Abstract: This application discloses a memory device having multiple memory cells, each configured to store different values of data using different resistance states. A memory built-in self-test system can prompt the memory device to perform memory read operations for the memory cells storing the data in the different resistance states, determine a separation between the different resistance states of at least a subset of the memory cells, and detect one or more of the memory cells has a degraded tunneling layer in a magnetic tunneling junction based on the separation between the different resistive states in the at least the subset of the memory cells. A built-in repair analysis circuit can perform a repair of a group of the memory cells including at least on one of the detected memory cells based on the detection of the memory cells having degraded tunneling layers in the magnetic tunneling junctions.

Abstract: An address-skipping trim search performed by a memory built-in self-test system comprises: perform memory read operations on one memory bank to determine whether it fails to correctly sense values of stored data based on a reference trim value for a previous memory bank; if the present memory bank fails, perform memory read operations to search for a new reference trim value for the present memory bank; or otherwise, treat the present reference trim value as the one for the present memory bank and proceed to testing a next memory bank. The range for searching for the new reference trim value can be limited by the present reference trim value.

Abstract: An address-skipping trim search performed by a memory built-in self-test system comprises: perform memory read operations on one memory bank to determine whether it fails to correctly sense values of stored data based on a reference trim value for a previous memory bank; if the present memory bank fails, perform memory read operations to search for a new reference trim value for the present memory bank; or otherwise, treat the present reference trim value as the one for the present memory bank and proceed to testing a next memory bank. The range for searching for the new reference trim value can be limited by the present reference trim value.