Extending design-for-test into the analog and mixed-signal domains

A growing need exists for the design and testing of mixed-signal communication systems. Among the many factors driving this need are the current high interest in personal communication devices, and a desire for ever faster information transmission rates over the existing telecommunication network. Many of today's communication systems are designed and tested using techniques that cannot be characterized as either digital or analog. The data being processed, and the processing techniques themselves, do not fall neatly into either the digital or analog categories. Two approaches to mixed-signal testing, using currently available test-set hardware and software, have been developed and are presented in this paper. The research being done on a third, experimental, self-test method — and the techniques for accessing internal test nodes — are also discussed.