A matrix-type electromagnetic decoupling enhanced de-embedding method for test fixtures

Abstract

The present invention discloses a matrix-type electromagnetic decoupling enhanced de-embedding method for a test fixture, which belongs to the field of radio frequency and microwave measurement. The method is performed by splitting the reliability test fixture into multiple substructures, measuring the S parameters of each substructure in sequence according to the preset radio frequency port order, and extracting the equivalent parasitic matrix and the equivalent mutual coupling matrix based on matrix transformation. Finally, the intrinsic S parameters of the device under test are accurately restored through matrix operations. This method can effectively strip off the parasitic effects and electromagnetic coupling interference introduced by the reliability test fixture and its complex structure, thereby significantly improving the accuracy of the test results. Compared with traditional de-embedding methods, the present invention is not only applicable to a wide frequency band range of 0-110GHz, but also has fast and high-precision decoupling capabilities for complex electromagnetic environments, and is suitable for de-embedding processing in radio frequency reliability testing.

Description

Technical Field

[0001] The present invention belongs to the field of radio frequency (RF) and microwave measurement, and in particular relates to a matrix-type electromagnetic decoupling enhanced de-embedding method for a test fixture. Background Art

[0002] As RF microsystems continue to develop toward high integration and miniaturization, their long-term stability and reliability issues in extreme environments are becoming increasingly prominent. When conducting reliability testing and performance degradation analysis on active structures (such as power amplifiers and transistors) and passive structures (such as interconnects), in addition to conventional RF parameters (S parameters), it is often necessary to simultaneously obtain non-RF parameters such as device resistance, capacitance, inductance, and contact voltage drop. This multi-dimensional testing requirement has led to increasingly complex test fixture structures, inevitably introducing parasitic parameters, non-ideal boundary effects, and high-frequency interference factors such as electromagnetic compatibility (EMC) and electromagnetic coupling, which significantly affect the accuracy of RF measurements. In order to accurately evaluate the true RF performance of devices in complex reliability test scenarios, it is urgent to introduce a de-embedding method with high resolution and electromagnetic decoupling capabilities to systematically remove measurement errors caused by the fixture structure and its additional effects, ensuring the physical consistency and engineering usability of the test results.

[0003] Existing de-embedding techniques for RF and microwave measurements can be divided into two main categories: one is a calibration-based de-embedding method based on standard components, represented by TRL and SOLT. This method is mainly suitable for fixture environments with simple structures and symmetrical ports. It usually has good accuracy in the low-frequency or mid-frequency bands, but its frequency range of application is limited, the standard component design is complex, and high connection repeatability requirements are required. Especially when faced with complex fixture systems, if there are non-ideal effects such as coupling, parasitics, and electromagnetic leakage, it is easy to lead to reduced de-embedding accuracy and even "past-embedding" problems, affecting the accurate extraction of the intrinsic parameters of the device under test. "Past-embedding" refers to the excessive elimination of the influence of additional structures on the device under test. The other type of full-wave de-embedding method is centered on full-wave simulation assistance. It usually constructs a three-dimensional electromagnetic model of the fixture and device, and combines simulation and measured data to extract and compensate errors. This method has certain advantages when dealing with non-standard structures or complex interconnections, but it relies on detailed modeling and high-quality simulation, is greatly affected by factors such as material parameters and boundary condition settings, has high computational costs, low engineering implementation efficiency, and lacks unified modeling specifications, making it difficult to widely promote in actual testing.

[0004] Therefore, how to construct a de-embedding method suitable for complex fixtures for reliability testing and with high-precision electromagnetic decoupling has become an important technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a matrix-type electromagnetic decoupling enhanced de-embedding method for a test fixture, which can effectively remove non-ideal effects such as coupling, parasitics, and electromagnetic leakage in the reliability test fixture structure, and achieve high-precision extraction of the intrinsic S parameters of the device under test in a wide frequency range of 0-110GHz.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a matrix-type electromagnetic decoupling enhanced de-embedding method for a test fixture, the method comprising:

[0007] Step 1: Construct an overall measurement structure consisting of the device under test and the reliability test fixture, denoted as left-DUT-right. Based on the distribution characteristics of coupling, parasitic, and electromagnetic leakage non-ideal effects, the structure is split into five functional substructures: left, left-DUT, DUT, DUT-right, and right.

