Andrea Fant

A 13.2b optical proximity sensor system with 130klx ambient light rejection capable of heart rate and blood oximetry monitoring

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.

Integrated High Resolution Digital Color Light Sensor in 130 nm CMOS Technology

This article presents a color light detection system integrated in 130 nm CMOS technology. The sensors and corresponding electronics detect light in a CIE XYZ color luminosity space using on-chip integrated sensors without any additional process steps, high-resolution analog-to-digital converter, and dedicated DSP algorithm. The sensor consists of a set of laterally arranged integrated photodiodes that are partly covered by metal, where color separation between the photodiodes is achieved by lateral carrier diffusion together with wavelength-dependent absorption. A high resolution, hybrid, ∑∆ ADC converts each photo diode’s current into a 22-bit digital result, canceling the dark current of the photo diodes. The digital results are further processed by the DSP, which calculates normalized XYZ or RGB color and intensity parameters using linear transformations of the three photo diode responses by multiplication of the data with a transformation matrix, where the coefficients are extracted by training in combination with a pseudo-inverse operation and the least-mean square approximation. The sensor system detects the color light parameters with 22-bit accuracy, consumes less than 60 μA on average at 10 readings per second, and occupies approx. 0.8 mm2 of silicon area (including three photodiodes and the analog part of the ADC). The DSP is currently implemented on FPGA.