Built In Test for VLSI: Pseudorandom Techniques

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Test System Requirements for Built-in Test

Any electronic assembly with built-in test requires some interaction with the outside environment to support the test function. This may merely be power and a “start test” signal. In more complex situations, initialization sequences and special clocking may be required. The means by which these outside support and control functions are provided to the part under test is given the generic title of a “tester.” The tester may be used to invoke various levels of built-in test, some which rely mainly on the test structure built into the part and others that rely more on the tester's intelligent manipulation of the part under test. This extended function of the tester prompts one to think of it as a system including its computer and control programs. In the following, the functions of the test system will be explored.

Most built-in test implementations are designed to provide a go/no-go indication at a package or assembly boundary. This identification of a field or line replaceable unit is a key attribute of built-in test, but there is a need for more precise diagnosis if repair is to be accomplished on the failed unit. This repair may take several forms. Usually a unit that is removed in the field is sent to a repair depot. At this stage, ...