[0008] Left, left-DUT, DUT, DUT-right, and right represent the left fixture area, the left fixture-DUT composite structure area, the DUT area, and the DUT-right fixture area, respectively. The RF port excitation sequence of each substructure should be strictly consistent with the RF excitation sequence of the overall structure.

[0009] Step 2: Measure the S parameter matrices of the overall measurement structure and the five functional substructures respectively, and convert them into ABCD matrices. The ABCD matrix represents the linear relationship between the voltage and current between the input and output of the two-port network. It is the basic parameter model that describes the network transmission characteristics. To express the ABCD matrix of the structure; based on the principle of matrix operation, the equivalent parasitic matrix between the fixture and the device under test and the equivalent mutual coupling matrix between the fixtures are gradually extracted: 、 、 ; The equivalent parasitic ABCD matrix introduced by the connection between the left structure and the DUT structure; The equivalent parasitic ABCD matrix introduced by the connection between the DUT structure and the right structure; The equivalent mutual coupling matrix generated for the electromagnetic compatibility and electromagnetic coupling of the five functional substructures;

[0010] Step 3: Using the two extracted equivalent parasitic ABCD matrices and one extracted equivalent mutual coupling matrix, extract the ABCD matrix of the device under test using the following method:

[0011]

[0012] in is the ABCD matrix of the DUT after de-embedding, The ABCD matrix is ​​the same as the above-mentioned overall measurement structure, but due to process influence or reliability problem, the reliability of the matrix is ​​degraded.

[0013] Step 4: By converting the ABCD matrix of the de-embedded device under test into an S-parameter matrix, the matrix de-embedding of the reliability test fixture is completed.

[0014] Furthermore, the specific structure of the ABCD matrix is:

[0015] ;

[0016] Among them, A1, B1, C1, and D1 correspond to the S parameter matrix transformation to obtain the parameters of the first row and first column, the parameters of the first row and second column, the parameters of the second row and first column, and the parameters of the second row and second column of the ABCD matrix; S 11 、S 12 、S 21 、S 22 Corresponding to the parameters of the first row and first column, the parameters of the first row and second column, the parameters of the second row and first column, and the parameters of the second row and second column of the measured S parameter matrix, Z0 is 50 ohms.

[0017] Furthermore, the extraction method in step 2 is as follows:

[0018] ;

[0019] ;

[0020] ;

[0021] in, 、 、 、 、 、 The ABCD matrices corresponding to the overall measurement structure left-DUT-right, substructure left, substructure left-DUT, substructure DUT, substructure right, and substructure DUT-right respectively. The superscript -1 indicates that the inverse matrix operation is performed on the ABCD matrix.

[0022] Furthermore, the method of converting to S parameter matrix in step 4 is:

[0023] .

[0024] The method of the present invention has the following beneficial effects:

[0025] This invention provides a matrix-based electromagnetic decoupling-enhanced deembedding method for test fixtures. Without relying on traditional standard components, this method extracts and compensates for non-ideal effects such as parasitic parameters, inter-port coupling, and electromagnetic leakage introduced by the fixture's structural complexity by segmented testing of the substructure's S parameters. This method combines ABCD matrix transformation with matrix operations, thereby achieving high-precision restoration of the intrinsic RF characteristics of the device under test. This method is particularly suitable for complex reliability test fixtures containing heterogeneous ports, multi-layer interconnects, or asymmetric structures, and exhibits excellent deembedding stability and result consistency across a wide frequency range of 0–110 GHz. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention provides a reliability test fixture with a four-point probe port and a radio frequency port, a device under test, and a schematic diagram of the overall structure of the device under test and the reliability test fixture.

[0027] Figure 2 This is a structural diagram of the present invention that only includes the left clamp part (left).

[0028] Figure 3 This is a structural schematic diagram of the left-side fixture and device under test combination left-DUT provided by the present invention.

[0029] Figure 4 This is a schematic structural diagram of a separate device under test (DUT) provided by the present invention.

[0030] Figure 5 This is a schematic structural diagram of the present invention that only includes the right side clamp part right.

[0031] Figure 6 This is a structural schematic diagram of the device under test and the right-side fixture combination DUT-right provided by the present invention.

[0032] Figure 7 This is a comparison chart of the S11 parameter of the device under test after using the electromagnetic decoupling enhanced de-embedding method provided by the present invention and the S parameter of the ideal device.

[0033] Figure 8 This is a comparison chart of the S12 parameters of the device under test and the S parameters of the ideal device after using the electromagnetic decoupling enhanced de-embedding method provided by the present invention.

