Gated scan output flip-flop

摘要

A scannable storage circuit is provided that has a separate a scan output buffer for driving the scan output. The scan output buffer is coupled to the storage element in a parallel manner with the data output buffer so that normal data propagation is not delayed. The scan output buffer is gated by a scan enable input so that the scan output is quiescent when the storage circuit is not in scan mode. The selectively enabled scan output buffer is embodied with only four transistors.