Design, single calibration and measurement method of radio frequency impedance measurement clamp

Abstract

The invention belongs to the field of electrical parameter measurement, and discloses a design, single calibration and measurement method of a radio frequency impedance measurement clamp, and the design method comprises the steps: employing a symmetric structure, taking an SMA connector of a coaxial structure as a port connected with a vector network analyzer (VNA), taking a coplanar waveguide as a connecting line between the SMA connector and a device under test (DUT), and connecting the SMA connector and the DUT; four patch bonding pads are arranged on the coplanar waveguide, so that the radio frequency impedance measurement clamp for the DUT with different packaging and different impedance ranges is realized.

Description

Technical Field

[0001] The present invention relates to the field of electrical parameter measurement, and in particular to a design, single calibration and measurement method of a radio frequency impedance measurement fixture. Background Art

[0002] At low frequencies, discrete electronic components such as resistors and capacitors and the networks they form can be considered ideal components, but at high frequencies, their non-ideal characteristics begin to manifest themselves. If their parasitic parameters are not considered, their high-frequency models will be inaccurate. It is necessary to obtain the non-ideal characteristics of the above components as a reference for RF circuit design; for complex passive networks, their port impedance is difficult to calculate theoretically, so it is also necessary to measure their port impedance.

[0003] When the RF test system with an impedance analyzer or vector network analyzer (VNA) as the core and the device under test (DUT) both have coaxial connectors, it is easy to connect them for measurement. However, since RF components come in a variety of sizes and shapes, such as surface mount components, plug-in components, etc., no single connector type is suitable for all situations. At this time, a measurement fixture needs to be designed to serve as the electrical and mechanical interface between the RF test system and the device under test.

[0004] The existing PCB-based impedance measurement fixture can only be used for DUTs of one package or size, and there are multiple impedance measurement methods for different frequencies and impedance ranges. Therefore, multiple fixtures have to be designed to meet different measurement requirements, which makes the selection and use of impedance measurement fixtures complicated and is not conducive to the rapid acquisition of component impedance information.

[0005] When performing impedance measurement, the influence of the impedance measurement fixture itself cannot be ignored, and the fixture should be calibrated to eliminate the influence of the fixture itself. Currently commonly used calibration methods, such as SOLT calibration (requires short circuit, open circuit, and terminated load calibration of the two ports of the measurement fixture, as well as two-port direct calibration), TRL calibration (requires two-port direct calibration, port short circuit / open circuit calibration, and delayed transmission line calibration), etc., require multiple operations and the production of multiple PCBs. Although the impedance measurement has higher accuracy over a wider frequency band, the operation and calculation are more complicated. It is necessary to simplify the calibration process on the basis of meeting the required accuracy requirements. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a design, single calibration and measurement method of a radio frequency impedance measurement fixture.

[0007] The present invention provides a design method for a radio frequency impedance measurement fixture, the design method comprising:

[0008] A symmetrical structure is adopted, with a coaxial SMA connector as the port connected to the vector network analyzer VNA, a coplanar waveguide as the connecting line between the SMA connector and the device under test DUT, and four patch pads are set on the coplanar waveguide to realize the RF impedance measurement fixture of the device under test DUT with different packages and different impedance ranges.

[0009] The present invention also provides a radio frequency impedance measurement fixture, comprising: a left half M of the fixture L The left half of the fixture includes the SMA connector and the coplanar waveguide connected to it, and the right half of the fixture M R With the left half M L Symmetrical, the right half has four additional patch pads on the coplanar waveguide, and the middle part M DUT It is the DUT network of the device under test.

[0010] The present invention also provides a single calibration method for a radio frequency impedance measurement fixture, the calibration method is used to perform a single calibration on the radio frequency impedance measurement fixture, and comprises:

[0011] Measuring the two-port through-S parameters of the calibration fixture is the calibration S parameters;

[0012] Convert the calibration S parameters into calibration Z parameters to obtain the Z parameter equivalent circuit diagram;

[0013] The Z parameter equivalent circuit diagram is symmetrically split to obtain the Z parameter of half of the calibration fixture;

[0014] The Z parameters of half of the calibration fixture are converted into an ABCD matrix to de-embed the system impedance and finally obtain the impedance spectrum of the device under test (DUT).

