Increasing reconfigurability with memristive interconnects

Abstract

The design of on-chip interconnects is largely governed by the size and power of the devices being connected. While large components like memory controllers, video decode accelerators, and cores can afford the overhead of a large packet switching NoC router, smaller components like adders or other ALUs cannot. Instead, they are typically connected via simple wires, limiting their runtime reconfigurability. The notable exception - FPGAs - use an interconnect which allows extreme reconfigurability, but the FPGA pays for it in area, power, and latency costs. Less costly reconfigurable interconnects, therefore, could allow hardware designers to expose more reconfigurability while limiting area and power costs. This paper presents the design of a high-radix circuit switching crossbar design using memristors. This design utilizes Phase Change Memory (PCM), overcoming some of its limitations such as leakage power and low voltage operation. The very small size of memristors shrinks the area, power, and latency of crossbars by up to 16x, 4.4x, and 2.4x, respectively, leaving little interconnect overhead but wiring overhead. As a tool for designers, memristive interconnects offer significant potential to increase runtime design flexibility.