High Sensitivity Color CMOS Image Sensor with WRGB Color Filter Array and Color Separation Process Using Edge Detection

We have developed a CMOS image sensor with a novel color filter array (CFA) where one of the green pixels of the Bayer pattern was replaced with a white pixel. A transparent layer has been fabricated on the white pixel instead of a color filter to realize over 95% transmission for visible light with wavelengths of 400-700 nm. Pixel pitch of the device was 3.3 um and the number of pixels was 2 million (1600H x 1200V). By introducing the Bayer-like White-Red-Green-Blue (WRGB) CFA and by using the low-noise color separation process, signal-to-noise ratio (SNR) was improved. Low-illumination SNRs of interpolated R, G, and B values have been increased by 6dB, 1dB, and 6dB respectively, compared with those of the Bayer pattern. The false color signals at the edge have been suppressed by newly developed color separation process using edge detection. This new CFA has a great potential to significantly increase the sensitivity of CMOS/CCD image sensors with digital signal processing technology.