Patent attributes
A test circuit includes a scan chain and a wrapper chain. The wrapper chain shifts in a test pattern according a first clock. The scan chain is coupled to the wrapper chain via a logic combination of a circuit under test. The wrapper chain is configured to transmit the test pattern to the scan chain via the logic combination according to a second clock in a capture phase. The wrapper chain includes a first, a second wrapper cell, and an asynchronous register. The first wrapper cell sequentially shifts in two bits of the test pattern in the shift-in phase. The second wrapper cell shifts in the first bit of the test pattern in the shift-in phase. The asynchronous register conducts the first wrapper cell to the second wrapper cell in the shift-in phase, and latches the second wrapper cell in the capture phase.
