Methods and circuits are described for reducing power consumption within
digital logic circuits by blocking the passage of clock signal transitions to the
logic circuits when the clock signal would not produce a desired change of state
within the logic circuit, such as at inputs, intermediary nodes, outputs, or combinations.
By way of example, the incoming clock is blocked if a given set of logic inputs
will not result in an output change of state if a clock signal transition were
to be received. By way of further example, the incoming clock is blocked in a data
flip-flop if the input signal matches the output signal, such that receipt of a
clock transition would not produce a desired change of state in the latched output.
The invention may be utilized for creating lower power combinatorial and/or sequential
logic circuit stages subject to less unproductive charging and discharging of gate capacitances.