Low-power test sets under test-related primary input constraints

Abstract

This paper considers the generation of low-power test sets under test-related primary input constraints. Such constraints are used for addressing tester limitations related to the application of tests at-speed. Specifically, the paper considers the switching activity which measures the power dissipation during the fast functional clock cycles of broadside tests with constrained primary input vectors. For a functional broadside test, the switching activity during the fast functional clock cycle is guaranteed not to exceed the switching activity possible during functional operation. Therefore, functional broadside tests are appropriate as low-power tests. In addition, the switching activity of functional broadside tests can be used for bounding the switching activity of other tests in a low-power test set. The paper observes that functional broadside tests for computing the bound should be generated under the same primary input constraint as the low-power test set. This is important since primary input constraints affect the switching activity possible in parts of the circuit that are influenced by the primary inputs. It helps ensure that the switching activity in other parts of the circuit will not be higher, or not be restricted to be lower, than during functional operation.