Memory circuits with built-in self-test

A built-in self-test (BIST) circuit and a method for testing a memory device, especially applicable in a DRAM requiring a complex test algorithm. Two finite machines are used instead of a single finite state machine used in the conventional circuit. Therefore, the pipeline technique can be applied to divide the test pattern generation process into stages, leading to a higher-speed design. In addition, a technique of protocol based relaxation is also presented. By imposing a certain protocol on the two communicating finite machines, the timing criticality is further relaxed. Synthesis results show that the proposed BIST circuit can operate at the speed of as high as 450MHz using 0.25 mu m CMOS technology.