A Place and Route Aware Buffered Steiner Tree Construction

Absrracr- In order ro achieve riming closure on increasingly com- plex IC designs, buffer insenion needs ro be perjfoformed on thousands of ners wirhin an integrared physical synthesis system. In mosr of previous works, buffers my be inserred at any open space. Even when there may appear ro be space for buffers in rhe alleys between large block, rhese regions are ofren densely packed or may be useful larer rofrr critical paths. In addition, a buffer solution my imdver- renrly force wires ro go rhrough muring congesred regions. Therefore, wirhin physical synrhesis, a buffer inserrion scheme needs to be aware of both placement congestion and rouring congesrion of rhe exisring layour and so if has fo be able ro decide when ro insen buffers in dense regions ro achieve criticolperjfomnce improvemenr and when ro uri- lize rhe sparser regions of the chip. Wirh the proposed Steiner free adjusfmenf technique, this work aims at finding congestion-aware buffered Sfeiner frees. Our free adjusrmenf rechnique rakes U Sreiner tree us inpur, modifies the free and simultaneously handles the objec- rives of riming, placement and rouring congesrion. To our knowledge, this is thefirst srudy which simultaneously considers rhese three ob- jectives for the buffered Sreiner free problem. Experimental results confirm rhe effecriveness of OUT algorirhm while ir achieves up ro 2Ox speed-up when comparing with rhe stare-ofrhe-arr alRorithm (51.