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.