Energy-Effective Sub-Threshold Interconnect Design Using High-Boosting Predrivers

This paper investigates the performance of the interconnects with repeater insertion in the subthreshold region. A 3X complementary metal-oxide-semiconductor (CMOS) predriver and a 4X one are proposed to enhance the driving capability. As compared to the conventional repeater, the proposed ones have higher energy efficiency. In addition, the results of Monte Carlo analysis indicate that the propose predrivers have higher concentration under the process and temperature variation than conventional one at 0.15 V. A test chip with 3X and 4X predrivers for 10-mm on-chip bus has been fabricated in 65 nm SPRVT CMOS process. The measured results show that the 3X (4X) predrivers can achieve 5 Mb/s (1.5 Mb/s) data rate at 0.15 V with an efficiency of 35.2 fJ (32.8 fJ).