Constraint driven I/O planning and placement for chip-package co-design

System-on-chip and system-in-package result in increased number of I/O cells and complicated constraints for both chip designs and package designs. This renders the traditional manually tuned and chip-centered I/O designs suboptimal in terms of both turn around time and design quality. In this paper we formally introduce a set of design constraints suitable for chip-package co-design. We formulate a constraint-driven I/O planning and placement problem, and solve it by a multi-step algorithm based upon integer linear programming. Experiment results using real industry designs show that the proposed algorithm can effectively find a large scale I/O placement solution and satisfy all given design constraints in less than 10 minutes. In contrast, the state-of-the-art without considering those design constraints simply cannot meet all design constraints by relying solely upon the conventional iterative approach.