An improved top-down chip planning method that reduces the effects of differences of the estimated shapes in the floorplan and the final layouts are introduced. In a fully recursive approach, each cell is planned several times with different presumptions. Bottom-up adjustment steps use refined shape functions instead of rigid dimensions. Although such bottom-up adjustment steps were performed, the general direction is top-down. The convergence of the procedure can be ensured. The method is described in detail and some experimental results are provided. Several real large test designs (the largest example has nearly 300000 standard cells) have been performed with the PLAYOUT design system to compare the pure top-down approach with the new method.>

The result of many floorplanning algorithms is a placement of macrocells. A novel technique for the improvement of a given placement is presented which is based on the optimization of the channel densities by refining the cell positions. The authors introduce a distance function for each channel representing the channel width. This width can be altered by shifting adjacent cells along each other by an offset. They present an optimization to find offsets for adjacent cells which lead to a minimal area demand of the total layout. The method is based on a genetic algorithm, an iterative improvement procedure. Results are presented.>

A complete datamodel for an integrated VLSI design system is developed in a stepwise manner. This datamodel introduces a unified view of all design domains and hierarchy levels that result in a considerable simplification of the communication among the design tools. We defined five basic objects: cell, interface, contents, instance and configuration for high level description of all design data. The model also covers views, types, alternatives, versions and the design history. In particular our handling of the configuration demonstrates reasonable response times, due to the strict avoidance of redundant information and the storage of complex objects. This datamodel can be directly used for the implementation of an efficient object-oriented design database.