Two color asynchronous event photo pixel

The paper presents a dichromatic asynchronous event pixel for use in an address event representation (AER) vision sensor. The pixel has been produced with the AMS 0.35 mum CMOS process. The sensitivity to two distinct color spectra is achieved by the concept of stacked photo diodes, PN-junctions at different depths below the surface of the silicon chip, which results in different absorption spectra. The pixel emits short pulses at a frequencies proportional to the photo currents of the junctions. The pixel is shown to clearly distinguish light sources of two different colors.