Abstract
This paper presents an adaptive interface ASIC consisting of a low-noise analog front-end and a successive-approximation ADC. The entire analog signal processing chain is fully-differential for better immunity to common-mode noise and interferences. To make the interface adaptive to different biopotential signals, the bandwidth and gain of the analog front-end are configurable. The ADC is designed for rail-to-rail operation and the input full-scale is adjustable so that the resolution requirement can be relaxed. Fabricated in 0.18-mu m CMOS, 95-nV/root Hz input-referred noise density and more than 100-dB CMRR are obtained. Operating in 10-bit mode, the ADC exhibits -1/+0.3-LSB DNL and -1.3/+0.8-LSB INL for 1-V rail-to-rail input. The whole interface IC consumes 36 mu W from a single 1-V supply, making it suitable for a wide range of low-voltage and low-power biomedical applications.