Ultra-wideband surface-mount frequency multiplier and its test fixture based on three-dimensional metal micromachining

Abstract

The present invention discloses an ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining and a test fixture thereof. The ultra-wideband surface-mount frequency multiplier comprises a waveguide-probe transition structure, a low-pass filter, a diode chip, an impedance matching network, and a probe-waveguide transition structure, which are sequentially connected from the radio frequency signal input to the output end, and relates to the field of wireless communication technology. The waveguide-probe transition structure at the input and output ends provides a waveguide interface connecting the frequency multiplier and the test fixture; the micro-coaxial low-pass filter is used to limit the flow direction of the frequency multiplier signal, and adopts a T-shaped SIR branch loading structure to achieve additional controllable transmission zero points and improve the stopband performance; the diode chip is used to achieve frequency multiplication and is mounted in an inverted manner on the table formed by the upward extension of the inner conductor of the coaxial line. The diode chip has an I-shaped and a X-shaped shape, and the end is directly connected to the outer conductor, which helps to improve the heat dissipation performance of the device; the impedance matching network is used to achieve impedance matching between the front circuit and the output port.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communications, and in particular relates to an ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining and a test fixture thereof. Background Art

[0002] With the development of wireless communication technology, the millimeter wave / terahertz frequency band has attracted increasing attention. Due to the high operating frequency and wide bandwidth of the millimeter wave / terahertz frequency band, the corresponding communication devices have the advantages of small size and large information capacity, which helps to achieve miniaturization, lightweight and high efficiency of communication systems.

[0003] Although millimeter-wave / terahertz technology has been widely applied in a variety of fields, including imaging, high-speed communications, astronomical exploration, and meteorological satellites, it still faces numerous limitations and challenges in practical applications, one of which is processing technology. Obviously, the devices and systems in these frequency bands are very small, making them unsuitable for processing using traditional printed circuit board technology and computer numerical control (CNC) machine tools. The former is mainly used to process planar transmission lines (which have high transmission loss, severe dispersion effects, and limited power capacity), while the latter is mainly used to process metal waveguides (which are large and costly). In recent years, various micromachining technologies have been developed both domestically and internationally to manufacture millimeter-wave / terahertz devices and systems, including CNC machining, deep silicon etching (DRIE), SU8 photoresist, 3D printing, and three-dimensional metal micromachining (often referred to as micro-coaxial processing). CNC machining is a well-established technology, first used for millimeter-wave / terahertz device processing. However, as device size decreases, machining precision requirements become increasingly stringent, significantly increasing the time and cost of CNC machining, making it unsuitable for large-scale manufacturing. Furthermore, because CNC-machined devices utilize subtractive manufacturing, they must be broken down into multiple modules, processed separately, and then assembled together. This demands high assembly precision and inevitably introduces certain assembly errors. DRIE and SU8 photoresist techniques also require assembly. Silicon and SU8 photoresist have poor mechanical strength, making them prone to breakage during assembly and application. Furthermore, SU8 photoresist has poor thermal conductivity and requires a high ambient temperature for application. Therefore, DRIE and SU8 photoresist techniques also have significant limitations in practical application. 3D printing, due to its integrated molding process, eliminates assembly errors. However, for millimeter-wave / terahertz frequency bands, 3D printing suffers from lower precision (approximately 50-100 μm) and requires support structures during printing, thus presenting significant limitations in practical application. Three-dimensional metal micromachining technology is a new process improved based on the UV-LIGA lithography process. It integrates multiple technologies such as lithography, electroplating and polishing. Using pure copper as raw material, it can process air-filled rectangular micro-coaxial lines and rectangular waveguide structures. Like 3D printing technology, it is one-piece molding and has high processing accuracy (about 5μm). Since the raw material is copper, it has good mechanical properties and thermal conductivity. It can realize the integration of communication systems through vertical stacking or interlayer interconnection technology, and has good application prospects.

