Synthesis of complex signals on test equipment

A traditional signal definition exhaustively lists every attribute and condition that it was thought the signal could possibly have. However, it is often the case that we are only interested in controlling a limited number of signal attributes and conditions. The traditional method is inflexible in this respect, leading to problems when trying to map different capabilities in a signal standard, as required for ATP (Automated Test Program) portability. In this paper we consider a concept called a Signal Graph to define a model of a single, complete signal. Each component in the Signal Graph identifies a feature or behavior that our signal will exhibit. The Signal Graph is a mechanism whereby we can define a set of features that we require, which can then be mapped onto a series or collection of suitable resources (e.g. algorithm, PC card, bus instrument, etc.). We show how complex, 'user defined' signals can be created and then mapped onto real hardware to provide a portable ATE (Automatic Test Environment) signal description, which can be used on a variety of ATEs. This paper draws upon IEEE standard SDTD (Signal Definition and Test Description) standard to utilize common components and interfacing techniques and shows how a single test description can be used for both simulation and execution.