The impact of 3-dimensional integration on the design of arithmetic units

3-dimensional integration technology stacks multiple die on top of each other with a dense die-to-die interface. This enables a circuit designer to replace long wires with short vertical interconnects, thus reducing wire-related delay and power consumption. In this research, we evaluate the impact of a 3D fabrication technology on the latency and power of arithmetic functional units. Specifically, we study integer adders and shifters as they have very different delay characteristics. An adder's critical path latency is dominated by logic/gate delays, while a shifter's latency is more greatly affected by wire delay. We demonstrate that the potential benefits of a 3D technology are the greatest when applied to wire-bound circuits. In particular, a barrel shifter implemented in 3D exhibits a 9% reduction in latency with a simultaneous 8% reduction in energy