[0004] Another challenge in the field of millimeter wave / terahertz technology is the realization of high-power terahertz sources. Frequency signals below the terahertz band can be generated by traditional microwave devices (such as amplifiers, oscillators, etc.), and frequency signals above the terahertz band can be generated by optoelectronic devices. Both microwave devices and optoelectronic devices find it difficult to directly and effectively generate signals in the terahertz frequency band between the two. Therefore, how to realize high-power terahertz sources has always been a key research topic. Currently, there are many methods to generate terahertz sources, such as optical mixing, infrared pumped gas lasers, quantum cascade lasers, and Schottky or heterojunction barrier variable reactance diodes. Frequency multipliers made using Schottky diodes have the advantages of relatively low cost, small size, and the ability to operate at room temperature, so they have been widely used.

[0005] The traditional design of a frequency doubler involves mounting a diode onto a quartz substrate, which is then mounted within a waveguide cavity to implement the frequency doubler. This introduces two assembly errors, leading to performance degradation, with the second error often being the primary source of error. An improved approach, integrating the diode onto a dielectric substrate, eliminates the first assembly error. However, due to the dielectric substrate's weak mechanical strength and its insertion into a waveguide cavity during assembly, it is prone to warping, which affects the performance of the diode and planar auxiliary circuitry, resulting in performance degradation. Using waveguides instead of microstrip / stripline circuits to implement some of the auxiliary circuitry can reduce the size of the dielectric substrate, thereby mitigating the effects of this deformation. However, this significantly increases the size of the frequency doubler, hindering integration. Summary of the Invention

[0006] In order to solve the problems existing in the prior art, the present invention provides a design method for an ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining, aiming to design a broadband frequency multiplier structure with excellent performance, small size, low processing cost and large-scale application.

[0007] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: an ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining, including an outer conductor and a waveguide probe transition structure, a low-pass filter, a diode chip, an impedance matching network and a probe waveguide transition structure connected in sequence from the radio frequency signal input to the output end. The waveguide probe transition structure and the probe waveguide transition structure provide a waveguide interface connecting the frequency multiplier to the test fixture; the low-pass filter is used to limit the flow direction of the frequency multiplier signal, suppress the frequency multiplier signal from flowing to the input end, and make it flow only from the output end. The low-pass filter adopts a structure with a loaded T-shaped SIR branch; the diode chip is used to achieve signal frequency multiplication, and the inner conductor of the coaxial line at the diode chip is provided to extend two mesas upward. The diode chip is mounted on the mesas in an inverted manner. The shape of the diode chip is "I" and "X", and the diode chip is connected to the outer conductor; the impedance matching network is used to achieve impedance matching between the front circuit and the output port.

[0008] One side of the waveguide-probe transition structure and the probe-waveguide transition structure is a coaxial line with an impedance of 50Ω, and the other side is a standard waveguide. Both the waveguide-probe transition structure and the probe-waveguide transition structure are transition structures. The transition structure includes a back cavity and a protruding rectangular probe. The back cavity provides a short-circuit surface for the waveguide structure. The rectangular probe is used to achieve impedance matching and mode matching between the waveguide and the coaxial line. The electromagnetic energy transmission mode in the coaxial line is TEM mode, and in the waveguide is TE10 mode.

[0009] There are five orders of low-pass filters. The first-order, third-order and fifth-order resonators are all in the form of high-impedance transmission lines. The second-order and fourth-order resonators are in the form of loaded branches, which are equivalent to low-impedance transmission lines. They can generate three out-of-band suppression zero points, which are near 110, 170 and 340 GHz respectively. Among them, the two zero points in the 100-200 GHz band are used to improve the stop-band suppression performance.

[0010] The total length of the low-pass filter is W7 = 1900 μm, the width of the inner conductor at both ends of the low-pass filter is L9 = 178 μm and L 10 =150μm, the width of the conductor inside the branch of the second-order resonator is L 11 =50μm, the width of the conductor inside the branch of the fourth-order resonator is L 12 =300μm, the length of the conductor inside the second-order resonator branch is W 16 =685μm, the length of the conductor inside the branch of the fourth-order resonator is W 17 +W 18 , W 17 =265μm, W 18 =290μm.

[0011] The diode chip is provided with four pairs of reverse-parallel diodes to realize a balanced structure.

[0012] The inner conductor where the diode chip is arranged extends upward to form two mesas, and the diode chip is attached upside down on the mesas.

[0013] The impedance matching network is realized by connecting a low impedance line in series between the diode chip and the probe waveguide transition structure. The low impedance line is equivalent to a capacitor. The specific dimensions of the low impedance line are: the total length of the low impedance line is W 26 =339μm, the width of the low impedance line is L 13 =300μm.

