A method and apparatus for s-parameter testing of high frequency soft band
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ACCELINK TECHNOLOGIES CO LTD
- Filing Date
- 2021-10-08
- Publication Date
- 2026-07-21
AI Technical Summary
Existing technologies cannot effectively test the high-frequency softband S-parameters of asymmetric designs, and the testing methods are complex or costly.
By combining two identical test pieces into a port-symmetrical combination and testing them using the same fixture, the S-parameter combination can be obtained. The S-parameters of each part can be calculated based on the port symmetry, simplifying the fixture manufacturing and testing process and reducing equipment errors.
It enables simplified testing of asymmetric high-frequency softband S-parameters, reduces testing costs, improves testing accuracy, and simplifies subsequent algorithm processing.
Smart Images
Figure CN115951193B_ABST
Abstract
Description
[Technical Field]
[0001] This invention relates to the field of optical communication testing, and in particular to a method and apparatus for testing the S-parameters of high-frequency softband. [Background Technology]
[0002] In the field of optical communication device packaging, S-parameters, or scattering parameters, are crucial parameters in microwave transmission. High-frequency flexible bandgap (HF / FLAP) is an important connection method between optical devices and printed circuit boards (PCBs). As optical device speeds increase, performance testing of HF / FLAP becomes increasingly important, and S-parameters are a key aspect of this testing. Conventional S-parameter testing methods for optical devices require ensuring that the interfaces at both ends of the device under test (DUT) are identical before directly connecting the DUT to the coaxial interface of the fixture. However, for HF / FLAP devices with asymmetrical designs at both ends, the interfaces differ, making conventional coaxial testing methods unsuitable.
[0003] To address the S-parameter testing challenges of asymmetric high-frequency flexible strip designs, existing testing methods include: 1. Mounting the high-frequency flexible strip onto a PCB, fabricating a corresponding PCB fixture, and calibrating the fixture using a PCB calibration kit; 2. Mounting the high-frequency flexible strip onto a PCB, fabricating a corresponding PCB fixture, providing a through connection to the fixture, and then calibrating the fixture using time-domain measurements; 3. Testing using a high-frequency probe. If the first method is used, a corresponding PCB calibration kit must be fabricated to calibrate the PCB fixture before the S-parameters of the high-frequency flexible strip can be obtained. However, regardless of whether the first method uses Short Open Load Thru (SOLT), Short Open Load Reflect (SOLR), or Thru Reflect Line (TRL), calibration kits for open circuits, short circuits, loads, through connections, or transmission lines are fabricated. These require precise design to meet calibration quality requirements. If the second method is used, complex time-domain algorithms are required for post-processing, and the parameters used in the time-domain transformation will affect the final test results. If the third method is used, existing probe calibration pieces can be used for calibration, but high-frequency probes and probe calibration pieces are expensive, which undoubtedly increases the testing cost.
[0004] Therefore, how to overcome the shortcomings of existing technologies and solve the problem of inconvenient or high testing costs for high-frequency soft-strip S-parameters of asymmetric designs is a problem to be solved in this technical field. [Summary of the Invention]
[0005] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention solves the problem of inconvenient testing of S-parameters of high-frequency softband asymmetric designs.
[0006] The embodiments of the present invention adopt the following technical solutions:
[0007] In a first aspect, the present invention provides a method for testing the S-parameters of a high-frequency flexible band, specifically comprising: connecting a first port of a first fixture to a first port of a first device under test (DUT), connecting a first port of a second fixture to a first port of a second DUT, and connecting the second ports of the first DUT and the second DUT to each other; obtaining a first S-parameter combination between the combination of the first DUT and the second DUT and the first fixture and the second fixture, wherein the first DUT and the second DUT are identical, and the first fixture and the second fixture are identical; connecting a first port of a third fixture to a second port of the first DUT, connecting a first port of a fourth fixture to a second port of the second DUT, and connecting the first ports of the first DUT and the second DUT to each other; obtaining a second S-parameter combination between the combination of the first DUT and the second DUT and the third fixture and the fourth fixture, wherein the third fixture and the fourth fixture are identical; and obtaining the S-parameters of the first DUT and the second DUT respectively based on the first S-parameter combination and the second S-parameter combination.
