| 摘要 |
PROBLEM TO BE SOLVED: To provide a timing constraint setting method capable of reducing the amount of low threshold cells used.SOLUTION: The timing constraint setting method of an embodiment includes: performing provisional placement using only the high threshold cells of a cell library 12 on the basis of the clock skew distribution set forth in an inputted timing constraint 11, with a value derived by subtracting an improvement in speed due to low threshold cells as a margin 13 from an original clock cycle being a layout clock cycle (step S1); verifying the timing of a signal propagation path on the basis of the result of provisional placement (step S2); extracting a path for which timing violation was detected by the timing verification (step S3); analyzing details of delay propagation relating to the detected path (step S4); and calculating a clock skew amount distributed to a signal propagation path relating to the detected path and updating the timing constraint 11 on the basis of the analysis result and outputting a timing constraint 21 for definite placement (step S5). |