[0014] The dielectric support strips are arranged at intervals, the spacing between two adjacent dielectric support strips is 700μm, the thickness is H2=20μm, the total length is L4+2×L5, L4=440μm, L5=30μm, the width at both ends is W1=150μm, and the width in the middle is W2=100μm.

[0015] A release hole is provided on the outer conductor to assist in washing the adhesive. The length, width and height of the release hole are L8=250μm, W 10 =200μm, H3=200μm.

[0016] The test fixture of the ultra-wideband surface-mount frequency multiplier described in the present invention includes a back cavity plate, a waveguide connecting plate and a flange. The back cavity plate is used to provide the back cavity structure required for the input and output transition part of the frequency multiplier. The back cavity plate is provided with an input back cavity and an output back cavity. The waveguide connecting plate connects the frequency multiplier and the flange. The flange is a rectangular parallelepiped as a whole and is divided into four pieces perpendicular to its own connecting surface. The split surface is located at the mid-plane position, and the distance parallel to the length direction of the frequency multiplier is adjustable.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects: the present invention can effectively solve the shortcomings of traditional design ideas; since the relevant auxiliary circuit is realized by a micro-coaxial line made of copper, it has good mechanical stability and a small size. At the same time, the waveguide-probe transition structure at the input and output ends also avoids the error of the second part. Although the error of the first part still exists, it is not the main source of error and has little impact on the performance of the frequency multiplier. The ultra-wideband surface-mount frequency multiplier described in the present invention has signal output in the range of 100-200GHz, realizing ultra-wideband output.

[0018] Furthermore, the fifth-order low-pass filter is loaded with two T-shaped SIR branch structures. Compared with the traditional step impedance low-pass filter, it can achieve additional controllable transmission zeros while ensuring the design principle remains unchanged, which can suppress a specific frequency band range and thus improve the suppression effect of the stop band.

[0019] Furthermore, the diode chip is mounted in an inverted manner on a reserved pad composed of the inner conductor of the extended coaxial cable. By designing the shape of the diode chip into an "I" shape and a "X" shape, the chip is in direct contact with the outer conductor, which increases the heat dissipation channel and effectively reduces the thermal resistance. At the same time, the reverse-parallel diode pair can achieve a balanced structure, thereby offsetting all even harmonic components and leaving only odd harmonic components, thereby improving the utilization efficiency of signal power.

[0020] In summary, compared to conventional designs that implement all auxiliary circuits on waveguides and planar circuits, the frequency multiplier designed in this invention offers the advantages of reduced assembly errors, improved mechanical stability, smaller size, and ease of disassembly and replacement. Furthermore, because the three-dimensional metal micromachining process allows for mass production, the frequency multiplier designed in this invention can be used in large-scale practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] To more clearly illustrate the embodiments of the present invention or the prior art solutions, the following briefly introduces the drawings used in the embodiments or the prior art solutions. It should be noted that the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0022] The present invention will design a broadband frequency multiplier based on three-dimensional metal micromachining technology and Schottky diodes, which can provide certain reference significance for the future development of frequency multipliers in the millimeter wave / terahertz field.

[0023] Figure 1 Schematic diagram of a rectangular coaxial line based on a three-dimensional metal micromachining process provided by an embodiment of the present invention, (a) is a schematic diagram of a cross-section of the rectangular coaxial line, and (b) is a schematic diagram of a dielectric strip supporting a suspended inner conductor;

[0024] Figure 2 Schematic diagram of the input and output transition structure of an ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining provided by an embodiment of the present invention, (a) is a schematic diagram of the input end waveguide probe transition structure, and (b) is a schematic diagram of the output end probe waveguide transition structure;

[0025] Figure 3 Schematic diagram of a low-pass filter based on a three-dimensional metal micromachining process provided by an embodiment of the present invention, (a) is an overall schematic diagram of the low-pass filter, (b) and (c) are schematic diagrams of the inner conductor of the low-pass filter;

[0026] Figure 4Schematic diagrams of the diode chip portion of an ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining provided by an embodiment of the present invention. (a) is an overall schematic diagram of the "I"-shaped diode chip portion, (b) is an overall schematic diagram of the "X"-shaped diode chip portion, and (c) is a schematic diagram of the inner conductor of this portion.

