Abstract: The large amount of test data is one of the challenges in SoC test,and the test data compression is an effective method to deal with this challenge.A new test data compression method of a dual run length alternating compression was presented.0 run length and 1 run length can be coded alternately,and the type of next run length can be obtained according to the previous run length type.So the type of run length is not represented in code words,and hence the length of the needed code word is reduced.Experimental results show that the method can achieve higher compression ratio compared with the similar method,and decompression structure is very simple,so the goal of reducing the cost of test can be achieved.

Key words: Test data compression,Dual run length,Don’t care bit