A Study on Discharge Current and Radiation Noise of ESD from Charged Metal and Charged Human Body

In this study, we measure the discharge current and the radiation noise of electrostatic discharge from charged metal and charged human body to investigate the characteristics of the current and noise of the ESD. In the measurement of the discharge current and the radiation noise, we used the ESD apparatus of approaching discharge with gap control and current probe and digital storage oscilloscope those bandwidth are 1 GHz. The applied voltage to the hemispherical metal electrode and human body is varied from plusmn2 kV to plusmn10 kV. From experimental results, we found the followings; 1) The characteristic of discharge current and radiation noise does not depend on the discharge polarity of ESD from charged metal. In contrast, that depends on the polarity of ESD from charged human body. 2) Radiation noise has a relationship to the waveform of discharge current. The radiation noise is stronger at 1-peak discharge current and weaker at 2-peaks. 3) The radiation noise of ESD from charged human body is stronger in positive discharge and weaker in negative discharge. 4) There is some case that the amplitude and maximum frequency of radiation noise of 1-peak discharge current in ESD from charged human body in positive discharge are equivalent or larger than that of 2-peaks from charged metal. 5) Radiation noise is not necessarily weak although the applied voltage is lower. 6) There is a strong relationship between the resonance component of discharge current at just after the 1st peak and the radiation noise in the viewpoint of duration and frequency component.