Calibration method of electrostatic discharge target link transfer impedance
By calibrating the transfer impedance of the electrostatic discharge target link, the problem of inaccurate transfer impedance in the calibration of electrostatic discharge simulators was solved, achieving higher measurement accuracy and calibration of current waveform parameters.
Patent Information
- Application Number
- CN202511988022.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-26
- Publication Date
- 2026-04-28
AI Technical Summary
In the current electrostatic discharge simulator calibration process, the transfer impedance value is inaccurate because the link is not in an ideal state, which affects the accuracy of the measurement results.
By connecting a DC current source, an ammeter, and an oscilloscope, and aligning the current target adapter with the electrostatic discharge target, the transfer impedance of the electrostatic discharge target-attenuator-cable link is calibrated, and the accurate current amplitude is calculated using the low-frequency transfer impedance formula.
This improved the reliability of the calibration system, reduced measurement errors, and enabled accurate calibration of the current waveform parameters of the electrostatic discharge simulator.
Smart Images
Figure CN121934004A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrostatic discharge technology, and particularly relates to a calibration method for the transfer impedance of an electrostatic discharge target link. Background Technology
[0002] Electrostatic discharge (ESD) susceptibility testing is a critical electromagnetic compatibility (EMC) test, and the key testing equipment used in this test is an ESD simulator. The calibration accuracy of the ESD pulse parameters directly affects the accuracy of the measurement results, and various industries have always attached great importance to the calibration of ESD simulators.
[0003] Internationally, electrostatic discharge (ESD) tests are generally performed according to IEC 61000-4-2 (the authoritative international standard for electrostatic discharge (ESD) immunity testing). Domestically, GB / T 17626.2 (electromagnetic compatibility testing and measurement techniques for ESD immunity testing) is generally used as a reference. This standard requires that when calibrating the current waveform parameters of the ESD simulator, the contact discharge head of the ESD simulator should be in contact with the ESD target, and electrostatic interference should be applied. The output of the ESD target is connected to an attenuator to input the electrostatic pulse signal into an oscilloscope.
[0004] The calibration of the electrostatic discharge simulator consists of two steps: first, the calibration of the electrostatic high voltage; and second, the calibration of the electrostatic pulse waveform. The calibration device used for the electrostatic pulse waveform calibration is an electrostatic discharge target.
[0005] Traditionally, current waveform calibration involves circuit analysis of impedance matching, calculation of attenuator coefficients, and determination of the current amplitude relationship between the voltage readings from the oscilloscope and the electrostatic pulse current. Then, formulas are used to calculate the first peak current, 30ns peak current, 60ns peak current, etc., corresponding to different voltage levels.
[0006] Theoretically, this calculation method is sound, but in practice, it has been found that the link cannot be in an ideal state due to factors such as cable bending, attenuator coefficient, and the connection between the attenuator and the cable. When using the theoretical transfer impedance value to calibrate the electrostatic discharge gun, the measurement results will be biased.
[0007] To address the issues encountered during the calibration of the aforementioned equipment, a calibration method for the transfer impedance of an electrostatic discharge target link is provided. This method can be used by electromagnetic compatibility metrology units and testing institutions in domestic military, automotive, and electronics industries.
[0008] This calibration method can provide a relatively accurate transfer impedance for the electrostatic discharge target-attenuator-cable link, and can directly calculate the first peak current of the electrostatic discharge simulator discharge current and other current amplitudes that need to be measured through this transfer impedance.
[0009] It should be noted that the above content falls within the inventor's technical knowledge and does not necessarily constitute prior art. Summary of the Invention
[0010] To address the aforementioned problems, the present invention aims to provide a calibration method for the transfer impedance of an electrostatic discharge target link. This method primarily solves the problem of errors caused by using the theoretical transfer impedance of the electrostatic discharge target. The calibration method provided by the present invention can calibrate the transfer impedance after the electrostatic discharge target-attenuator-cable link is connected. This calibration value can be used for verification during electrostatic discharge gun operation, pre-use inspection, and calibration.
[0011] To achieve the above objectives, this invention proposes a calibration method for the transfer impedance of an electrostatic discharge target link, the calibration method being as follows:
[0012] S1: Complete circuit connection;
[0013] Connect the DC current source and the ammeter. The output terminals of both the ammeter and the DC current source are connected to the current target adapter via the first RF line. Align the current target adapter with the electrostatic discharge target. The output terminal of the electrostatic discharge target is connected to the attenuator and then to the oscilloscope via the second RF line.
[0014] S2: Enables the DC current source to output a current value of 0.9-1.1A (typical value is 1A), corrects the input current value by acquiring the ammeter reading, and reads the oscilloscope reading at 50Ω impedance.
[0015] S3: Read and record the current value of the ammeter and the voltage value of the oscilloscope respectively. Substitute the read current value of the ammeter and the voltage value of the oscilloscope into the formula of low-frequency transfer impedance, and calculate the low-frequency transfer impedance of the electrostatic discharge target-attenuator-second RF line link.
