System and method for calibrating interface of device under test
The combination of the signal generator, the measuring unit and the calculating unit solves the problem of high interface cost of the network analyzer calibration device in the prior art, realizes a more economical and easier to apply calibration method, and improves the calibration accuracy.
Patent Information
- Application Number
- CN202380094790.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-02-24
- Publication Date
- 2025-09-19
AI Technical Summary
In high-speed device testing, especially testing above 5 GHz, existing technologies require the use of expensive network analyzers to calibrate the device interface under test, resulting in high costs and difficulty in application.
Provided are a system and method for calibrating an interface of a device under test, which avoids dependence on a network analyzer by using a detachable signal generator and a measurement unit in combination with a load board and a calculation unit and utilizing first and third calibration signals for calibration.
This method realizes efficient and economical calibration of the device under test interface without using a network analyzer, improving the accuracy and ease of calibration.
Smart Images
Figure CN120677397A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a system and method for calibrating an interface of a device under test, and more particularly to a system and method for calibrating an interface of a device under test for testing high-frequency / high-speed devices exceeding 5 GHz. Background Art
[0002] Especially when testing high-speed devices, especially those operating above 5 GHz, it is necessary to compensate for transmission loss to ensure adequate signal quality for the device under test (hereinafter also referred to as "DUT"). Transmission loss generally refers to the cumulative decrease in waveform energy intensity as a wave propagates away from its source, or as the wave propagates through a specific area or type of structure.
[0003] Various methods are known in the art to avoid or reduce transmission losses. For example, test heads can be factory-calibrated by the tester manufacturer before shipment. However, the DUT interface is typically established by the customer and calibrated by measuring the S-parameters of the DUT interface signal path. In this case, the customer must prepare expensive network analyzers and probing tools. Summary of the Invention
[0004] It is therefore an object of the present invention to provide a system and method for more easily calibrating a DUT interface, particularly without requiring the use of a network analyzer.
[0005] The above object is achieved by a system for calibrating an interface of a device under test according to claim 1 and a method for calibrating an interface of a device under test according to claim 13. Preferred embodiments of the invention are indicated by the dependent claims.
[0006] Specifically, the present invention provides a system for calibrating an interface of a device under test, the system comprising: - a test head comprising a signal generator and a measurement unit, wherein the signal generator and the measurement unit are detachable and directly electrically connected to each other via a first signal line; - a DUT unit comprising a load board, wherein the load board comprises an input port and an output port; wherein the input port and the output port are electrically connected to each other via a second signal line; and - A computing unit.
[0007] The load board may be a printed circuit board (PCB) or other component used in electrical and electronic engineering to connect electronic components to each other in a controlled manner. The measuring unit may be a digital converter.
[0008] The first signal line ensures that the cable end of the test head is connected to the shortest possible distance.
[0009] The signal generator is configured to generate a first calibration signal, and the system is configured to transmit the first calibration signal to the measurement unit and the input port. The first calibration signal can be white noise, or a pulse or random phase modulated signal with a wide range of frequency components.
[0010] The measurement unit is configured to measure a second calibration signal based on the first calibration signal received from the signal generator; and to measure a third calibration signal based on the first calibration signal received from the DUT unit via the output port.
[0011] In addition, the calculation unit is configured to calculate a main calibration signal based on the first, second and third calibration signals, and further calibrate the device under test interface based on the calculated main calibration signal.
[0012] The above system ensures that calibration can be performed without a network analyzer, which is more cost-effective and easier to use, especially for customers themselves. Calibration is typically based on a primary calibration signal, which is based on first, second, and third calibration signals. This means that a first calibration signal generated by a signal generator is transmitted to a measurement unit via a first signal line. The measurement unit then measures a second calibration signal based on the first calibration signal. Furthermore, the first calibration signal is transmitted to an input port of the DUT unit. The measurement unit then measures a third calibration signal, which is received at an output port of the DUT unit.
