Symmetric transparent BIST for RAMs

Abstract

The paper introduces the new concept of symmetric transparent BIST for RAMs. This concept allows to skip the signature prediction phase of conventional transparent BIST approaches and therefore yields a significant reduction of test time. The hardware cost and the fault coverage of the new scheme remain comparable to that of a traditional transparent BIST scheme. In many cases, experimental studies even show a higher fault coverage obtained in shorter test time.

DPSC SRAM transparent test algorithm

“…As explained in the above Section, the transformed transparent test algorithm can test more faults. Table 3 describes the comparison between the new algorithm and Nicolaidis' [9] and the symmetric ⇑ (w0); ⇑ (r0,w1); ⇑ (r1,w0); ⇓ (r0,w1); ⇓ (r1,w0); ⇓ (r0) [10]. It is obvious that the complexity of the new algorithm is quite less than those of the other transparent algorithms.…”

“…Another important issue in memory testing field is the application of the periodic or transparent testing which ensures high reliability of storage data during a lifetime of operation. The March algorithms, which have been widely used for the test of memory, can easily be transformed to transparent test algorithms, which leave the memory contents unchanged [8][9][10]. With a transparent BIST, RAMs can be tested periodically in a running system, without keeping the stored data elsewhere for the duration of the test, and then rewriting the data on the RAM after the test has completed.…”

“…Then the two signatures are compared with each other in the last step. Symmetric transparent test methodology is developed to reduce the test time by removing the signature generation cycle [10]. In this algorithm, the transformed transparent algorithm is made to be symmetric by adding extra state.…”

An Efficient Transparent Test Scheme for Embedded Word-Oriented Memories

“…Concept of transparent testing, which leaves the original contents of the circuit under test unchanged after the testing is completed, has been used for the application of memory testing [3,6,8,9,[11][12][13][17][18][19]. One major advantage of transparent testing is that it can ensure the reliability of storage data during a life-time operation.…”

“…Several transparent test schemes have been reported in [3,6,8,9,[11][12][13][17][18][19]. These schemes transform the march tests, which have been widely used to test random access memories, into transparent march tests.…”