Evolutionary and revolutionary interconnect technologies for performance enhancement of subthreshold circuits

Subthreshold circuits have become attractive for various ultra-low power electronic applications. In subthreshold circuits, supply voltage is below the threshold voltage of transistors. This paper discusses both evolutionary and revolutionary interconnect technologies needed to enhance the speed and energy efficiency of subthreshold circuits. It is demonstrated that lowering copper interconnect width and height-to-width aspect ratio by half offers 3.5 improvement in energy-delay product of subthreshold circuits. Also, carbon nanotube and graphene nanoribbon interconnects can offer more than 20 and 10 times improvement in energy delay product of subthreshold circuits, respectively. Impact of repeater insertion, driver sizing, and interconnect spacing adjustment for subthreshold circuits have also been modeled.