RL-Huffman encoding for test compression and power reduction in scan applications

This article mixes two encoding techniques to reduce test data volume, test pattern delivery time, and power dissipation in scan test applications. This is achieved by using run-length encoding followed by Huffman encoding. This combination is especially effective when the percentage of don't cares in a test set is high, which is a common case in today's large systems-on-chips (SoCs). Our analysis and experimental results confirm that achieving up to an 89% compression ratio and a 93% scan-in power reduction is possible for scan-testable circuits such as ISCAS89 benchmarks.