Best Match: Enhanced Hybrid-Row-Height Standard Cell Placement with Macro Blockages

Hybrid-row-height IC design incorporates placement rows of two or more distinct heights which do not have to be integer multiples of a single height. This design strategy is more flexible for optimizing power, performance, and area simultaneously. Several attempts have been made to deal with the hybrid-row-height standard cell placement problem with customizable row configuration by intelligently leveraging a commercial placement tool. Here we propose an enhanced algorithm, Best Match, to determine the best matching row configuration for a given netlist which leads to minimal disturbance to the initial timing-optimized placement after placement legalization. Our row planning approach has a number of enhancements over previous works, including (1) consideration of horizontal displacement of cells in addition to vertical displacement of cells, (2) precise positioning of the hybrid rows, and (3) ability to handle macros in a design. As a result, we obtained a much smaller total displacement of cells after placement legalization compared to the state-of-the-art works. The experimental results show that our approach outperforms the flow-based method in [9] with 48.4%, 24.9%, and 68.8% reduction in the total displacement of cells, final routed wirelength, and post-route total negative slack, respectively. It yielded 13.4% reduction in the total displacement of cells, 4.5% reduction in the final routed wirelength, and 26.3% reduction in the post-route total negative slack compared to [7]. Furthermore, compared to the legalized placement generated by a commercial tool under the uniformly hybrid row configuration, the routed wirelength and post-route total negative slack are reduced by 27.4% and 91.8%, respectively, under the customized row configuration determined by Best Match.