[0008] Preferably, the S-parameters of the first device under test (DUT) and the second DUT are obtained respectively, specifically including: obtaining a first correspondence between the S-parameters corresponding to each port in the first S-parameter combination and the S-parameters of each port of the first DUT and the second DUT; obtaining a second correspondence between the S-parameters corresponding to each port in the second S-parameter combination and the S-parameters of each port of the first DUT and the second DUT; and obtaining the S-parameters of the first DUT and the second DUT based on the first and second correspondences.
[0009] Preferably, obtaining the S-parameters of the first device under test (DUT) and the S-parameters of the second DUT specifically includes: obtaining the S-parameters of the first DUT based on the S-parameters from the first port to the second port and the S-parameters from the second port to the first port of the first DUT; and obtaining the S-parameters of the second DUT based on the S-parameters from the first port to the second port and the S-parameters from the second port to the first port of the second DUT.
[0010] Preferably, the method further includes: obtaining a first error model of the first port of the first fixture and the first port of the second fixture, and a second error model of the first port of the third fixture and the first port of the fourth fixture; calibrating the first S-parameter combination and the second S-parameter combination using the first error model and the second error model; and obtaining the S-parameters of the first test piece and the second test piece respectively based on the calibrated first S-parameter combination and the calibrated second S-parameter combination.
[0011] Preferably, the first S-parameter combination and the second S-parameter combination are calibrated using a first error model and a second error model, specifically including: obtaining a third correspondence between the error values of each port in the first error model and the S-parameter values of each port in the first S-parameter combination, and a fourth correspondence between the error values of each port in the second error model and the S-parameter values of each port in the second S-parameter combination; and calibrating the first S-parameter combination and the second S-parameter combination according to the third and fourth correspondences.
[0012] Preferably, obtaining the first S-parameter combination between the combination of the first device under test (DUT) and the second DUT and the first fixture and the second fixture specifically includes: sending radio frequency signals to the first DUT and the second DUT through the first fixture and the second fixture respectively; obtaining the S-parameters of each port of the first fixture and the combination of the first DUT and the second DUT with different signal directions, and the S-parameters of each port of the second fixture and the combination of the first DUT and the second DUT with different signal directions, as the first S-parameter combination.
[0013] Preferably, obtaining the second S-parameter combination between the combination of the first device under test (DUT) and the second DUT and the third and fourth clamps specifically includes: sending radio frequency signals to the first DUT and the second DUT through the third clamp and the fourth clamp respectively; obtaining the S-parameters of the third clamp and the combination of the first DUT and the second DUT at different signal directions at each port, and the S-parameters of the fourth clamp and the combination of the first DUT and the second DUT at different signal directions at each port, as the second S-parameter combination.
[0014] Preferably, before connecting the first fixture to the first port of the first device under test, the method further includes: performing initial calibration on the network analyzer to obtain the error model of the network analyzer; and calibrating the calibration plane to the first port of the first fixture, the first port of the second fixture, the first port of the third fixture, and the first port of the fourth fixture, respectively, according to the error model of the network analyzer.
[0015] On the other hand, the present invention provides an apparatus for testing the S-parameters of a high-frequency flexible band, specifically comprising a first clamp 1, a second clamp 2, a third clamp 3, and a fourth clamp 4. Specifically, the first port of the first clamp 1 is consistent with the first port of the first device under test 5, the first port of the second clamp 2 is consistent with the first port of the second device under test 6, and the first port of the first device under test 5 is consistent with the first port of the second device under test 6; the first port of the third clamp 3 is consistent with the second port of the first device under test 5, the first port of the fourth clamp 4 is consistent with the second port of the second device under test 6, and the second port of the first device under test 5 is consistent with the second port of the second device under test 6; the second ports of the first clamp 1, the second clamp 2, the third clamp 3, and the fourth clamp 4 are consistent with the ports of the network analyzer 7.
[0016] Preferably, the ports of the first clamp 1, the second clamp 2, the third clamp 3, the fourth clamp 4, the first test piece 5, and the second test piece 6 are connected through any one of the following interfaces: waveguide flange, waveguide adapter, and waveguide connector.
[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: by using two devices under test (DUTs) to form a DUT combination with symmetrical ports, the S-parameters of different port combinations with different port connections of the two DUTs are tested, and the S-parameters of each DUT are obtained by calculating based on the symmetry of the ports. The required fixture is simple to manufacture, the testing process is simple, and the subsequent algorithm processing is convenient. In a preferred embodiment, the test results are further corrected by the fixture error to avoid equipment errors during testing and obtain more accurate S-parameter test results. [Attached Image Description]
[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments of the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.
