ESD simulator tip voltage at the instant of test

It is pointed out that, for air-discharge (as compared with contact-mode) ESD (electrostatic discharge) testing, the actual voltage at the tip of an ESD simulator at the instant of test can depend on simulator design. Different simulator designs give different test outcomes, particularly for plastic-enclosed products. In one ESD simulator design, the constant-voltage configuration, simulator voltage remains constant during victim approach. In another design, the isolated-capacitor configuration, the tip voltage may decrease as it approaches the equipment victim. A third design, called the quasi-isolated capacitor design, is proposed. It retains the advantages of the constant-voltage configuration and high accuracy for the basic simulator voltage. Its output voltage is also invariant, for practical purposed, with capacitance change due to victim approach. However, it does retain the advantage of the isolated-capacitor design when it is desired