Abstract
In the present study, using a 50Ω tapered coaxial type adapter and a S-parameter technique, we measured the transfer impedance of a commercially available IEC calibration current target used for the immunity testing against electrostatic discharges (ESDs), which is being prescribed in the International Electrotechnical Commission (IEC) 61000-4-2, and thereby reconstructed the waveforms of discharge currents injected onto the target from their observed output voltages for contact and air discharges of an ESD generator. As a result, we found that the transfer impedance is almost 1+j0Ω at frequencies below 1GHz, while due to resonance phenomena occurring at frequencies around 2GHz and 5GHz, resistive and reactive components significantly change at frequencies over 1GHz, though their absolute values are slightly larger than 1Ω. This result has revealed that the reconstructed discharge currents agree well with the observed voltages with a rise time of almost 1ns for the contact discharges and air discharges with slow approach of an ESD gun with charge voltages above 2kV, while in the case for the observed voltage with a rapid rise time shorter than a hundred pico-seconds for the air discharges with fast approach, the reconstructed discharge current has a bit gentle rising slope and a slightly lower level of the first current peak.
