Majority-Based Test Access Mechanism for Parallel Testing of Multiple Identical Cores

The increased use of multicore chips diminishes per-core complexity and also demands parallel design and test technologies. An especially important evolution of the multicore chip has been the use of multiple identical cores, providing a homogenous system with various merits. This paper introduces a novel test access mechanism (TAM) for parallel testing of multiple identical cores and identifying faulty cores to derate the chip by excluding it. Instead of typical test response data from the cores, the test output data used in this paper are the majority values, that is, the typical test responses from the cores. All the cores can thereby be tested in parallel and test costs (in both test pins and test time) are exactly the same as for a single core. The proposed TAM can be implemented with on-chip comparators and majority analyzers. The experimental results in this paper show that the proposed TAM can test multiple cores with minimal test pins and test time and with hardware overhead of <0.1 %.