An optimization approach to the synthesis of multichip architectures

An optimization approach to the high level synthesis of VLSI multichip architectures is presented in this paper. This research is important for industry since it is well known that these early high level decisions have the greatest impact on the final VLSI implementation. Optimal application-specific architectures are synthesized here to minimize latency given constraints on chip area, I/O pin count and interchip communication delays. A mathematical integer programming (IP) model for simultaneously partitioning, scheduling, and allocating hardware (functional units, I/O pins, and interchip busses) is formulated. By exploiting the problem structure, using polyhedral theory, the size of the search space is decreased and a new variable selection strategy is introduced based on the branch and bound algorithm. Multichip optimal architectures for several examples are synthesized in practical cpu times. Execution times are comparable to previous heuristic approaches, however there are significant improvements in optimal schedules and allocations of multichips. This research breaks new ground by 1) simultaneously partitioning, scheduling, and allocating in practical cpu times, 2) guaranteeing globally optimal architectures for multichip systems for a specific objective function, and 3) supporting interchip communication delay, interchip bus allocation, and other complex interface constraints.<>