A circuit receives a parameter signal at a set or reset input, a clock signal at a clock input and a constant digital value at a data input. A synchronous signal is output from the circuit: wherein when the parameter signal is in a first state, then the output synchronous signal has the digital value; wherein when the parameter signal transitions to a second state, then the output synchronous signal transitions to an inverse of the digital value at substantially the same time; and wherein when the parameter signal transitions back to the first state, then the output synchronous signal transitions to the digital value on a next clock edge.