[0027] Figure 5 Schematic diagram of an output impedance matching network for an ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining provided by an embodiment of the present invention, (a) is a schematic diagram of the impedance matching network as a whole, and (b) is a schematic diagram of the inner conductor of the impedance matching network;

[0028] Figure 6 An overall schematic diagram of an ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining provided by an embodiment of the present invention (the diode chip is shaped like an "I").

[0029] Figure 7 An overall schematic diagram of an ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining provided by an embodiment of the present invention (the diode chip is shaped like a cross);

[0030] Figure 8 An overall schematic diagram of a test auxiliary fixture for an ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining provided by an embodiment of the present invention;

[0031] Figure 9 A cross-sectional view of a test auxiliary fixture for an ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining provided by an embodiment of the present invention;

[0032] Figure 10 The test results of the output power of an ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining provided by an embodiment of the present invention are shown. DETAILED DESCRIPTION

[0033] In order to make the objects, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. It should be noted that the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the claims of the present invention.

[0034] In the description of the embodiments of the present invention, it should be understood that the orientations or positional relationships indicated by terms such as “length direction” and “vertical direction” are based on the orientations or positional relationships shown in the accompanying drawings. These are only for the convenience of describing the embodiments of the present invention and simplifying the description, and cannot be considered as indicating that the elements or devices indicated are in a specific orientation.

[0035] In the first aspect of an embodiment of the present invention, an ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining is designed, comprising a waveguide probe transition structure 1, a low-pass filter 2, a diode chip 3, an impedance matching network 4 and a probe waveguide transition structure 5. The waveguide probe transition structure 1 and the probe waveguide transition structure 5 are respectively located at the input and output ends of the radio frequency signal, so as to realize impedance matching and mode matching between the waveguide and the coaxial line, and play a role in transition of electromagnetic energy between the waveguide and the coaxial line; the low-pass filter is used to suppress the frequency-doubled signal from flowing to the input end so that it can only flow out from the output end. The present invention adopts a step impedance low-pass filter structure with a T-shaped SIR branch loading structure; the diode chip is used to realize the frequency doubling function of the signal, and a pair of reverse-parallel diodes is used in the design to realize a balanced structure to improve the efficiency of signal power utilization; the impedance matching network is used to realize impedance matching between the previous circuit and the output port, and is realized by a section of series low-impedance line.

[0036] The signal of the present invention is sequentially input from the waveguide probe transition structure 1, passes through the low-pass filter 2, the diode chip 3, the impedance matching network 4, and is output from the probe waveguide transition structure 5.

[0037] In the description of the embodiments of the present invention, the structural dimensions given are preferred parameters. With reference to the embodiments of the present invention, the dimensional parameters of each component may be modified to further obtain the actual required performance.

[0038] See also Figure 1 , Figure 1 A schematic diagram of a rectangular coaxial line based on a three-dimensional metal micromachining process provided in an embodiment of the present invention, (a) is a schematic diagram of a cross section of the rectangular coaxial line, and (b) is a schematic diagram of a dielectric strip supporting a suspended inner conductor.

[0039] The rectangular coaxial transmission line based on three-dimensional metal micromachining technology used in the present invention has a five-layer topological structure, such as Figure 1 As shown in (a), the first and fifth layers form the upper and lower walls of the outer conductor of the rectangular coaxial line. The second, third, and fourth layers constitute the side walls of the outer conductor of the rectangular coaxial line. The inner conductor of the rectangular coaxial line is located in the third layer. The thickness of each layer is H1 = 100μm, the width of the outer conductor is L1 = 400μm, and the width of the inner conductor is L2 = 178μm (the width of the inner conductor can be different values according to different impedance requirements; the impedance used in the present invention is 50Ω). After adding the side wall thickness, the width of the outer conductor is L3 = 600μm. In addition, since the inner conductor is suspended in the outer conductor, the inner and outer conductors are fixedly connected relative to each other by adding periodic dielectric support strips. Typically, the spacing between the two support strips is 700μm, and their thickness is H2 = 20μm. Figure 1(b) shows a top view of the support bar, and its corresponding specific dimensions are L4 = 440 μm, L5 = 30 μm, W1 = 150 μm, and W2 = 100 μm.

