ESD generator pulse verification using high-performance oscilloscopes

Your task

Making sure a product is resilient to electrostatic discharge (ESD) is essential for compliance with international standards such as IEC 61000-4-2. Accurate and repeatable ESD testing demands a functioning ESD generator that can generate pulses with precisely defined characteristics.
The generator output, specifically pulse shape, must be verified prior to testing and is best done with a calibrated ESD target and a lab-class oscilloscope. The ESD events defined in the standards will generate several 10ths of amperes of peak current with rise times less than 1 ns which can flow into sensitive electronic circuits. This can damage components, may cause latch-up effects in integrated circuits or cause complex electronic circuits to malfunction. The ESD waveform with the relevant parameters in line with the standard is shown in the graph.

Every ESD generator must comply with the waveform requirements and parameters prior to testing. If the polarity of the specified waveform is positive, it also needs to be tested with a negative pulse. In the waveform below, an ESD pulse may consist of high frequency components up to few GHz. Accurately capturing and characterizing such a signal requires high bandwidth and a high sample rate. The standard requires a minimum bandwidth of 2 GHz and a sample rate of at least 8 Gsample/s. After capturing the waveform accurately, current and time parameters need to be measured and verified against specified tolerances.

Rohde & Schwarz solution

The R&S®RTO6 oscilloscope and the R&S®RTO6-K155 EMC/ESD test option expand the standard oscilloscope firmware with a suite of measurement, analysis and visualization tools for electromagnetic compliance/electrostatic discharge (EMC/ESD) analysis and characterization. In detail, the EMC/ESD analysis option provides predefined measurement functions that comply with the parameters defined in the standard. A pass/fail check criteria can also be applied, and predefined levels selected. Deeper analysis of the captured waveform is possible with the customizable measurement functions. History and trend functions let users capture many measurements and view them at a glance. A report can also be generated to document the verification of the tested ESD generator.

Predefined measurement parameters

All relevant parameters are predefined in the EMC/ESD test category and can be selected as shown in the menu below. In addition to parameters, the slope of the applied waveform must be defined when executing the test. The relevant parameters are:

• Rise time (tr): Time between 10 % and 90 %
• First peak (Ip1): Level of the first positive/negative peak
• Second peak (Ip2): Maximum/minimum level in a specified time range
• I30: Level at 30 ns after the reference point
• I60: Level at 60 ns after the reference point

Result lines can be activated for all parameters to indicate the measured value within a waveform.

Pass/fail criteria

Pass/fail criteria are essential for standard compliance. All predefined parameters in line with the standard can be selected and applied to the pass/fail check.

After the test is executed, the measurement results will indicate if the measured value is within the limits or not.

Customized measurement parameters

For deeper analysis, two additional, customizable parameters can be selected to characterize the waveform based on user-defined levels and delay. The relevant parameters are:

• Lvl@delay: Level at a specified delay after the reference point
• Time to value: Duration from the beginning to specified level

Summary

R&S®RTO6 oscilloscope with the R&S®RTO6-K155 EMC/ESD test option is ideal for verifying ESD pulse generator prior to testing your device for ESD immunity. Users can rely on superior measurement hardware and trust predefined measurement functions to check parameters against the specified tolerance. Even deeper analysis of the waveform is possible with flexible predefined measurement functions. A report can be generated after the test. The solution is a great tool for speeding up your ESD immunity testing necessary for most electronic products.