Patent ID: 6789055
Filing Date: 2004-09-07
Classification: G06F

Abstract:
A timing verification checking value extracting method comprising:a pulse producing step for producing two input pulses having a pulse time difference of which a setting value is set to an initial setting value in advance; a simulation step for supplying each of the input pulses produced in the pulse producing step to an input terminal of a to-be-timing-verified circuit and judging, until a simulation completion time set in advance, whether or not an output pulse output from an output terminal of the to-be-timing-verified circuit in response to the input pulses is meets or exceeds a predetermined measurable criterion; an optimum simulation completion time determining step for determining an optimum simulation completion time, which is to be used in the simulation step as the simulation completion time in simulation stages following a first simulation stage, according to a level change time at which the output pulse is changed to a stable level in the first simulation stage; a pulse time difference resetting step for resetting the setting value of the pulse time difference between the input pulses, which is to be produced in the pulse producing step in a succeeding simulation stage following a current simulation stage, according to the judgment of the simulation step of the current simulation stage by changing the setting value of the pulse time difference by a changing degree, and reducing the changing degree of the pulse time difference in cases where the judgment of the simulation step in the current stage differs from that in a simulation stage preceding to the current stage; a convergence judging step for judging whether or not the changing degree of the pulse time difference reset in the pulse time difference resetting step is within a prescribed range and making the pulse producing step, the simulation step, the optimum simulation completion time determining step and the pulse time difference resetting step be repeatedly performed until the changing degree of the pulse time difference becomes within the prescribed range; and a checking value extracting step for extracting the pulse time difference between the input pulses as a timing verification checking value according to the judgment performed in the convergence judging step.