US Patent 9355743 Memory array test logic

A test circuit for a static random access memory (SRAM) array includes a plurality of stages coupled in a ring. Each stage includes a plurality of bit cells to store information, a bit line and a complementary bit line coupled to the plurality of bit cells, and a plurality of word lines coupled to the plurality of bit cells. Subsets of the plurality of word lines of each of the plurality of stages are selectively enabled based on signals asserted on the complementary bit line of another one of the plurality of stages. The test circuit also includes inversion logic deployed between two of the plurality of stages.