Insertion of an Optimal Number of Repeaters in Pipelined Nano-interconnects for Transient Delay Minimization

Abstract

A novel and highly accurate finite-difference time-domain model is developed for bundled single-walled carbon nanotube (SWCNT) interconnects by considering a fixed configuration that consists of a CMOS driver, a bundled SWCNT interconnect system, and an optimal number of repeaters. Using superposition theorem, this iterative model is applied to the entire chain of repeaters to calculate the total closed-loop delay. An accurate transfer function is modeled for the chain of equi-spaced repeaters in the interconnect system. The transfer function is further used to develop an analytical model for closed-loop delay, considering the optimum number of repeaters as dependent parameter. Further, in order to determine the minimum delay, an analysis is performed to find out the optimum number of repeaters for a given interconnect length. In addition, a detailed study is carried out to observe the impact of interconnect length on time delay, the time delay reduction on increasing the number of repeaters and the effect of excitation magnitude on time delay with power delay product. It is observed that by using SWCNT interconnects, the total number of repeaters and the time delay are reduced by more than 40 and 50%, respectively, compared with the copper (Cu) interconnects. However, the proposed model achieves extreme accuracy, with 4% relative tolerance at maximum, in predicting interconnect performance based on comparison with the HSPICE simulations.