A fingerprint opto-detector using lateral bipolar phototransistors in a standard CMOS process

An integrated photodetector array has been fabricated using lateral bipolar phototransistors. These transistors are ten times as responsive (/spl lambda/=660 nm) as identically sized vertical bipolar phototransistors and arrays of this transistor consume less power than charge-coupled device arrays of the same size. The image processing for this array is accomplished through the use of a current mode comparator.