Image Number 5 for United States Patent #6559701.
A method of reducing power rail transients on integrated circuits. The power rail transients are reduced by controlling clock skew in a manner which minimizes dI/dT current demands. The method provides that the phase of the clock to latches/flip flops is shifted in order to spread out the number of simultaneous switching elements. By controlling the number of simultaneous switching devices, a significant reduction in time rate of current demanded from the power rails can be achieved, thereby reducing the magnitude of V.sub.SS /V.sub.DD voltage transients due to parasitic inductances and resistances supplying power to the integrated circuit. Theoretically, the entire timing spread of the slack graph for clock skew can be used to control the number of simultaneous switching devices.