Edge sensitive single clock latch apparatus with a skew compensated scan function

摘要

A latch circuit possesses a scan capability, has a single clock input line, and possesses a locking feature whereby input data, once locked in the latch, is insensitive to further changes in state of the input data. The latch also possesses a novel selection apparatus which functions to select either a scan data input line or a system data input line in accordance with the binary state of a system gate input line, the selection apparatus developing an output signal, the binary state of which is locked in the latch in response to a predetermined state of a clock pulse conducted via the single clock line. Clock skew compensation is provided via the locking feature. During a scan mode, clock skew compensation is provided when the clock pulse is received for a period of time after termination of reception of a scan pulse conducted via the system gate input line.