A 200 Hz-to-10 kHz bandwidth 11.83-ENOB level-crossing ADC with single continuous-time comparator

Abstract

A fixed-window level-crossing analog-to-digital converter (LC-ADC) with only one continuous-time comparator is proposed for the biomedical electronics. Compared with the traditional LC-ADC that needs at least two comparators, the proposed LC-ADC utilizes only one continuous-time comparator, which significantly reduces the power consumption of LC-ADC. A highly digital detection circuit is proposed as a replacement of the comparator that used in previous LC-ADCs to monitor the varying direction of the folded signal. Due to the simplified circuit scale of the circuit used to detect the signal varying direction, considerable power is saved. Designed with a 0.18 μm CMOS technology, the core area of this LC-ADC is 0.007 mm2. With a 1.8 V supply voltage and 1 kHz input signal frequency, it achieves 73.1 dB SNDR by consuming 20.1 μW power. The figure-of-merit value is 19.3 mm2 fJ/Conversion.