Abstract — Modern FPGAs are not only increasing in size but have also become more complex with many new features not found in the previous FPGA generation. This demands more powerful physical design automation tools and better solutions for both old and new problems. In this paper, we describe a novel netbased force-directed FPGA placement algorithm. It outperforms the state-of-the-art FPGA performance-driven placement tool, VPR [9], with 10.7 % shorter critical path delay and 11.5% shorter total wire length after routing over a set of MCNC benchmarks. In addition, we describe the new constrained I/O placement problem in modern FPGAs and present a powerful integer linear programming based approach to solve it. We applied our proposed method...