A novel variation-aware low-power keeper architecture for wide fan-in dynamic gates

Abstract

Substantial increase in leakage current and threshold voltage fluctuations are making design of robust wide fan-in dynamic gates a challenging task. Traditionally, a PMOS keeper transistor has been employed to compensate for leakage current of pull down (NMOS) network. However, to maintain acceptable noise margin level in sub-100 nm technologies, large PMOS is necessary, which results in substantial contention (during pull down) and severe loss of performance. In this paper, a novel keeper architecture is proposed which is capable of significantly reducing the contention and improving the performance and power consumption. Using circuit simulations, superior characteristics of the proposed keeper is demonstrated in comparison to those of the traditional as well as state-of-the-art keepers. It is shown that for an 8-input OR gate, in presence of 15% Vth fluctuations, the proposed architecture can lead to 20%, 15%, and more than 40% reduction in power consumption, mean delay, and standard deviation of delay, respectively, when compared to traditional keeper circuit. Copyright 2006 ACM.