[0015] Preferably, measuring the two-port direct-through S parameters of the calibration fixture includes: welding copper sheets with the same width as the middle signal line to both ends of the signal line to achieve two-port direct-through, and measuring the two-port S parameters of the calibration fixture.

[0016] Preferably, converting the calibration S parameters into calibration Z parameters comprises:

[0017]

[0018] In the formula, Z C11 ~Z C22 is the Z parameter of the two-port through-hole impedance measurement fixture; S C11 ~S C22 is the S parameter of the two-port direct-through impedance measurement fixture; Z0 is the characteristic impedance, which is generally 50Ω.

[0019] Preferably, symmetrically dividing the Z parameter equivalent circuit diagram includes:

[0020] The Z parameter matrix of the left half fixture:

[0021]

[0022] The designed fixture is approximately symmetrical, so the right half fixture is the left half fixture with two ports swapped.

[0023]

[0024] Preferably, converting the Z parameters of half of the calibration fixture into an ABCD matrix comprises:

[0025]

[0026] The present invention also discloses a method for measuring a radio frequency impedance measurement fixture, wherein the method uses the radio frequency impedance measurement fixture after a single calibration to perform impedance measurement, and comprises:

[0027] Measure the system S parameters of the calibration fixture-DUT;

[0028] Convert the system S parameters into an ABCD matrix;

[0029] If the impedance measurement method is the series / parallel through method, the ABCD matrix of the device under test DUT is obtained by calculating the ABCD parameter matrix of the half calibration fixture, and the impedance of the device under test DUT is obtained from the ABCD matrix of the device under test;

[0030] If the impedance measurement method is the reflection method, the system S parameters are converted to Z parameters. Combined with the calibrated Z parameter equivalent circuit diagram, the system circuit analysis is performed to obtain the DUT impedance.

[0031] Preferably, the ABCD matrix of the device under test DUT includes:

[0032] By M DUT Get the impedance Z of the device under test DUT DUT include:

[0033] For the series thru calibration method:

[0034]

[0035] For the parallel thru calibration method:

[0036]

[0037] Among them, Y DUT is the admittance of the DUT, is the impedance Z of the DUT DUT The reciprocal of .

[0038] Preferably, if the impedance measurement method is a reflection method, obtaining the impedance of the device under test (DUT) includes:

[0039] The S parameters of the fixture two-port direct pass are converted into Z parameters, which correspond to the input impedance of the system port 1 when the port 2 is short-circuited.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The present invention adopts a symmetrical structure, uses a coaxial SMA connector as a port connected to a vector network analyzer VNA, and a coplanar waveguide as a connecting line between the SMA connector and the device under test DUT. In addition, four patch pads are arranged on the coplanar waveguide to adapt to different electronic components and different measurement methods, thereby realizing impedance measurement of devices under test DUT with different packages and different impedance ranges on the same fixture;

[0042] The present invention obtains the information required for calibration by measuring the S parameters of the designed fixture two-port direct network, and realizes the de-embedding of the system impedance through the conversion between the S parameters, Z parameters, ABCD parameters and matrix operations, and finally obtains the impedance spectrum of the device under test DUT. The calibration method only needs a single measurement to obtain the data required for calibration, thereby simplifying the calibration process on the basis of meeting the required accuracy requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0044] Figure 1 Three methods for measuring impedance using a VNA according to an embodiment of the present invention, wherein (a) is a reflection method, (b) is a series through method, and (c) is a parallel through method;

[0045] Figure 2 Schematic diagram of impedance amplitude and frequency range applicable to three methods of measuring impedance using VNA according to an embodiment of the present invention;

[0046] Figure 3 It is a schematic diagram of the ABCD matrix cascade connection of the impedance measurement fixture and the device under test according to an embodiment of the present invention;

[0047] Figure 4 A structural diagram of a measuring fixture according to an embodiment of the present invention;

[0048] Figure 5 Schematic diagram of the Z matrix equivalent circuit of the measuring fixture according to an embodiment of the present invention;

[0049] Figure 6 It is an equivalent circuit diagram of impedance measurement using the series through method, reflection method, and parallel through method according to an embodiment of the present invention;

