Hierarchical propagation of geometric constraints for full-custom physical design of ICs

Abstract

In industrial environments, full-custom layout design of analog and mixed-signal ICs is done hierarchically. In order to increase design efficiency, cell layouts are reused in the design hierarchy. Constraints forming relations between instances in different hierarchical contexts are of critical importance. While implementing a cell layout, these constraints have to be available in the cell's context. In this paper, a general definition of hierarchical constraints for a constraint-driven design flow is given. Furthermore it is shown, how top-down declared constraints can be propagated into another hierarchical context. Only by propagation they become visible and verifiable for bottom-up cell design. The feasibility of our proposed methodology is shown by applying it to a modular Smart Power IC of the automotive industry.