[0013] In one embodiment, the second calibration signal is a signal having at least one modified signal parameter of the first calibration signal, wherein the at least one modified signal parameter is caused by transmission loss, such as transmission loss of the first signal line. This embodiment enables more detailed measurement and calibration of the DUT interface because the transmission loss can be taken into account during calibration.
[0014] In this context, in another embodiment, the third calibration signal is a signal having at least one modified signal parameter of the first calibration signal, wherein the modified signal parameter is caused by a transmission loss, such as a transmission loss of the second signal line.
[0015] In another specific embodiment, the at least one signal parameter is one of frequency, amplitude, and phase.
[0016] In a further preferred embodiment, the DUT's input port and the DUT's output port are directly connected to each other via a second signal line. Therefore, this embodiment is referred to as a "short DUT." The term "directly connected" implies that there is no (active) circuitry between the input port and the output port. In other words, a "short DUT" contains only one transmission path: the second signal line, which directly connects the input port and the output port. Advantageously, this embodiment allows for accurate determination of transmission loss.
[0017] Furthermore, in a specific embodiment, the DUT unit comprises a device under test, and wherein the input port is connected to the device under test via a first electrical connection, and the output port is connected to the device under test via a second electrical connection.
[0018] In a preferred embodiment, the first electrical connection and the second electrical connection have the same length. This embodiment provides a symmetrically designed DUT interface to ensure more accurate and better calibration.
[0019] In this context, the length of the first signal line between the signal generator and the measurement unit of the test head should be as short as possible. In addition, depending on the design of the DUT, the lengths of the first electrical connection and the second electrical connection should also be as short as possible to keep transmission loss to a minimum.
[0020] Specifically, the present invention further provides a method for calibrating an interface of a device under test, the method comprising the following steps: - generating a first calibration signal by a signal generator at a test head, and transmitting the first calibration signal to a measurement unit at the test head via a first signal line; - the measuring unit measures a second calibration signal based on the first calibration signal; - transmitting the first calibration signal to an input port of the DUT unit; - the measurement unit measures a third calibration signal at the output port of the DUT unit based on the first calibration signal; - calculating a main calibration signal based on the first, second and third calibration signals; and - calibrating the device under test interface based on the calculated main calibration signal.
[0021] In a preferred embodiment, calculating the master calibration signal further comprises the following steps: - calculating, by a calculation unit, Fourier transform functions of the first calibration signal, the second calibration signal, and the third calibration signal.
[0022] In another embodiment, calculating the master calibration signal further comprises the following steps: The calculation unit calculates transfer functions of the second calibration signal and the third calibration signal based on the first calibration signal.
[0023] In this context, the above-mentioned "S-parameters" and the term "transfer function" have the same meaning.
[0024] In addition, in a specific embodiment, calculating the main calibration signal further includes the following steps: - calculating a complex division of the calculated transfer function of the second calibration signal and the third calibration signal.
[0025] In addition, calculating the master calibration signal also includes the following steps: - calculating a complex square root of the calculated complex division of the second calibration signal and the third calibration signal.
[0026] In another preferred embodiment, the complex square root of the calculated complex division of the second calibration signal and the third calibration signal is calculated in each frequency interval.
