Research On Compression Method Of Test Data Based On Transformation

As the size of the integrated circuit is increasing,the amount of test data increases,resulting in increased cost of test data storage and extended application time,resulting in an increase in chip test costs.Nowadays,most of the cost of chip manufacturing is brought about by testing,reducing test costs is an urgent need to solve the problem of integrated circuits.Test data compression can effectively reduce the amount of test data,shorten the test application time and reduce test power consumption,has become a very important research area of the research.During the test,the compressed test data is stored in the tester,and then sent to the chip decompressing and testing.This thesis mainly studies the test excitation compression and does the following work:(1)A test data compression method based on reference bit-stream compatible transform is proposed.The method is based on the technology of transforming and decomposing compression,Check the relationship of compatibility between the reference bit-stream and the residual component who obtained by transforming the original bit-stream.If the principal component can be found by transforming,its residual component is compatible with the reference bit-stream,then the residual component can be replaced with a reference bit-stream.If the original bit-stream cannot find a principal component by transforming so that the residual component is compatible with the reference bit-stream,the reference bit-stream is replaced by this bit-stream and continues to transform.The method finally divides the test set into a principal component set and a reference bit-stream set.During circuit testing,the test set can be restored by XOR they,then loaded the test set into the circuit under test.The hardware cost of this method is small,and the coding efficiency can be improved at the same time.The experimental results show that the average compression rate of experimental test set can reach 78.62%(2)A method of improving the compression ratio of test data by using modified transformation matrix is proposed.Based on the decompose test data compression method,we change the Hadamard matrix used in the transformation,increasing the code number of the first few bits of the Hadamard matrix.So that the transformation matrix matches the characteristics of the original bit-stream.Using this method,the experimental results show that the modified Hadamard matrix is improved by 1.32%than using the original matrix in Golomb code.Combining method(1)using ALT-FDR for coding,the average compression ratio was 4.53%higher than the original method of decompose test set.The above two methods,the hardware cost is relatively simple,you can completely restore the test data,do not disrupt the order of the test vector to ensure that the test set of fault coverage unchanged.In this paper,the Mintest test set of ISCAS89 circuit is experimented.The results show that the two methods can improve the average compression ratio of the test data.