[0050] Figure 7 is a calibration and measurement flow chart of an impedance measurement fixture according to an embodiment of the present invention;

[0051] Figure 8 A schematic diagram of a three-dimensional electromagnetic simulation model of a measuring fixture according to an embodiment of the present invention;

[0052] Fig. 9 A comparison diagram of the impedance measurement results before and after the series through-line method calibration and the theoretical value according to an embodiment of the present invention;

[0053] Fig.10 A comparison diagram of the impedance measurement results before and after the calibration using the reflection method according to an embodiment of the present invention and the theoretical value;

[0054] Fig.11 This is a comparison chart of the impedance measurement results before and after calibration using the parallel through-line method according to an embodiment of the present invention and the theoretical value. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the embodiments of the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0057] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0058] Embodiment 1

[0059] The embodiment of the present invention provides a design, single calibration and measurement method of a radio frequency impedance measurement fixture.

[0060] The present invention adopts a symmetrical structure, uses a coaxial SMA connector as a port connected to a vector network analyzer VNA, and a coplanar waveguide as a connecting line between the SMA connector and the device under test DUT. In addition, four patch pads are arranged on the coplanar waveguide to adapt to different electronic components and different measurement methods, thereby realizing impedance measurement of devices under test DUT with different packages and different impedance ranges on the same fixture;

[0061] The present invention obtains the information required for calibration by measuring the S parameters of the designed fixture two-port direct network, and realizes the de-embedding of the system impedance through the conversion between the S parameters, Z parameters, ABCD parameters and matrix operations, and finally obtains the impedance spectrum of the device under test DUT. The calibration method only needs a single measurement to obtain the data required for calibration, thereby simplifying the calibration process on the basis of meeting the required accuracy requirements.

[0062] VNA impedance measurement principle:

[0063] VNA is a high-performance measuring instrument widely used in the testing and analysis of microwave and radio frequency circuits. It can accurately measure the circuit's amplitude-frequency characteristics, phase-frequency characteristics, impedance characteristics and other parameters, providing important test data support for circuit design, debugging and optimization.

[0064] The measurement principle of VNA is to use the amplitude and phase information of the vector signal to calculate the S parameters of the circuit under test by measuring the reflection coefficient and transmission coefficient, thereby obtaining various characteristic parameters of the circuit, including impedance, gain, phase, etc.

[0065] There are three methods for impedance measurement based on VNA: reflection method, series through method and parallel through method. The corresponding connection methods are as follows: Figure 1 (a)- Figure 1 The above three methods are introduced below.

[0066] (1) Reflection method:

[0067] The reflection method is used to measure the reflection coefficient of the measured object. Reflection coefficient Γ x (S 11 ) and the port impedance are as follows:

[0068]

[0069] Among them, Z o It is the characteristic impedance of the measurement circuit, usually 50Ω; Z xis the impedance of the DUT. According to the formula, the measured reflection coefficient follows the impedance (Z x ) changes between -1 and 1. x Equal to Z o The highest accuracy is obtained when the impedance is farther away from the characteristic impedance point. The reflection coefficient curve changes more slowly, resulting in reduced impedance measurement accuracy. Impedance is calculated using the following formula:

[0070]

[0071] The impedance measurement range for reflection method is usually accurate from 2Ω to 1.5kΩ (depending on the required accuracy and measurement frequency).

[0072] (2) Series direct method:

[0073] The series thru method measures impedance by connecting the DUT into a "series transmission". The series thru method is most effective when measuring high impedance values: the 10% accuracy range is about 5Ω to 20kΩ, which is about ten times higher than the reflection method. Impedance is calculated by the following formula:

[0074]

[0075] (3) Parallel direct method:

[0076] The shunt-through method measures impedance by connecting the DUT into a "parallel transmission". This method is suitable for low impedance testing and is usually used to measure in the milliohm range. The 10% accuracy range is 1mΩ to 10Ω, which is lower than the range that a typical impedance analyzer can achieve. Impedance is calculated by the following formula:

[0077]

[0078] Through the above three methods, the measurement of impedance in different ranges can be roughly covered. The corresponding ranges are as follows: Figure 2 shown.