[0027] Preferably, the transfer function of the second calibration signal and the third calibration signal based on the first calibration signal is implemented by the following formula:
[0028] Where X is the calculated Fourier transform of the first calibration signal, Y SC is the calculated Fourier transform of the second calibration signal, and Y di is the calculated Fourier transform of the third calibration signal The advantages and preferred embodiments listed with respect to the system should apply correspondingly to the method, and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The above and other features and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention, taken in conjunction with the accompanying drawings, in which like reference numerals represent like features, and in which: Figure 1 A test head of a system for calibrating an interface of a device under test according to the present invention is shown; Figure 2 Shown according to Figure 1 The test head is connected to the DUT unit according to the present invention; Figure 3 A "short DUT" according to the present invention is shown; Figure 4 Shown according to Figure 1 a straight-line view of the electrical connections of the test head; Figure 5 Shown according to Figure 2A straight-line view of the electrical connections of the configuration; Figure 6 Another alternative embodiment of the DUT unit is shown; and Figure 7 A comparison graph is shown between various measurements using a network analyzer and the system and method according to the present invention. DETAILED DESCRIPTION
[0030] Figure 1 shows the interface used to calibrate the device under test 6 (see Figure 2 ) system 2. Test head 4 includes a signal generator 8 and a measurement unit 10, wherein the signal generator 8 and the measurement unit 10 are detachable and directly electrically connected to each other via a first signal line 12. Test head 4 also includes a channel module 14, which carries the signal generator 8 and the measurement unit 10, as well as possible electrical wiring to further connect the two components 8 and 10 to each other via the first signal line 12. The first signal line 12 is also called a "short cable" and is preferably as short as possible. In other words, the first signal line 12 ensures that the cable ends of the test head 4 are connected to each other over the shortest possible distance.
[0031] Figure 2 Shows the Figure 1 Test head 4. Figure 2 The difference of the embodiment of the present invention is that the test head 4 is now electrically connected to a DUT unit 16 (device under test unit). The DUT unit 16 is part of the device under test interface 6, wherein the device under test interface 6 may also include other components, which, incidentally, are not necessary for describing the system and method according to the present invention.
[0032] DUT unit 16 includes a load board 18, a DUT socket 20, and a device under test 22. Load board 18 includes an input port 44 and an output port 46. Input port 44 and output port 46 are electrically connected to each other via a second signal line 28, wherein second signal line 28 is configured in or on load board 18 and mounted in or on device under test 22. Therefore, in other words, device under test 22 can be understood as a calibration device under test or "short DUT" 19. In addition, system 2 includes a computing unit 11, which is configured to communicate with test head 4 and / or other components of system 2, and will be explained in more detail below.
[0033] To measure necessary signals as will be described later, the signal generator 8 is connected to the input port 44 via the input port 24 , and the measuring unit 10 is connected to the output port 46 via the output port 26 through the electrical connector 30 (eg pogo pins).
[0034] like Figure 3As shown in FIG. 1 , a “short DUT” 19 according to the present invention is shown. Figure 3 As can be seen, there is no active circuit between the input port 44 and the output port 46. Instead, only the second signal line 28 connects the two ports 44, 46. In other words, there is only one transmission path, which directly connects the input port 44 and the output port 46.
[0035] Figure 4 Display according to Figure 1 FIG2 is a linear diagram of a specific embodiment of a device under test (DUT) 2. In a first step of calibrating DUT interface 6, signal generator 8 generates a first calibration signal S1 and transmits it to measurement unit 10 via first signal line 12. Measurement unit 10 receives a second calibration signal S2 based on first calibration signal S1. In other words, measurement unit 10 receives a signal, namely, second calibration signal S2 having at least one modified signal parameter of first calibration signal S1, where the at least one modified signal parameter is caused by, for example, transmission losses in first signal line 12. Therefore, transmission losses can be taken into account for the calibration of system 2.
[0036] exist Figure 5 The next step in the calibration process is explained in . Figure 5 Shows the Figure 2 Input port 24 is connected to device under test 22 via first electrical connection 32 , and output port 26 is connected to device under test 22 via second electrical connection 34 .
[0037] In this embodiment, test head 4 is connected to DUT unit 16, and first calibration signal S1 is also transmitted to measurement unit 10 through DUT unit 16. Measurement unit 10 then receives third calibration signal S3 based on first calibration signal S1. Compared to the above steps, measurement unit 10 receives a signal, namely, third calibration signal S3, that has at least one modified signal parameter of first calibration signal S1, where the at least one modified signal parameter is caused by, for example, transmission loss in second signal line 28. Therefore, calibration can take into account further transmission loss in system 2.
[0038] The calculation of the main calibration signal can be mathematically summarized as follows: Calculation 1: Perform FFT (Fast Fourier Transform) on each signal
[0039] Where "x" is the first calibration signal S1, "y sc " is the second calibration signal S2, and "y di ” is the third calibration signal S3.
