Patent ID: 7836415

Claim:
A circuit design method performed in a circuit design system including a computer having computer-readable instructions embodied on a computer-readable storage device, in which the computer-readable instructions when executed by the computer causes the computer to design a circuit, said circuit design method comprising: calculating power to be consumed by each of cells by using layout data in which a placement and routing is completed; calculating a current IR drop value by calculating a voltage decreased due to an IR drop for each cell by using the power for each cell; specifying a greatest IR-drop value which indicates a voltage where a greatest IR-drop occurs, from IR-drop values of the cells calculated in the calculating the IR-drop, and specifying a cell having the greatest IR-drop value, when a repeat process is a first time; determining whether a difference between the current IR drop value and a previous IR drop value of the cell specified in the specifying the greatest IR-drop value is equal to or less than a predetermined value, when the repeat process is a second time or later; and defining a voltage after the IR drop occurs for each cell by using the IR drop value when the difference is greater than the predetermined value, wherein after the cell having the greatest IR-drop value is specified, the computer is caused to repeat the calculating the power by using the defined voltage, the calculating the current IR drop value by using a recalculated power, and the defining the value after the IR drop occurs until the difference becomes equal to or less than the predetermined value.