In bus routing, if signal bits in a bus structure share a common routing topology, routability is increased by avoiding twisted patterns and variation immunity. The bus routing problem has become significantly important because of increasing complexity of bus structures for multichip-module, I/O pins, or on-chip memories in advanced technology. We present and evaluate a compact topology-aware bus routing method that can both compactly synthesize the routing topology of the bus and minimize design rule violations even in designs with high bus density and high track utilization. Our proposed method completed the bus routing in the runtime limit of the ICCAD-2018 contest and achieved 66% reduction in total cost compared with the winner of that contest.

We propose a fence-region-aware mixed-height standard cell legalization that can optimize the placement of standard cells that have more than a two row height in various shapes of the fence region. The algorithm consists of pre-legalization and mixed-height standard cell legalization steps to prioritize cell legalization; then a quality refinement step that uses simulated annealing reduces the displacement. Our proposed method achieved 63% improvement in the average quality score and 72% improvement in average runtime, compared to the winners of the ICCAD-2017 contest.

Incremental timing-driven placement (TDP) is one of the most crucial steps for timing closure in a physical design. The need for high-performance incremental TDP continues to grow, but prior studies have focused on optimizing only setup timing slacks, which can be easily stuck in local optima. In this paper, we present a useful skew methodology based on a maximum mean weight cycle (MMWC) approach in the incremental TDP. The proposed useful skew methodology finds an optimal clock latency for each flip-flop, and the clock latency is implemented by moving the flip-flops and/ or reassigning them to local clock buffers. With the proposed TDP method, we effectively reduce the early slack of ICCAD 2015 contest benchmarks, and achieve 124(%) and 78(%) of total quality score improvement compared to the 2015 contest winner, and early slack histogram compression (EHC) method, respectively. Moreover, with fewer iterations in the optimization, the runtime of our predictive useful skew method is an average of 7.4 times faster than an EHC method.