Patent ID: 7231570

Claim:
A method for broadcasting compressed scan data patterns driven through N compressed scan inputs into decompressed scan data patterns stored in M scan chains, where N<M, using two or more decompressors separated by intermediate scan chains, in a scan-based integrated circuit, in a selected scan-test mode or selected self-test mode, the scan-based integrated circuit containing one or more scan chains, each scan chain comprising one or more scan cells coupled in series, the decompressors and intermediate scan chains embedded between the N compressed scan inputs and the M scan chains, with the N compressed scan inputs driving the first decompressor inputs, and the last decompressor outputs driving the M scan chains inputs; said method comprising: (a) shifting-in said decompressed scan data patterns to all said scan cells in said scan-based integrated circuit by broadcasting said compressed scan data patterns driven through said N compressed scan inputs into said decompressed scan data patterns stored in said M scan chains using said two or more decompressors during a shift-in operation; (b) capturing a scan data response to all said scan cells during a selected capture operation; and (c) shifting-out said scan data response for comparison or compaction during a shift-out operation.