical direction between the top circuit board, the second connection layer, the third connection layer and the bottom layer.

2. The radio frequency switch matrix according to claim 1, characterized in that: Also included is a ground layer, which is disposed between the second connecting layer and the third connecting layer.

3. The radio frequency switch matrix according to claim 1, characterized in that: The number of the N output channels on the second connection layer is equal to the number of the N′ output channels on the third connection layer, and the output channels on the second connection layer are staggered with the output channels on the third connection layer.

4. The radio frequency switch matrix according to claim 1, characterized in that: Five RF switch chips are mounted on the top circuit board, and the N output channels on the second connection layer are equal to the N' output channels on the third connection layer, and the output channels on the second connection layer are staggered with the output channels on the third connection layer.

5. The radio frequency switch matrix according to claim 1, characterized in that: The stacked structure includes at least five input ports and at least twenty output ports, wherein the second connection layer is provided with at least ten output ports, and the third connection layer is provided with at least ten output ports and five input ports.

6. The radio frequency switch matrix according to claim 1, characterized in that: The size of the stacked structure is no more than 50*50*2.5m 3 .

7. The radio frequency switch matrix according to claim 1, characterized in that: In the stacked structure, signal transmission between two adjacent layers of circuit boards is connected via a signal transmission line, and the two adjacent layers of circuit boards are provided with a vertical connection transition structure.

8. The radio frequency switch matrix according to claim 7, characterized in that: The vertical connection transition structure is connected to the signal transmission lines on the upper and lower circuit boards respectively. The vertical connection transition structure includes bonding wires. The bonding wires pass through vias and are connected to the transition sections on the lower circuit board. The transition sections are connected to the signal transmission lines on the lower circuit board.

9. A radio frequency switching circuit, characterized in that: A radio frequency switch matrix comprising any one of claims 1 to 8; A PCB board, wherein the top surface of the PCB board is connected to the bottom surface of the RF switch matrix, and the bottom surface of the PCB board is distributed with input ports and output ports of a number corresponding to the RF switch circuit.

10. The radio frequency switch circuit according to claim 9, characterized in that: A plurality of solder joint structures are distributed on the top surface of the PCB board, and five input ports and twenty output ports are distributed on the bottom surface of the PCB board.

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