Short line matching microwave transmission structure for high-temperature superconducting quantum voltage standard

Abstract

The invention relates to a short line matching microwave transmission structure for a high-temperature superconducting quantum voltage standard, and the structure comprises a transmission matching structure which comprises a bonding wire group and a matching network; the bonding wire group is respectively connected with the coplanar waveguide and the matching network, parasitic impedance is introduced, and the parasitic impedance and initial load impedance of the coplanar waveguide form composite load impedance; the coplanar waveguide is used for transmitting a microwave signal to the Josephson junction array, and quantum voltage is generated through coupling; wherein the matching network is used for receiving a microwave signal and comprises an adjusting assembly, and the adjusting assembly is used for adjusting a capacitance value and / or an inductance value of the matching network, so that the matching network realizes impedance matching between input impedance and composite load impedance under the microwave signal in a preset frequency range. The power entering the junction array chip and the uniformity of the microwave amplitude are improved, and the output quality of the junction is improved.

Description

Technical Field

[0001] This application relates to the field of microwave technology, and in particular to a short-line matched microwave transmission structure for high-temperature superconducting quantum voltage standards. Background Technology

[0002] The standard voltage generated by the standard battery used in traditional voltage references is affected by temperature, vibration, and charging / discharging, and the value drifts over time, making it difficult to unify the values ​​reproduced by different countries. Quantum voltage standard systems based on Josephson junction arrays can be divided into two types according to their operating temperature: low-temperature Josephson junctions (4.2K liquid helium) and high-temperature Josephson junctions (77K liquid nitrogen).

[0003] Low-temperature superconducting materials, due to their highly mature technology, can integrate thousands to tens of thousands of junctions through precision photolithography, stably outputting quantum DC voltages at the 10-volt level. However, they are extremely expensive, difficult to maintain, and result in bulky equipment that is difficult to deploy in the field. High-temperature superconducting materials, on the other hand, have significantly higher critical temperatures and can operate in the relatively readily available liquid nitrogen environment. This leads to a substantial reduction in cooling costs and greatly simplifies the cooling system.

[0004] However, due to limitations in the properties of high-temperature superconducting materials and the bottlenecks in fabrication processes, it is difficult to achieve stable and controllable large-scale series integration of Josephson junction arrays, preventing the output voltage amplitude from reaching the level of low-temperature superconducting Josephson junction arrays. Furthermore, for series-connected junction arrays, the more junctions there are, the higher the upper limit of the voltage generated by the array, but the lower the probability of it simultaneously being in a quantum voltage step state under certain conditions. Summary of the Invention

[0005] Based on this, it is necessary to address the technical problems in the existing technology by providing a short-line matched microwave transmission structure for high-temperature superconducting quantum voltage standards, which can at least enable the junction array to output a higher-order voltage step and improve the upper limit of the output voltage of a single junction.

[0006] In a first aspect, this application provides a short-line matched microwave transmission structure for a high-temperature superconducting quantum voltage standard system, comprising:

[0007] Transmission matching structure, including bonding wire bundles and matching network;

[0008] The bonding wires are connected to the coplanar waveguide and the matching network, respectively, and introduce parasitic impedance. The parasitic impedance and the initial load impedance of the coplanar waveguide form a composite load impedance. The coplanar waveguide is used to transmit microwave signals to the Josephson junction array and couple to generate quantum voltage.

[0009] The matching network is used to receive microwave signals and includes an adjustment component. The adjustment component is used to adjust the capacitance and / or inductance of the matching network so that the matching network achieves impedance matching between the input impedance and the composite load impedance under microwave signals within a preset frequency range.

[0010] In some embodiments, the bonding wire group includes at least three bonding wires respectively connected to the coplanar waveguide; the center-to-center spacing of the bonding wires ranges from 0.25mm to 0.35mm.

