Method and program for designing semiconductor integrated circuits, and semiconductor integrated circuit designing apparatus
Two paths (arrival and required paths) as a target of analysis are united into a single path, and an on-chip random variation component σr about a plurality of nodes of the single path is calculated. Next, an on-chip variation component σchip is calculated on the basis of the on-chip random variation component σr and an on-chip systematic variation component σs. Subsequently, a delay variation Docv is calculated on the basis of a reference delay Dbase of the entire path and the on-chip variation component σchip.
1. A method of designing a semiconductor integrated circuit that is formed of a connection of a plurality of nodes and that has a clock path serving as a clock signal propagation route and a data path serving as a data signal propagation route, said method comprising the steps of: (a) uniting said clock path and said data path into a single path and calculating a standard deviation of random variation components of said plurality of nodes of said united path; (b) calculating a standard deviation of on-chip variation components on the basis of said standard deviation of the random variation components and a standard deviation of systematic variation components of said plurality of nodes of said united path; and (c) calculating a delay variation on the basis of said standard deviation of on-chip variation components and a reference delay of an entirety of said united path.
2. The semiconductor integrated circuit designing method according to claim 1 , wherein, in said step (a), in calculating said standard deviation of the random variation components, the random variation components of said plurality of nodes are respectively weighted with delays.
3. The semiconductor integrated circuit designing method according to claim 1 , wherein said plurality of nodes include a multi-stage-structured node having a fixed delay component, and in said step (a), said multi-stage-structured node is divided into divided stages and said divided stages are incorporated as separate nodes in the calculation of said standard deviation of the random variation components.
4. The semiconductor integrated circuit designing method according to claim 1 , further comprising the steps of: (d) calculating a standard deviation of components including all variations, including other chip variation components in addition to said on-chip variation components; and (e) setting a range of coverage of said standard deviation of the on-chip variation components such that a maximum value of said standard deviation of the on-chip variation components does not exceed a maximum value of said standard deviation of the components including all variations.
5. An apparatus for designing a semiconductor integrated circuit, wherein said semiconductor integrated circuit is formed of a connection of a plurality of nodes and has a clock path serving as a clock signal propagation route and a data path serving as a data signal propagation route, said apparatus comprising: an on-chip random variation component calculating block that unites said clock path and said data path into a single path and calculates a standard deviation of random variation components of said plurality of nodes of said united path; an on-chip variation component calculating block that calculates a standard deviation of on-chip variation components on the basis of said standard deviation of the random variation components and a standard deviation of systematic variation components of said plurality of nodes of said united path; and a delay variation calculating block that calculates a delay variation on the basis of said standard deviation of on-chip variation components and a reference delay of an entirety of said united path.