What's Missing from Design for Testability?

Louis Y. Ungar, President, Advanced Test Engineering (A.T.E.) Solutions
EETimes (12/14/2015 06:00 AM EST)

For years, engineers have neglected the "design" part of design-for-test. DFT shouldn't be an afterthought and test engineers can take on some of the task.

Design for Testability (DFT) is comprised of two very important terms. "Testability" is a condition of a circuit that makes it possible, easy, and cost-effective to test and diagnose the circuit (unit) under test (UUT). There is a wide acceptance that such a characteristic should be part of electronics ICs, boards and systems, too. After all, without DFT, faults can go undetected, making them difficult to repair. For far too long, the "Design" part of DFT that has been neglected.

Clearly, the features needed for implementing DFT, such as controllability, observability and diagnosability must be incorporated into a design. DFT shouldn't be an afterthought or a redesign activity. Designers must purposely create testable circuits. DFT is, however, more problematic than it appears. Let's examine the hurdles and see what we can do to improve design activities for testability.

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