Using data compression in automatic test equipment for system-on-chip testing

Compression has been used in automatic test equipment (ATE) to reduce storage and application time for high volume data by exploiting the repetitive nature of test vectors. The application of a binary compression method to an ATE environment for manufacturing is studied using a technique, referred to as reuse. In reuse, compression is achieved by partitioning the vector set and removing repeating segments. This process has O(n²) time complexity for compression (where n is the number of vectors) with a simple hardware decoding circuitry. It is shown that for industrial system-on-chip (SoC) designs, the efficiency of the reuse compression technique is comparable to sophisticated software techniques with the advantage of easy and fast decoding. Two shift register-based decompression schemes are presented; they can be either incorporated into internal scan chains or built in the tester´s head. The proposed compression method has been applied to industrial test and data and an average compression rate of 84% has been achieved.