An Unbalanced Clock Based Dynamic Comparator: A High-Speed Low-Offset Design Approach for ADC Applications

Abstract

Currently, dynamic comparator approach necessitates in high-speed and power eÿcient analog-to-digital converter applications due to its high latching speed and ultra-low power consumption. In this paper, a novel dynamic comparator is proposed to reduce latch delay and offset. The comparator benefits from add-on cross-coupled transistors in latch structure and unbalanced clocks to enhance comparison speed and to lessen input offset voltage occurred due to mismatch in cross-coupled circuits in latch stage. The derivations for delay and input offset voltage are presented for proposed dynamic comparator with meticulous Monte-Carlo simulations. The results are verified by simulations in CADENCE SPECTRE at 1 V supply voltage and 90 nm CMOS technology. A comparative analysis between the proposed dynamic comparator and the previous reported comparators has been presented. It is observed that the delay is reduced up to 46 % and 6 % as compared to conventional and two phase dynamic comparator, respectively. Moreover, the proposed design consumes 53.36 µW power only. The Monte-Carlo simulation shows that the standard deviation of input offset voltage is 10.8 mV which is 12 % and 77 % of conventional and two phase dynamic comparator, respectively