[0011] In some embodiments, the matching network includes at least two impedance matching units;

[0012] At least two impedance matching units, including:

[0013] The input terminal of the first impedance matching unit is used to receive the microwave signal;

[0014] The input of the second impedance matching unit is connected to the output of the first impedance matching unit, and the output is connected to the input of the bonded wire assembly.

[0015] In some embodiments, the first impedance matching unit includes:

[0016] The first capacitor is configured such that its first terminal is used to receive the microwave signal and its second terminal is grounded.

[0017] The first inductor is configured such that its first terminal is connected to the first terminal of the first capacitor, and its second terminal is grounded.

[0018] The first coplanar waveguide is configured such that its first end is connected to the first end of the first capacitor;

[0019] The second impedance matching unit includes:

[0020] The second capacitor is configured such that its first end is connected to the second end of the first coplanar waveguide, and its second end is grounded.

[0021] The second inductor is configured such that its first terminal is connected to the second terminal of the second capacitor, and its second terminal is grounded.

[0022] The second coplanar waveguide is configured such that its first end is connected to the second end of the first coplanar waveguide, and its second end is connected to a bonding wire assembly.

[0023] In some embodiments, the preset frequency range is 1GHz-20GHz.

[0024] In some embodiments, the length of the bonding wire is on the order of mm.

[0025] In some embodiments, the short-line matched microwave transmission structure further includes a control module electrically connected to the adjustment component and configured to output an adjustment signal according to any frequency within a preset frequency range, thereby controlling the adjustment component to change the capacitance and / or inductance values ​​to achieve impedance matching at the corresponding frequency.

[0026] In some embodiments, the control module includes:

[0027] The processor unit is used to calculate the required capacitance and / or inductance values ​​based on the microwave signal frequency within a preset frequency range, and to generate corresponding adjustment signals;

[0028] The interface unit is used to receive external frequency control commands and transmit the adjustment signals to the adjustment components of the matching network.

[0029] Secondly, this application also provides a high-temperature superconducting quantum voltage standard system, including the short-line matched microwave transmission structure described in any of the above embodiments.

[0030] In some embodiments, the high-temperature superconducting quantum voltage standard system includes:

[0031] The microwave signal module includes a microwave source and a time base module connected to the microwave source; the microwave source is used to provide microwave signals, and the time base module is used to provide traceable time signals to the microwave source using a rubidium atomic clock;

[0032] Josephson junction array, connected to a coplanar waveguide.

[0033] In the short-wire matched microwave transmission structure for high-temperature superconducting quantum voltage standards provided in the above embodiments, the microwave signal generated by the microwave signal module and coupled to the Josephson junction array is transmitted through a matching network in the matching structure. This network adjusts the capacitance and / or inductance values ​​to achieve impedance matching between the input impedance and the composite load impedance. This effectively eliminates reflections caused by impedance mismatch at the bond wire group, thereby ensuring uniform microwave voltage amplitude across the Josephson junction, improving the voltage output quality of the Josephson junction array, and increasing the possibility of outputting quantum voltage.

[0034] In addition, the matching network's adjustment components can be adjusted after manufacturing or deployment by adjusting the corresponding values ​​of the capacitor and / or inductor elements within the impedance matching unit. This allows the matching network to dynamically adjust the impedance matching within a preset frequency range, adapting to different operating frequencies or wideband operation without requiring the replacement of physical components, thus improving flexibility and versatility.

[0035] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 The IV curve of the Josephson single-junction in the RSJ model;

[0038] Figure 2 This is a schematic diagram of the curve of the Bessel function;

[0039] Figure 3 This is a schematic diagram illustrating impedance matching achieved by the transmission matching structure provided in one embodiment of this application;

[0040] Figure 4 This is a schematic diagram of the test system structure of the high-temperature superconducting quantum voltage standard system provided in one embodiment of this application;

[0041] Figure 5 for Figure 4 The circuit principle block diagram of the structure within the dashed box;

[0042] Figure 6 This is a schematic diagram of the equivalent circuit model of the bond wire;

[0043] Figure 7 A comparison of the frequency response of S21 transmission parameters under different parasitic parameters;

[0044] Figure 8 This is a circuit schematic diagram of a matching network provided in one embodiment of this application;

[0045] Figure 9 for Figure 8 The simulation results of the circuit structure shown are illustrated.

