Power reflection techniques in susceptibility tests of electronic devices

A setup for statistical tests of electronic devices with fast transients is described. It contains a transient generator, the test box for the device-under-test (DUT), and a delay line along with a digitizing oscilloscope and personal computer. The purpose is to find a relationship between the damage threshold and time-dependent functions of the voltage, current, and power and the total energy absorbed in the DUT. The outgoing pulse of the generator is compared with the pulse reflected by the electronic device. An evaluation method based on time-domain reflectometry (TDR) and the Fourier transform is developed, taking into account experimental uncertainties. The minimum requirements for the digitizing scope are a sample frequency of at least 500 MHz and sufficient storage depth. The results are compared to measurements with known impedances of the DUT (Resistors, short circuit and open end) for voltages below 2 kV; the differences are below 5%, which is tolerable in comparison to the maximum measuring error of the digitizing scope (typically 5%).<>