A 13.2 b Optical Proximity Sensor System With 130 klx Ambient Light Rejection Capable of Heart Rate and Blood Oximetry Monitoring

Abstract

A system for measuring optical proximity based on reflection of modulated light is presented. Its novel input stage topology comprising an ac coupled TIA and a two stage dc rejection circuit based on a synthesized inductance, provides readouts with a resolution better than 13.2 ENOB. This allows the sensor system to be flexibly used also for heart rate and blood oximetry monitoring.