BSM pin assignment with differential pairing on multiple layer designs

Bottom Surface Metals (BSM) pin assignment for high frequency signals on a package device is a tedious manual job. Recently, proposed a network flow based method to assign BSM automatically for one layer without routing blockages. In this paper, we extend the work of to do BSM pin assignment on multiple layers with routing blockages. also considers BSM differential pairing constraints, but the pairing is limited to horizontal and vertical pairs. As technology advances, diagonal BSM pairs start to present in designs which makes the BSM pairing algorithm in not applicable any more. In this work, we present an optimal BSM pairing algorithm based on maximum weight matching. The experimental results demonstrate the effectiveness and efficiency of our algorithms.