A method for decompressing compressed data

Abstract

The invention discloses a decompression method for compressed data. Storage of whole original test data is converted into storage of irrational numbers; in the test process, firstly, a common computer connected with automatic test equipment estimates single-precision or double-precision decimals corresponding to the irrational numbers, the length of runs corresponding to an integer part and front k-bit decimal parts is converted into test vectors, and then the test vectors are sequentially input to a detected chip through an ATE channel; the runs represented by the k+1 bit are converted into test vectors according to the formula shown in the specification, and then the test vectors are input to the detected chip through the ATE channel till k reaches the pre-calculated number of the runs corresponding to the original test data length; the test result is compared with a theoretical value, if the result is identical with the theoretical value, the detected chip passes a test, and if the result is not identical with the theoretical value, the detected chip does not pass the test. An extraction operation is converted into simple operations such as addition, subtraction, multiplication and division through a quadratic sum formula, the complex operation is simplified, squares of big data are converted into decimals, and restoration of the dynamic code compression technology is achieved.

Description

technical field [0001] The invention relates to a method for restoring compressed test data in an external built-in self-test method for a system chip, in particular to a method for decompressing compressed data. Background technique [0002] With the increase of the scale of integrated circuits, the huge amount of test data has become one of the main problems affecting the test of integrated circuits. The ITRS report shows that in 2019, testing a chip requires 20,370 test patterns, which is 240 times the number of 85 test patterns that need to be tested in 2009; 150 times the compression ratio of 80. [0003] The research on test data compression technology mainly focuses on three aspects: test set compression (Test SetCompaction), built-in self-test (Built-in Self-Test, BIST) and static code compression. (1) The test set is compressed. This technology refers to reducing the number of test vectors by compressing some test cubes with don't carebits (Don't carebits) under ...

AI Technical Summary

Problems solved by technology

However, there is a problem of how to restore the irrational numbers to the original test set in this technology. The difficulty is how to expand the irrational numbers into decimals

Using traditional methods, computers cannot complete the square root operation of big data

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