Patent ID: 6654712
Filing Date: 2003-11-25
Classification: G06F

Abstract:
A method to reduce variations in signal delays along paths in a design of an integrated circuit by balancing wire widths, the method comprising:(aâ€²) selecting a node in a tree of circuit paths; (a) performing a circuit simulation to determine simulated signal delays along all circuit paths based on first wire widths for a given circuit, wherein the first wire widths are wire widths for branches on a level directly below the selected node; (b) running a delay model analysis to calculate predicted signal delays along the circuit paths based on first wire widths for the given circuit; (c) calculating a correction difference for the predicted signal delays from the simulated signal delays, comprising: calculating a correction difference for each branch leaving a selected node by multiplying a SPICE simulated clock signal delay for a branch entering the a selected node by a user-input change factor and by the value of one minus the quotient of an average SPICE simulated clock signal delay for all branches below the branch leaving the selected node over an average SPICE simulated clock signal delay for all branches below the branch entering the selected node; (d) deriving delay targets from the correction difference, comprising: deriving a delay target for each branch leaving the selected node by adding the delay target for the branch leaving the selected node to the Elmore predicted clock signal delay for the branch leaving the selected node; (e) calculating second wire widths using the delay model analysis to meet the delay targtets; (f) setting the first wire widths equal to the second wire widths; (g) iteratively repeating steps (a) through (f) until the variations in the signal delays alone the circuit paths reach a near zero condition; (h) repeating steps (a) through (g) for the selected node in the tree of circuit paths; (i) selecting another node; and (j) repeating steps (aâ€²) through (h) for the selected node in the tree of circuit paths.