High performance photodetector for modulated lighting - high sensitivity, high selectivity, high suppression of background, and wide dynamic range

A new sensing scheme for high-sensitivity and wide-dynamic-range position detection is presented. A correlation circuit and a current-mode suppression circuit of a constant illumination allow high sensitivity, high selectivity, and high suppression of a background illumination. A logarithmic-response circuit is employed to avoid saturation for wide dynamic range. The photodetector can quickly detect the modulated light by the pixel-parallel sensing. It has advantages in applications which require both availability in various backgrounds and a safe light projection for human eyes. The photodetectors have been developed and successfully tested. The high sensitivity under -18 dB signal-to-background ratio (SBR) is realized in over 472 dB dynamic range. The minimum SBR is -22.8 dB and the maximum frame rate is 2000 fps. In addition, the photodetector shows high selectivity in a multiple light system due to the suppression of orthogonally modulated light.