Oscilloscope influence on the calibration uncertainty of the pulse rise time of ESD simulators

Abstract

In the paper an approach to contribution of the oscilloscope in uncertainty estimation of the rise time by measurement of the ESD discharge current is performed. Correlation between input signal and the displayed voltage at the oscilloscope called here transmittance is measured and approximated with the second order low pass filter along with the Gauss filters. Voltage at the oscilloscope input is calculated as the product of the analytically expressed current and measured input impedance of the oscilloscope. Moreover measurement uncertainty of input impedance and oscilloscope transmittance are built in the uncertainty estimation. The approach is compared with the two rules concerning conservative estimation of the rise time of oscilloscopes as stated in C. Mittermayer and A. Steiniger (for original article see IEEE Trans. on instrumentation and measurement Vol. 48, No. 6, p. 1103-7, December 1999). Presented calculations of the uncertainty of the rise time for pulses with different rise time shows advantages and better suitability of the novel method by measurement of the ESD discharge current