[0016] Preferably, when applying the calculated low-frequency transfer impedance, first read the first peak voltage, the voltage at 30ns, and the voltage at 60ns on the oscilloscope, and then calculate the first peak current, the current amplitude at 30ns, and the current amplitude at 60ns corresponding to the first peak voltage, the voltage at 30ns, and the voltage at 60ns using the low-frequency transfer impedance.
[0017] Preferably, the specific steps of S1 are as follows:
[0018] First, connect the positive terminal of the DC current source output to the input terminal of the calibrated ammeter. Then, connect both the ammeter output and the negative terminal of the DC current source to the first RF line and the current target adapter.
[0019] After aligning the current target adapter with the electrostatic discharge target, tighten the screws in the through holes to connect the inner core of the current target adapter with the inner core of the electrostatic discharge target, and reliably connect the outer shell with the outer shell.
[0020] Preferably, the formula for the low-frequency transfer impedance is:
[0021] Low-frequency transfer impedance = oscilloscope voltage measurement / ammeter current measurement.
[0022] The calibration method for electrostatic discharge target link transfer impedance proposed in this invention can bring the following beneficial effects:
[0023] 1. The calibration method of the present invention uses a current target adapter to connect to the current target, converting the current target into a commonly used radio frequency connector, thereby improving the reliability of the calibration system and reducing measurement errors.
[0024] 2. The low-frequency transfer impedance parameter in the calibration method of this invention can be used to calibrate the current waveform parameters of the electrostatic discharge simulator. By introducing an ammeter, the input current at the input end of the current target can be monitored in real time, further improving the accuracy of the transfer impedance calibration. Attached Figure Description
[0025] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:
[0026] Figure 1 This is a schematic diagram of the module connection method used in the calibration method of the present invention. Detailed Implementation
[0027] To more clearly illustrate the overall concept of the present invention, a detailed description will be provided below with reference to the accompanying drawings and examples.
[0028] A calibration method for the transfer impedance of an electrostatic discharge target link, the calibration method being as follows:
[0029] S1: Complete circuit connection;
[0030] Connect the DC current source and the ammeter. The output terminals of both the ammeter and the DC current source are connected to the current target adapter via the first RF line. Align the current target adapter with the electrostatic discharge target. The output terminal of the electrostatic discharge target is connected to the attenuator and then to the oscilloscope via the second RF line.
[0031] S2: Enables the DC current source to output a current value of 0.9-1.1A (typical value is 1A), corrects the input current value by acquiring the ammeter reading, and reads the oscilloscope reading at 50Ω impedance.
[0032] S3: Read and record the current value of the ammeter and the voltage value of the oscilloscope respectively. Substitute the read current value of the ammeter and the voltage value of the oscilloscope into the formula of low-frequency transfer impedance, and calculate the low-frequency transfer impedance of the electrostatic discharge target-attenuator-second RF line link.
[0033] When applying the calculated low-frequency transfer impedance, first read the first peak voltage, the voltage at 30ns, and the voltage at 60ns on the oscilloscope. Then, calculate the first peak current, the current amplitude at 30ns, and the current amplitude at 60ns corresponding to the first peak voltage, the voltage at 30ns, and the voltage at 60ns using the low-frequency transfer impedance.
[0034] The specific steps of S1 are as follows:
[0035] First, connect the positive terminal of the DC current source output to the input terminal of the calibrated ammeter. Then, connect both the ammeter output and the negative terminal of the DC current source to the first RF line and the current target adapter.
[0036] After aligning the current target adapter with the electrostatic discharge target, tighten the screws in the through holes to connect the inner core of the current target adapter with the inner core of the electrostatic discharge target and the outer shell with the outer shell.
[0037] Preferably, the formula for the low-frequency transfer impedance is:
[0038] Low-frequency transfer impedance = Oscilloscope voltage measurement / Ammeter current measurement
[0039] An electrostatic discharge (ESD) simulator is a device that uses a dedicated high-voltage electrostatic generator to simulate the electrostatic discharge process in nature, in order to test the immunity of a device or subsystem under test to ESD interference. An ESD simulator requires the use of an ESD target for periodic verification or calibration of the discharge current waveform.
[0040] This invention designs a calibration method for the link transfer impedance of an electrostatic discharge target, and in particular, a calibration method for the link transfer impedance of an electrostatic discharge target used in the calibration of an electrostatic discharge simulator, applicable to electrostatic discharge targets used in GB / T17626.2.
[0041] The module connection method used in the calibration method is as follows:
[0042] S1: Complete circuit connection;
[0043] Connect the DC current source and the ammeter. The output terminals of both the ammeter and the DC current source are connected to the current target adapter via the first RF line. Align the current target adapter with the electrostatic discharge target. The output terminal of the electrostatic discharge target is connected to the attenuator and then to the oscilloscope via the second RF line.
