Integrated high resolution digital color light sensor in 130 nm CMOS technology

Strle, Drago (author), Nahtigal, Uroš (author), Batistell, Graciele (author), Zhang, Vincent Chi (author), Ofner, Erwin (author), Fant, Andrea (author), Sturm, Johannes (author)

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 mm$^2$ of silicon area (including three photodiodes and the analog part of the ADC). The DSP is currently implemented on FPGA.

• Language: English
• Keywords: color light detection, high-resolution photo current measurements, measurements of light in CIE XYZ color luminosity space, RGB color sensor, CMOS-integrated color light sensor system, color signal processing
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FE - Faculty of Electrical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2015
• Number of pages: Str. 17786-17807
• Numbering: Vol. 15, iss. 7
• PID: 20.500.12556/RUL-130483
• UDC: 681.5:535-2
• ISSN on article: 1424-8220
• DOI: 10.3390/s150717786
• COBISS.SI-ID: 11077972
• Publication date in RUL: 15.09.2021

Record is a part of a journal

• Title: Sensors
• Shortened title: Sensors
• Publisher: MDPI
• ISSN: 1424-8220
• COBISS.SI-ID: 10176278

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.
• Licensing start date: 22.07.2015

Secondary language

• Language: Slovenian
• Keywords: zaznavanje barvne svetlobe, visokoločljivo merjenje foto toka, meritev spektra svetlobe v svetlobnem prostoru CIE XYZ, RGB barvni senzor svetlobe

Projects

• Funder: Other - Other funder or multiple funders
• Funding programme: FFG (FIT-IT)
• Acronym: COSMOS