[0046] Figure 10 This is a simplified circuit diagram of a matching network provided in one embodiment of this application;

[0047] Figure 11 This is a circuit schematic diagram of a matching network provided in another embodiment of this application;

[0048] Figure 12 for Figure 11 The S-parameter simulation results of the circuit structure shown are illustrated.

[0049] Figure 13 The figure shows the simulation results of S-parameters without impedance matching.

[0050] Explanation of reference numerals in the attached figures:

[0051] 10. Microwave signal module; 11. Microwave source; 12. Time base module; 13. Microwave connector; 2. Josephson junction array; 30. Transmission matching structure; 31. Bonding wire group; 32. Matching network; 321. First impedance matching unit; 3211. First capacitor; 3212. First inductor; 3213. First coplanar waveguide; 322. Second impedance matching unit; 3221. Second capacitor; 3222. Second inductor; 3223. Second coplanar waveguide. Detailed Implementation

[0052] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0054] When using the terms “including,” “having,” and “comprising” as described herein, another component may be added unless explicitly qualifying terms such as “only,” “consisting of,” etc. are used. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.

[0055] It should be understood that although the terms “first,” “second,” etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of this application, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0056] In this application, unless otherwise expressly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a direct connection or an indirect connection through an intermediate medium, or the internal connection of two components or the interaction between two components. For those skilled in the art, if the connected circuits, modules, units, etc., transmit electrical signals or data to each other, they should be understood as "electrical connection," "communication connection," etc.

[0057] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, integrals, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, integrals, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items. In the description of this specification, references to the terms “some embodiments,” “other embodiments,” etc., mean that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0058] Microwave coupling methods are mainly divided into two types: on-chip microwave coupling and microwave irradiation coupling. On-chip microwave coupling is generally simpler in structure and more flexible in deployment, while microwave irradiation can transmit microwaves at higher frequencies.

[0059] Resistively Shunted Junction (RSJ) Model: Josephson Junction has two operating states as follows: Figure 1 As shown, where I c R represents the critical current. n Indicates the normal resistance. Figure 1 Figure a shows the IV curve of the Josephson junction without microwave application. Figure 1 Figure b shows the IV curve after applying microwaves. The voltage step generated by the single junction is as follows:

[0060]

[0061] in, The frequency of the applied microwave is represented by , n is the order of the quantum voltage step, and Φ0 = 2.067 × 10⁻¹⁵ Wb is the magnetic flux quantum. The width of the voltage step generated by the single junction is:

[0062]

[0063] Among them, V e It is the amplitude of the microwave voltage on the Josephson junction, e is the elementary charge, and J is the amplitude of the microwave voltage on the Josephson junction. n Let represent the nth-order Bessel function. The expression for the Bessel function is as follows: Figure 2 As shown:

[0064] The quantum voltage generated by a single junction is on the order of μV. To obtain a higher quantum voltage output, Josephson junctions are usually connected in series to form an array. As the number of series junctions increases, the upper limit of the theoretical output voltage of the array also increases, but the individual junctions' I... c R n Differences in the quantum voltage steps make it difficult to synchronize and enter a stable quantum voltage step state—and the more junctions there are, the lower the probability of this synchronization. Ultimately, this results in the quantum voltage steps output by the array exhibiting problems such as uneven width, low overlap of current ranges, and poor long-term stability, significantly degrading the overall step quality.

[0065] Furthermore, due to structural limitations, chips and microwave circuits cannot be connected using standard microwave devices; bonding wires are typically required. Because of the impedance mismatch between the bonding wires and standard microwave devices, signal reflection occurs at the bonding wires, resulting in power loss. Figure 2 And combined with quantum voltage width I n From the expression, we can see that the amplitude of the microwave voltage on the junction also affects the width of the quantum voltage step, which in turn affects the output effect of the final junction array.