[0034] Figure 9 The figure shows a comparison between the S21 parameter of the device under test and the S parameter of the ideal device after using the electromagnetic decoupling enhanced de-embedding method provided by the present invention.

[0035] Figure 10 The figure shows a comparison between the S22 parameter of the device under test and the S parameter of the ideal device after using the electromagnetic decoupling enhanced de-embedding method provided by the present invention. DETAILED DESCRIPTION

[0036] The present invention discloses a matrix-type electromagnetic decoupling enhanced de-embedding method for a test fixture, and takes a fixture having both four-point probe ports and radio frequency ports as an example to illustrate the specific implementation steps of the method of the present invention.

[0037] The structure to be de-embedded used in the embodiment of the method of the present invention is as follows: Figure 1 The figure shows the overall structure of the device under test and the reliability test fixture, designated as left-DUT-right. This structure consists of the device under test and the reliability test fixture interconnected via a "connector fixture port" and a "connector device port." The reliability test fixture also features a four-point probe port and an RF coplanar waveguide port, enabling compatibility with multiple measurement modes. During implementation, the electromagnetic decoupling-enhanced deembedding method based on matrix extraction proposed in this invention is used to model and decouple this complex fixture structure. Ultimately, the RF parameters measured for the overall structure are processed to accurately restore the intrinsic RF parameters of the device under test.

[0038] The method of the present invention needs Figure 1 Based on the overall structure of the device under test and the reliability test fixture shown in the figure, the structure is split according to the functional modules to achieve high-precision de-embedding processing. Specifically, five sub-structures need to be constructed, namely: the structure left that only contains the left fixture part (such as Figure 2 As shown), the left fixture and the device under test combined structure left-DUT (as shown Figure 3 As shown), a separate device under test structure DUT (such as Figure 4 As shown), the structure right containing only the right fixture part (as shown Figure 5 As shown) and the device under test and the right fixture combination structure DUT-right (as shown Figure 6 As shown). In each of the above structures, the "RF Port 1" and "RF Port 2" marked in the figure correspond to the first port and the second port in the S-parameter test process, respectively. When using the matrix extraction type electromagnetic decoupling enhanced de-embedding method of the present invention, the excitation and reception signals must be applied strictly according to the order of the port markings in the figure to ensure that the port mapping in the matrix calculation process is accurate and consistent. After completing the structure splitting and port order definition, high-precision de-embedding can be performed by the following steps. The specific details are as follows:

[0039] Step 1: The RF port 1 of the left-DUT-right structure, left structure, left-DUT structure, DUT structure, right structure and DUT-right structure corresponds to port 1 in the conventional S parameter measurement, and the RF port 2 corresponds to port 2 in the conventional S parameter measurement. The S parameters of the six structures are tested in turn to obtain the S parameter matrix. 、 、 、 、 and And through the following method of converting the S parameter matrix into the ABCD matrix, the S parameter matrix is ​​converted into 、 、 、 、 and .

[0040] ;

[0041] Among them, A1, B1, C1, and D1 correspond to the S parameter matrix transformation to obtain the parameters of the first row and first column, the parameters of the first row and second column, the parameters of the second row and second column, and the parameters of the second row and second column of the ABCD matrix; S 11 、S 12 、S 21 、S 22 Corresponding to the parameters of the first row and first column, the parameters of the first row and second column, the parameters of the second row and second column, and the parameters of the second row and second column of the measured S parameter matrix; in addition, Z0 is 50 ohms.

[0042] Step 2: Convert the converted left structure, left-DUT structure, and ABCD matrix of DUT structure 、 and The equivalent parasitic ABCD matrix introduced by the connection between the left structure and the DUT structure is obtained by the following conversion method: .

[0043] ;

[0044] Step 3: Convert the converted right structure, DUT-right structure and DUT structure into ABCD matrix 、 and The equivalent parasitic ABCD matrix introduced by the connection between the right structure and the DUT structure is obtained by the following conversion method: .

[0045] ;

[0046] Step 4: Convert the converted left-DUT-right structure, left structure, left-DUT structure, DUT structure, right structure and DUT-right structure into an ABCD matrix 、 、 、 、 and , and the equivalent parasitic ABCD matrix extracted above 、 The equivalent mutual coupling matrix is ​​obtained through the following conversion method.

