Combining linear and nonlinear test vector compression using correlation-based rectangular encoding

A technique is presented here for improving the compression achieved with any linear decompressor by adding a small nonlinear decoder that exploits bit-wise and pattern-wise correlation present in test vectors. The proposed nonlinear decoder has a regular and compact structure and allows continuous-flow decompression. It has a very important feature which is that its design does not depend on the test data. This simplifies the design flow and allows the decoder to be reused when testing multiple cores on a chip. Experimental results show that combining a linear decompressor with the small nonlinear decoder proposed here significantly improves the overall compression