[0040] Thereafter, the calculation unit 11 executes “Calculation Formula 2” as follows: Formula 2: Calculate the transfer function for each setting
[0041] Among them, "T SC " is the transfer function of the second calibration signal S2, "T di ” is the transfer function of the third calibration signal S3.
[0042] In the next step, the complex division of the transfer function "T deembed ”: Equation 3: Calculate the division of Tdi and Tsc to de-embed the signal path in the test head
[0043] The final step involves calculating the complex square root "T" according to "Equation 4" ow ”: Formula 4: Calculate T in each frequency interval deembed The complex square root of (this will yield the transfer function of the "one-way" signal path of the "DUT interface")
[0044] It should be noted that the above calculation method is for exemplary purposes and is used for the described specific embodiment of the system. In addition, other calculation methods can also be applied as long as they are mathematically equivalent results.
[0045] from Figure 5 As can be seen, the system design (particularly with respect to the lengths of first and second electrical connections 32, 34) is symmetrical. In an alternative embodiment, the lengths of first and second electrical connections 32, 34 are different and therefore asymmetrical. According to this alternative embodiment, the calculation of the primary calibration signal is also different. Assuming the length of the first electrical connection is "1" and the length of the second electrical connection is "α," "Equation 5" must be applied instead of "Equation 4": Formula 5: Calculate T in each frequency interval deembed Instead of calculating Equation 4 (which would give the transfer function for the "one-way" signal path of the "DUT interface"),
[0046] If 1 = α, then "Calculation 5" and "Calculation 4" are equivalent. In this case, the electrical connection is symmetrical and includes Figure 5 The same length as shown in the specific embodiment.
[0047] Figure 6An alternative embodiment of the DUT unit 16 is shown. In this embodiment, the DUT socket 20 and the device under test 22 are not provided. Therefore, this easier to design DUT unit 16 is called a "short load board".
[0048] Figure 7 A graph comparing two different measurements is shown. One measurement was performed conventionally using a network analyzer. The other was performed using the system and method of the present invention. As can be seen from the graph, there is only a slight difference between the two curves. However, this difference is not of practical importance.
[0049] The present invention is not limited to the foregoing specific embodiments. On the contrary, those skilled in the art may also derive other variations of the present invention therefrom without departing from the purpose of the present invention. In addition, in particular, all individual features described in conjunction with the specific embodiment examples may also be combined with each other in other ways without departing from the purpose of the present invention.
[0050]
Explanation of symbols
Claims
1. A system (2) for calibrating an interface (6) of a device under test, the system (2) comprising: - a test head (4), comprising a signal generator (8) and a measurement unit (10), wherein the signal generator (8) and the measurement unit (10) are detachable and directly electrically connected to each other via a first signal line (12); - a DUT unit (16) comprising a load board (18), wherein the load board (18) comprises an input port (44) and an output port (46); wherein the input port (44) and the output port (46) are electrically connected to each other via a second signal line (28); and - a computing unit (11); in - the signal generator (8) is configured to generate a first calibration signal (S1), and the system (2) is configured to transmit the first calibration signal (S1) to the measurement unit (10) and the input port (44); - The measuring unit (10) is configured to: - measuring a second calibration signal (S2) based on the first calibration signal (S1) received from the signal generator (8); and - measuring a third calibration signal (S3) based on the first calibration signal (S1) received from the DUT unit (16) via the output port (46); The calculation unit (11) is configured to calculate a main calibration signal based on the first, second and third calibration signals (S1, S2, S3), and further calibrate the device under test interface (6) based on the calculated main calibration signal.
2. The system (2) as claimed in claim 1, The second calibration signal (S2) is a signal having at least one modified signal parameter of the first calibration signal (S1), wherein the at least one modified signal parameter is caused by transmission loss.
3. The system (2) as claimed in claim 1 or 2, The third calibration signal (S3) is a signal having at least one modified signal parameter of the first calibration signal (S1), wherein the at least one modified signal parameter is caused by transmission loss.