[0047] ;

[0048] Step 5. At this point, all equivalent parasitic matrices and equivalent mutual coupling matrices have been extracted. Test the new left-DUT-right structure except step 1 in the order of RF ports to obtain the S parameter matrix and convert it into an ABCD matrix. The ABCD matrix of the target device under test after de-embedding can be obtained by stripping off the influence of the left structure, right structure, equivalent parasitic matrix and equivalent mutual coupling matrix through the following method: .

[0049] ;

[0050] Step 6: De-embed the ABCD matrix Convert to S parameter matrix as follows .

[0051] ;

[0052] Step 7: De-embed the S parameter matrix Compared with the initial measurement By comparison, the S parameters after de-embedding and the S parameters of the ideal device are compared as shown in the figure below. Figure 7 、 Figure 8 、 Figure 9 、 Figure 10 As shown in the figure, the comparison diagrams of S11, S12, S21, and S22 parameters with the S parameters of the ideal device are respectively shown. It can be seen that the S parameters completely overlap in the range of 0.1GHz-110GHz, which verifies the consistency of the amplitude and phase of this method in the complex domain.

[0053] It should be noted that the electromagnetic decoupling enhanced de-embedding method proposed in this embodiment is not only applicable to the structure used in this case, but also to any other fixture used for reliability testing or fixtures with complex structures.

Claims

1. A matrix-type electromagnetic decoupling enhanced de-embedding method for a test fixture, characterized in that: The method includes: Step 1: Construct an overall measurement structure consisting of the device under test and the reliability test fixture, denoted as left-DUT-right. Based on the distribution characteristics of coupling, parasitic, and electromagnetic leakage non-ideal effects, the structure is split into five functional substructures: left, left-DUT, DUT, DUT-right, and right. Left, left-DUT, DUT, DUT-right, and right represent the left fixture area, the left fixture-DUT composite structure area, the DUT area, and the DUT-right fixture area, respectively. The RF port excitation sequence of each substructure should be strictly consistent with the RF excitation sequence of the overall structure. Step 2: Measure the S parameter matrices of the overall measurement structure and the five functional substructures respectively, and convert them into ABCD matrices. The ABCD matrix represents the linear relationship between the voltage and current between the input and output of the two-port network. It is the basic parameter model that describes the network transmission characteristics. To express the ABCD matrix of the structure; based on the principle of matrix operation, the equivalent parasitic matrix between the fixture and the device under test and the equivalent mutual coupling matrix between the fixtures are gradually extracted: 、 、 ; The equivalent parasitic ABCD matrix introduced by the connection between the left structure and the DUT structure; The equivalent parasitic ABCD matrix introduced by the connection between the DUT structure and the right structure; The equivalent mutual coupling matrix generated for the electromagnetic compatibility and electromagnetic coupling of the five functional substructures; Step 3: Using the two extracted equivalent parasitic ABCD matrices and one extracted equivalent mutual coupling matrix, extract the ABCD matrix of the device under test using the following method: ； in is the ABCD matrix of the DUT after de-embedding, The ABCD matrix is ​​the same as the above overall measurement structure, but due to process influence or reliability issues, the reliability of the matrix has been degraded. Step 4: By converting the ABCD matrix of the de-embedded device under test into an S-parameter matrix, the matrix de-embedding of the reliability test fixture is completed.

2. A matrix-type electromagnetic decoupling enhanced de-embedding method for a test fixture according to claim 1, characterized in that: The specific structure of the ABCD matrix is: ； Among them, A1, B1, C1, and D1 correspond to the S parameter matrix transformation to obtain the parameters of the first row and first column, the parameters of the first row and second column, the parameters of the second row and first column, and the parameters of the second row and second column of the ABCD matrix; S 11 、S 12 、S 21 、S 22 Corresponding to the parameters of the first row and first column, the parameters of the first row and second column, the parameters of the second row and first column, and the parameters of the second row and second column of the measured S parameter matrix, Z0 is 50 ohms.

3. The matrix-type electromagnetic decoupling enhanced de-embedding method for a test fixture according to claim 1, wherein: The extraction method in step 2 is as follows: ； ； ； in, 、 、 、 、 、 The ABCD matrices corresponding to the overall measurement structure left-DUT-right, substructure left, substructure left-DUT, substructure DUT, substructure right, and substructure DUT-right respectively. The superscript -1 indicates that the inverse matrix operation is performed on the ABCD matrix.

4. The matrix-type electromagnetic decoupling enhanced de-embedding method for a test fixture according to claim 2, wherein: The method for converting to the S parameter matrix in step 4 is: 。

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