Abstract: A interface board is provided with a first and second contact instruments each comprising a first and second contact terminal groups to which a first to third type semiconductor devices having different numbers of external terminals used can be connected. The first contact terminal group of the first contact instrument is connected to the corresponding terminals of the second contact terminal group of the second contact instrument using bridging lines. One end of each bridging wire is connected to a driver output pin of an channel provided in pin electronics. The other end of the bridging wire is connected to a comparator input pin of the IO channel provided in the pin electronics. The first contact terminal group of the second contact instrument is connected, using different connection lines, to a driver output pin and a comparator input pin of an IO channel provided in the pin electronics.

Abstract: The present invention is directed to the use of a DDS to generate a high purity reference signal with high frequency resolution by switching a frequency tuning word (FTW) between particular values for particular time durations to produce two or more closely spaced frequencies that appear at the DDS output as a single frequency. Given a DDS switching between F1 and F2 such that F1 is present for time T1 and F2 is present for time T2, with the total period of the repeating pattern being T=T1+T2, in order for the output of the DDS to produce a single high-purity frequency that is the time-weighted average of the alternating frequencies, the condition |F1?F2|<<?/T must be satisfied. The time-weighted average frequency Favg=(T1·F1+T2·F2)/(T+T2). By an appropriate choice of T1 and T2, Favg can be set to any frequency between these two frequencies.