Variable accuracy parameter modeling in statistical timing

摘要

Systems and methods compute a mean timing value of an integrated circuit design for variables using a first timing calculation of relatively higher accuracy; and calculate a first timing value of the integrated circuit design for the variables, using a second timing calculation having a relatively lower accuracy. Such systems and methods calculate second timing values of the integrated circuit design for additional sets of variables using the second timing calculation; and calculate finite differences of each of the second timing values to the first timing value. Thus, these systems and methods calculate a statistical sensitivity of the first timing value to the additional sets of variables based on the finite differences. Further, such systems and methods calculate a statistical sensitivity of the mean timing value to the additional sets of values based on the statistical sensitivity of the first timing value to the additional sets of values.

主权项

1. A method comprising:
receiving an integrated circuit design into a computer; automatically computing a mean timing value of at least one portion of said integrated circuit design for a first set of manufacturing process variables, voltage variables, and temperature variables (PVT variables) using a first timing calculation, having a first accuracy and having a first time and computer resource cost, using said computer; automatically calculating a first timing value of said at least one portion of said integrated circuit design for said first set of PVT variables using a second timing calculation, having a second accuracy and having a second time and computer resource cost, using said computer; automatically calculating second timing values of said at least one portion of said integrated circuit design for additional sets of PVT variables that are different from said first set of PVT variables using said second timing calculation using said computer; automatically calculating finite differences of each of said second timing values to said first timing value using said computer; automatically calculating a statistical sensitivity of said first timing value to said additional sets of PVT variables based on said finite differences using said computer; automatically calculating a statistical sensitivity of said mean timing value to said additional sets of PVT variables based on said statistical sensitivity of said first timing value to said additional sets of PVT variables using said computer; and automatically outputting said mean timing value and said statistical sensitivity of said mean timing value to said additional sets of PVT variables from said computer for use in modifying said integrated circuit design to improve operating speed and decrease malfunction of integrated circuits fabricated according to said integrated circuit design, said second accuracy being lower than said first accuracy, and said second time and computer resource cost being lower than said first time and computer resource cost.