[0019] Figure 1 A flowchart of the S-parameter signal of the device under test for a high-frequency softband circuit provided in this embodiment of the invention;
[0020] Figure 2 A flowchart of a method for testing the S-parameters of a high-frequency softband circuit according to an embodiment of the present invention;
[0021] Figure 3 A flowchart illustrating the S-parameter signal between the first and second fixtures in a method for testing S-parameters of a high-frequency flexible band, provided as an embodiment of the present invention;
[0022] Figure 4 A flowchart illustrating the S-parameter signal flow between the third and fourth fixtures in a method for testing S-parameters of a high-frequency flexible band according to an embodiment of the present invention.
[0023] Figure 5 A flowchart of another method for testing the S-parameters of a high-frequency softband circuit provided in an embodiment of the present invention;
[0024] Figure 6 Another method for testing the S-parameters of a high-frequency flexible band provided in this embodiment of the invention is illustrated in the flow chart of the S-parameter signal between the first fixture and the second fixture.
[0025] Figure 7 A flowchart illustrating the S-parameter signal between the third and fourth fixtures in another method for testing S-parameters of a high-frequency flexible band provided in this embodiment of the invention.
[0026] Figure 8 A schematic diagram of a device for testing the S-parameters of a high-frequency flexible band according to an embodiment of the present invention;
[0027] Figure 9 A schematic diagram of the test piece connection structure of a device for S-parameter testing of high-frequency flexible bands provided in an embodiment of the present invention;
[0028] Figure 10 A schematic diagram of the test piece connection structure of another high-frequency flexible band S-parameter testing device provided in an embodiment of the present invention;
[0029] The accompanying figure is labeled as follows:
[0030] 1: First clamp, 2: Second clamp
[0031] 3: Third clamp, 4: Fourth clamp
[0032] 5: First device under test, 6: Second device under test.
[0033] 7: Network Analyzer.
Detailed Implementation Methods
[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0035] This invention is an architecture of a specific functional system. Therefore, the specific embodiments mainly describe the functional logic relationship of each structural module, and do not limit the specific software and hardware implementation methods.
[0036] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.
[0037] To measure asymmetric RF high-frequency flexible bands, this embodiment uses two devices under test (DUTs) connected with identical interfaces to form a DUT assembly. After connection, the other two interfaces at both ends of the assembly are also identical. Therefore, the DUT assembly can be considered a DUT with symmetrical ports on both sides, and only the S-parameters of the overall DUT assembly need to be tested using a fixture. Furthermore, since the ports on both sides of the high-frequency flexible band are different, it is necessary to connect the two sets of identical ports of the two DUTs separately to form two different DUT assemblies. The S-parameters of the two DUT assemblies are measured using fixtures corresponding to different ports, and then the S-parameters of each DUT are calculated separately based on the device symmetry.
[0038] In this embodiment, for simplicity, the two devices under test (DUTs) are referred to as the first DUT and the second DUT, respectively. The two types of ports on both sides of the DUTs are referred to as the first port and the second port, respectively. The DUT combination connected to the second port of the first DUT and the second port of the second DUT is called DUT combination A, and the DUT combination connected to the first port of the first DUT and the first port of the second DUT is called DUT combination B. The fixture corresponding to the first port type is called fixture A, and the two fixtures A connected to the two ends of DUT combination A are called the first fixture and the second fixture, respectively. The fixture corresponding to the second port type is called fixture B, and the two fixtures B connected to the two ends of DUT combination B are called the third fixture and the fourth fixture, respectively.
[0039] In actual testing, it is necessary to obtain the S-parameters between all ports of the device under test (DUT). In this embodiment, the S-parameter signal flow diagram of the DUT is as follows: Figure 1 As shown. Typically, S-parameters between different ports are identified by subscripts, and S is labeled according to the signal transmission direction. 12 S is the reverse transmission coefficient from port 1 to port 2. 21 S is the forward transmission coefficient from port 1 to port 2. 11 S is the input reflection coefficient of the first port. 22 This is the output reflection coefficient of the second port. In this embodiment, to further distinguish different combinations of tested components, S is identified. 11A The S-parameters are the S-parameters from the first port to the first port of the test component assembly A, i.e., the S-parameters from the first port of the first test component to the first port of the second test component. Other identifiers follow the same pattern.
