Test Compression Using Extended Nonlinear Binary Codes

The linear binary codes can be extended by a relatively high number of nonlinear check bits in such a way that the code words preserve the value of the maximum number of independently specified bits from the original linear code words. A substantial improvement can be achieved in the field of sequential pattern compression using these nonlinear codes. The number of scan chains loaded in parallel can be increased while the number of specified bits is kept. We propose an algorithm that finds the appropriate nonlinear modification circuit structure and verifies the test pattern quality for different numbers of care bits in a test pattern.