Abstract: A multiplexed data flip-flop circuit (500) is described in which a multiplexer (510) outputs functional or scan data, a master latch (520) generates a master latch output signal at a hold time under control of a master clock signal, a slave latch (540) generates a flip flop output signal at a launch time under control of a slave clock signal, clock generation circuitry (550) generates a second clock signal that has a DC state during a functional mode and has a switching state during a scan mode, and data propagation logic circuitry (564) uses the first and second clock signals to generate the master and slave clock signals during a scan mode to delay the launch time of the slave latch with respect to the hold time of the master latch.

Abstract: The present invention provides a latch circuit that is operable to generate a pulse from first and second clock signals to allow gates in a datapath to propagate data with minimal latency. The first clock signal is a version of the system clock and the second control signal is a time-shifted, inverted version of the system clock signal. Each of the individual latches in a datapath comprises data propagation logic. In one embodiment of the invention, the data propagation logic uses the first and second clock signals to generate an “implicit” pulse. In another embodiment of the invention, the data propagation logic uses the first and second clock signals to generate an “explicit” pulse. The implicit and explicit pulses are used to control the transmission gate of the latch to provide propagation of data through the latch with minimal latency.

Abstract: The present invention provides a latch circuit that is operable to generate a pulse from first and second clock signals to allow gates in a datapath to propagate data with minimal latency. The first clock signal is a version of the system clock and the second control signal is a time-shifted, inverted version of the system clock signal. Each of the individual latches in a datapath comprises data propagation logic. In one embodiment of the invention, the data propagation logic uses the first and second clock signals to generate an “implicit” pulse. In another embodiment of the invention, the data propagation logic uses the first and second clock signals to generate an “explicit” pulse. The implicit and explicit pulses are used to control the transmission gate of the latch to provide propagation of data through the latch with minimal latency.

Abstract: A low-power pipelined data processor (20) includes a branch prediction mechanism for speculatively placing branch target instructions into the fetch, decode, dispatch, and execute pipeline when a branch is predicted to be taken. To save power the data processor (20) selectively disables one or more pipeline resources (24) associated with placing the branch target instructions into the pipeline according to the strength of the prediction. If the prediction is weakly not taken, the data processor (20) enables the pipeline resource (24) to prevent disruptions to the pipeline if the branch resolves as taken during the cycle. However if the prediction is strongly not taken, the pipeline resource (24) is disabled to save power, which outweighs the infrequent resolution to taken. In one embodiment, the data processor (20) disables a branch target instruction cache (24) if history bits corresponding to the branch instruction stored in a branch history table (26) indicate strongly that the branch will not be taken.