Power and Area Optimization of 3D Networks-on-Chip Using Smart and Efficient Vertical Channels

3D NoC offers greater device integration, faster vertical interconnects and more power efficient inter-layer communication due to the beneficial attribute of short through silicon via (TSV) in 3D IC technologies. However, TSV pads used for bonding to a wafer layer, occupy significant chip area and result in routing congestions and expensive manufacturing process. This can lead to a significant reduction in 3D ICs’ yield and higher power densities compared to 2D NoCs. In this paper, a power-efficient and low-cost inter-layer communication scheme is proposed as one way to mitigate these challenges. Instead of using a pair of unidirectional channels for inter-layer communication, utilizing a high-performance bidirectional channel enables a system to benefit from low-latency nature of the vertical interconnects and to remarkably reduce the number of TSVs. Additionally, we present a forecasting-based dynamic frequency scaling technique for reducing the power consumption of the inter-layer communication. Our extensive simulations demonstrate significant area and power improvements compared to a typical symmetric 3D NoC.