[0040] Figure 2 Schematic diagram of the input and output transition structure of an ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining provided in an embodiment of the present invention, (a) is a schematic diagram of the input end waveguide probe transition structure, and (b) is a schematic diagram of the output end probe waveguide transition structure.

[0041] The present invention uses a rectangular micro-coaxial transmission line to implement the relevant circuits of the frequency multiplier. Since the standard waveguide corresponding to the input frequency band is WR-19, with dimensions of a1=4.775mm and b1=2.388mm, and the standard waveguide corresponding to the output frequency band is WR-6.5, with dimensions of a2=1.651mm and b2=0.826mm, in order to connect to the fixture of the waveguide interface during testing, it is necessary to design a waveguide-coaxial line transition structure respectively. The waveguide probe transition structure 1 and the probe waveguide transition structure 5 are both transition structures. The transition structure includes a back cavity and an extended rectangular probe. The back cavity is used to provide a suitable short-circuit surface for the waveguide to reduce energy reflection. The back cavity is manufactured together with the fixture through CNC technology. The rectangular probe is used to achieve impedance matching and mode matching between the waveguide and the coaxial line; reference Figure 2 (a) and Figure 2 (b) The dimensions of the probe structure at the input end are as follows: the distance between the probe and the coaxial line is W3 = 502 μm, the width of the probe is W4 = 578 μm, and the length of the probe is L6 = 976 μm. The dimensions of the probe structure at the output end are as follows: the distance between the probe and the coaxial line is W5 = 106 μm, the width of the probe is W6 = 249 μm, and the length of the probe is L7 = 464 μm.

[0042] Figure 3 A schematic diagram of a low-pass filter based on a three-dimensional metal micromachining process provided by an embodiment of the present invention, wherein: Figure 3 (a) is the overall schematic diagram of the low-pass filter. Figure 3 (b) and Figure 3 (c) is a schematic diagram of the inner conductor of the low-pass filter.

[0043] The design concept of low-pass filter 2 is improved based on the traditional step-impedance low-pass filter. A T-shaped SIR branch loading structure is used to equivalently replace the low-impedance line part in the traditional design concept. While ensuring the design principle remains unchanged, it can achieve wide stopband suppression and high steepness. The position of the out-of-band suppression zero point can also be freely adjusted according to needs. The low-pass filter designed in this application has a total of five resonators, loaded with two T-shaped SIR branches. The low-pass filter 2 includes five resonators. The first-order resonator A, the third-order resonator C, and the fifth-order resonator E are all in the form of high-impedance transmission lines. The second-order resonator B and the fourth-order resonator D are in the form of loaded branches. The loaded branch of the second-order resonator B has a constant cross-section along the length direction, while the loaded branch of the fourth-order resonator D changes in two steps along the length direction. The low-pass filter is loaded with two T-shaped SIR branches, which acts as a low-impedance transmission line. This structure can produce three out-of-band suppression zeros, respectively, near 110 GHz, 170 GHz, and 340 GHz. Among them, the two zeros in the 100-200 GHz band can be used to improve the stopband suppression performance. In addition, the rectangular coaxial line is air-filled, but the air-filled part is photoresist during processing. In order to facilitate the cleaning of the glue after processing, some release holes need to be periodically opened on the outer conductor. The position of the release holes should be arranged as much as possible according to the principle of not affecting signal transmission. The specific dimensions of the optimized low-pass filter and release hole are as follows: the total length of the low-pass filter is W7 = 1900 μm, the lengths of the two branches are W8 = 460 μm and W9 = 330 μm, and the length, width and height of the release hole are L8 = 250 μm and W 10 = 200 μm, H3 = 200 μm, the size of the two branches relative to each other is W 11 =420μm, W 12 =50μm, the width of the inner conductor at both ends is L9=178μm, L 10 =150μm, the width of the conductor in the two branches is L 11 =50μm, L 12 =300μm, the length of the inner conductor of each part is W 13 =668μm, W 14 =1152μm, W 15 =80μm, W 16 =685μm, W 17 =265μm, W 18 =290μm.

[0044] Figure 4 A schematic diagram of a diode chip portion of an ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining provided by an embodiment of the present invention. Figure 4 (a) is the overall schematic diagram of the “I”-shaped diode chip. Figure 4(b) is the overall schematic diagram of the "cross" shaped diode chip part. Figure 4 (c) is a schematic diagram of the inner conductor of this part.