[0040] Example 1:
[0041] When testing the S-parameters of high-frequency flexible bands, the asymmetrical nature of the two ends (i.e., inconsistent port types) prevents direct connection to the coaxial interface of existing S-parameter testing fixtures. Therefore, it is impossible to directly use a network analyzer to obtain various performance data for S-parameter testing. To address this issue, this embodiment provides a simple and effective S-parameter testing method for high-frequency flexible bands with inconsistent port types. The method provided in this embodiment...
[0042] Specifically, such as Figure 2 As shown, the steps of the method for testing the S-parameters of high-frequency flexible bands provided in this embodiment of the invention are as follows.
[0043] Step 101: Connect the first port of the first fixture to the first port of the first device under test, connect the first port of the second fixture to the first port of the second device under test, connect the second port of the first device under test and the second port of the second device under test to each other, and obtain the first S-parameter combination between the combination of the first device under test and the second device under test and the first fixture and the second fixture.
[0044] In the method provided in this embodiment, two preliminary measurements are required based on the two different ports of the device under test (DUT). First, the second ports of the first DUT and the second DUT are interconnected to form a test combination A. The ports on both sides of the test combination A are the first ports. After connecting the network tester through the first and second clamps corresponding to the first ports, each S-parameter between the ports of the test combination A can be obtained, i.e., the first S-parameter combination. To ensure the symmetry of the test combination A and the entire measurement path in step 101, the first DUT and the second DUT need to use the same devices, and the first clamp and the second clamp also need to use the same devices.
[0045] During measurement, radio frequency signals are emitted to the first and second devices under test (DUTs) via the first and second clamps, respectively. According to... Figure 3 The signal flow diagram shown allows for the acquisition of S-parameters for different signal directions at each port of the combination of the first fixture with the first device under test (DUT) and the second DUT, as well as the S-parameters for different signal directions at each port of the combination of the second fixture with the first DUT and the second DUT, which are used as the first S-parameter combination. Specifically, the first S-parameter combination includes the following data: S 11A It is the S-parameter from the first port of the first device under test to the first port of the first device under test, S 21A It is the S-parameter from the first port of the first device under test to the first port of the second device under test. 12A The S-parameters are the distance from the first port of the second device under test to the first port of the first device under test. 22A It is the S-parameter from the first port of the second device under test to the second port of the second device under test.
[0046] Step 102: Connect the first port of the third fixture to the second port of the first test piece, connect the first port of the fourth fixture to the second port of the second test piece, connect the first port of the first test piece and the second port of the second test piece to each other, and obtain the second S-parameter combination between the combination of the first test piece and the second test piece and the third fixture and the fourth fixture.
[0047] After obtaining the first S-parameter combination, the S-parameters of the two devices under test (DUTs) cannot be directly obtained. It is necessary to connect the first ports of the first and second DUTs to form a test combination B. The ports on both sides of test combination B are second ports. After connecting the network tester through the third and fourth clamps corresponding to the second ports, each S-parameter between the ports of test combination B can be obtained, i.e., the second S-parameter combination. Similarly, to ensure the symmetry of test combination B and the entire measurement path in step 102, the third and fourth clamps must also use identical components.
[0048] During measurement, corresponding to step 101, radio frequency signals are emitted to the first and second devices under test (DUTs) via the third and fourth clamps, respectively. Figure 4 The signal flow diagram shown allows for the acquisition of S-parameters for different signal directions at each port of the combination of the third fixture with the first and second devices under test (DUTs), as well as S-parameters for different signal directions at each port of the combination of the fourth fixture with the first and second DUTs, which are used as the second S-parameter combination. Specifically, the second S-parameter combination includes the following data: S 11B It is the S-parameter from the second port of the first device under test to the second port of the second device under test, S 21B It is the S-parameter from the second port of the first device under test to the second port of the second device under test, S 12B It is the S-parameter from the second port of the second device under test to the second port of the first device under test, S 22B It is the S-parameter from the second port of the second device under test to the second port of the second device under test.
[0049] Step 103: Obtain the S-parameters of the first test piece and the second test piece according to the first S-parameter combination and the second S-parameter combination, respectively.
[0050] Since the first and second S-parameter combinations each contain a set of S-parameters between the ports of the first and second devices under test (DUT), the S-parameters of the first DUT and the second DUT can be obtained by combining the data from the first and second S-parameter combinations based on the symmetry of the signal path.
[0051] In specific implementation, such as Figure 5 As shown, the S-parameters of the first device under test and the second device under test can be obtained using the following steps.
