Reconstruction of discharge currents injected on calibration target from electrostatic discharge generators

In the present study, measurements were made in the frequency range from 300kHz to 6GHz of the transfer impedance of a commercially available calibration target used for the immunity testing against electrostatic discharges (ESDs) that the International Electrotechnical Commission (IEC) prescribes, and thereby the waveforms of discharge currents injected onto the target were reconstructed from their observed output voltages for contact and air discharges of an ESD generator with a charge voltage of 2kV. As a result, it was confirmed that the transfer impedance has an absolute value of almost 1 Ω at frequencies up to 6 GHz, while resonance phenomena were observed at frequencies around 2 and 5 GHz. This result has demonstrated that the reconstructed discharge current waveforms agree well with those of the observed voltages for the contact discharge and air discharge with slow approach, producing the current with a rise time of almost 1 ns, while the reconstructed current has a slightly small peak and gentle rising part in comparison with those of the observed voltage for the air discharge with fast approach, which gives the current within a rapid rise time of a hundred pico-seconds.