[0079] However, it should be noted that the impedance measurement fixture is affected by factors such as the transition from coaxial to coplanar waveguide and from coplanar waveguide to DUT, the distributed inductance of the trace itself, the distributed capacitance between the trace and the ground, and the processing accuracy. It cannot be considered as having no influence, which is particularly serious under high-frequency conditions. Therefore, the fixture should be calibrated to eliminate the test result errors caused by the above factors.

[0080] Calibration principle: Figure 3 and Figure 4 The ABCD matrix cascade diagram and structure diagram of the designed impedance measurement fixture are shown respectively. L The left half of the fixture includes the SMA connector and the coplanar waveguide connected to it, and the right half of the fixture M RSymmetrical to the left half (the extra pads on the right half are only used for parallel through-connection impedance measurement and do not change the electrical performance of the coplanar waveguide). DUT is the DUT network of the device under test. The ABCD matrix of the entire impedance measurement system is

[0081] M C =M L M DUT M R

[0082] It should be added that if the parallel through method is used to measure impedance, since the length of the actual object to be tested is small from the center, the fixture is considered to be an approximately symmetrical structure. In this case, the same calibration method is still valid in the lower frequency band. In this case, M DUT correspond Figure 4 The welding point of the test piece in the parallel through-line method.

[0083] If you want to know the real impedance information of the device under test, you should exclude the left half M L With the right half M R There are many circuit matrices used to represent circuit information, such as Z matrix, Y matrix, ABCD matrix, S parameter matrix, etc. Because the ABCD matrix can be cascaded, it is beneficial to M L With M R In order to de-embed the impedance measurement fixture, the ABCD matrix is ​​used to represent the information of the impedance measurement fixture. The ABCD matrix is ​​as follows:

[0084]

[0085] Among them, V1 and I1 are the network input voltage and current, and their reference directions are non-correlated reference directions; V2 and I2 are the network output voltage and current, and their reference directions are correlated reference directions;

[0086] During calibration, copper sheets with the same width as the middle signal line are welded to both ends of the signal line to achieve two-port direct connection and measure the two-port S parameters of the entire system.

[0087] The copper sheet can be regarded as a short-circuited DUT, and the corresponding ABCD matrix is:

[0088]

[0089] At this time, the matrix of the entire system is

[0090] M C =M L M R

[0091] The designed fixture is symmetrical on both sides. In a two-port network, the Z matrix has a corresponding equivalent circuit. If the Z parameter matrix can be obtained, it is convenient to use circuit theory calculation, so the S parameters of the fixture two-port pass-through are converted into Z parameters:

[0092]

[0093]

[0094] In the formula, Z C11 ~Z C22 is the Z parameter of the two-port through-hole impedance measurement fixture; S C11 ~S C22 is the S parameter of the two-port direct-through impedance measurement fixture; Z0 is the characteristic impedance, which is generally 50Ω.

[0095] like Figure 5 , get the Z matrix equivalent circuit of the impedance measurement fixture and divide the equivalent circuit into two parts to get the Z parameter matrix of half fixture (left half):

[0096]

[0097] The designed fixture is approximately symmetrical, so the right half fixture is the left half fixture with two ports swapped.

[0098]

[0099] Convert the Z matrix to an ABCD matrix:

[0100]

[0101] According to the above formula, M L and M R It should be noted that the left and right sides of the fixture have the same structure but different port correspondences, so M L and M R If they are not equal, the ports should be swapped for conversion.

[0102]

[0103] At this time, remove the short-circuit copper sheet and replace it with the DUT. For the series and parallel through calibration methods, the ABCD matrix M of the DUT network is DUT It is easy to obtain, among which, M L -1 and M R -1 For the above M L and M R The inverse matrix of :

[0104]

[0105] M DUT Get the impedance Z of the DUT DUT The equivalent circuit diagrams of the three impedance measurement methods are as follows: Figure 6 shown.

[0106] For the series thru calibration method:

[0107]

[0108] For the parallel thru calibration method:

[0109]

[0110] In the above formula, Y DUT is the admittance of the DUT, is the impedance Z of the DUT DUT The reciprocal of .