[0052] Step 201: Obtain the first correspondence between the S-parameters corresponding to each port in the first S-parameter combination and the S-parameters of each port of the first device under test and each port of the second device under test.
[0053] according to Figure 3 In the signal flow diagram, the first correspondence between each S-parameter in the first S-parameter combination and the first S-parameter of each port of the two devices under test can be represented by Formula 1.
[0054]
[0055] Wherein, the left side of the formula represents the value of the first S-parameter combination measured in step 101, S 11A It is the S-parameter from the first port of the first device under test to the first port of the first device under test, S 21A It is the S-parameter from the first port of the first device under test to the first port of the second device under test. 12AThe S-parameters are the distance from the first port of the second device under test to the first port of the first device under test. 22A These are the S-parameters from the first port of the second device under test (DUT) to the second port of the second DUT. The right side of the formula shows the correspondence derived from the signal flow diagram; these cannot be directly obtained as specific values and are only used as variable indicators. 12 S is the reverse transmission coefficient from the first port to the second port of the device under test. 21 S is the forward transmission coefficient from the first port to the second port of the device under test. 11 S is the input reflection coefficient at the first port of the device under test. 22 Let S be the output reflection coefficient of the second port of the device under test. In the formula of this embodiment, since the first and second devices under test are the same, the S-coefficients between each port are theoretically the same. Therefore, S... 12 S 21 S 22 S 11 Using the same notation indicates that the S-system values are the same between the corresponding ports in the first and second devices under test.
[0056] Step 202: Obtain the second correspondence between the S-parameters corresponding to each port in the second S-parameter combination and the S-parameters of each port of the first device under test and each port of the second device under test.
[0057] according to Figure 4 In the signal flow diagram, the second correspondence between each S-parameter in the second S-parameter combination and the S-parameter of each port of the two devices under test can be expressed by formula 2.
[0058]
[0059] Wherein, the left side of the formula represents the value of the second S-parameter combination measured in step 102, S 11B It is the S-parameter from the second port of the first device under test to the second port of the second device under test, S 21B It is the S-parameter from the second port of the first device under test to the second port of the second device under test, S 12B It is the S-parameter from the second port of the second device under test to the second port of the first device under test, S 22B S represents the S-parameters from the second port of the second device under test to the second port of the second device under test. The right side of the formula shows the correspondence derived from the signal flow diagram; specific values cannot be directly obtained and are only used as variable indicators. 12 S is the reverse transmission coefficient from the first port to the second port of the device under test. 21 S is the forward transmission coefficient from the first port to the second port of the device under test. 11 S is the input reflection coefficient at the first port of the device under test. 22 Let S be the output reflection coefficient of the second port of the device under test. Similarly, S... 12 S21 S 22 S 11 Using the same notation indicates that the S-system values are the same between the corresponding ports in the first and second devices under test.
[0060] Step 203: Obtain the S-parameters of the first test piece and the second test piece according to the first correspondence and the second correspondence.
[0061] After obtaining the two sets of correspondences, the S-parameters of the test piece can be calculated using the specific values of the S-parameters between each port in the first and second S-parameter combinations obtained by measurement.
[0062] In the specific application scenario of this embodiment, the high-frequency softband of the device under test does not contain active devices, ferrite, or plasma; it is simply a passive bidirectional device. The two ports themselves have reciprocal characteristics, and the S-parameters from the first port to the second port and from the second port to the first port are the same, that is, S in Formulas 1 and 2... 21 =S 12 .
[0063] Formulas 3, 4, and 5 can be derived from Formulas 1 and 2.
[0064]
[0065]
[0066]
[0067] Using Formula 5, by substituting the specific values of each S-parameter in the first S-parameter combination measured in step 101 and the second S-parameter combination measured in step 102, the S-parameters of the first device under test (DUT) can be obtained based on the S-parameters from the first port to the second port and the S-parameters from the second port to the first port. Similarly, the S-parameters of the second DUT can be obtained based on the S-parameters from the first port to the second port and the S-parameters from the second port to the first port.
[0068] Furthermore, to improve the accuracy of S-parameter measurement, before measuring the first and second S-parameter combinations, a first error model of the direct path between the first and second ports of the first and second fixtures, and a second error model of the direct path between the first and fourth ports of the third and fourth fixtures, can be obtained. The first and second error models are then used to calibrate the first and second S-parameter combinations. Based on the calibrated first and second S-parameter combinations, the S-parameters of the first and second test pieces are obtained, respectively. This reduces the measurement and calculation errors caused by fixture A.
