Research On Test Data Compression Method Based On Tri-State Signal

With the continuous development of very large scale integration,the size and structure of the chip is getting bigger and bigger,and the amount of test data required for testing the chip is increasing,so that the cost of testing the chip is improved.The test power is also constantly increasing,which has a bad influence on the chip structure,resulting in a decrease in the yield of the chip.In view of the increase of test data and test power during the development of integrated circuits,this dissertation researches the problems by using the characteristics of tri-state signal.The main work is as follows:A test data compatible compression method based on tri-state signal is proposed.Firstly,the method optimizes the preprocessing operation of the test set,mainly by performing partial input reduction,test pattern reordering operation and test pattern adjacent filling on the test set,and makes the ratio of don't care bit X in the test set and the compatibility between the test patterns improved.Subsequently,the pre-processed test set is subjected to tri-state signal coding compression,and the test set is divided into multiple scan slices that is subjected to compatible coding compression.The experimental results show that the proposed scheme achieves a better compression ratio,and the average test compression ratio can reach 76.17%.At the same time,the test power and area overhead are not significantly improved.A test data compression method for broadcast scan test based on tri-state signal control is proposed.Firstly,the method divides the test patterns in the test set into test pattern groups,and can perform broadcast scan input for each group;then scan slice is divided within each group into three types,corresponding to tri-state signal.Then,the test patterns groups are optimized for capture power,and the test response is filled for non-sparse scanning slices.Finally,the encoding of each scanning slice in the group is calculated according to the tri-state signal,and the non-sparse scanning slice uses the broadcast scan input,sparse scan slices are compressed using LFSR reseeding.The experimental results show that the method can achieve good compression ratio and optimize the test power.