[0111] The impedance calculation of the reflection method is slightly complicated, but it can also be obtained through circuit analysis. First, convert the S parameters of the two-port direct pass of the fixture into Z parameters, which correspond to the input impedance of the system port 1 when port 2 is short-circuited. Then, Figure 6 The circuit shown in (b) can calculate Z DUT :

[0112]

[0113] in, Z in To measure the input impedance of the fixture-DUT system, S 11_ref is the corresponding single-port reflection parameter, which is the directly measured data; a=Z C11 -Z C12 ; b = 2·Z C12 .

[0114] The impedance measurement fixture calibration and measurement flow chart is shown in Figure 7 .

[0115] The technical solution of the present invention is as follows: Figure 8 As shown in the figure, the performance of the designed impedance measurement fixture is verified in the 3D electromagnetic simulation software HFSS. In order to fully verify the performance of the fixture in each function, the following test scheme is adopted, corresponding to the impedance range applicable to the three impedance measurement methods, and the test frequency band is 100kHz-200MHz:

[0116] 1. Reflection method, test 2Ω resistor in series with 1uH inductor and 0.3nF capacitor in parallel.

[0117] 2. Series through method, test 15kΩ resistor in series with 100uH inductor and 8pF capacitor in parallel.

[0118] 3. Parallel through method, test 0.01Ω resistor, 50nH inductor, 50nF capacitor series network.

[0119] The test results of the three schemes are as follows Figure 9-11 As shown in the results, the calibration method proposed in the present invention greatly improves the impedance curve of the DUT. The error between the impedance amplitude of the calibrated component and the theoretical value is within 5%, and the phase error is within 1%, which can meet the impedance test requirements of the 100kHz-200MHz frequency band.

[0120] Embodiment 2

[0121] This embodiment provides a method for measuring and calculating the impedance of a DUT using a radio frequency impedance measurement fixture, including:

[0122] 1) Measurement of fixture two-port through-S parameters and fixture-DUT system S parameters

[0123] Impedance measurement system such as Figure 3 As shown, it consists of a VNA, a designed impedance measurement fixture, a DUT, and necessary connecting cables. The VNA used uses the Virtual Instruments Software Architecture (VISA) to implement the initial setting, calibration, measurement, and other operations of the VNA on the host computer.

[0124] When the VNA is working, port 1 injects the stepped frequency swept sine excitation signal into the impedance measurement system through the SMA connector, and ports 1 and 2 detect the received RF signal response. The ratio of the signal received by ports 1 and 2 to the excitation signal sent by port 1 is the reflection coefficient S. 11 and the transmission coefficient S 21 Similarly, the reflection coefficient S corresponding to the excitation signal emitted by port 2 is 22 and the transmission coefficient S 12 The combination of the above coefficients is the two-port S parameter. The host computer controls the VNA to measure and save the S parameters as a .snp file for subsequent data processing.

[0125] First, perform initial settings and calibration on the VNA. The initial settings include the start and end frequency settings, intermediate frequency bandwidth, input power, number of scan points, etc. The VNA is calibrated using SOLT calibration, and the VNA's built-in SOLT algorithm will complete the calibration to the VNA coaxial line end.

[0126] Weld a copper sheet on the signal line of the impedance measurement fixture to put the fixture in a two-port straight-through state. Connect the two ports of the fixture to the two ports of the VNA respectively to measure its S parameters (called calibrated S parameters).

[0127] Replace the copper sheet with the DUT, repeat the above process, and measure the S parameters (called system S parameters).

[0128] 2) Calculate the DUT impedance from the measured S parameters

[0129] Depending on the impedance measurement method, the DUT impedance data is calculated from the measured S parameters. See the calculation process for details. Figure 7 , see the technical solution for the relevant calculation formula. You can write corresponding programs on Python to perform batch data processing.

[0130] It should be noted that the method of the embodiment of the present disclosure can be performed by a single device, such as a computer or a server. The method of the present embodiment can also be applied in a distributed scenario and completed by multiple devices cooperating with each other. In the case of such a distributed scenario, one of the multiple devices can only perform one or more steps in the method of the embodiment of the present disclosure, and the multiple devices will interact with each other to complete the described method.

