Data and clock signal voltages within an integrated circuit

An integrated circuit 2 has data processing circuitry processing a data signal passing along a data path 14. Clocked circuitry coupled to the data processing circuitry serves to regulate passage of the data signal along the data path. The data signal is supplied at a data signal voltage amplitude and the clock signal is supplied at a different clock signal voltage amplitude. The clock signal voltage amplitude is higher than the data signal voltage amplitude. A separate clock signal power supply grid 12 is provided in addition to the data power supply grid 10.