Simultaneous assignment of power pads and wires for reliability-driven hierarchical power quad-grids

For a given floorplan in hierarchical power quad-grids(HPQGs) with the IR-drop constraint and the electromigration constraint, an iterative two-phase approach is proposed to design reliability-driven HPQGs to assign limited power pads and power wires to supply the required current and satisfy the current density constraint for each power branch and the IR-drop constraint for each power node with minimizing total wiring area. The experimental results show that the iterative two-phase approach uses less total wiring area under limited power pads to release all the IR-drop constraints in reasonable CPU time for the tested examples.