ABSTRACT
This chapter reviews several smart functions and materials. It describes smart functions and the output from pixels and introduces various pixel structures for smart Complementary metal-oxide-semiconductor (CMOS) image sensors. In the direct output mode, the photocurrent is directly output from the photodetector: photodiode (PD) or phototransistor. The photocurrent from a PD is usually transferred using current mirror circuits with or without current multiplication. The sensor consists of a conventional Silicon-CMOS image sensor and a Germanium PD array formed underneath the CMOS image sensor. In the sensor, circuits are added to calculate a global operation summing the number of on-state pixels, allowing cumulative evolution to be obtained in an intensity histogram. Pulse frequency modulation-based photosensors are used in biomedical applications, such as in ultra low light detection in biotechnology. The integration of light sources in a CMOS image sensor will open many applications, such as ultra small camera systems and autonomous robot vision.