[0069] For fixture A, the first port of the first fixture and the first port of the second fixture are directly connected via waveguide flanges or other means to form a straight-through path for fixture A. The signal flow diagram is as follows. Figure 6 As shown. The second port of the first fixture and the second port of the second fixture are coaxial RF ports, which can be directly connected to the RF line of the network analyzer. By measuring the through path, the six measurement results of Formulas 6-11 can be obtained, which is the first error model of the through path of fixture A.
[0070]
[0071]
[0072]
[0073]
[0074]
[0075]
[0076] Among them, E 00A E represents the error term from the second port of the first fixture to the second port of the second fixture. 01A E represents the error term from the second port of the first fixture to the first port of the first fixture. 10A E represents the error term from the first port of the first fixture to the first port of the first fixture. 11A This is the error term from the first port of the first fixture to the first port of the second fixture. Since the first fixture and the second fixture are identical in this embodiment, therefore, E... 01A It is also the error term from the second port of the second fixture to the first port of the second fixture, E 10A It is also the error term from the first port of the second fixture to the first port of the second fixture. ELF A This is an intermediate value in the formula, used to substitute into subsequent formulas for error compensation. 11ThruA S represents the measurement of the straight-through path by fixture A. 11 Parameters. Formulas 10 and 11 are switching terms, representing the ratio of (incident wave) a2 / (reflected wave) b2 at port 2 when the RF source is turned on at port 1. These should be used according to the actual port transmission and reception conditions.
[0077] Similarly, for clamp B, the third and fourth clamps are directly joined together via waveguide flanges or other means to form a straight-through path for clamp B. The signal flow diagram is as follows. Figure 7As shown. The second port of the third fixture and the second port of the third fixture are coaxial RF ports, which can be directly connected to the RF line of the network analyzer. By measuring the through path, the six measurement results of Formulas 14-19 can be obtained, which is the second error model of the through path of fixture B.
[0078]
[0079]
[0080]
[0081]
[0082]
[0083]
[0084] Among them, E 00B E represents the error term from the second port of the third fixture to the second port of the fourth fixture. 01B E is the error term from the second port of the third fixture to the first port of the third fixture. 10B E is the error term from the first port of the third fixture to the first port of the third fixture. 11B The error term from the first port of the third fixture to the first port of the fourth fixture. Since the third and fourth fixtures are identical in this embodiment, therefore, E 01B It is also the error term from the second port of the fourth fixture to the first port of the fourth fixture, E 10B It is also the error term from the first port of the fourth fixture to the first port of the fourth fixture. ELF B S is an intermediate value in the formula, used to substitute into subsequent formulas for error compensation. 11ThruB When measuring the S of the straight-through path using fixture B. 11 Parameters. Formulas 20 and 21 are switching terms, representing the ratio of incident wave (a2) / reflected wave (b2) at port 2 when the RF source is turned on at port 1. These should be used according to the actual port transmission and reception conditions.
[0085] After obtaining the two sets of error models, the correspondence between each set of error models and the corresponding S-parameter combinations can be further obtained, thereby completing the error compensation.
[0086] According to Formulas 6-11, the third correspondence between the error values of each port in the first error model and the S-parameter values of each port in the first S-parameter combination can be obtained, as shown in Formulas 18 and 19.
[0087]
[0088]
[0089] Based on formulas 14-19, the fourth correspondence between the error values of each port in the second error model and the S-parameter values of each port in the second S-parameter combination can be obtained, as shown in formulas 20 and 21.
[0090]
[0091]
[0092] After inputting the above error model and correspondence into the network analyzer, the first S-parameter combination and the second S-parameter combination can be calibrated according to the third and fourth correspondences.
[0093] Furthermore, to reduce the measurement errors of the network analyzer itself, an initial calibration is required before all measurements are performed, without connecting any device under test (DUT). This calibrates the network analyzer to its 12-term error model, and calibrates the calibration plane to the RF cable port connected to the fixture. Based on the network analyzer's error model, the calibration plane is calibrated to the first port of the first fixture, the first port of the second fixture, the first port of the third fixture, and the first port of the fourth fixture, respectively. In practice, the original SOLT calibration method or other existing calibration methods can be used for the initial calibration of the network analyzer.