[0044] Specifically:
[0045] First, connect the positive terminal of the DC current source output to the input terminal of the calibrated ammeter, and then connect the ammeter output and the negative terminal of the DC current source to the first RF line and the current target adapter.
[0046] After aligning the current target adapter with the electrostatic discharge target, tighten the screws in the through holes to connect the inner core of the current target adapter to the inner core of the electrostatic discharge target, and the outer shell (ground) to the outer shell (ground). Connect the output terminal of the electrostatic discharge target to an attenuator and then to an oscilloscope via an RF cable.
[0047] S2: Enables the DC current source to output a current value of 0.9-1.1A, and reads the oscilloscope reading at a 50Ω impedance.
[0048] Note that even if a constant current source is used, the current cannot be guaranteed to be 1A. Therefore, an ammeter needs to be connected in series between the DC current source and the current target adapter in the calibration link. The input current value is corrected by collecting the ammeter reading.
[0049] S3: Read and record the current value of the ammeter and the voltage value of the oscilloscope respectively. Substitute the read current value of the ammeter and the voltage value of the oscilloscope into the formula for low-frequency transfer impedance, and calculate the low-frequency transfer impedance of the link between the electrostatic discharge target-attenuator-second RF line.
[0050] Assuming the ammeter reads a current of 0.956A and the oscilloscope reads a voltage of 200mV, substituting these values into the formula for low-frequency transfer impedance: Low-frequency transfer impedance = Oscilloscope voltage measurement / Ammeter current measurement, the low-frequency transfer impedance is calculated to be 209.21mV / A. This can be interpreted as the oscilloscope reading a peak voltage of 209.21mV when the electrostatic pulse is 1A.
[0051] When applying the calculated low-frequency transfer impedance, first read the first peak voltage, the voltage at 30ns, and the voltage at 60ns on the oscilloscope. Then, calculate the first peak current, the current amplitude at 30ns, and the current amplitude at 60ns corresponding to the first peak voltage, the voltage at 30ns, and the voltage at 60ns using the low-frequency transfer impedance.
[0052] For example: the electrostatic discharge simulator is set to 2kV contact discharge, and a single contact discharge test is performed with the tip of the electrostatic discharge simulator against the center of the current target. The oscilloscope is set to an appropriate measurement range and triggered once.
[0053] Assume that the first peak voltage read at this time is 1500mV, the voltage at 30ns is 800mV, and the voltage at 60ns is 400mV.
[0054] Based on the calculated low-frequency transfer impedance, the first peak current is determined to be 7.15A, the current at 30ns is 3.82A, and the current at 60ns is 1.91A. This demonstrates that this calibration method can calibrate the current waveform parameters of an electrostatic discharge simulator.
[0055] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.
Claims
1. A method for calibrating the transfer impedance of an electrostatic discharge target link, characterized in that, The calibration method is as follows: S1: Complete circuit connection; Connect the DC current source and the ammeter. The output terminals of the ammeter and the DC current source are both connected to the current target adapter through the first RF line. The current target adapter is aligned with the electrostatic discharge target. The output terminal of the electrostatic discharge target is connected to the attenuator and then connected to the oscilloscope through the second RF line. S2: Enables the DC current source to output a current value of 0.9-1.1A, corrects the input current value by acquiring the ammeter reading, and reads the oscilloscope reading at 50Ω impedance; S3: Read and record the current value of the ammeter and the voltage value of the oscilloscope respectively. Substitute the read current value of the ammeter and the voltage value of the oscilloscope into the formula for low-frequency transfer impedance, and calculate the low-frequency transfer impedance of the electrostatic discharge target-attenuator-second RF line link.
2. The calibration method for the electrostatic discharge target link transfer impedance according to claim 1, characterized in that, When applying the calculated low-frequency transfer impedance, first read the first peak voltage, the voltage at 30ns, and the voltage at 60ns on the oscilloscope, and then calculate the first peak current, the current amplitude at 30ns, and the current amplitude at 60ns corresponding to the first peak voltage, the voltage at 30ns, and the voltage at 60ns using the low-frequency transfer impedance.
3. The calibration method for the electrostatic discharge target link transfer impedance according to claim 2, characterized in that, The specific steps of S1 are as follows: First, connect the positive terminal of the DC current source output to the input terminal of the measured ammeter, and then connect both the ammeter output and the negative terminal of the DC current source to the first radio frequency line and the current target adapter. After aligning the current target adapter with the electrostatic discharge target, tighten the screws in the through holes to connect the inner core of the current target adapter with the inner core of the electrostatic discharge target, and reliably connect the outer shell with the outer shell.
4. The calibration method for the electrostatic discharge target link transfer impedance according to claim 3, characterized in that, The formula for the low-frequency transfer impedance is: Low-frequency transfer impedance = oscilloscope voltage measurement / ammeter current measurement.