4. The system (2) as claimed in claim 2 or 3, The at least one signal parameter is one of the following: -frequency; -amplitude; -Phase.
5. The system (2) according to any one of claims 1 to 4, in, In order to calculate the main calibration signal, the calculation unit (11) is configured to calculate the Fourier transform function of the first calibration signal (S1), the second calibration signal (S2) and the third calibration signal (S3).
6. The system (2) according to any one of claims 1 to 5, in, In order to further calculate the main calibration signal, the calculation unit (11) is further configured to calculate the transfer functions of the second calibration signal (S2) and the third calibration signal (S3) based on the first calibration signal (S1).
7. The system according to claim 6, in, In order to further calculate the main calibration signal, the calculation unit (11) is further configured to calculate a complex division of the calculated transfer function of the second calibration signal (S2) and the third calibration signal (S3).
8. The system (2) as claimed in claim 7, in, In order to further calculate the main calibration signal, the calculation unit (11) is further configured to calculate the complex square root of the calculated complex division of the transfer function of the second calibration signal (S2) and the transfer function of the third calibration signal (S3).
9. The system (2) as claimed in claim 8, The calculation unit (11) is configured to calibrate the device under test interface (6) based on the value of the calculated complex square root.
10. The system (2) according to any one of claims 1 to 9, The input port (44) and the output port (46) are directly connected to each other via the second signal line (28).
11. The system (2) according to any one of claims 1 to 10, The DUT unit (16) includes a device under test (22), and one input port (24) is connected to the device under test (22) via a first electrical connection (32), and one output port (26) is connected to the device under test (22) via a second electrical connection (34).
12. The system (2) as claimed in claim 11, The first electrical connection (32) and the second electrical connection (34) have the same length.
13. A method for calibrating an interface of a device under test (6), the method comprising the following steps: - generating a first calibration signal (S1) by a signal generator (8) of a test head (4), and transmitting the first calibration signal (S1) to a measurement unit (10) of the test head (4) via a first signal line (12); - the measuring unit (10) measures a second calibration signal (S2) based on the first calibration signal (S1); - transmitting the first calibration signal (S1) to an input port (44) of a DUT unit (16); - the measurement unit (10) measures a third calibration signal (S3) at the output port (46) of the DUT unit (16) based on the first calibration signal (S1); - calculating a main calibration signal based on the first, second and third calibration signals (S1, S2, S3); and - calibrating the device under test interface (6) based on the calculated main calibration signal.
14. The method of claim 13 , wherein calculating the master calibration signal further comprises the steps of: - A calculation unit (11) calculates the Fourier transform functions of the first calibration signal (S1), the second calibration signal (S2) and the third calibration signal (S3).
15. The method of claim 14, wherein calculating the master calibration signal further comprises the steps of: The calculation unit (11) calculates the transfer functions of the second calibration signal (S2) and the third calibration signal (S3) based on the first calibration signal (S1).
16. The method of claim 15, wherein calculating the master calibration signal further comprises the steps of: - calculating a complex division of the calculated transfer function of the second calibration signal (S2) and the third calibration signal (S3).
17. The method of claim 16, wherein calculating the master calibration signal further comprises the steps of: - calculating the complex square root of the calculated complex division of the transfer function of the second calibration signal (S2) and the transfer function of the third calibration signal (S3).
18. The method of claim 17, further comprising the steps of: - calculating in each frequency interval the complex square root of the calculated complex division of the transfer function of the second calibration signal (S2) and the transfer function of the third calibration signal (S3).
19. The method according to any one of claims 15 to 18, The transfer function for calculating the second calibration signal (S2) and the third calibration signal (S3) based on the first calibration signal (S1) is completed by the following formula: Where X is the calculated Fourier transform of the first calibration signal (S1), Y SC is the calculated Fourier transform of the second calibration signal (S2) and Y di is the calculated Fourier transform of the third calibration signal (S3).