An Energy-Efficient Comparator with Dynamic Floating Inverter Pre-Amplifier

Xiyuan Tang, Begum Kasap, Linxiao Shen, Xiangxing Yang, Wei Shi, Nan Sun

Abstract: This paper presents an energy-efficient comparator with a novel dynamic pre-amplifier (pre-amp). By using an inverterbased input pair powered by a floating reservoir capacitor, the pre-amp realizes both current reuse and dynamic bias, thereby significantly boosting gm/ID and reducing noise. Moreover, it greatly reduces the influence of the input common-mode (CM) voltage on the comparator performance, including noise, offset, and delay. A prototype comparator in 180nm achieves 46uV input-referred noise while consuming only 1pJ per comparison under 1.2V supply. This represents >7x energy efficiency boost compared to a Strong-Arm (SA) latch. It achieves the highest reported energy efficiency to authors' best knowledge.