Test and design-for-test of mixed-signal integrated circuits

This tutorial aims to introduce circuit designers to the problems of making integrated circuits more testable. An efficient test procedure for a complex, mixed-signal application specific integrated circuit (ASIC), must take several factors into consideration: stimuli generation, sufficient access, single test output, simple measurement set and system-level decomposition. These factors worth attention for specific circuits classes, since there is no universal method valid for any kind of analog and/or mixed-signal function. Attention is paid to integrated filters and integrated analog-to-digital and digital-to-analog converters, as they are today the main analog and mixed-signal cores found in state-of-the-art complex systems-on-chips (SoC). In particular, the possibilities offered by techniques using small circuit modifications are specially focused, as the means to improve circuit testability, and thus the fault coverage, while avoiding at most to degrade the performance of the final electronic system. Practical silicon examples are presented, trying to give a flavour on the pros and cons that design for test is offering nowadays to integrated circuit designers. To meet the goals stated above, the following topics are addressed in this tutorial: introduction to mixed-signal test (main test concepts, digital vs. analog testing, test practice in integrated circuit industry, design and test inter-relations), testing approaches (fault-based, specification-based, techniques for testing filters, techniques for testing converters), and design-for-test techniques (enhancing testability, built-in self-test and on-line test). This tutorial is intended for professionals interested in analog and mixed-signal integrated circuits in general: designers interested in how to consider tests in early design phases, test engineers interested in incorporating test within the design flow, and academics involved in research and education on test procedures and strategies.