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 and a data path, said method comprising the steps of:
(a) uniting said clock path and said data path into a single path;
(b) calculating, using a computer system, a standard deviation of random variation components of said plurality of nodes of said united path, the random variation components being respectively weighted with delays;
(c) 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
(d) 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 said clock path serves as a clock signal propagation route and said data path serves as a digital signal propagation route.
3. The semiconductor integrated circuit designing method according to claim 1 , wherein said plurality of nodes include a multi-stage-structured node that is divided into divided stages and having a fixed delay component.
4. The semiconductor integrated circuit designing method according to claim 3 , wherein in step (a), said divided stages are incorporated as separate nodes in the calculation of said standard deviation of the random variation components.
5. The semiconductor integrated circuit designing method according to claim 1 , further comprising the steps of:
(e) calculating a standard deviation of components including other chip variation components in addition to said on-chip variation components; and
(f) 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 chip variation components.