[0066] Please see Figures 3-5 Based on this, this application provides a short-line matched microwave transmission structure for a high-temperature superconducting quantum voltage standard system, wherein the system includes:

[0067] Microwave signal module 10, used to provide microwave signals, has an input impedance Z0;

[0068] Josephson junction array 20 is used to receive microwave signals transmitted via a coplanar waveguide and couple with the microwave signals to generate a quantum voltage; the coplanar waveguide has an initial load impedance Z. L .

[0069] The microwave transmission structure includes:

[0070] The transmission matching structure 30 includes a bonding wire group 31 and a matching network 32; the bonding wire group 31 is connected to the coplanar waveguide and introduces a parasitic impedance Z. RLC Parasitic impedance Z RLC With initial load impedance Z L A composite load impedance Z1 is formed; the matching network 32 is connected to the microwave signal module 10 and the bonding wire group 31 respectively.

[0071] The matching network 32 includes an adjustment component (not shown), which is used to adjust the capacitance and / or inductance values ​​of the matching network 32, so that the matching network 32 achieves impedance matching between the input impedance Z0 and the composite load impedance Z1 under microwave signals within a preset frequency range, specifically as follows: Figure 3 As shown; the material of Josephson junction array 20 includes any high-temperature superconducting material.

[0072] Specifically, the high-temperature superconducting quantum voltage standard system testing system is constructed as follows: Figure 4 As shown, the DC signal section, consisting of an ammeter and a current source, provides bias current to the Josephson junction array 20 and measures the quantum voltage; the microwave signal output by the microwave signal module 10 and the transmission matching structure 30 is coupled to the Josephson junction array 20 to generate the quantum voltage.

[0073] Specifically, microwaves, as electromagnetic waves with frequencies ranging from 300MHz to 300GHz, have wavelengths between 1m and 1mm. For microwaves, the wavelength is no longer significantly longer than the transmission line length. At any given moment, the current and voltage values ​​at different locations on the transmission line are no longer the same. Microwave transmission in an impedance-matched transmission line is a traveling wave state, where only the incident wave exists and there are no reflected waves; the voltage amplitude is the same at all locations on the transmission line. If there are mismatch points in the transmission line, reflection will occur, resulting in a reflected wave. In this case, the line will exhibit a superposition of the incident and reflected waves, forming a standing wave or a traveling-standing wave state. At this point, the amplitude at different locations on the microwave transmission line is no longer the same.

[0074] Therefore, in the above embodiments, by adding a matching network 32 with adjustable matching points before the bonding wire group 31, the phenomenon of uneven microwave coupling is eliminated, forming microwaves in a traveling wave state, so that the V induced on the junction array e Similarly, it increases the possibility of the output quantum voltage step of the junction array, and also increases the possibility of generating higher-order steps. For Josephson junction arrays with a limited number of junctions, it can effectively increase the upper limit of its quantum voltage output.

[0075] The following is in conjunction with the appendix Figure 4 - Appendix Figure 13 The short-line matched microwave transmission structure provided in this application will be further explained.

[0076] Figure 4 The circuit block diagram of the dashed section is as follows: Figure 5 As shown, the microwave signal module 10 includes a time base module 12 that uses a rubidium atomic clock to provide a traceable time signal to the microwave source 11, ensuring the reliability of the microwave signal frequency output by the microwave source 11. Of course, the microwave signal module 10 may also include other electrical components such as a microwave connector 13, but since these are not the focus of this invention, they will not be discussed further here.