[0131] It should be noted that some embodiments of the present disclosure are described above. Other embodiments are within the scope of the attached claims. In some cases, it should be understood that the size of the serial number of each step in the above embodiment does not mean the order of execution, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention. The actions or steps recorded in the claims can be performed in an order different from that in the above embodiment and still achieve the desired results. In addition, the process depicted in the accompanying drawings does not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0132] The embodiments of the present disclosure are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present disclosure should be included in the scope of protection of the present disclosure.

Claims

1. A method for designing a radio frequency impedance measurement fixture, characterized in that: The design method comprises: A symmetrical structure is adopted, with a coaxial SMA connector as the port connected to the vector network analyzer VNA, a coplanar waveguide as the connecting line between the SMA connector and the device under test DUT, and four patch pads are set on the coplanar waveguide to realize the RF impedance measurement fixture of the device under test DUT with different packages and different impedance ranges.

2. A radio frequency impedance measurement fixture, characterized in that: include: The left half of the fixture M L The left half of the fixture includes the SMA connector and the coplanar waveguide connected to it, and the right half of the fixture M R With the left half M L Symmetrical, the right half has four additional patch pads on the coplanar waveguide, and the middle part M DUT It is the DUT network of the device under test.

3. A single calibration method for a radio frequency impedance measurement fixture, the calibration method being used to perform a single calibration on the radio frequency impedance measurement fixture according to claim 2, characterized in that: include: Measuring the two-port through-S parameters of the calibration fixture is the calibration S parameters; Convert the calibration S parameters into calibration Z parameters to obtain the Z parameter equivalent circuit diagram; The Z parameter equivalent circuit diagram is symmetrically split to obtain the Z parameter of half of the calibration fixture; The Z parameters of half of the calibration fixture are converted into an ABCD matrix to de-embed the system impedance and finally obtain the impedance spectrum of the device under test (DUT).

4. The calibration method according to claim 3, characterized in that: Measuring the two-port direct-through S parameters of the calibration fixture includes: welding copper sheets with the same width as the middle signal line to both ends of the signal line, thereby achieving two-port direct-through, and measuring the two-port S parameters of the calibration fixture.

5. The calibration method according to claim 3, characterized in that: Converting calibrated S parameters to calibrated Z parameters involves: In the formula, Z C11 ~Z C22 is the Z parameter of the two-port through-hole impedance measurement fixture; S C11 ~S C22 is the S parameter of the two-port direct-through impedance measurement fixture; Z0 is the characteristic impedance, which is generally 50Ω.

6. The calibration method according to claim 5, characterized in that: Symmetrical segmentation of the Z parameter equivalent circuit diagram includes: The Z parameter matrix of the left half fixture: The designed fixture is approximately symmetrical, so the right half fixture is the left half fixture with two ports swapped.

7. The calibration method according to claim 6, characterized in that: Converting the Z parameters of half of the calibration fixture into an ABCD matrix consists of:

8. A method for measuring a radio frequency impedance measurement fixture, wherein the method uses the radio frequency impedance measurement fixture after single calibration according to claim 3 to perform impedance measurement, characterized in that: include: Measure the system S parameters of the calibration fixture-DUT; Convert the system S parameters into an ABCD matrix; If the impedance measurement method is the series / parallel through method, the ABCD matrix of the device under test DUT is obtained by calculating the ABCD parameter matrix of the half calibration fixture, and the impedance of the device under test DUT is obtained from the ABCD matrix of the device under test; If the impedance measurement method is the reflection method, the system S parameters are converted to Z parameters. Combined with the calibrated Z parameter equivalent circuit diagram, the system circuit analysis is performed to obtain the DUT impedance.

9. The measuring method according to claim 8, characterized in that: The ABCD matrix of the device under test (DUT) includes: By M DUT Get the impedance Z of the device under test DUT DUT include: For the series thru calibration method: For the parallel thru calibration method: Among them, Y DUT is the admittance of the DUT, is the impedance Z of the DUT DUT The reciprocal of .

10. The measuring method according to claim 8, characterized in that: If the impedance measurement method is the reflection method, the impedance of the device under test (DUT) includes: The S parameters of the fixture two-port direct pass are converted into Z parameters, which correspond to the input impedance of the system port 1 when the port 2 is short-circuited.

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