Ambient light detectors using conventional cmos image sensor process

Abstract

A CMOS light detector configured to detect specific wavelengths of light includes a first sensor and a second sensor. The first sensor includes CMOS photocells that are covered by a colored filter layer of a first color that has a first transmittance that allows both light of the specific wavelengths and light of other wavelengths to pass. The second sensor including further CMOS photocells, at least some of which are covered by both a colored filter layer of the first color and a colored filter layer of a second color, stacked one above the other in either order, where the colored filter layer of the second color has a second transmittance that allows light of the other wavelengths to pass. The first sensor produces a first photocurrent, and the second sensor produces a second photocurrent, when light including both the specific and other wavelengths is incident upon the detector. A differential photocurrent, produced by determining a difference between the first and second photocurrents, has a spectral response with at least part of the light of other wavelengths cancelled.