Wrapper scan chain balance algorithm based on mean-value allowance

Testing is considered as a bottle-neck for the development of SoC. This paper proposes a new wrapper scan chain balance algorithm for minimizing IP testing time. This algorithm calculates the mean value of wrapper scan chains firstly, then a value range is generated with a given allowance, this value range is called Mean-Value Allowance in this paper. The IP internal scan chains are sorted in descending order of the length. Every time the longest internal scan chain is successively assigned to a wrapper scan chain, until whose length is in the value range indicated by Mean-Value Allowance. Experiments on all the test sets in ITC'02 SoC Test Benchmarks approve that this algorithm effectively reduces the IP testing time through wrapper scan chain balance design.