[0077] Please see Figures 6-9 In some embodiments, the bonding wire group 31 includes at least three bonding wires respectively connected to the coplanar waveguide. Due to limitations in the fabrication process of Josephson junction array chips, such as Figure 4The distance between the bonding terminals on the junction array chip and the bonding terminals on the printed circuit board (PCB) typically needs to be 3mm-5mm. In this embodiment, the actual bonding wire length used is on the order of mm, specifically 4mm in length, 0.2mm in height, and 35μm in width. The equivalent module of the bonding wire is as follows: Figure 6 As shown. From input port Z in The impedance expression at this point is:

[0078]

[0079] An equivalent circuit model of the bond wire was established in ANSYS Q3D Extractor software. Since the preset frequency range is 1GHz-20GHz, in this embodiment, the solution frequency is selected as 10GHz. The extracted circuit model is shown below. Figure 6 The parasitic parameters obtained in the equivalent circuit are: C = 47.59 fF, R = 1.46 Ω, L = 3.13 nH. When the load impedance Z... L =50Ω, for Figure 3 The parameters in the figure are used as standard values ​​of 2nH, 2Ω, and 50fF, and are varied up and down to obtain the following results: Figure 7 The diagram shows a comparison of the frequency response of the S21 transmission parameters under different capacitances C, inductances L, and resistors R.

[0080] It should be understood that in this embodiment, the transmission process from the microwave source 11 to the coplanar waveguide on the PCB uses standard 50Ω characteristic impedance microwave connection devices. Of course, other characteristic impedance microwave connection devices can be selected according to the actual application scenario.

[0081] Depend on Figure 7 It can be seen that, at the millimeter level, the inductance L has the greatest impact on the results, while changes in capacitance C and resistance R have little effect. The more bonding wires and the greater their spacing, the better the effect. In this embodiment, three parallel bonding wires are provided, with their centers spaced 0.3 mm apart. The resulting inductance matrix is ​​as follows:

[0082]

[0083] The equivalent inductance at this point is:

[0084]

[0085] Substituting the values ​​into the calculation, the equivalent inductance is 1.51nH, which is a significant decrease compared to 3.13nH before parallel connection. According to... Figure 7 It can be seen that even without impedance matching, there is a significant improvement.

[0086] Based on this, a fixed-point matching structure was used at 10 GHz with C=50fF, R=2Ω, and L=1nH, 2nH, and 3nH respectively. A grounded coplanar waveguide (CPWG) was used as the microwave transmission line, and the signal termination (TermG) represented the input / output ports. Using a Rogers high-frequency board with a thickness of 1.5mm and a dielectric constant of 3.38, and a transmission line thickness of 0.035mm, the design and simulation were performed using the Smith chart, resulting in the following... Figure 8 The matching network circuit schematic shown, and as follows Figure 9 The simulation results, from top to bottom, represent impedance matching at a 10GHz frequency with inductance values ​​of 3nH, 2nH, and 1nH. The S-parameters describe how the RF signal responds to the values ​​at the device ports by specifying the amplitude and phase of the reflected signal. S11 represents the reflection coefficient of port 1 when port 2 is matched; S22 represents the reflection coefficient of port 2 when port 1 is matched; S12 represents the reverse transmission coefficient from port 2 to port 1 when port 1 is matched; and S21 represents the forward transmission coefficient from port 1 to port 2 when port 2 is matched.

[0087] Depend on Figure 9 It is known that in impedance matching of bonding wires on the order of mm, reducing the equivalent inductance by connecting multiple bonding wires in parallel before impedance matching can improve the bandwidth after matching.

[0088] Please see Figures 10-11 In some embodiments, the matching network 32 includes at least two impedance matching units.

[0089] like Figure 10 As shown, in the first impedance matching unit 321, the first terminal of the first capacitor 3211 is connected to the output terminal of the microwave signal module, and the second terminal is grounded; the first terminal of the first inductor 3212 is connected to the first terminal of the first capacitor 3211, and the second terminal is grounded; the first terminal of the first coplanar waveguide 3213 is connected to the first terminal of the first capacitor 3211. In the second impedance matching unit 322, the first terminal of the second capacitor 3221 is connected to the second terminal of the first coplanar waveguide 3213, and the second terminal is grounded; the first terminal of the second inductor 3222 is connected to the second terminal of the second capacitor 3221, and the second terminal is grounded; the first terminal of the second coplanar waveguide is connected to the second terminal of the first coplanar waveguide 3213, and the second terminal is connected to the bonding wire group 31.