[0045] The diode chip is processed separately, so a mounting position needs to be reserved. The inner conductor can be extended upward to form two mesas, and the diode chip can be mounted on them upside down. In addition, the shape of the diode chip is designed to be an "I" shape and a "X" shape. After mounting, it can directly contact the outer conductor. The part of the diode chip 3 extending out of the body is connected to the outer conductor; the heat dissipation channel of the diode chip is increased, which can improve the heat dissipation performance of the frequency multiplier. The present invention is designed with four pairs of reverse parallel diode chips to achieve the frequency doubling function, such as Figure 4 As shown. The total length of this part is W 19 =797μm, the common sidewall thickness is W 20 =62μm, the length of the inner conductor is W 21 =135μm, W 22 =100μm, W 23 =200 μm, and the height of the mesa is H4 =300 μm.

[0046] Figure 5 A schematic diagram of an output impedance matching network of an ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining provided by an embodiment of the present invention. Figure 5 (a) is the overall schematic diagram of the impedance matching network. Figure 5 (b) Schematic diagram of the inner conductor of the impedance matching network.

[0047] In order to offset the effect of the imaginary part of the output port impedance, the present invention implements impedance matching by adding a low-impedance line (equivalent to a capacitor) in series, thereby improving the reflection characteristics of the output end and increasing the output power of the frequency multiplier, while basically not affecting the characteristics of the input part of the frequency multiplier. The specific dimensions of the impedance matching part are as follows: the total length is W 24 =802μm, the length of the left transmission line connected to the low impedance line is W 25 =191μm, the length of the low impedance line is W 26 = 339μm, the length of the right transmission line connected to the low impedance line is W 27 = 273μm, the width of the low impedance line is L 13 =300μm.

[0048] Figure 6 and Figure 7 The overall schematic diagrams of an ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining provided by an embodiment of the present invention are respectively (the shapes of the diode chips are "I" and "X" respectively); Figure 8 and Figure 9They are respectively an overall schematic diagram and a cross-sectional view of a test auxiliary fixture for an ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining provided by an embodiment of the present invention; Figure 10 The test results of the output power of an ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining provided by an embodiment of the present invention are shown.

[0049] The overall structure of the frequency multiplier formed by combining the various parts is as follows Figure 6 and Figure 7 As shown, in order to test the performance of the frequency multiplier, the present invention also designs a set of auxiliary test fixtures, such as Figure 8 and Figure 9 As shown in the figure, the first part of the fixture is the back cavity plate 101, which is used to provide the back cavity structure required for the input and output transition part of the frequency multiplier 102, namely the input back cavity 101a and the output back cavity 101b. The second part is the waveguide connecting plate 103, which connects the frequency multiplier 102 and the third part flange 104. It is worth noting that the flange structure 104 designed by the present invention can be compatible with frequency multipliers of different lengths in the same frequency band. The flange 104 is a rectangular parallelepiped as a whole and is divided into four pieces perpendicular to its own connecting surface, namely the first piece 104a, the second piece 104b, the third piece 104c and the fourth piece 104d. The dividing surface is located at the mid-plane position, and the distance parallel to the length direction of the frequency multiplier is adjustable, that is, by adjusting the distance d between the first piece 104a, the second piece 104b and the third piece 104c, the fourth piece 104d, so that the test fixture can be reused. Figure 10 This is the test result of a frequency multiplier provided by the present invention. It can be obtained that within the entire required output frequency band (110-170GHz), the output power is above 1.3mW, which can meet actual needs and prove the effectiveness of the designed frequency multiplier.

[0050] The above is a description of the design method for an ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining provided by the present invention. Those skilled in the art will appreciate the various variations in the specific implementation and scope of application based on the principles of the present invention. In summary, this description should not be construed as limiting the present invention.

