Instruments for automatic test

Every engineer has used test instruments. From the humble handheld multimeter to the most complex protocol analyzer, test instruments are used by engineers in the field and the design lab, in repair shops and environmental chambers, in research, and in quality assurance (QA). Visit any electronics lab and you'll likely find arrays of instruments, stacked three high on lab benches, all of them familiar tools from familiar manufacturers. Walk down the hall from the lab to the test floor at a semiconductor manufacturer, a contract PC manufacturer, or even a military repair depot, and the familiarity falls away. Instead of multimeters, oscilloscopes, and precision voltage sources, you will find systems full of specialized instrumentation, often made by unfamiliar companies. The corridor between the design lab and the test floor seems to connect two different worlds. This discontinuity is not because the laws of electronics are different in the two worlds; it’s caused by the constraints bounding the test engineer. These constraints have required the creation of a different breed of test instrument, called automatic test equipment (ATE). The line between lab equipment and ATE isn't a sharp one but it's sometimes sharp enough to necessitate entirely different instrument designs. This article explores some of the general themes driving production instrument designs and gives some examples of the impact of production requirements on ATE design. The challenge for ATE designers is to cover all the boundary conditions while making sure that performance is always valued and cost effective.