A 0.8V 8-bit low-power asynchronous level-crossing ADC with programmable comparison windows

Abstract

We propose a low-power asynchronous level-crossing analog-to-digital converter (LC-ADC) for use in a biomedical readout system. A comparator with programmable offset and a low-power single-bit digital-to-analog converter (DAC) are proposed to separate the comparison windows and fix the common-mode voltage of the comparator. Implemented in a 0.18 μm CMOS technology, the proposed LC-ADC uses a chip area of 220×230 μm2. Operating from a supply voltage of 0.8 V, the ADC input range can exceed the power supply voltage. It consumes 0.32 - 0.84 μW from 5 Hz to 5.1 kHz with an ENOB of 7.8.