Re-optimization Algorithm for Wrapper Scan Chains Balance Based on Twice-Assigned Method Using Dynamic Adjustment and Mean Value

Testing time of System on Chip (SoC) based on intellectual property (IP) has already become the bottleneck for the development of SoC. A new wrapper scan chain balance algorithm is proposed to minimize IP-core testing time. The balance algorithm is to find the standard-chain through the adjustment value and the mean-chain through the mean value. All the internal scan chains can be divided into two parts according to the length of standard-chain L: the scan chain set S_≥ within the length no less than L and the remaining part S<;. Compute the difference D between S_<; and the mean-chain. In the first assigned process, the scan chain set S_≥ regarded as mean-chain are uniformly distributed. Sort the scan chain set S_<; and the difference D in descending order. In the second assigned process, assign S_<; and the positive D to the enable shortest wrapper scan chain and assign the negative D to the enable longest wrapper scan chain successively. Experimental results on ITC´02 test benchmarks illustrate that the balance algorithm proposed in this paper is more effective and can get more balanced results when compared to the existing methods.