X-Masking for In-System Deterministic Test
[ 1 ] Instytut Radiokomunikacji, Wydział Informatyki i Telekomunikacji, Politechnika Poznańska | [ 2 ] Wydział Informatyki i Telekomunikacji, Politechnika Poznańska | [ P ] employee | [ SzD ] doctoral school student
2022
chapter in monograph / paper
english
- embedded-test
- in-system test
- scan-based testing
- test compression
- unknown states
- X-masking
EN In-system deterministic tests are used in safety-sensitive designs to assure high test coverage, short test time, and low data volume, typically through an input-streaming-only approach that allows a quick test delivery. The output side of the same scheme is, however, inherently vulnerable to un-known (X) states whose sources vary from uninitialized memory elements to the last-minute timing violations. Typi-cally, X values degrade test results and thus test response compaction requires some form of protection. This paper presents two X-masking schemes that complement the pri-mary (or level-A) blocking of unknown values by filtering out those X states that escape the first stage of masking and shall not reach a test response compactor or test result sticky-bits deployed by the on-chip compare framework. Ex-perimental results obtained for eleven industrial designs show feasibility and efficiency of the proposed schemes alto-gether with actual impact of X-masking on various test-related statistics.
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