CMOS Distance Sensor Based on Photon Mixing Device

We report on the design of a distance sensor based on a novel photon mixing device, fabricated in a standard CMOS technology. Our goal is to develop a distance measurement system which could be organized in array structure to realize a range-finding integrated camera. The overall system exploits the time of flight (TOF) method for the target distance measurement. The modulated light travels to a target and is back-scattered onto the mixing detector. The photon mixing device, based on two interdigitated n-well diffusions on a p-substrate, has been integrated together with dedicated read-out electronics, in a 500 um x 25 um pixel. The operation principle is based on the modulation of the space-charge region width by the applied voltage. A 128-pixel linear array has been designed in 0.35-um, 3.3-V CMOS technology (4 metal, 2 poly). An electro-optical characterization of the photon mixing device has been carried ou