What is DFT? Many designers just say it’s a pain in the ass. But TMAG has a more accurate description in mind. And they’d like to know if you agree. I blogged a few days ago about the 4/1 general meeting of TMAG (Testability Management Action Group). Well, the ‘Beyond DFT’ committee of said organization discussed/debated some basic definitions (presumably at this last meeting) as a basis of understanding. I would think it’s important that the members of any initiative all be reading from the same page. Here are the definitions they’ve put forward:
Testability is a property of a circuit that enables one to test it easily, or in some cases to test it at all, by being able to control and observe signal nodes that are buried within the circuit.
Design for Testability (DFT) is a methodology incorporated in the design of electronic circuits which takes into consideration the post-design testing phase, and which attempts to reduce the effort and cost of testing.
Structured Design for Test (Structured DFT) is a design technique, usually for ICs, which enables tests to be created automatically or algorithmically. One example of is the design of an IC with a scan structure that enables test for structural faults using a predefined test methodology. While the test may be long, it can be generated without test engineering involvement and test patterns created by computer programs can ensure nearly 100% fault detection of certain fault types.
Built-In Self-Test (BIST) is a method of design – generally for ICs – whereby the mission circuit tests itself. Though this is seldom performed strictly without additional circuitry, if the entire circuitry performing the test is contained within an IC, we call it self-test, in situ test, or built-in self-test.
Built-In Test (BIT) is similar to BIST in that it performs test of the circuit it resides in, but it is generally used at board and system levels and often uses extra hardware, software, and/or firmware to implement the test. When the added circuitry is substantial, it may be called embedded test. If BIT is implemented in software, it is called BIT software.
So what do you think? Send your opinions to LouisUngar@tmag4dft.org. Keep it constructive. Wanna know what I think? Well, it’s my blog, and you don’t have a choice, unless you re-direct your browser now… oh wait. One note before you move on: As this group gets off the ground, they are looking for support to pay the lawyers. Individual memberships are only $24, so make your pledge today. Just send an e-mail to Scott.Davidson@tmag4dft.org to advise him of your intend to support this noble cause. Now read on to see my opinions…
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