Reducing the Storage Requirements of a Test Sequence by Using One or Two Background Vectors
Irith Pomeranz, Sudhakar M. Reddy · IEEE Transactions on Very Large Scale Integration (VLSI) Systems · 2010
We describe a storage scheme for functional test sequences where a test sequenceTis associated with a primary input vectorBcalled a background vector.Tis stored by storing only the differences between its test vectors andB. We describe a procedure for computing a background vectorBfor a given test sequenceT. We also describe a procedure that modifiesTso as to reduce its storage requirements with respect toB. We present experimental results demonstrating that the single background vectorB, computed based onT, allowsTto be modified such that a vast majority of its entries are equal to the corresponding entries ofB. Consequently, storage ofTreduces to storage of a small number of entries. We also extend the discussion to storage ofTbased on two background vectors. A second background vector provides more flexibility in storingTas a list of entries where it is different from its background vectors. This contributes to a further reduction in storage requirements for certain circuits.