[0090] Specifically, l1 and l2 are typically 1 / 8λ and 3 / 8λ respectively, but this is not strictly limited. The lengths of l1 and l2 can also be adjusted by using variable capacitors and variable inductors. The length of subsequent structures is determined by the 10GHz matching point. The length of l3 has no impact on the result after matching and can be used to adjust the length of the transmission line.

[0091] For example, the capacitance values ​​of the first capacitor 3211 and the second capacitor 3221 can be changed by voltage control or mechanical adjustment, but not limited to; the inductance values ​​of the first inductor 3212 and the second inductor 3222 can be changed by magnetic core displacement or coil turns switching, but not limited to.

[0092] Since the capacitance C in the parasitic parameters remains largely unchanged with frequency, while the resistance R and inductance L do change with frequency (but the inductance changes only slightly above 1 GHz), and the resistance changes approximately linearly with frequency, changes in resistance have almost no impact on microwave transmission performance. Therefore, using parameters from 10 GHz to replace parasitic parameters from 1-20 GHz will not result in significant deviations.

[0093] Please see Figures 11-12 In some embodiments, the short-line matching microwave transmission structure further includes a control module (not shown), electrically connected to the adjustment component. The module includes a processor unit for calculating the required capacitance and / or inductance values ​​based on the microwave signal frequency within a preset frequency range and generating a corresponding adjustment signal; and an interface unit for receiving external frequency control commands and transmitting the adjustment signal to the adjustment component of the matching network. For example, by using the adjustment component and interface unit instead of manually tightening screws, the inductance / capacitance values ​​can be changed by rotating the screws, thereby achieving automatic switching of the impedance matching frequency point. Of course, other methods can also be used to adjust the capacitance and / or inductance values, which are not limited here.

[0094] Through the synergy of the aforementioned units, the control module can achieve closed-loop control of the matching network. Without manual disassembly or adjustment of the circuit, it can quickly adapt to any frequency within a preset frequency range, significantly improving the impedance matching efficiency and accuracy of short-line matched microwave transmission structures in multi-frequency scenarios. Specifically, taking C=50fF, R=2Ω, and L=2nH as examples, impedance matching at matching points at 5GHz, 10GHz, and 15GHz is performed respectively. The circuit schematic is shown below. Figure 11 As shown in the figure, the simulation results are as follows: Figure 12 As shown, the S-parameter curve without impedance matching is as follows: Figure 13 As shown.

[0095] To illustrate the above-mentioned technical solutions of this application, specific embodiments are described below.

[0096] The short-line matched microwave transmission structure used for high-temperature superconducting quantum voltage standards in this embodiment of the application has the following unexpected technical effects:

[0097] Compared to Josephson junction arrays without impedance matching at the bond lines, the standing wave or traveling-standing wave states further increase uncertainty, hindering the emergence of high-quality quantum voltage steps in large-scale arrays. For a Josephson junction array that has already been fabricated, its I...c R n Since the parameters are no longer easily adjustable, the short-line matched microwave transmission structure proposed in this application starts with microwave uniformity. First, it reduces the equivalent inductance by connecting multiple bonding wires in parallel. Then, it adds a matching network before the bonding wire group to suppress signal reflection caused by impedance mismatch at the bonding wire group. This effectively improves the microwave power utilization rate input to the Josephson junction array and ensures that the microwave voltage amplitude of each Josephson junction in the array is consistent. This supports the stable output of high-order quantum voltage steps of the junction array, breaks through the inherent upper limit of the single-junction output voltage, and greatly improves the stability and reliability of the output quantum voltage of the junction array.

