A 13.2b optical proximity sensor system with 130klx 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 inductive impedance, provides readouts with a resolution better than 13.2 ENOB. This allows the sensor system to be used without modifications also for heart rate and blood oximetry monitoring.