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

This paper 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 the Run-Length (RL) encoding followed by Huffman encoding. This combination is especially effective when the ratio of don´t cares in a test set is high which is a common case in today´s large SoCs. Our analytical analysis and the experimental results on ISCAS89 benchmarks confirm that achieving 32 to 85% compression ratio and 55 to 93% power reduction is possible for scan testable SoCs.