Research On Compression Scheme Based On Approximately Compatibility

More and more intellectual property cores are integrated on silica gel wafers,integrated circuit chip testing failure will encounter more complex,testing problems will increase rapidly,the test to be solved several problems: shorten test time,reduce test power,reduce the amount of test data,test data compression technology is now integrated test mainstream research methods.This article introduces the structure of system on chip,SOC testing principle,classification and challenge,and to some of the classic Huffman encoding scheme and compatible compression scheme is introduced,the scheme of encoding,encoding examples and find solution of the shortcomings of the scheme and improvement program.This article is based on the approximate compatibility analysis,from the view of the column of test vector to rearranged together with test large correlation;From the characteristics of serial data transmission of automatic test equipment,the adjacent test vectors for approximate maximum compatible compression,if the adjacent test vector incompatibility group number the is less than or equal to k value that is reference to the previous test vector to compress,otherwise direct to store;From incompatible group number of grouping test vectors,incompatible group number is uneven,encoding compression will be more complexity and the compression result is not very good,then to search for a compatible class is proposed,first with the right to construct complete undirected graph that will be extracted from the same incompatibility group number of sub graph,using graph coloring algorithm for that.Based on the prvious three ways,proposed a coding compression scheme based on maximum approximate compatibility,reordering the test vectors,adjacent test vectors can reach the maximum compatibility and make the(i+1)th test vector reference to the ith test vector,can be witn(i-1)th test vector indirect approximately compression,this method is put forward to make the adjacent test vector are maximum approximate compatibility,non adjacent to achieve indirect approximate compatibility,make the test data set as a whole for several groups can achieve good compression effect.This article is the ISCA'S standard circuit generated Mintest sets to analyse of test data compression rate based on C programming language platform,experiments show that the average compression rate reached 64.45%,and the hardware structure is simple,low area overhead,the scheme is feasible.