[0094] This embodiment provides a method for testing the S-parameters of high-frequency flexible strips. It requires only two sets of fixtures with identical ports, and the required calibration components are simple. There is no need to fabricate open-circuit, short-circuit, or load calibration components; a straight-through path is simply created by directly connecting the flanges. Furthermore, the calculation only requires the direct use of the parameter combination from two measurements, without the need for time-domain algorithms, making the calculation simple and requiring no special requirements for measurement settings.
[0095] Example 2:
[0096] Based on the method for testing the S-parameters of high-frequency flexible bands provided in Embodiment 1 above, the present invention also provides an apparatus for testing the S-parameters of high-frequency flexible bands that can be used to implement the above method.
[0097] like Figure 8 The diagram shown is a schematic representation of the device architecture according to an embodiment of the present invention. The device provided in this embodiment includes a first clamp 1, a second clamp 2, a third clamp 3, and a fourth clamp 4. In the accompanying drawings of this embodiment, interfaces with the same filling pattern are considered to be identical interfaces.
[0098] The first port of the first fixture 1 is consistent with the first port of the first device under test (DUT) 5, the first port of the second fixture 2 is consistent with the first port of the second DUT 6, and the first port of the first DUT 5 is consistent with the first port of the second DUT 6. The first fixture 1 and the second fixture 2 are identical, both being fixture A, achieving symmetry on both sides when forming the test path. The first end of fixture A is a coaxial RF port, which can be directly connected to the RF cable of the network analyzer; the second end corresponds to the first port of the DUT.
[0099] The first port of the third fixture 3 is consistent with the second port of the first device under test 5, the first port of the fourth fixture 4 is consistent with the second port of the second device under test 6, and the second port of the first device under test 5 is consistent with the second port of the second device under test 6. The third fixture 3 and the fourth fixture 4 are the same, both being fixture B, achieving symmetry on both sides when forming a test path. The first end of fixture B is a coaxial RF port, which can be directly connected to the RF line of the network analyzer; the second end corresponds to the first port of the device under test.
[0100] The second ports of the first clamp 1, the second clamp 2, the third clamp 3, and the fourth clamp 4 are consistent with the ports of the network analyzer 7 and are connected to the network analyzer 7 respectively. The network analyzer 7 completes the transmission and reception of radio frequency signals and the acquisition of measurement data.
[0101] like Figure 9 The device provided in this embodiment is connected to the test piece assembly A according to step 101 in embodiment 1, and then as shown... Figure 10 As shown, by connecting to the test piece assembly B according to step 102 in Embodiment 1, a symmetrical direct-through path connection between the two different ports of the test piece can be achieved. Measurements of the first and second S-parameter combinations between each port are obtained using a network analyzer for subsequent calculations. Furthermore, by directly connecting fixtures A and B according to the method in Embodiment 1, the relevant values of the first and second error models can be obtained for compensation of the S-parameter measurement results in subsequent calculations.
[0102] In specific implementation, the ports of the first clamp 1, the second clamp 2, the third clamp 3, the fourth clamp 4, the first device under test 5, and the second device under test 6 are connected via any one of the following interfaces: waveguide flange, waveguide adapter, and waveguide connector. In the preferred embodiment, a waveguide flange is used for connection to facilitate connection and improve connection accuracy.
[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for testing the S-parameters of a high-frequency softband circuit, characterized in that, Specifically: The first port of the first fixture is connected to the first port of the first test piece, the first port of the second fixture is connected to the first port of the second test piece, the second port of the first test piece and the second port of the second test piece are connected to each other, and the first S-parameter combination between the combination of the first test piece and the second test piece and the first fixture and the second fixture is obtained, wherein the first test piece and the second test piece are the same, and the first fixture and the second fixture are the same. The first port of the third fixture is connected to the second port of the first test piece, and the first port of the fourth fixture is connected to the second port of the second test piece. The first port of the first test piece and the first port of the second test piece are interconnected. The second S-parameter combination between the combination of the first test piece and the second test piece and the third and fourth fixtures is obtained, wherein the third and fourth fixtures are the same. Obtain the first correspondence between the S-parameters corresponding to each port in the first S-parameter combination and the S-parameters of each port of the first device under test and the second device under test; obtain the second correspondence between the S-parameters corresponding to each port in the second S-parameter combination and the S-parameters of each port of the first device under test and the second device under test; obtain the S-parameters of the first device under test and the second device under test based on the first and second correspondences. The expression for the first correspondence is: Wherein, the left side of the formula represents the value of the first S-parameter combination, S 11A It is the S-parameter from the first port of the first device under test to the first port of the first device under test, S 21A It is the S-parameter from the first port of the first device under test to the first port of the second device under test. 12A The S-parameters are the distance from the first port of the second device under test to the first port of the first device under test. 22A These are the S-parameters from the first port of the second device under test to the second port of the second device under test; The expression for the second correspondence is: Wherein, the left side of the formula represents the value of the second S-parameter combination, S 11B It is the S-parameter from the second port of the first device under test to the second port of the second device under test, S 21B It is the S-parameter from the second port of the first device under test to the second port of the second device under test, S 12B It is the S-parameter from the second port of the second device under test to the second port of the first device under test, S 22B It is the S-parameter from the second port of the second device under test to the second port of the second device under test.
