Abstract: The present invention comprises a method of optimizing a circuit design having a plurality of library cells. In one embodiment, the method includes the steps of providing a plurality of logically equivalent cells that vary in at least one design parameter, the plurality of logically equivalent cells having a relatively continuous spectrum of values of one of the design parameters, evaluating a selected characteristic of the circuit design; and replacing a cell in the circuit design with a cell an equivalent cell.

Abstract: The present invention provides a method for parallel optimization of an integrated circuit design based on the use of sets of cell instances that are independent from each other. Multiple changes to a design are analyzed in parallel by ensuring that no two cell instances that are being changed are in the same fan-in and fan-out cones. This property allows full timing analysis to be performed on a design such that multiple alternatives are explored in parallel and accurate results are obtained. By ordering the choice of cell instances to change and by ordering the alternatives to try, a greater degree of optimization is found earlier in the process.

Abstract: A method and apparatus for optimizing a circuit design using a library of cells in which a continuous spectrum of cells are provided. A library containing real and virtual cells is used so that cells can be selected across a wide spectrum of a design parameter, such as drive strength. The cells are provided in discrete steps small enough that the effect of having a continuous spectrum of cells is achieved. After optimization, only the cells finally selected need be actually synthesized, and when these constitute a small percentage of the total number of cells, the impact to library size and final placement and routing is minimized. Thus the ability to optimize across a continuous spectrum is achieved while preserving a cell library based design flow.