Bio-inspired circuitry of bee-bootstrap and Spider-latch comparator for ultra-low power SAR-ADC

Abstract

Purpose

There are many types of the ADCs implemented in the mobile and wireless devices. Most of these devices are battery operated and operational at low input voltage. SAR ADC is popular for its low power operations and simple architecture. Scientists are still working to make its working faster under the same low power area. There are many SAR-ADC implemented in the past two decades, but still, there is a big room for dual SAR-ADC.

Design/methodology/approach

The authors are presenting a dual SAR-ADC with a smaller number of components and blocks. The proposed ultra-low-power circuit of the SAR-ADC consists of four major blocks, which include Bee-bootstrap, Spider-Latch dual comparator, dual SAR-logic and dual digital to analog converter. The authors have used the 90-nm CMOS library for the construction of the design.

Findings

The power breaks down of the comparator are dramatically improved from 0.006 to 0.003 uW. The ultimate design has 5 MHz operating frequency with 25 KS/s sampling frequency. The supply voltage is 1.2 V with 35.724 uW power consumption. Signal-to-noise and distortion ratio and spurious-free dynamic range are 65 and 84 dB, respectively. The Walden's figure of merits calculated 7.08 fj/step.

Originality/value

The authors are proposing two-in-one circuit for SAR-ADC named as “dual SAR-ADC”, which obeys the basic equation of duality, derived and proved under the heading of proposed solution. It shows a clear difference between the performance of two circuit-based ADC and one dual circuit ADC. The number of components is reduced by sharing the work load of some key components.

Citation

Faheem, M.Y., Zhong, S., Wang, X. and Azeem, M.B. (2022), "Bio-inspired circuitry of bee-bootstrap and Spider-latch comparator for ultra-low power SAR-ADC", Circuit World, Vol. 48 No. 2, pp. 174-184. https://doi.org/10.1108/CW-11-2019-0165