Testing word oriented embedded RAMs using built-in self test

The author presents a built-in self test method for word-oriented embedded static RAMs. Based on bit-oriented march tests, which are very suitable for self-test applications, word-oriented extensions are presented and analyzed for fault coverage. The self-test algorithm gives a high fault coverage for digital faults. Besides simple stuck-at faults, it detects transition faults and multiple-access faults. Also, all two-coupling faults between arbitrary pairs of cells are detected, so no knowledge of the physical placement of the cells is required. A prototype of the hardware implementation of the BIST method shows that the overhead, especially for large RAMs, is quite modest. The self-test hardware can be parameterized to size, making automatic generation by a module compiler easy.<>