HBM tester waveforms, equivalent circuits, and socket capacitance

The Tektronix CT2 current probe is used to acquire more accurate Human Body Model waveforms with 0-ohm and 500 ohm tester loads than a CT1, owing to the CT2´s low-frequency performance. The integrals and centroids of these waveforms then readily yield precise values of tester circuit elements and effective socket capacitance. Expressions are derived for effective socket capacitance resulting from distributed capacitance along a transmission line connecting to an unmatched load. These lead to options for reducing the effective socket capacitance while retaining the lines for delivering the HBM pulse.