US Patent 11782092 Scan compression through pin data encoding

A method for testing a chip comprising: receiving N scan-in chains of test data; using the N scan-in chains of test data to perform tests on the chip; receiving a merged expected test-result and masking-instruction signal on X pins of the chip from the off-chip test equipment, X being less than 2*N; decoding the merged expected test-result and masking-instruction signal to extract N decoded output signals, each of the N decoded output signals corresponding to a respective chain of test results.