Correlating PIN-photodetector with novel difference-integrator concept for range-finding applications

Exploiting the benefits of PIN photodiodes, a correlating detector and a novel difference integrator concept were realized in a single-chip range-finder solution. The PIN photodetector performing already internal modulation has a responsivity of R=0.30A/W at 660nm. A bandwidth of f/sub 3dB/=250MHz with correlation gates on thin oxide, respectively 500MHz on field oxide were achieved. Both challenges of the distance measurement - high sensitivity for signals in the order of nW and accuracies of 1.6% (1.7%) for 10m (15m) - could be reached. The measurement range goes from 20cm to 15m. The chip was realized in a modified 0.6nm BiCMOS process. Effective pixel size is /spl sim/250 /spl times/170/spl mu/m/sup 2/ including the photoreceiver of /spl sim/100 /spl times/ 100 /spl mu/m/sup 2/ resulting in a fill factor of /spl sim/24%.