Self-adjusting output data compression: An efficient BIST technique for RAMs

Abstract

After write operations, BIST schemes for RAMs relying on signature analysis must compress the entire memory contents to update the reference signature. This paper introduces a new scheme for output data compression which avoids this overhead while retaining the benefits of signature analysis. The proposed technique is based on a new memory characteristic derived as the module-2 sum of all addresses pointing to non-zero cells. This characteristic can be adjusted concurrently with write operations by simple EXOR-operations on the initial characteristic and on the addresses affected by the change.