When zero picoseconds edge placement accuracy is not enough

In the last ten years, test equipment suppliers have driven improvements in edge placement accuracy taking it from /spl plusmn/225ps to sub-100ps through a combination of architectural improvements and new calibration technology. However with the adoption of high speed source synchronous buses such as HyperTransport and RapidIO on high performance devices, it is no longer sufficient to just look at the tester EPA component in the overall timing budget. Although test system accuracy is still very important, error terms from the DUT must also be considered. The proposed methodology of device strobed comparators addresses both test system and device error terms.