Analog design-for-testability for analog/mixed-signal ASICs

This paper discusses the concept and issues of Analog Design-for-Testability (ADFT) for analog/mixed-signal ASICs, and describes an algorithm for selecting the accessible nodes for excitation, a scheme for simplifying the ADFT with using of the macro-model circuit instead of the original circuit of the analog macros for including in ASIC chips, an architecture for a practically testable mixed-signal ASIC with using of MUXs and switching networks. Examples are illustrated to demonstrate the necessity of sufficient built-in accessible nodes for observability, the requirement of a few external directly accessible excitation terminals for controllability and the high demand of accuracy of measured test data besides the using of macromodel circuit for completeness in testing.