5.1.1 General-Purpose Testers versus Focused Bench Equipment

General-purpose mixed-signal testers must be capable of testing a variety of dissimilar devices. On any given day, the same mixed-signal tester may be expected to test video palettes, cellular telephone devices, data transceivers, and general-purpose ADCs and DACs. The test requirements for these various devices are very different from one another. For example, the cellular telephone base-band interface shown in Figure 1.2 may require a phase trajectory error test or an error vector magnitude test. Dedicated bench instruments can be purchased that are specifically designed to measure these application-specific parameters. It would be possible to install one of these stand-alone boxes into the tester and communicate with it through an IEEE-488 GPIB bus. However, if every type of DUT required two or three specialized pieces of bolton hardware, the tester would soon resemble Frankenstein's monster and would be prohibitively expensive.

The mixed-signal production tester cannot be focused toward a specific type of device if it is to handle a variety of DUTs. Instead of implementing tests like phase trajectory error and error vector magnitude using a dedicated bench instrument, the tester must emulate this type of equipment using a few general-purpose instruments. The instruments are combined with software routines to simulate the operation of the dedicated bench instruments.

5.1.2 Generic Tester Architecture

Mixed-signal testers come in a variety of "flavors" from a variety of vendors. Unlike the ubiquitous PC, testers are not at all standardized in architecture. Each ATE...