[0098] In the design of the matching network, adjustable capacitors and adjustable inductors are used to replace the short circuits and open circuits in short-line matching, so as to realize the dynamic adjustment of the impedance matching point, adapt to and utilize the wide operating frequency range of the Josephson junction array, and ensure that the matching parameters can be quickly calibrated within the preset frequency range to maintain an efficient impedance matching effect.

[0099] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0100] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A short-line matched microwave transmission structure, characterized in that, For use in high-temperature superconducting quantum voltage standard systems, including: Transmission matching structure, including bonding wire bundles and matching network; The bonding wire group is connected to the coplanar waveguide and the matching network respectively, and introduces parasitic impedance. The parasitic impedance and the initial load impedance of the coplanar waveguide form a composite load impedance. The coplanar waveguide is used to transmit microwave signals to the Josephson junction array and couple to generate quantum voltage. The matching network is used to receive the microwave signal and includes an adjustment component. The adjustment component is used to adjust the capacitance and / or inductance of the matching network so that the matching network achieves impedance matching between the input impedance and the composite load impedance under microwave signals within a preset frequency range.

2. The short-line matched microwave transmission structure according to claim 1, characterized in that, The bonding wire group includes at least three bonding wires respectively connected to the coplanar waveguide, and the center-to-center spacing of the bonding wires ranges from 0.25mm to 0.35mm.

3. The short-line matched microwave transmission structure according to claim 2, characterized in that, The matching network includes at least two impedance matching units; At least two of the impedance matching units, including: The input terminal of the first impedance matching unit is used to receive the microwave signal; The input of the second impedance matching unit is connected to the output of the first impedance matching unit, and the output is connected to the input of the bonding wire assembly.

4. The short-line matched microwave transmission structure according to claim 3, characterized in that, The first impedance matching unit includes: The first capacitor is configured such that its first terminal is used to receive the microwave signal and its second terminal is grounded. The first inductor is configured such that its first terminal is connected to the first terminal of the first capacitor, and its second terminal is grounded. The first coplanar waveguide is configured such that its first end is connected to the first end of the first capacitor; The second impedance matching unit includes: The second capacitor is configured such that its first end is connected to the second end of the first coplanar waveguide, and its second end is grounded. The second inductor is configured such that its first terminal is connected to the second terminal of the second capacitor, and its second terminal is grounded. The second coplanar waveguide is configured such that its first end is connected to the second end of the first coplanar waveguide, and its second end is connected to the bonding wire group.

5. The short-line matched microwave transmission structure according to claim 1, characterized in that, The preset frequency range is 1GHz-20GHz.

6. The short-line matched microwave transmission structure according to any one of claims 1-5, characterized in that, The length of the bonding wire is on the order of mm.

7. The short-line matched microwave transmission structure according to any one of claims 1-5, characterized in that, Also includes: A control module, electrically connected to the adjustment component, is configured to output an adjustment signal according to any frequency within a preset frequency range, controlling the adjustment component to change the capacitance value and / or the inductance value, thereby achieving impedance matching at the corresponding frequency.

8. The short-line matched microwave transmission structure according to claim 7, characterized in that, The control module includes: The processor unit is used to calculate the required capacitance and / or inductance values ​​based on the microwave signal frequency within the preset frequency range, and to generate corresponding adjustment signals. An interface unit is used to receive external frequency control commands and transmit the adjustment signal to the adjustment component of the matching network.

9. A high-temperature superconducting quantum voltage standard system, characterized in that, The microwave transmission structure including the short-line matching as described in any one of claims 1-8.

10. The high-temperature superconducting quantum voltage standard system according to claim 9, characterized in that, include: A microwave signal module includes a microwave source and a time base module connected to the microwave source; The microwave source is used to provide microwave signals, and the time base module is used to provide traceable time signals for the microwave source using a rubidium atomic clock; A Josephson junction array is connected to the coplanar waveguide.

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