2. The method for testing the S-parameters of high-frequency flexible bandgap devices according to claim 1, characterized in that, Also includes: Obtain a first error model of the first port of the first fixture and the first port of the second fixture, and a second error model of the first port of the third fixture and the first port of the fourth fixture. The first S-parameter combination and the second S-parameter combination are calibrated using the first error model and the second error model; Based on the calibrated first S-parameter combination and the calibrated second S-parameter combination, the S-parameters of the first test piece and the second test piece are obtained respectively.
3. The method for testing the S-parameters of high-frequency flexible bandgap radios according to claim 2, characterized in that, The calibration of the first S-parameter combination and the second S-parameter combination using the first error model and the second error model specifically includes: Obtain the third correspondence between the error values of each port in the first error model and the S-parameter values of each port in the first S-parameter combination, and the fourth correspondence between the error values of each port in the second error model and the S-parameter values of each port in the second S-parameter combination; The first S-parameter combination and the second S-parameter combination are calibrated based on the third and fourth correspondences.
4. The method for testing the S-parameters of high-frequency flexible bandgap devices according to claim 1, characterized in that, The acquisition of the first S-parameter combination between the combination of the first test piece and the second test piece and the first fixture and the second fixture specifically includes: Radio frequency signals are transmitted to the first device under test and the second device under test through the first clamp and the second clamp, respectively; The S-parameters of each port of the combination of the first fixture with the first device under test and the second device under test, and the S-parameters of each port of the combination of the second fixture with the first device under test and the second device under test, are obtained as the first S-parameter combination.
5. The method for testing the S-parameters of high-frequency flexible bandgap devices according to claim 1, characterized in that, The acquisition of the second S-parameter combination between the combination of the first and second test pieces and the third and fourth fixtures specifically includes: Radio frequency signals are transmitted to the first device under test (DUT) and the second DUT via the third and fourth clamps, respectively. The S-parameters of the third fixture combined with the first and second test devices for different signal directions at each port, and the S-parameters of the fourth fixture combined with the first and second test devices for different signal directions at each port, are obtained as the second S-parameter combination.
6. The method for testing the S-parameters of high-frequency flexible bandgap radios according to claim 1, characterized in that, Before connecting the first port of the first fixture to the first port of the first test piece, the method further includes: Perform initial calibration on the network analyzer and obtain the network analyzer's error model; Based on the error model of the network analyzer, the calibration plane is calibrated to the first port of the first fixture, the first port of the second fixture, the first port of the third fixture, and the first port of the fourth fixture, respectively.
7. An apparatus for performing S-parameter testing of a high-frequency softband circuit as described in any one of claims 1-6, characterized in that, Including the first clamp (1), the second clamp (2), the third clamp (3), and the fourth clamp (4), specifically: The first port of the first fixture (1) is consistent with the first port of the first test piece (5), the first port of the second fixture (2) is consistent with the first port of the second test piece (6), and the first port of the first test piece (5) is consistent with the first port of the second test piece (6). The first port of the third fixture (3) is consistent with the second port of the first test piece (5), the first port of the fourth fixture (4) is consistent with the second port of the second test piece (6), and the second port of the first test piece (5) is consistent with the second port of the second test piece (6). The second port of the first clamp (1), the second port of the second clamp (2), the second port of the third clamp (3), and the second port of the fourth clamp (4) are consistent with the port of the network analyzer (7).
8. The apparatus for testing the S-parameters of high-frequency flexible band according to claim 7, characterized in that, Specifically: The ports of the first fixture (1), the second fixture (2), the third fixture (3), the fourth fixture (4), the first test piece (5), and the second test piece (6) are connected through any one of the following interfaces: waveguide flange, waveguide adapter, and waveguide connector.