Description
After some repairs on a slightly older ESD simulator, you might feel the need to verify the output pulse—especially the voltage, though it would be helpful to view the actual waveform as well. The only problem is that these standardized ESD targets are ridiculously expensive for what amounts to just a bit of brass, stainless steel, some PTFE, and an N connector. Of course, there’s a bit more to that, especially getting everything just right. Because there is not much margin for error, while affordable RF connectors, cables and attenuators tend to have quite a liberal take on their claimed specifications.
In order to be able to calibrate the target + attenuator + cable to the requirements, we had to change the cable termination from BNC to SMA. Up to 1GHz we are with the ±0.5dB requirement. Up to about 4GHz we are also okay with ±1.2dB. To connect with the typical 2GHz oscilloscope, you have to add a SMA to BNC adapter. In order to measure beyond 6kV or so (25A pulse), additional attenuators might be needed (on the SMA side of the cable) since the 50Ω-mode input voltage of many oscilloscopes is limited to 5V.
The standard is not particularly clear on how to use this device. Particularly on how to set the scale of the oscilloscope. The verification is done by measuring some currents (3.75A/kV, rise time 800ps±25%, I30ns = 2A/kV, I60ns = 1A/kV). We use the Zsys method from annex B.3 of the standard, except performed directly on the scope. So we apply a 1A DC current to the target, then adjust the scale of the scope to get a representative indication of that current. Limit the DC current to pulses of a second or so to keep thermal effects to a minimum. When working with higher discharge voltages, it is a good idea to perform this DC-level calibration sort of frequently to catch failures of resistor elements should they occur.
We also carry a kit that includes the target adapter line!
Reviews
There are no reviews yet.