Demonstration of latency reduction in ultra-short distance interconnections using optical fanout

In this paper, we present a hybrid optoelectronic system capable of improving the performance of short-distance broadcast architectures such as arrays of gates, cells, or processors. By incorporating a layer of the optical fanout in the electrical fanout link, we utilize the electrical isolation advantage of the optical interconnects in addition to the absence of the parasitics. Our proof-of-concept circuits show improved signal latency even for a small electrical fanout to 32 minimum-sized inverters, corresponding to an electrical link length of 200 mu m in a 0.25-mu m technology. This is the first physical demonstration of the advantages of using optics in silicon very large scale integrated (VLSI) systems at these distances. We also demonstrate an advantage in the energy-delay-squared product for fanout to more than 250 minimum-sized inverters corresponding to a distance of 1.5 mm.