Claims

1. An ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining, characterized in that: The invention comprises a waveguide probe transition structure (1), a low-pass filter (2), a diode chip (3), an impedance matching network (4) and a probe waveguide transition structure (5) connected in sequence from the input end to the output end. The waveguide probe transition structure (1) and the probe waveguide transition structure (5) provide a waveguide interface for connecting the frequency multiplier to the test fixture; the low-pass filter (2) is used to limit the flow direction of the frequency multiplier signal, inhibit the frequency multiplier signal from flowing to the input end, and make it flow only from the output end. The low-pass filter adopts a structure with a loaded T-shaped SIR branch; the diode chip (3) is used to realize the frequency multiplication of the signal, and the inner conductor of the coaxial line at the diode chip (3) extends upward to two tables. The diode chip is mounted on the two tables in an inverted manner. The shape of the diode chip is "I" and "X", and the diode chip is connected to the outer conductor; the impedance matching network (4) is used to realize the impedance between the front circuit and the output port. Matching; one side of the waveguide probe transition structure (1) and the probe waveguide transition structure (5) is a coaxial line with an impedance of 50Ω, and the other side is a standard waveguide; the waveguide probe transition structure (1) and the probe waveguide transition structure (5) are both transition structures, and the transition structure includes a back cavity and a protruding rectangular probe, the back cavity provides a short-circuit surface for the waveguide structure, and the rectangular probe is used to achieve impedance matching and mode matching between the waveguide and the coaxial line. The low-pass filter (2) has five orders in total, the first-order resonator, the third-order resonator and the fifth-order resonator are all in the form of high-impedance transmission lines, and the second-order resonator and the fourth-order resonator are in the form of loaded branches, which are equivalent to low-impedance transmission lines; the diode chip (3) is provided with four pairs of reverse-parallel diode pairs to achieve a balanced structure; the impedance matching network (4) is realized in the form of a low-impedance line in series between the diode chip (3) and the probe waveguide transition structure (5), and the low-impedance line is equivalent to a capacitor.

2. The ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining according to claim 1, characterized in that: The electromagnetic energy transmission mode in the coaxial cable is the TEM mode, and in the waveguide is the TE10 mode.

3. The ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining according to claim 1, characterized in that: The low-pass filter (2) can generate three out-of-band suppression zero points, which are located near 110, 170 and 340 GHz respectively, of which two zero points in the 100-200 GHz band are used to improve the stop-band suppression performance.

4. The ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining according to claim 3, characterized in that: The total length of the low-pass filter (2) is W 7=1900 mm, the width of the inner conductor at both ends of the low-pass filter (2) is L 9=178mm and L 10 =150 mm, the width of the conductor inside the branch of the second-order resonator is L 11 =50mm, the width of the conductor inside the branch of the fourth-order resonator is L 12 =300 mm, the length of the conductor inside the branch of the second-order resonator is W 16 =685mm, the length of the conductor inside the branch of the fourth-order resonator is W 17 + W 18 , W 17 =265mm, W 18 =290mm.

5. The ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining according to claim 1, characterized in that: The specific dimensions of the low impedance line are: The total length of the low impedance line is W 26 =339mm, the width of the low impedance line is L 13 =300mm.

6. The ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining according to claim 1, characterized in that: The medium support strips are arranged at intervals, with the spacing between two adjacent medium support strips being 700mm and the thickness being H 2=20mm, total length is L 4+2× L 5. L 4=440mm, L 5=30mm, the width at both ends is W 1=150mm, the width in the middle is W 2=100mm.

7. The ultra-wideband surface-mount frequency multiplier based on three-dimensional metal micromachining according to claim 1, characterized in that: A release hole (6) is provided on the outer conductor, and the release hole (6) is used to assist in washing the glue. The length, width and height of the release hole (6) are respectively L 8=250 mm, W 10 =200 mm, H 3=200 mm.

8. The test fixture for the ultra-wideband surface-mount frequency multiplier according to any one of claims 1 to 7, characterized in that: The invention comprises a back cavity plate (101), a waveguide connecting plate (103) and a flange (104). The back cavity plate (101) is used to provide a back cavity structure required for the input and output transition part of the frequency multiplier (102). An input back cavity (101a) and an output back cavity (101b) are provided on the back cavity plate (101). The waveguide connecting plate (103) connects the frequency multiplier (102) and the flange (104). The flange (104) is in the shape of a rectangular parallelepiped as a whole and is divided into four pieces perpendicular to its own connecting surface. The dividing surface is located at the mid-plane position, and the distance parallel to the length direction of the frequency multiplier is adjustable.

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