We propose a routability-driven analytical placer that aims at distributing pins evenly. This is accomplished by including a group of pin density constraints in its mathematical formulation. Moreover, for mixed-size circuits, we adopt a scaled smoothing method to cope with fixed macro blocks. As a result, we have fewer cells overlapping with fixed blocks after global placement, implying that the optimization of the global placement solution is more accurate and that the global placement solution resembles a legal solution more. Routing solutions obtained by a commercial router show that for most benchmark circuits, better routing results can be achieved on the placement results generated by our pin density oriented placer.
展开▼
